CONSERVATION ELEMENT

OF THE

ALAMEDA COUNTY GENERAL PLAN

Adopted By Alameda County Board of Supervisors November 23, 1976

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AMENDMENTS TO ALAMEDA COUNTY CONSERVATION ELEMENT

(Adopted November 23, 1976)

Amended May 5, 1994

Board of Supervisors Resolution 94-272

New language is indicated in italics; deletions are shown in strikeout.

All references to "Livermore-Amador Planning Unit" or "LAPU" have been replaced with "East County Area." References are found in the following locations:

Page 1-7, third heading, first and second sentences in third paragraph, first and last sentences in fourth paragraph

Page 1-9, Heading b), first sentence in second paragraph

Page 1-11, First sentence of first paragraph , first sentence of fifth paragraph

Page 1-61, Heading following third paragraph, first and last sentences of fourth paragraph

Page 1-72, Heading following first paragraph, first sentence of second paragraph, first sentence of second paragraph

Page 1-73, first sentence of third paragraph, first sentence of fourth paragraph

Page 1-7, Heading and paragraph under "Livermore-Amador Planning Unit" have been modified to read as follows:

Livermore-Amador Planning Unit East County Area

The Livermore-Amador Planning Unit (LAPU) East County Area consists of 264,530 acres and represents about 56 percent of the land area in Alameda County. About six percent, or 14,620 acres, is incorporated into the Cities of Livermore or Pleasanton. The boundaries of the LAPU East County Area are defined by the County line near Bethany Reservoir to the north and Mt. Boardman to the south, and by Monument Peak to the west and Dublin to the County line at the northwest. The area stretches from the East Bay Hills (Sunol and Pleasanton Ridges) to the Eastern Units of the Diablo Range western edge of the San Joaquin Valley.

1 - CONSERVATION ELEMENT

I. INTRODUCTION

A. Authority B. Components of the Conservation Element C. Methods D. County-City Coordination

II. INVENTORY OF RESOURCES

A. Physiographic Description B. Generalized Geology C. Agriculture and Soil Resources Management D. Vegetation and Wildlife Resources E. Hydrologic Resources F. Mineral Resources

III. GOALS AND OBJECTIVES FOR CONSERVATION OF RESOURCES

IV. IMPLEMENTATION PROGRAM

Appendix A

Resolutions of Adoption of Conservation Element of the General Plan

I - CONSERVATION ELEMENT

I. INTRODUCTION

A. Authority

B. Components of the Conservation Element

C. Methods

D. County-City Coordination

II. INVENTORY OF RESOURCES

A. Physiographic Description

B. Generalized Geology

C. Agriculture and Soil Resources Management

D. Vegetation and Wildlife Resources

E. Hydrologic Resources

F. Mineral Resources

III. GOALS AND OBJECTIVES FOR CONSERVATION OF RESOURCES

IV. IMPLEMENTATION PROGRAM

Appendix A

Resolutions of Adoption of Conservation Element of the General Plan

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1-CONSERVATION ELEMENT

I. INTRODUCTION

A. Authority

Government Code Section 65302 (d) requires a conservation element of all city and county general plans, as follows:

A conservation element for the conservation, development, and utilization of natural resources including water and its hydraulic force, forests, soils, rivers and other waters, harbors, fisheries, wildlife, minerals, and other natural resources. That portion of the conservation element including waters shall be developed in coordination with any county-wide water agency and with all district and city water agencies which have developed, served, controlled or conserved water for any purpose for the county or city for which the plan is prepared. The conservation element may also cover:

(a) the reclamation of land and waters.

(b) flood control.

(c) prevention and control of the pollution of streams and other waters.

(d) regulation of the use of land in stream channels and other areas required for the accomplishment of the conservation plan.

(e) prevention, control and correction of the erosion of soils, beaches and shores.

(f) protection of watersheds.

(g) the location, quantity and quality of the rock, sand, and gravel resources.

The conservation element of the County's General Plan is a long-range plan with the following major goals:

• quality in the natural resource base;
• quality in the environment to provide attractive, safe, and satisfying places to live, work, and plan; and
• quality in the standard of living.

B. Components of the Conservation Element

The planned management of resources in Alameda County involves research in several areas:

• identification of natural resources;
• assessment of the degree of development and utilization of those resources;
• identification of areas of critical concern;
• determination of the carrying capacity or development potential of each resource;
• establishment of development and utilization criteria for each resource; and
• development of goals and policies for resource conservation; design of implementation program.

In a metropolitan county such as Alameda County, a significant portion of the flat area has been committed to urban and industrial uses, often without consideration of consequences to natural resources. Economic decisions for resource development and conservation must be carefully examined in the future to prevent further deterioration of the environment. Decisions on resource development must be balanced with the need for preserving and maintaining a diverse and aesthetic environment. The objective of the conservation element is to provide economic and environmental information critical to the development of resources, land use, and the preservation of environmental balance. It should also provide an education as well as sensitivity to valuable renewable and non-renewable resources.

C. Methods

The California State Office of Planning and Research has issued guidelines for the preparation of the Conservation Element of the General Plan and in those Guidelines established a general methodology for developing the conservation element. The resources which are to be discussed in this conservation element are only limited by those resources present in Alameda County. The natural resources included for consideration here are:

• Physiographic, topographic, and geologic resources
• Agriculture and soil resources
• Vegetation and wildlife resources
• Water resources
• Mineral resources
• Other natural resources such as air and space

Once the above resources have been adequately identified, the relationships between the resources will be analyzed and the areas of critical concern identified. The State Guidelines also indicate that the carrying capacity and development capacity of various land areas should be developed with the goal of minimizing the ecological disruption and conserving natural resources. The implication here is that the assessment of natural resources within an area should include a consideration of $the$ renewable $or$ non-renewable nature of the resource. Indeed this approach will be utilized in addition to designation of certain areas of the County as "Resource Management Area."

D. County-City Coordination

The major portion of County-City Coordination in the Conservation Element has taken place in the Solid Waste Management Technical Advisory Committee 1973-1975 which is described in the Preface to this element (page P-1). Other coordination has taken place in the preparation of the Hayward Area Shoreline Policies with the City of Hayward, also described in the preface.

II. INVENTORY OF RESOURCES

A. Physiographic Description of Alameda County

Alameda County is located on the east side of southern San Francisco Bay. Within its boundaries is 735 miles of land and 77 square miles of bay. Elevations range from sea level along the 36 miles of bay shoreline to 3,817 feet in the Diablo Range south of Livermore. The County is approximately thirty-two miles in length in a north-south direction and 45 miles in width in an east-west direction. The County is a diverse combination of land types and forms ranging from salt water marshes along the bay plain to moderately high uplands and intermontaine valleys. Thus, the climate varies from a marine type along the bay fringes to fog-shrouded Redwood forest in the East Bay Hills, to arid range sites of open grassland savannah in the portion of the County adjacent to the San Joaquin Valley. Conditions vary depending upon the mean sea level, altitude, and the topography, as well as the distance from the ocean and bay.

Overall climate-Mediterranean microclimates

The Bay Plain varies from three miles in width at the north end of the County, in the Berkeley-Albany area, to eight miles at the south, near Fremont. The bay plain is composed of geologically recent fluvial and alluvial deposits of the late Cenozoic period. In this portion of the County is located the major portion of the high density urbanization which comprises the urban core of the Eden and Central Metropolitan Planning Units. The southerly and less densely populated part of the bay plain still retains much of the rural character of the past, although this is rapidly disappearing around the cities of Fremont, Newark, and Union City. In the South Bay vicinity are tidal flats and marshes, salt ponds, the Alameda Creek-Coyote Hills Regional Park, and portions of the South San Francisco Bay National Wildlife Refuge Complex.

East of the Bay Plain are the East Bay Hills which are a part of the western and central portion of the Diablo Range. The County extends east through the Diablo Range to the western edge of the San Joaquin Valley. Within this area is located the Livermore and Amador Valleys, which are the largest of the intermontaine valleys in the coastal range. The eastern portion of the County varies from gently rolling terraces and alluvial plains to the steep to very steep V-shaped upland areas Well used and possibly historic trade routes, now permanent interstate freeways, exist through natural passes located east of Hayward, through Dublin Canyon and through Mission Pass in the Mission Hills east of Fremont. The highest points in the East Bay Hills are Monument Peak, 2,594 feet, and Mission Peak, 2,517 feet, both east of Fremont. The East Bay ridge provides a dramatic background for San Francisco Bay and the coastal plain on the west slopes and a scenic background on the east slopes for the Livermore-Amador Valley. The large intermontaine coastal valley, the Livermore and Amador Valley, is separated from the bay plain by eight miles of foothills in the north, east of Castro Valley, and about four miles in the Mission Pass area.

GENERALIZED GEOLOGIC AND GROUND WATER MAP OF ALAMEDA COUNTY

WATER-BEARING UNITS

QUATERNARY ALLUVIUM - Includes older alluvial fan deposits, (unconsolidated basin deposits, younger fluvial deposits, younger alluvial fan deposits, and stream channel waterial). Also included are dune sands, the Merritt sand and the Temescal formation. Comprise interbedded and interlensed, fine- to coarse-grained sands and gravels, silts, and clays. Clay and silt layers predominate in most of the area. The clean sands and gravels have the highest permeability and are the principal aquifers. Clay and silt layers have low permeability and form confining beds or lenses.

DEFORMED OLDER ALLUVIUM SEDIMENTS - Includes the Livermore and Santa Clara formations of Plio-Pleistocene age and the Tassajara formation of upper Pliocene age. Poorly to moderately consolidated, clayey, silty, or sandy gravels, and silts and clays with thin tuffaceous beds. These sediments yield water to wells, but the high percentage of interstitial fines restricts permeability, thus limiting yield to wells.

NONWATER-BEARING UNITS

TERTIARY ROCKS - Include Hambre, Briones, Sobrante, Monterey, Temblor, Tice, Oursan, Neroly, Cierbo, Rodeo, Hambre, and Tice formations of Miocene age, and San Ramon and Kirker formations of Oligocene and upper Eocene age. Consist mainly of marine sandstone, siltstone, and shale with some chert, tuff, and conglomerate. Potable ground water, if any, occurs in secondary openings such as joints and fractures, although minor quantities of water may be recovered from near-surface rocks. The Orinda formation of Mio-Pliocene age consists of nonmarine claystone, siltstone, sandstone and conglomerate, with small amounts of tuff and limestone. The abundance of fines makes it essentially nonwater-bearing.

CRETACEOUS ROCKS - Include the Oakland conglomerate and the Niles Canyon, Del Valle, and Shepherd Creek formations of the Panoche group. Comprise marine sandstone, shale, conglomerate, and siltstone, all of marine origin. Potable ground water, if any, occurs where secondary openings have been formed by fractures, joints, and shear zones, and where connate brines have been flushed from the rocks.

JURASSIC ROCKS - Marine sedimentary rocks, composed mainly of the Franciscan formation. Composed primarily of graywacke (sandstone), with smaller amounts of interbedded siltstone and shale. Minor rock types include conglomerate, red and green chert, and volcanic and metamorphic rocks. Small amounts of potable water for local domestic use have been found in fractures, joints, and shear zones, and where connate brines have been flushed from the rocks.

⬚ figure

Major ridgelines and peaks (East Bay Ridge, Mount Diablo, Mount Hamilton, and Arroyo del Valle) separates the County into three significant hydrologic units and two areas of minor hydrologic significance. All hydrologic units are extremely important when considering various aspects of water resources management. The hills surrounding the Livermore and Amador Valleys are predominately open primarily devoted to agriculture or some form of recreation. In the extreme northeastern corner of the County, a small flat area extends into the San Joaquin Valley. Some of this area is devoted to agricultural crop production; the foothill portion is similar to the grasslands of the Altamont vicinity and the Great Valley Foothills.

Approximately fifty-six percent of the County contains hills with a slope of twenty-five percent or greater. The distribution of the area of 25 percent or greater slope is 34 percent in the western portion of the County and 72 percent in the eastern portion. With the exception of residential development in the Oakland and Berkeley hills, small developed portions in the Hayward hills, and minor development in the Pleasanton area, the major portion of the East Bay Ridge and Diablo Range in Alameda County remains undeveloped. Most of the undeveloped East Bay Ridge area is shown as open area on the County General Plan; and all the ridges on the north, east, south, and west sides of the Livermore-Amador Valley are undeveloped and shown as open space on the County General Plan. Much of the open use is presently utilized for some form of agriculture, depending on soil fertility, capability, and type.

Central Metropolitan Planning Unit

The Central Metropolitan Planning Unit consists of the cities of Alameda, Albany, Berkeley, Emeryville, Oakland, and Piedmont. In the 1968 Estimate of Existing Land Use, approximately ninety percent of the 51,030 acres in the planning unit were developed and in residential, commercial, industrial, public or semi-public, or vacant uses. All of the land area in the CMPU is incorporated; approximately 5,030 acres are in major parks and recreation uses, and 4,310 acres are vacant urban. The cities occupy the area from the crest of the East Bay Hills to the bayfront, from Albany to the northern limit of San Leandro, in a wide variety of densities and land uses. Approximately fifty-five to sixty percent of the population and industrial activity in the County is located in the CMPU.

Eden Planning Unit

Included in this planning unit are the cities of San Leandro and Hayward and the unincorporated communities of San Lorenzo and Castro Valley. The Eden Planning Unit consists of a total of 76,430 acres of which 27,890 acres are incorporated and 48,540 are unincorporated. Over 38,000 acres of this area are uncultivated and undeveloped. As described previously, the EPU occupies an area between the East Bay Hills and the San Francisco Bay. Most of the development is along the bay plain and is concentrated in the cities mentioned above. The southern portions of the eastern boundary of the planning unit is Sunol Ridge.

Washington Planning Unit

The Washington Planning Unit begins south of Hayward and includes the cities of Fremont, Newark, and Union City; the unincorporated area to the west; and a Rural-Recreation Area to the east of the foothills. The 1968 land use survey showed 91 percent of the 79,280 acres in this planning area incorporated into one of the three cities. In the same survey, 47,310 acres were designated as in agricultural and open uses, while 29,120 acres were assigned to residential, commercial, industrial and other uses. As in the other areas to the north in the County, the predominant area of urbanization in this planning unit is the bay plain between the foothills and the bay. Unique to this area is the Alameda Creek-Coyote Hills Regional Park near the edge of the bay and the adjacent South San Francisco Bay National Wildlife Refuge to the south.

Livermore-Amador Planning Unit

The Livermore-Amador Planning Unit (LAPU) consists of 264,530 acres and represents about 56 percent of the land area in Alameda County. About six percent, or 14,620 acres, is incorporated into the Cities of Livermore or Pleasanton. The boundaries of the LAPU are defined by the County line near Bethany Reservoir to the north and Mt. Boardman to the south, and by Monument Peak to the west and Dublin to the County line at the northwest. The area stretches from the East Bay Hills (Sunol and Pleasanton Ridges) to the Eastern Units of the Diablo Range western edge of the San Joaquin Valley.

Topography within the LAPU is quite varied and ranges from gently sloping lowlands to very steep canyons. Approximately seventy-two percent of the area has a slope of 25 percent or greater. Land-type divisions may be made based upon topography into at least three categories: upland site, terrace sites, or valley or lowland sites. The location of the boundary of each unit is different depending upon the basic information used in the interpretation. Basically, however, the LAPU consists of the northern section of the Diablo Range surrounding the Livermore, Amador, and Sunol Valleys.

B. Generalized Geology of Alameda County:¹

The general geologic setting of Alameda County is shown on the Generalized Geologic and Ground Water Map of Alameda County. Active and potentially active fault traces are shown on a map in the Seismic Element of the County General Plan.

a) Geology of the Western Portion of Alameda County

The part of Alameda County which lies west of the active Calaveras Fault includes the East Bay Hills from Albany on the north to the Mission District east of Fremont. Also included in this area is the Bay Plain from the base of the foothills to the edge of the San Francisco Bay. The rocks in the hills are older and considerably more complex than the relatively recent alluvial deposits of the Bay Plain. The complexity of the rocks in the hills is a function of their history of deformation and diversity of type and characteristics. For example, in the Berkeley-Albany hills, the following formations have been identified: Mesozoic ultrabasic intrusive rocks, Franciscan, Eocene marine, Plicene volcanic, middle and/or lower Pliocene non-marine, and Pleistocene nonmarine. As one progresses south in the hills from Oakland to Fremont, the predominant formation becomes a sequence of upper Cretaceous marine sandstones and shales with strips of ultrabasic intrusive and metasedimentary rocks (Mesozoic), Pliocene volcanic, and middle and/or lower Pliocene nonmarine sediments occur along the western base of the hills. The East Bay hills are separated from the Bay Plain to the west by the active Hayward Fault system.

The plain west of the foothills in Alameda County is comprised of Quaternary Alluvial deposits which have washed down from the hills and have been deposited on top of the older rock formations. One may visualize the process of formation of this plain as a progressive accumulation of layers of materials of varying composition and permeability. Some of the layers which have been identified in the Quaternary alluvial deposits have come directly from the hills and some are a result of sedimentation of clays and muds while the area was partially or wholly submerged. This layering has occurred in such a fashion around the creeks pouring into the bay that humps, or cones, have formed at San Leandro, San Lorenzo, and Alameda Creek. These cones which are presently sources of ground water for residential and agricultural uses are called the San Leandro, San Lorenzo, and Niles Cones, respectively.

The alluvial deposits underlying the Bay Plain have been subdivided into several units by the U.S. Geological Survey (Helley and others, 1972) based upon variations in gross lithology and degree of induration.

Along the very western edge of the Bay Plain, the geologic formations do not alter appreciably from those mentioned in the previous paragraphs but the combined importance of the geologic, biologic, and man-interference with the bay and tidelands has resulted in both an interest-ing and sensitive environmental area. The historic marshes are undergoing a change to the characteristic plain, which is observed further inland. Indian shell mounds which were once located on the shores of the bay several centuries ago are now several miles from the shore. The bayshore areas are underlain chiefly by Younger Bay Mud, a predominantly soft gray silty clay (Goldman, 1969). The Younger Bay Mud locally contains lenses of fine, water saturated sand.

b) Geology of Livermore-Amador Planning Unit

The LAPU is located in the northwest-trending coastal range and is predominantly east of the active Calaveras Fault system. There are several unique features about the area. The upland sites which surround the Livermore Valley are composed of geologically older consolidated nonwater-bearing rock formations. This material also forms the foundation of the Livermore Valley at considerable depths. In the uplands area south of Livermore, the Franciscan Formation may be observed. This is the oldest formation and constitutes a major portion of the uplands. The Franciscan Formation is described as "graywacke, locally abundant red and green thin-bedded chert, siltstone and silty shale, minor conglomerate, limestone, blue-grey glaucophane-bearing schist and related metamorphic rocks. The Franciscan Formation in the Diablo Range is generally considered to be of Jurassic and possibly pre-Jurassic age."[^p15-1]

In the upland areas around Patterson Pass and the Carnegie Fault, a division occurs between the Franciscan and the younger Del Valle Formations. This area stretches between Corral Hollow and Interstate 580 and is a jumbled mixture of upper Cretaceous marine, upper Miocene marine, and middle and/or lower Pliocene non-marine sedimentary rocks. Recent geologic studies suggest that some of the fault systems in this complex area are potentially active (Wright, 1974).

The region north of I-580 is underlain primarily by upper Cretaceous marine sedimentary rocks similar to those exposed in the East Bay Hills south of Castro Valley to Niles Canyon.

Again in the uplands areas between Niles Canyon and Monument Peak, the Cretaceous and Miocene marine and middle and lower Pliocene non-marine formation units are found interspersed with each other.

<a name="footnote-1"></a>[^p15-1]: "Stratigraphic Nomenclature-San Jose Sheet" in Explanatory Data San Jose Sheet, Geologic Map of Calif. Calif. State Department of Conservation, Division of Mines and Geology, Olaf P. Jenkins Edition, 2nd Printing, 1972 Cedar Mountain and along the portions of Cedar Ridge, Main Ridge and Apperson Ridge.

The upland formations primarily consist of marine sedimentary and meta sedimentary rocks. Only small amounts of igneous rock are apparent. Examples of Mesozioc ultra basic intrusive rocks may be observed in the uplands near the southern end of Del Valle Reservoir and east of Calaveras Reservoir.

The Livermore Valley was formed by an east to west downfold along the Calaveras Fault. The alluvial terraces and plains, recognizable at the mid-level elevations or rolling foothills north and south of Livermore constitute a second broad physiographic division of the LAPU area. This transition zone is divided into two areas based upon geologic units.

The foothills north of Livermore on the south slopes of Mt. Diablo, and in the prominent foothills along Doolan, Collier, and Tassajara Creeks north of Livermore and Arroyo Las Positas are underlain by middle and/or lower Pliocene non-marine sedimentary rocks identified as the Orinda and Neroly Formations.

The Orinda Formation has been subdivided into the Tassajara and Green Valley formations and is characterized by "red, gray, or brown, loosely consolidated sandstone and conglomerate, subordinate amounts of shale, claystone, limestone lenses, and tuffaceous bentonitic clay."¹ The Tassajara Formation, more appropriately associated with this area, consists of "brown to gray mudstone, andesitic sandstone, conglomerate, and minor bentonitic and pumiceous tuff."¹ The Orinda is basically a continental flood plain deposit with discontinuous marine beds at the base.²

South of Livermore and Pleasanton the low foothills consist of Plio-Pleistocene non-marine sedimentary deposits of the Livermore gravel formation. The Livermore gravel is characterized by "loosely consolidated sand, gravel, clay, and local tuff beds (contains Pliocene fresh water invertebrate fauna and Pleistocene vertebrate fauna.)"(State of California, 1972.)

The low lands of the Livermore Valley consist of recent alluvial deposits surrounding minor areas underlain by the Orinda and Livermore formations. Surficial portions of the alluvial sequence have been subdivided by the U.S. Geological Survey into several units based on gross lithologic characteristics and degree of induration (Helley and others, 1972). Studies by the California Department of Water Resources (1974) have revealed similar horizontal and vertical variations in the subsurface. Goundwater contained in the recent alluvial deposits and in the Livermore Formation represent a significant resource and minor amounts of ground water have also been produced from the Tassajara formation.

Within the LAPU, at least 17 faults have been identified. Some show possible evidence of geologically recent movement. Some form groundwater barriers in Pleistocene materials and others appear to be old faults that affect only Pliocene or older bedrock materials.

As mentioned above, the Livermore Valley has developed in an east-west dipping downfold or syncline terminating against the Calaveras Fault and the uplifted Pleasanton Ridge block. At the base of the Altamont Hills is the Greenville Fault which terminates near Arroyo Las Positas. In the southern section of the Altamont Foothills, the Patterson Pass, Tesla, Carnegie, and Corral Hollow Faults are found. The faults run parallel to each other between the Livermore and San Joaquin Valleys. East of Altamont Pass near Grant Line Road is the Midway Fault which is located in a local depression along Grant Line Road.

The faults found in the upland hills between Tesla Creek and the Mission Hills (Monument Peak) are the Valle, Williams, Verone, Indian Creek, McGuire Peaks, Welch and Calaveras. Among these, the Calaveras and Verone-Williams-Valle Systems appear to be the most prominent.

Within the lowlands of the Livermore Valley, several faults have been identified; they are the Livermore Fault and its branch, the Parks Fault, the Pleasanton Fault and its branches, and the northern section of the Calaveras Fault. In the vicinity of Dublin, the Gravel Pit and the Dublin Faults are observed in the foothills.

Slope:

The greater portion of the Livermore-Amador Planning Unit is in the greater than 30 percent slope category. In the valley lowlands, much of the land is level with from zero to five percent slope. The fringes of the foothills around the entire Livermore and Amador Valleys consist of 5-15 percent slope.

In the foothills north of Livermore around Doolan and Collier Canyon and in the Altamont hills, the slopes are gentle, rarely exceeding 30 percent and generally falling within the 15-30 percent range.

South of Livermore and Pleasanton, the Upland areas of the Diablo Range consist of a high proportion of 30-50 percent slope hills. Some ravines range to nearly 70 percent slope. Within the upland area, there are plateaus and canyons which fall into the 5-15 and 15-30 percent ranges; but these areas are minimal.

Although slope considerations, alone, may severely limit development of a site, interpretation of the degree of constraint is included in the Soils Resources discussion, since interpretation of slope is included as part of the Soil Survey.¹

C. Agriculture and Soil Resources Management

Factors of Soil Formation¹

Soil has been defined as a dynamic natural body on the surface of the earth in which plants grow; it is composed of mineral and organic materials and living forms. Soils differ in their appearance, composition, management requirements, and productivity within short distances. The factors that influence soil development are 1) climate, 2) living organisms, 3) parent material, 4) relief, and 5) time. Every soil is affected to some extent by all five factors, but the relative importance of each factor in soil development varies from one soil to another.

Climate.--The climate of the Alameda County Area is of two main types--oceanic and subhumid mesothermal. The oceanic type is characterized by cool, moist winters and cool summers with frequent sea breezes and early morning fog. The subhumid mesothermal type is characterized by cool, moist winters and hot dry summers. The boundary between the two types runs roughly in a southeast-northwest direction from the Calaveras Dam to Dublin. Differences in annual rainfall are associated with differences in relief and vary widely over short distances. For example, annual rainfall ranges from 8 inches in the northeastern corner of the Area to 25 inches at a point in the uplands 15 miles farther south.

In the sections of low rainfall, many of the soils are calcareous and alkaline in reaction. In the sections of high rainfall, the soils are slightly acid to strongly acid. Soils formed under the oceanic climate are darker in most places and contain more organic matter than soils formed in similar material under the subhumid mesothermal climate. Also, soils that developed under low rainfall have accumulated carbonates in the upper portions, whereas the soils that developed under high rainfall have been leached of carbonates.

Living organisms.--The vegetation of the Area was the most important part of the complex of living organisms that affected soil development. The activities of animals were of minor importance. Earthworms, insects, and bacteria were most active in soils containing a large amount of organic matter. In such soils they break down plant and animal remains to humus.

The influence of native vegetation was greatest in the dark Clear Lake soils in the northern part of the Livermore Valley and in the basin areas. In the uplands this vegetation consisted of thick stands of perennial grasses, such as Needlegrass, and of scattered Oak; in the basin areas it consisted of perennial grasses, sedges, and willows. The Linne soils also exemplify the influence of native vegetation. They developed under thick stands of perennial grasses and scattered Oak. These soils are dark gray and contain a relatively large amount of organic matter. In contrast, the Gaviota soils developed under a sparse stand of grasses, Rabbitbrush, and California Sage and contain a small amount of organic matter. The Vallecitos soils have accumulated even a smaller amount of organic matter under a combined woodland-grassland type of vegetation. The percentage

of woodland varied, but it consisted primarily of Blue Oak, California Live Oak, Black Oak, Laurel, California Buckeye, and other woody plants. Some scattered Digger Pine and Coulter Pine were on higher elevations and on the sheltered north-facing slopes of these soils. The understory consisted of California Fescue, Needlegrass, Blue Wildrye, and Millicgrass. This kind of vegetation did not favor the accumulation of large amounts of organic matter.

The vegetation in the brush-covered areas consisted of Chamise, Manzanita, Ceanothus, Rabbitbrush, California Sage, and a sparse stand of grasses. Little organic matter has accumulated in the soils and land types in these areas.

Farming in the area has affected and will affect the direction and rate of development of the soils. The soil-forming processes changed most by man's activities are the accumulation of organic matter and the leaching of soluble salts. The rate of accumulation of organic matter has been reduced, and in some soils, the organic matter has been depleted. Cultivation and grazing have almost eliminated the native perennial grasses, and annual grasses, forbs, and weeds have been introduced by settlers. The forage produced is removed continuously by grazing and by burning residue from dry-farmed grain. Artificial drainage of the basin areas has reduced the amount of organic matter in the soils by improving aeration and thus increasing the oxidation of the organic matter. In the well-drained soils in the valleys, the amount of organic matter may have been increased by the continual use of irrigated pasture. Even though the forage is removed, the root system is extensive and tends to increase the amount of organic matter in the soil. Also, soluble salts and some of the carbonates are leached from these soils by irrigation water and through improved drainage.

Parent material.--The parent material of soils in the uplands consists of sedimentary and metasedimentary rocks of different composition and different geologic ages, intruded in some places by basic and ultrabasic igneous rocks. The sedimentary and metasedimentary rocks contain folds and faults in a very complex system. The sharp differences in the parent rocks tend to produce distinctive differences in soils.

In areas where the parent material consisted of the hard, metasedimentary rocks, the soils are shallow, have a low content of organic matter, and contain gravel or chert fragments that weather slowly. The Vallecitos soils are an example.

In areas where the parent material was interbedded sedimentary rock, the minerals weather easily because calcium carbonate is the principal cementing agent. In these areas the soils are usually deep, are fine textured, and have a calcareous subsoil. The Diablo soils are typical of this group.

In areas where serpentine, the predominant intrusive rock, was the parent material, the Henneke soils developed. They are reddish brown throughout, are shallow, and have low fertility.

The high terraces south of the Livermore Valley consists of poorly sorted gravel, sand, and clay that were deposited by fresh water: The deposits have a smooth surface that has a gentle incline of 10 to 30 degrees toward the valley. The Positas soils, which are low in fertility and have distinct B horizons, occur in this area.

The parent material of soils in the valleys consists predominantly of recent alluvium. In the southern part of Livermore Valley, the alluvium is typically and medium textured and contains variable amounts of gravel. The gravel is predominantly quartz and is strongly resistant to weathering. The Livermore soils that developed in this alluvium have faint horizons. In the northern part of the Livermore Valley and in the Amador Valley, the soils developed from fine-textured alluvium. The streams are small, and they flow from areas that have fine-textured soils.

Relief.--The Alameda Areas consists primarily of gently sloping to very steep uplands of the Mt. Diablo Range and of intermountain valleys. The northeastern corner of the Area is in the San Joaquin Valley. The slope and the size of the streams largely determine the texture of the soils in the valley. In areas adjacent to the larger streams, coarse-textured and gravelly soils, such as the Livermore and Pleasanton, have developed. The Pescadero and Solano soils formed on low terraces along the basins and basin rims. They have hogwallowed microrelief and an accumulation of salts and alkali. Soils, such as Gaviota, formed on the very steep slopes. They are shallow, and their horizons are faint. The Los Osos and Diablo soils occur in other upland areas and have characteristic landslide and seep areas formed at times when the soils were saturated.

Time.--The soils of the Alameda Area range from young to very old. The Yolo and Sycamore soils are adjacent to the larger streams. They are young and show little horizon differentiation. These soils receive new sediments from floods that occur at frequent intervals. On the terraces and alluvial fans, the soils, such as Positas, are older. Their suface layer is leached of bases, and the B2t horizons have had a distinct increase in the content of clay. The soils in the uplands, such as the Vallecitos, also reflect greater age by their distinct horizon differentiation.

Major Processes of Soil Formation¹

Several processes take place in the formation of soil horizons. The differentiation of horizons in most soils is the result of two or more of the following processes: (1) Accumulation of organic matter; (2) leaching of carbonates and soluble salts; (3) translocation of silicate clay materials; (4) reduction and transfer of iron; (5) accumulation of soluble salts and alkali.

Organic matter has accumulated in the A horizon of all soils in the Alameda Area. Most of the organic matter is in the form of humus. The quantity is small in some soils but is fairly large in others. In such soils as Livermore very gravelly coarse sandy loam, the faint A horizon has a small amount of organic matter. In such soils as Clear Lake clay, the thick A horizon contains a fairly large amount of organic matter.

Leaching of carbonates and salts has occurred in most of the soils in the Area. In some soils, the carbonates have been leached out of the solum; in other soils, the carbonates and salts have been leached only from the A horizon. Leaching has had little effect in the removal of carbonates from soils that are strongly calcareous throughout, and the calcium content has kept the clays flocculated.

Translocation of silicate clay minerals has occurred in some soils in the Area. The clay films on ped faces and in root channels, as well as colloidal bridges between the sand grains, indicate the movement of silicate clay minerals from the A horizon. These soils have B horizons that range from faint to distinct.

Reduction and transfer of iron has occurred in all of the poorly drained and imperfectly drained soils. This process, called gleying, has been important in horizon differentiation in the poorly drained Clear Lake clay soils. The gray colors in the deeper horizons of the wet soils indicate a reduction of iron oxide. The reduction is commonly accompanied by the transfer of iron. In some of the well-drained soils, iron has been transferred from the A horizon to the B and C horizons where it has been deposited, has been oxidized, and has given these horizons a reddish-brown color. In other soils, iron has been segregated within the deeper horizons and occurs as yellowish-red or reddish-brown mottles. These soils were formed under moderately good drainage. Drainage of soils in valleys and basins has been improved either by stream cutting, by artificial drainage, or by pumping water for irrigation or domestic use.

Soluble salts accumulate in some soils or on the surface when water evaporates. Thus, salty soils commonly occur in low areas, and many have a periodically high or permanently high water table. A high water table or a perched water table exists naturally above an underlying, impervious stratum.

May different kinds of salt occur in saline soils. The normally neutral, or nearly neutral, salts, such as the chlorides and sulfates of sodium, calcium, and magnesium, do not make the soil strongly alkaline; but an excessive amount of exchangeable sodium may cause a strongly alkaline reaction.

The exchangeable cations in a soil greatly influence its properties. Calcium clays are mildly alkaline to moderately alkaline and are not easily dispersed. Conversely, sodium clays are strongly alkaline to very strongly alkaline and are more easily dispersed. If a high concentration of salt is maintained in the soil, the colloids are flocculated; but if drainage improves and excess salts are removed, the sodium clays become strongly alkaline or very strongly alkaline and are easily dispersed in water.

As drainage in soils improves, the excessive amounts of salts are leached. The sodium clays, which are easily dispersed, are puddled or run together. Some of the colloids also move downward from the surface layer and accumulate in the layer beneath. After a long period, most of the fine material has accumulated in the B horizon, and mostly silt and sand are left in the A horizon. Weathering of minerals in the B horizon also contributes to its high content of clay.

If leaching continues for a long time, the A horizon of the soil finally becomes acid. The B horizon becomes very slightly acid to strongly alkaline and has well-developed columnar structure. This horizon underlies a distinct leached A2 horizon. The soil generally has hogwallowed relief. Apparently, the horizon is eroded, and the B horizon is exposed in many places. Locally, the shallow depressions are called slickspots.

DESCRIPTION OF THE SOILS¹

There are several land types and twenty-five different soil areas on the General Soil Map for Alameda County. The Miscellaneous land types are named primarily in terms of land form or in terms of material. The soils areas are named by the major series that occur within each area. A soil series is a group of soils that has about the same kind of profile, or sequence of layers. Except for different texture in the surface layer, all the members of one soil series have major horizons of layers that are similar in thickness, arrangement, and other important characteristics. Some soil areas on the General Soil Map have the same soil series for which they are named, but differ by properties or qualities of major importance to use and management. These are separated (or phased) by indicating differences such as slope, erosion, coarse fragment, drainage, salt and alkali or surface texture. In Alameda County, some of the soil series have been separated for major differences in slope and drainage.

The soil series names in the area adjacent to the San Francisco Bay are tentative and may be changed in the future. Any changes in names will not affect the usefulness of the map because the soil properties and qualities do not change and the names are only a means of identifying the mapping units.

The twenty-eight mapping units for Alameda County are organized into eight groups based on soil characteristics and qualities, and one group including the three miscellaneous types. The nine major groups and mapping units within each group are described below:

Group I - Areas dominated by very deep, well drained, loamy soils on level to nearly level alluvial fans and low terraces. Yolo-Sorrento-Sycamore (drained) association Rincon-Zamora association Pleasanton-Livermore association Livermore association Group 2 - Areas dominated by deep, somewhat poorly drained, loamy soils of the low flood-plains and coastal plains. Sycamore association Baywood association, wet variant Group 3 - Areas dominated by very deep, slowly permeable soils on nearly level to gently rolling alluvial fans. Cropley-Rincon association Cropley-Rincon association, 2 to 9 percent slopes. Group 4 - Areas dominated by gray or dark gray, clayey soils of the basin rims and basins. Clear Lake-Sunnyvale association, drained Clear Lake association Sunnyvale-Castro association

Group 5 - Saline-Alkaline soils of the basin rims with moderately slow or slowly permeable subsoils. Solano-Pescadero association, eroded Group 6 - Undulating to very steep, shallow to moderately deep, gravelly and loamy soils developed to high terraces. Positas association, 2 to 15 percent slopes, eroded Positas-Perkins association, 15 to 30 percent slopes, eroded Positas-Perkins association, 30 to 60 percent slopes, eroded Group 7 - Areas dominated by clayey upland soils developed on soft shales and fine-grained sandstone. Diablo-Altamont association, 9 to 30 percent slopes, eroded Diablo-Altamont association, 30 to 50 percent slopes, eroded Altamont-San Benito association, 9 to 30 percent slopes, eroded Linne-Altamont association, 9 to 30 percent slopes, eroded Group 8 - Areas dominated by loamy, upland soils developed on sedi- mentary rock with some intrusions of oasic and ultra- basic igneous rock. Los Gatos-Gaviota association, 30 to 70 percent slopes, eroded Los Osos-Millsholm association, 9 to 30 percent slopes Los Osos-Millsholm association, 30 to 70 percent slopes, eroded Climara-Los Osos association, 30 to 50 percent slopes, eroded Henneke association, 50 to 75 percent slopes, severely eroded Vellecitos-Gaviota association, 30 to 70 percent slopes, eroded Group 9 - Other soils. Tidal Flats Made Soils, over bay mud Gravel pits

Agricultural Resources

The resource value of agricultural lands is derived primarily from the crops that are grown on them. The agricultural lands of Alameda County not only benefit from the climate, soils and water supply, but also the close proximity of both a large consumer area and a deep water port. Non-agricultural benefits of our agricultural resources include water management, recreation and visual/ aesthetic enjoyment. A secondary benefit is derived from having the land in an open condition.

Many farmers and ranchers in Alameda County provide multiple opportunities for the production and maintenance of other resources through their agricul- tural operations besides those which are of direct economic value to his agricultural or livestock operation. Such actions are complimentary to the balance of renewable resources as well as the production of a marketable com- modity and the conservation of non-renewable resources. Many farmers and ranchers permit more than one type of use of their land which doesn't inter- fere with their operations. Many of their regular annual activities (such as brush clearing, and controlled burning) improve habitat values for live- stock and crops, as well as game and non-game species. Such a multiplicity of complimentary uses is applied to federal lands under guidelines developed by the Forest Service and the Bureau of Land Management and also may apply to land in private ownership in Alameda County.

Following mapping by the Soil Conservation Service of the soil types in Alameda County, several methods of rating the soils as to their potential for certain kinds of agricultural crop production were developed; two of the most commonly used national systems are the land capability classification groups and the "prime lands" systems. The capability classfication groups the twenty eight soil types in Alameda County into seventeen capability units which each show unique characteristics with respect to agricultural production. The simplified "prime lands" system designates lands as "prime agricultural," "prime rangeland" or "unique agricultural" based upon the agricultural potential of the land. These methods of rating agricultural lands allow farmers as well as government officials to identify, manage and protect the county's agricultural resources.

Land Capability Classification

The capability classification is an interpretative grouping made primarily for agricultural purposes. The classification begins with individual soils and groups them into different categories primarily on their ability to produce common cultivated crops and pasture plants without soil deterioration over a long period of time.

The land capability classification provides three different levels of information. These are as follows:

1. Land Capability Classes - The broadest category placing all soils in eight capability classes. These are arranged from I to VIII with limitations in soil use and risks of soil damage increasing from I to VIII.

2. Land Capability Subclass - This category is a subdivision of the capability class to show the kind of limitation or hazard. Four subclasses are used: e (erosion), w (wetness), s (soil), and c (climate). These subclasses are subdivided by adding an Arbaic numeral which is designated as a unit. This numeral is used to show a secondary major limitation or to supplement the major limitation and is defined in terms of a significant soil property.

3. Land Capability Unit - This unit is a group of soils that are similar in use and management and provides the most specific information in Land Capability Classification. The capability unit is symbolized by a combination of the class, subclass and unit.

In assigning soils to capability groupings, certain basic assumptions must be made. These assumptions are required to group souls consistently and to use the groupings properly. The assumptions for classifying the soils of Alameda County are:

1. Classification is based on the effects of combinations of climate and permanent soils characteristics on risks of soil damage, limitations in use, productive capacity, and soil management requirements.

2. A moderately high level of management is assumed - one that is practical and within the ability of a majority of the farmers and ranchers.

3. Soils considered feasible for improvement by drainage, irrigation, removing salts and/or exchangeable sodium, or by protecting from overflow are classified according to their continuing limitations in use, or the risk of soil damage, or both, after the improvements have been installed.

4. The capability classification of the soils in an area may be changed when major reclamation projects are installed.

5. Capability groupings may be changed as new information about the soils becomes available.

PLATE I

SOIL ASSOCIATIONS AND CAPABILITY CLASSES¹

ALAMEDA COUNTY

⬚ figure

THIS MAP IS INTENDED FOR GENERAL PLANNING. EACH DELINEATION MAY CONTAIN SOILS DIFFERENT FROM THOSE SHOWN ON THE MAP. USE DETAILED SOIL MAPS FOR OPERATIONAL PLANNING, AND ON-SITE INSPECTION FOR MORE DETAILED DECISIONS.

1 - See legend on following page.

Source: U.S.D.A. Soil Conservation Service. June, 1966

NOTE: This is a generalized map to be used only for general purposes and will be supplemented by more detailed maps when available.

A land capability classification symbol is composed of three symbols that indicate the class, subclass and unit of the capability unit.

Classes

Land Suited for Cultivation and Other Uses

Class I - Soils in Class I have few limitations that restrict their use.

Class II - Soils in Class II have some limitations that reduce the choice of plants or require moderate conservation practices.

Class III - Soils in Class III have severe limitations that reduce the choice of plants or require special conservation practices or both.

Class IV - Soils in Class IV have very severe limitations that restrict the choice of plants, require very careful management, or both.

Land Generally Not Suited for Cultivation

Class V - Soils in Class V have little or no erosion hazard but have other limitations that are impractical to remove.

Class VI - Soils in Class VI have severe limitations that make them generally unsuited for cultivation.

Class VII - Soils in Class VII have very severe limitations that make them unsuited for cultivation.

Class VIII - Soils and land forms in Class VIII have limitations that preclude their use for commercial plant production and restrict their use to recreation for wildlife, water supply, or aesthetic purposes.

Subclasses

(The Major Problem)

e - erosion w - wetness s - soil limitation c - climatic limitation

Units

(The Secondary Problem)

IIIe5 0 - Coarse underlying material 1 - Erosion hazard 2 - Drainage or overflow 3 - Slowly permeable subsoils 4 - Coarse textures 5 - Fine textures 6 - Salinity or alkali 7 - Stony or rocky 8 - Cemented layers or bedrock 9 - Low fertility or toxic elements 10 - Organic soils

Following are the capability units found in Alameda County. Plate I also shows the mapping of these units.

Identifying Prime Agricultural Lands

To preserve the productive capacity and aesthetic value of agricultural land resources a system of identifying prime agricultural lands has been established as a part of a nationwide program of the Soil Conservation Service. The best land for producing food, feed, fiber, forage and oil-seed crops is mapped as Prime Agriculture, Prime Range or Unique-Agriculture. The two "Prime" designations are based on the types of soils present as mapped in the Alameda County Soil Survey and the "Unique" designation is based on the use of the land as well. The specific criteria for grouping soils as Prime, Unique and other are provided by the Soil Conservation Service. (See Plate 2, page 14a.)

Prime Agricultural Land

Prime farmland is land best suited for producing food, feed, forage, fiber, and oilseed crops, and also available for these uses (the land could be cropland, pastureland, rangeland, forest land, or other land but not urban builtup land or water). It has the soil quality, growing season, and moisture supply needed to produce sustained high yields of crops economically when treated and managed, including water management, according to modern farming methods. The criteria set up for Alameda County is the same as that suggested by USDA-Soil Conservation Service.

1. Adequate moisture supply during the growing season. This can be either rainfall or by irrigation.

2. The soils have a pH between 4.5 and 8.4 in all horizons within a depth of 40" or in the root zone if the root zone is less than 40". This range of pH is favorable for growing a wide variety of crops without adding large amounts of amendments.

3. No water table or a water table that is maintained at a sufficient depth so as not to adversely affect a crop.

4. The soils can be managed so that, in all horizons within a depth of 40 inches or in the root zone if the root zone is less than 40", during part of each year the conductivity of saturation extract is less than 4mmhos/cm and the exchangeable sodium percentage (ESP) is less than 15.

5. The soils are not flooded frequently during the growing season (less often than once in 2 years).

6. The soil does not have a serious erosion hazard.

7. The soil has a permeability of at least 0.05 inches per hour in the upper 20 inches.

8. Less than 10 percent of the surface layer in these soils consists of rock fragments coarser than 3 inches. These soils present no particular difficulty in cultivating.

Soil series in the Alameda Area (County) soil surveys that fit within this criteria are listed on Table 1.

Prime Range Land

Approximately one-half of the acreage of Alameda County is used for livestock production. The gross income from livestock in 1974 was about $4,700,000. Since livestock production is important to Alameda County, prime rangeland should be recognized and identified. The criteria used for prime range land[^] are:

1. Land capable of producing enough natural forage to feed one animal unit per acre for one month under normal conditions. The quantity of forage produced should be sufficient to feed the animal unit and provide enough cover the protect the soil resource year after year.

2. Land of less than 45 percent slopes.

Soils that fit this criteria in Alameda County are listed on Table 1.

Certain of these prime range soils also have a high value on the production of dryland grain and grain hay. These are:

Unique Agricultural Land

Unique farmland is land other than prime farmland that is used for the production of specific high value food and fiber crops. It has the special combination of soil quality, location, growing season, and moisture supply needed to produce sustained high quality and/or high yields of a specific crop when treated and managed according to modern farming methods.

Unique farmland has the following characteristics:

1. It is used for a specific high value crop.

2. It has an adequate moisture supply for the specific crop.

3. It combines favorable factors of soil quality, growing season, temperature, humidity, air drainage, elevation, aspect, or other conditions that favor the growth of a specific crop.

(*Almost all of the hills and mountains in Alameda County are used for livestock production. Some of the areas are very steep or rocky or shallow soils, or any combination of limiting factors which do not make them prime range land -- but because of these limiting factors, their highest use is livestock and production.)

[^]: *Almost all of the hills and mountains in Alameda County are used for livestock production. Some of the areas are very steep or rocky or shallow soils, or any combination of limiting factors which do not make them prime range land -- but because of these limiting factors, their highest use is livestock and production.

TABLE 1 - PRIME AGRICULTURAL SOILS OF ALAMEDA COUNTY ¹

TABLE 1 (cont.)

TABLE 2 - PRIME RANGE SOILS ¹

PLATE 2

PRIME AGRICULTURAL LANDS

ALAMEDA COUNTY

⬚ figure

THIS MAP IS INTENDED FOR GENERAL PLANNING. EACH DELINEATION MAY CONTAIN SOILS DIFFERENT FROM THOSE SHOWN ON THE MAP. USE DETAILED SOIL MAPS FOR OPERATIONAL PLANNING, AND ON SITE INSPECTION FOR MORE DETAILED DECISIONS

LEGEND

PA - Prime Agricultural Land PR - Prime Range Land UA - Unique Agricultural Land O - Other Land

Source: U.S.D.A. Soil Conservation Service. June, 1966

NOTE: This is a generalized map to be used only for general purposes and will be supplemented by more detailed maps when available.

Alameda County has crops and areas that fit into these criteria. Livermore very gravelly coarse sandy loam (Lm - IVs4) soil is used for high quality grape production. There are areas along the bay where the soils are classed as IIIw5 - Clear Lake clay, IIIw4 - Laugenour loam, and IVw6 - Willows clay, but due to intensive management and the favorable climate are able to produce two and three crops of high value vegetables per year (cauliflower, cabbage, lettuce, romaine, miscellaneous vegetables). Flowers and nursery stock are another high value crop that does not require prime agricultural soils, but a high degree of management and ideal growing climate.

These unique crops of Alameda County are usually high in cash value and also lend an air of identification. Locating and mapping of these area of Alameda County will need to be done on an individual survey basis due to lack of information on specific types of soil and land involved.

Plate 2 shows the extent of prime agricultural, prime range and unique agricultural lands in Alameda County. Notice that with the minor exception of the "unique" lands, these categories relate only to the soil types, not to the use of the land and consequently cover much developed land. Preliminary estimates of the acres of prime and unique lands in Alameda County are given below:

History of Agriculture in Alameda County

The history of agriculture in the County dates back to the middle of the last century when early settlers discovered the potential of the rich soil and mild climate along the bay floodplain. In fact, it was the agricultural resources of the area which gave the Eden Township its name. Fruit culture and vegetable production soon gained prominence in both the Eden and Washington Townships. Wheat continued to be the mainstay in the Murray Township until it was discovered that the climate and valley soils were well suited to the production of quality wine grapes.

The Livermore Valley has never been a large producer of wines, but it has long had recognition as an area for the production of high quality white wines.

The importance of fresh fruit and vegetable production on the floodplain of the East Bay grew as the San Francisco area increased in population. This urban area provided an ideal market for the high yields of the fertile Alameda County plains.

In recent times the relative importance of various agricultural commodities has changed. Urbanization of the western part of the County has eliminated most of the fruit and nut orchards. The Fremont and Union City areas are more specialized, concentrating on cole crops and lettuce.

Trends in Agriculture

An examination of the County Agricultural Commissioners' reports for the period 1950 through 1968 gives an indication of trends in agriculture in the County.

The bulk of the income from agricultural commodities produced in the County is from irrigated crops and from livestock. About 4 percent of a total agricultural income of 36 million dollars in 1968 came from non-irrigated or dry-farmed crops.

Irrigated crop acreage as reported by the Agricultural Commissioner, has gone from about 28,000 acres in 1950 to 19,500 in 1968. There was a peak of over 33,000 acres irrigated in 1955. Since 1955 there has been a steady decrease averaging about 1,000 acres of irrigated cropland per year.

The largest decrease in acreage among irrigated crops between 1950 and 1968 was incurred by field crops, followed by fruit and nut crops, and then by row crops, which lost very little acreage. This would be expected when viewed from an economic point of view since field crops give a lower rate of return per acre than orchard and row crops.

Since 1968 some other trends have been manifest. The acres in field crops declined slightly from 1968 to around 1971 and then showed a slight increase through 1975. The acres in fruit and nut crops and especially row crops have decreased through 1975. Cut flowers, bedding plants, vegetables and other nursery products grown in green houses have shown little change from 1968 through 1975. The count of livestock and poultry in Alameda County has seriously declined particularly in 1973 when a major poultry grower moved. Production of the relatively minor apiary products has been erratic in the last eight years as it always is but has shown neither a growth nor a decline trend. There are approximately 3,000 people directly employed in Alameda County agriculture excluding the many thousands indirectly employed such as at the canneries.

Despite the downward trend in the number of acres in several types of agriculture, rising productivity and inflation have maintained the value of farm production in Alameda County at within 10% of the same point for the last eleven years. With acreage holding steady, the value of field crops has more than doubled between 1968 and 1975. While this value of vegetable crops slumped from 1968 to 1971, it has since remained relatively constant. Excluding the years 1973 and 1974, when unusually high per acre yields were obtained, the value of fruit and nut crops produced in Alameda County has remained rather constant. Nursery stock and products led by cut flowers, now the County's most valuable agricultural products, have grown steadily in the last decade. The value of poultry and livestock produced in Alameda County has remained relatively constant except for a very successful year in 1974 in spite of declining head counts.

Table 3 gives the value of various crop types produced in Alameda County between 1968 and 1975.

TABLE 3

VALUE OF AGRICULTURAL PRODUCTION BY TYPE OF CROP: ALAMEDA COUNTY, 1968-1975, ($MILLION)

History of Urbanization in Alameda County

A look at the way in which urbanization has progressed in each of the Sounty County planning units gives an indication of the impact this urbanization has had on agriculture in the County. The Central Metropolitan Planning Unit is not considered because it developed before the decline of agriculture in the County.

Particular attention is given to irrigated lands, as opposed to dry farmed or grazing lands, because most of the urbanization has taken place on irrigable land,

The loss of agricultural lands began with the expansion of Hayward and San Leandro during World War II. The Eden Planning Unit has been an area dominated by orchard crops of apricots, prunes and cherries before their demise under urban pressures. The 1966 crop survey done by the State Department of Water Resources showed only 300 acres of irrigated cropland remaining in an area approximately equal to the south half of the Eden Planning Unit.

Most of the urban growth in the Washington Planning Unit has been since 1950 when it had a population of less than 20,000. The latest population estimate is 144,500 as of January 1, 1970. This growth in population resulted in a decrease of irrigated acreage from 18,000 acres in 1960 when the population was 60,926 to 8,300 acres in 1966 according to the State Department of Water and Resources report. The population in July 1966 was estimated to be 122,500.

This is a loss of almost 10,000 acres of irrigated lands in six years with an increase in population of about 61,500 over the same time period.

The Livermore-Amador Valley Planning Unit also shows a high recent growth pattern. It has increased from a population of about 16,000 in 1950 to 79,400 as of January 1, 1970. The State's report shows 6,400 acres as irrigated in 1960 when the population was 29,640, and the same irrigated acreage in 1966. The same report shows an increase in urban acreage of 2,800 acres, having increased from 7,400 in 1960 to 10,200 in 1966. Much of the development in the Livermore-Amador Valley occurred on non-irrigated lands and some lands not previously irrigated were brought into production between 1960 and 1966.

As was pointed out above, the total irrigated acreage for Alameda County over the thirteen year period from 1955 to 1968 has gone from 33,000 acres to about 20,000 acres. Most of this decrease is attributable to urbanization.

With the urbanization of County lands has come increased levels of air pollution. Whether or not air pollution has had a deleterious effect on agriculture is the subject of some debate and is being studied further by scientists of both pollution control and agricultural backgrounds.

The Role of Agriculture in the Economy of the County

The importance of agriculture to the economy of the County might best be evaluated by a review of the number of jobs and the amount of money involved.

Data from the California State Department of Employment shows that there were 20,800 people employed either directly in agriculture or in food processing in Alameda County for the year 1968. Alameda County Planning Department projections to the year 1972 indicate employment of 21,400 in the same categories. These figures represent about 4.7% of total employment in the County for 1968 and an estimated 4.3% in 1972.

The economic impact of agriculture includes the manufacture and distribution of farm supplies, processing of food and other agricultural products and distribution of farm commodities. The combined aspects of agriculture is terms "agribusiness".

Agribusiness employs nearly 25% of all those employed in manufacturing in the County as there were 16,100 persons employed in Food and Kindred Products in addition to 4,700 employed directly by agriculture for a total of 20,800 out of a total manufacturing employment of 84,800 in 1968.

The Food and Kindred Products portion of agribusiness had a payroll of over 100 million dollars in 1963 compared to about 500 million for all manufacturing.

Alameda County owes a large share of its employment in food processing to its strategic location and port facilities. Many of the products grown in the Central Valley and shipped through Alameda County are processed here before shipment to markets throughout the world via the Port of Oakland.

The annual gross income of agricultural products in the County has not varied much since 1945, even with the decrease in agricultural lands. Gross income hit a peak in 1952 of over 38 million dollars and was between 31-33 million from 1961 to 1965. The 1968 figure was 36 million dollars. The true value of these figures is distorted to the extent that inflation has affected dollar values.

The reason for the apparent paradox--a decrease in agricultural land with no decrease in gross income--is explained by the fact that land use is intensified and yields are increased by use of new varieties and technological improvements as pressure for other land uses increases. Indicative of this trend is the fact that greenhouse and nursery stock production grossed 7.3 million dollars in 1950 and 16.1 million dollars in 1968. Population pressures affect ornamental horticulture less than any other agricultural enterprise because it requires very little land and has a very high rate of return per acre.

LOCATION OF MAJOR AGRICULTURAL ENTERPRISES

Greenhouse and Nursery Stock

Some of the greenhouse industry is interspersed with urban development in San Lorenzo, San Leandro and Hayward. Fremont and Union City also have an appreciable greenhouse industry. There are several factors working against the greenhouse industry. Among these are land prices age of producer, lack of modern equipment and smog. Smog has a serious effect on carnations and orchids.

Grapes

The production of wine grapes has continued in the County since the days of the missions and it looks as though they will remain for a long period of time. There were 500 acres planted near Sunol this year and 500 acres more are planned for next year.

Wines produced in Livermore Valley are widely known for their quality. Added to the value of the grapes and wine is the scenic beauty of the vineyards and the prestige value of producing some of the worlds finest wines.

Row Crops

About 75 percent of the Alameda County row crops mapped by the Department of Water Resources in 1966 were in the Fremont-Alvarado areas while the remainder was in the Livermore-Amador Valley. In addition to these areas, the portion of the County which touches the floor of the Central Valley is primarily used for row crops.

The Fremont-Alvarado area warrants special mention here as it is one of only four areas in the State in which head lettuce can be raised throughout the summer. All four areas, which have a coastal climate in combination with prime soils and adequate water, are presently under heavy pressure from forces of urbanization.

Hay and Grain

Dry farmed hay and grain acreage is holding steady as most of these crops are grown in the hill areas away from urban pressure.

Irrigated pasture and alfalfa are being converted to urban use or to more intensive agricultural uses. In both the Livermore and the Washington Planning Unit the acreage of pasture and alfalfa combined decreased about 30% between 1960 and 1966 according to the State Report.

Livestock Production

Over half of the total area of the County is presently in range land is shown as uncultivated agriculture on the General Plan. Since there is not likely to be much decrease in range land in the near future, the livestock industry, with the exception of dairying, is expected to remain stable.

Poultry Production

During World War II there was a large poultry industry centered in the Castro Valley-Hayward area on several thousand family farms; however, between 1950 and 1968 both egg and meat production in the County have been reduced to less than half the 1950 level having gone from 7.5 million to 3.6 million dollars gross income.

D. Vegetation and Wildlife Resources

1. Classification of Natural Communities - Shoreline Area

The western portion of Alameda County consists of an urban corridor running between Berkeley and Fremont with a narrow fringe of marshlands along the Bay and considerable open space in the East Bay Hills. Of the 206,740 acres in the Central Metropolitan, Eden, and Washington Planning Units, approximately 80,810 acres would fall into the land use categories of uncultivated/undeveloped or major parks and recreation. Conditions in the East Bay Hills are similar to that found in the lowland hills in the Livermore Valley. The plant-animal-human interference patterns will be discussed. Numerous Environmental Impact Reports prepared by cities and the County on projects located in the Hills describe localized environmental settings. Also of great utility

and importance is the report done for the City of Hayward, the Hayward Hill Study¹ This report contains detailed discussions of all natural physical-biological conditions unique to the Hill Area in Alameda County.

Less often mentioned, but more in need of reduction of all forms of pressure from human interference (through coordinated planning), is the narrow and fragile Bay marshland lying between San Leandro and Fremont.

The remnants of what was once an undisturbed system of marshes and estuaries provides the diversity of habitat necessary to support many species of aquatic and terrestrial animals. The extensive salt evaporation ponds have provided a unique and sensitive habitat. The abundance of animal life in this rich habitat is a continuing proof of the health and vitality of the area.

Introduction²

Historically, most of the Hayward Shoreline Study Area was subject to tidal action, either as mudflats or salt marsh. The remainder were uplands probably covered with grassland or brush. Old accounts tell of abundant marine life in the Bay, including sea otters and salmon. The present land use is dominated by man's activities; the marine life is vulnerable to man's pollution of the Bay.

Most of the original salt marsh has been diked off from tidal action and thus destroyed. In the portion north of the San Mateo Bridge, the diked areas are mainly dry and are used for sanitary landfill and grazing. In the portion south of the San Mateo Bridge, most of the diked land is in salt ponds.

The shoreline environment or ecosystem (involving the interrelationship of organisms and environment) consists of many parts: open water in the Bay; mudflats exposed at low tides; shoreward stands of cordgrass; and landward, pickleweed. The vegetation serves as the broad food base for marsh and bay animals, and as habitat for many species.

Six different ecosystems have been recognized in the Shoreline Area: SHALLOW BAY WATER, TIDAL MUDFLATS, SALT MARSH, SALT PONDS AND DIKES, MINOR MISCELLANEOUS HABITATS (dry dikes areas and seasonal fresh water ponds, and upland habitats: fields and pastures, isolated hills, and residential-industrial areas).

SHALLOW BAY WATER AND TIDAL MUDFLATS

These two important habitats are represented by some 9,500 acres in the planning area. In some respects the open bay and mudflat areas appear to be distinct entities, but on the other hand, they are united by a number of physical and biological circumstances into a larger ecological unit which is difficult to subdivide.

The bay shoreline environment is dominated by a tidal rhythm that consists of two high tides of unequal magnitude and two low tides also of different heights during the course of a 25-hour "lunar day." Although this constant movement of tremendous quantities of salt water affects the open bay, tidal influences are most dramatic along the strip of periodically-exposed mudflats - the intertidal zone.

The shallow bayshore waters of the planning area teem with a wide variety of minute marine organisms that form the first links or base levels of food chains and energy pyramids that eventually incorporate all the larger fish, birds, and mammals that live, feed, and die along the edge of the bay. The microscopic planktonic plant life is dominated by diatoms, with over 25 genera found in San Francisco Bay.

In terms of minute animals life, protozoans are similarly quite abundant - sometimes to the degree of twenty thousand per quart of salt water - and include at least six different genera, mainly ciliated and flagellated forms. In addition, Harvey (1971) recognizes four major groups of planktonic invertebrate animals in the bay that feed on the microscopic marine life and in turn are preyed upon by larger forms. They are (1) polychaete larvae (segmented worms), (2) copepods (crustaceans) - the most abundant, in concentrations of up to 75 per quart, (3) fish larvae, and (4) snail larvae. Also, there are two ecologically important types of shrimp that inhabit the local waters: the Black-tail Shrimp (Crago nigricauda), and the Bay Shrimp (Crago franciscorum), once highly prized for human food.

About 125 species of fish have been reported from San Francisco Bay, some of which are known to be quite abundant. Great numbers of Striped Bass (Roccus saxatilis) come through the bay to spawn, as do some Steelhead Trout (Salmo Gairdnerii). Certain bait fish like Northern Anchovy (Engraulis mordax) and bottom fish like shiner Seaperch (Cymatogaster aggregata) are very numerous as well. While there is evidence that the diversity of fish species decreases southward in San Francisco Bay, at least twenty South Bay fish attain some degree of commonness. Seventy species were found by the California Department of Fish and Game in a 1963-66 study in the central and south parts of the bay. At the closest station, although seven miles northwest of Hayward, from 2 to 17 species were found per month by sample (average 9). Those in greatest numbers were the Northern Anchovy, Pacific Herring, Jacksmelt, Shiner Perch (May, December) and English Sole.

The thriving community of organisms that live on and in the bay muds is a major element of the shoreline environment. Here as in the shallow water, plants and animals range from microscopic to moderate-sized forms. Many of them serve as initial or intermediate steps or links in chains of food, transfers of energy, and in webs of interrelationship which often extend beyond the muds to the open water or may reach inland to the bay plain.

PLATE 3 SALMON AND STEELHEAD TROUT IN SAN FRANCISCO BAY

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Source : S. F. Bay Conservation and Development Commission, San Francisco Bay Plan Supplement, page 48.

Like the shallow water, the moist bay muds are inhabited by large numbers of small, relatively simple forms of life. Single-celled blue-green algae may abound on the surface, and types of multicellular red algae and green algae (such as the conspicuous Sea Lettuce, (Ulva sp.) may be found in quantity as well. Even so, the chief photosynthetic organisms are probably benthic (bottom-dwelling) diatoms, found within the upper centimeter of the muds.

Well over one hundred species of invertebrates have been collected from San Francisco Bay muds. Among these are certain roundworms (nematodes), ribbon worms (nemerteans), and such segmented worms (annelids) as Nereis diversicolor and the Pile Worm, Neanthes succinea. Crustacens present in or around the muds include small amphipods (such as Ampelisca milleri), commercial crabs (Cancer magister), and Shore Crabs (Hemigrapsus oregonensis), with barnacies (Balanus spp.) living on nearby objects. The east shore community of burrowing animals includes a number of moluscs - both "filter feeders" (strainers) such as mussels and clams the commonest species being the Macoma inconspicus, and "deposit feeders" (that ingest mud) like the California Horn Snail (Certhidea californica).

The complex biological environment that has been outlined above is indispensable for supporting the huge populations of waterfowl that seasonally visit the shallow waters and mudflats of San Francisco Bay. Cogswell (1973) lists 94 species of waterfowl that have been observed in the Hayward shoreline planning area; of these, 72 can be expected in the bay or on the tideflats. They range from rare winter visitants like Whistling Swans (Olor columbianus) and Snow Geese (Chen hyperborea) that are only irregularly seen to massive flocks of Western Sandpipers (Ereunetes mauri) that at times may number one hundred thousand or more.

In many respects the highly-conspicuous waterfowl population seems to dominate the total wildlife picture along the edge of the bay. Annually the Pacific Flyway deposits additional hundreds of thousands of migrating birds to whom San Francisco Bay is a vitally important feeding and resting area. Some pass through in spring and fall, while others stay to winter in the shelter of the bay. When these are temporarily added to the resident breeding waterfowl population, the numbers of birds found locally can attain remarkable proportions: densities of up to twenty thousand shorebirds per shoreline mile have been reported. In all, South Bay shoreline habitats supply food, shelter, and resting places through the winter for perhaps seventy percent of all the diving ducks and shore birds of the Pacific Flyway. The South Bay and within it, the Hayward Shoreline area supports major segments of these large numbers.

While the implications of such sheer numbers can be staggering, the dynamic, ever-changing nature of the waterfowl population is equally as impressive from an ecological point of view. The over-all population is always in a state of flux - a dynamic equilibrium - as the component species alternately arrive and leave to add or subtract their numbers from the total, and so from week to week the waterfowl picture changes in terms of dominant types and relative numbers. Even during the course of a day the shorebirds shift from place to place within a given area as the tidal rhythm superimposes itself upon the longer seasonal cycle.

As was mentioned earlier, waterfowl ecology in our area is inextricably bound to the bayshore muds and shallows with their diversity of invertebrates and fish. Since most waterfowl seem to be capable of detecting differences between the two common shore area habitats, one of the most useful ways to distinguish bay water from tideflats is by a comparison of their bird populations. As a rule, the open bay waters are visited by loons, greves, pelicans, cormorants, geese, mergansers, phalaropes, and terns, and are also preferred by most diving ducks; when disturbed, several of the "dabbling" ducks will leave shore to congregate in floating "rafts" on the water as well. Conversely, tideflats host herons, egrets, plovers, avocets, stilts, and probing shorebirds.

The environmental importance of the bay water-tideflat complex is considerable. Plant productivity for the mudflats may in places exceed two thousand pounds per surface acre, a figure which - in the absence of pollutants in excessive sedimentation - could even be increased. Together, the phytoplankton and bottom-dwelling vegetation of the water and mud operate as an "interdependent biochemical factory" that harnesses solar energy, releases oxygen, absorbs carbon dioxide and hydrogen sulfides, and fixes carbonates, nitrates, and phosphates. Much of this material is transformed through a variety of channels and organisms to ultimately provide the wealth of invertebrate and vertebrate animal life that characterizes the bayshore environment. The ebb and flow of tides maintain a vital circulation system that disperses nutrients that come from within and beyond the shoreline area.

SALT MARSH

At one time the salt marsh habitat was one of the dominant elements of the Hayward shoreline, both in terms of the area it covered and in its ecological significance. Today in the planning area, less than four hundred acres remain - about five percent of the original total - that still deserve this designation. There are two major salt marsh areas, encompassing approximately 250 acres, located north and south of the mouth of the Alameda Creek Flood Control channel. A third diked marsh of moderate extent has been mapped northwest of Turk Island, along Plumber Slough, elsewhere, lesser strips and patches can be found along some of the creek channels and bordering parts of the bay.

Salt marshes generally occur at levels slightly higher than (and inland from) the tideflats but, like the mudflats, exist in a "not-quite-water, not-quite-land" situation. The environmental rigors of a salt marsh community include, among others, regular fluctuations of temperature and tide. To plants and animals alike, the salt marsh is a "chemical desert" with a scarcity of fresh water, a salty, alkaline soil, and an exposure to the drying effects of wind and evaporation - conditions which in many ways are as severe to life as those of a climatic desert.

Salt Marsh Vegetation

Most types of Bay Area vegetation, whether native or introduced, would find such environmental conditions prohibitively hostile. But in the salt marshes, two major plant associations have evolved to utilize and flourish under these circumstances; together, they form the basis of a remarkably rich and productive habitat. In our area each of these associations is dominated by a single plant species: generally speaking, most salt marsh acreage consists of a solid, dense groundcover of Pickeweed (Salicornia sp.), with strips of Cordgrass (Spartina foliosa) occupying the shallow sloughs. Studies have shown that substratas usually have a lower shear strength and dry density under Cordgrass than under a Pickelweed marsh, and that soil erodibility and moisture content tend to be higher when associated with Cordgrass than with Pickelweed. Cordgrass is tremendously important in the economy of a salt marsh because of its extremely high productivity. Termed the "staff of life" for bay animals, it helps purify the air and produces five to ten times more nutrient material and oxygen per acre than well-known commercial crops such as wheat. Although it provides habitat and foraging niches for certain animals, Cordgrass become most ecologically valuable when it decomposes, thereby releasing nutrients that are washed into intertidal water to feed invertebrates and fertilize algae beds.

Unlike Cordgrass, which can endure up to 21 hours of continuous submergence, Pickleweed - the most widespread salt marsh plant - is less water tolerant and begins its best growth at the average high tide line. Its curious, succulent stems are characteristic of bayshore soils with salt contents as high as 6[^1/2] percent, and its root masses give stability to the banks of brackish channelways.

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Wildlife of the Salt Marshes

A variety of insects can be found in or around the salt marshlands, including moths, butterflies, beetles, ants, wasps, bumblebees, and the like. As its name implies the Salt Marsh Fly (Ephydra spp.) lives only around the marshes and salt ponds; likewise, the Salt Marsh Mosquito (Aedes Squanmiger, A. dorsalis) lays its eggs in quiet marshland ponds away from tidal currents.

Some salt marshes around San Francisco Bay play host to common shallow water fish such as anchovies, smelt, sculpin, and surfperch at high tide, with Three-spine Stickleback (Gasterosteus aculeatus) sometimes remaining in nearby sloughs and potholes; however, it is not known if such species inhabit marshlands of the planning area. Similarly, Gopher Snakes (Pituophis catenifer) are reputed to invade upper salt marsh areas in the South Bay, but observations have not confirmed this along the Hayward shore.

In the planning area some 27 species of birds have been observed in salt marsh habitat, and at least eight others - perhaps more - may be found there from time to time as well. Over half of these are waterbirds, including a relatively high proportion of "wading" birds, probing shorebirds, and rails, while the rest are species usually associated with adjacent inland areas, such as hawks, insectivorous birds, and others. Two of these birds, the Clapper Rail (Rallus longirostris) and a subspecies of Song Sparrow (Melospiza melodia pusillula), are critically dependent upon the salt marsh habitat for their survival. An estimated thirty to fifty Clapper Rails - officially listed by the U. S. Fish and Wildlife Service as an endangered species - live in the patches of salt marsh at the mouth of the Alameda Creek channel, where they nest amidst the Pickleweed. Cogswell (1973) believes the Black Rail (Laterallus jamaicensis), rare to our area, may occur there as well.

The Song Sparrow subspecies, also a local resident, is restricted in its range to salt marshlands and adjacent dikes about San Francisco Bay from Richmond southward; probably their total population in the planning area is at least three to four hundred. In addition, the bulk of the planning area lies between the known ranges of a rare species of Salt Marsh Harvest Mice (Reithrodontomys spp.), the Red-bellied Harvest Mouse (R. raviventris), endemic to South Bay San Francisco, San Pablo and Suisun Bay salt marshes, and a close relative, the Western Harvest Mouse (R. megalotis), which is widespread over most of western United States. Interestingly, the Red-bellied Harvest Mouse feeds on Pickleweed, drinks salt water, and excretes salt with its urine. By elimination of its habitat, this species is threatened with extinction. In our area, Harvey (1971) suggests that one of the two may possibly inhabit the salt marshes at the channel mouth of Alameda Creek.

Ecological Overview

Despite their spatial limitations, the strips and patches of salt marsh along the Hayward shoreline occupy a prominent place in the over-all environmental picture of the planning area. They support a wealth of interrelated - and sometimes specially adapted - organisms that range from inconspicuous algae growing on Pickleweed stems to graceful Marsh Hawks soaring overhead. They have served as part of a special "evolutionary laboratory" that today provides sanctuary for several rare and endangered species. And their luxuriant swaths of Cordgrass have helped earn the salt marshes their position as the most productive type of natural vegetation in North America.

For the ecological reasons outlined above, salt marshes should be given very high environmental priority in any plan for the use of bayshore lands.

SALT PONDS AND DIKES

Salt Production

Around South San Francisco Bay, much of what were formerly inland tidelands have been diked to create evaporating ponds for salt extraction. In the planning area, slightly over five thousand acres are presently in diked and ponded areas, and additional land, now dry, can be recognized as prior salt pond sites.

Salt ponds represent one of the most variable planning area habitats from the standpoint of the plant and animal life they are capable of supporting. Dissolved oxygen levels in the water increase and decrease significantly through time, creating a problem for pond life that is aggravated at night because aquatic plants consume, rather than release, oxygen in the dark, thereby further reducing the amount of this vital gas. In fact, decaying organisms can totally deplete the available oxygen at times, locally creating what is termed an "anoxic" situation. The availability of nutrients may likewise beomce a limiting factor for life and growth, as nutrient materials are rapidly assimilated by plants and animals in the low salinity ponds and remain "tied up" there until they are eventually released by bacterial action. All of these elements contribute to the rigors of the salt pond environment.

Even so, an interesting diversity of living forms inhabit at least some of the salt ponds. Probably the major food-producing organisms are a variety of algae and dinoflagellates. Rotifers, roundworms, and Mud Snails (Nassarius sp.) are among the invertebrate animals that flourish in some of the salt ponds, feeding on the algae and on each other. Other common to abundant organisms include Scuds or Fairy Shrimp (Callianassa sp.), Brine Shrimp (Artemia salina), copepods, Waterboatman (Trichocorixa reticulata), Brine Flies (Ephydra cineria), seed shrimp, and polychaete worms.

Certain fish may also inhabit the salt ponds. Threespine Sticklebacks (Gasterosteus aculeatus) are sometimes prevalent in low-salinity waters, while Topsmelt (Atherinops affinis) are capable of tolerating slightly high salt concentrations. Above six percent salinity the last remaining fish perish. The mudsucker, (Gillichthys mirabilis) survives in salty water and has been grown commercially as bait fish in some of the Leslie Salt Company ponds.

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WHITE PELICAN

CLAPPER RAIL (RARE AND ENDANGERED)

LEAST TERN (RARE AND ENDANGERED)

SONG SPARROW (RARE AND ENDANGERED)

BLACK-NECKED STILT

BUFFLEHEAD

RED-BELLIED HARVEST MOUSE (RARE AND ENDANGERED)

Waterfowl of the Salt Ponds

Of vertebrate animals that inhabit the salt pond areas, birds are by far the most conspicuous. In one study of five ponds during a two-year period (Anderson, 1970), over three hundred thousand birds were sighted in an area of about 2,500 acres. Comparable waterfowl abundance can be demonstrated in the Hayward shoreline planning area - ducks have been seen in concentrations of over ten thousand per square mile on local low-salinity ponds, while 17,000 Ruddy Ducks (Oxyura jamaicensis) have been sighted in one day on two salt ponds south of the old Alameda Creek channel.

Bird diversity also tends to be unusually high in the salt pond habitat. Of the 94 waterbirds that have been observed in the planning area, better than 65 - over seventy percent - have been sighted in salt pond areas; and interestingly, at least a dozen "land" birds can be found here at times as well. Most salt pond birds also spend a good deal of time locally in other types of habitat. A large number of "open bay" species visit the ponds, including greves, geese, cormorants, phalaropes, Bonaparte's Gulls (Larus philadelphia), and terns, while Scaup (Aythya sp.) and other ducks feed heavily on the ponds, especially in rough weather. Similarly, many mudflat birds - such as herons, egrets, plovers, probing shorebirds, American Avocets (Recurvirostra americana), Black-necked Stilts (Himantopus mexicanus), and gulls - can be found in salt pond areas, especially during periods of high tide. Black-bellied Plovers, and nearly all the species of Sandpipers (i.e., the bulk of the tideflat feeders) use the salt ponds during high tide periods primarily for roosting. A few birds even show strong preference for the salt pond habitat such as the White Pelican (Pelecanus erythrorynchos) and the Eared Grebe (Podiceps caspicus) and the Bufflehead (Bucephala albeola), a diving duck, also occur most regularly on salt ponds, particularly those of middle-range salinities where Brine Shrimp abound. Also, all of the world's three existing phalarope species - the Red Phalarope (Phalaropus fulicarius), Wilson's Phalarope (Steganopus tricolor), and the Northern Phalarope (Lobipes lobatus) - occur on salt ponds of the Hayward area shoreline as migrants, two of them seeming to show marked preference for those ponds over other local habitats.

Recent studies of the relationship between salt ponds and wildlife have revealed some interesting facts about the food sources of salt pond waterfowl. Greves, for instance, were found to ingest quantities of Brine Shrimp; shorebirds ate considerable numbers of Brine Fly larvae and puparla; Water-boatman appear to be a key food item of phalaropes; and polychaete worms were an important source of nourishment to Willets. Some birds exhibited dietary habits that may restrict them to certain of the ponds; as one example, certain ducks consumed rather high proportions of Widgeon Grass seeds, which in turn are produced only in ponds of relatively low salinity. In any event, waterbirds are not evenly distributed along the salt pond salinity sequence. Dabbling ducks, Coots, and fish-eating birds (such as terns, egrets, mergansers, and pelicans) prefer waters with the lowest salt content. On the other hand, diving ducks, grebes, phalaropes, and Bonaparte's Gulls demonstrate a high degree of salinity tolerance and a preference for food items existing in ponds of higher salinity. Shorebirds, however, will use for roost purposes ponds that are shallow enough for wading, irrespective of salinity.

Harvey (1973) has tentatively ranked salt ponds of the planning area according to relative wildlife value. Based on cursory observation he would, in general, rank the ponds between Coyote Hills Slough and Alameda Creek as highest in wildlife value. The western section of ponds between Alameda Creek and the San Mateo Bridge were ranked as of moderate value, and those of the eastern portion were thought to have a low value. Also, the ponds north of the approach to the San Mateo Bridge appeared to be of moderate value. However, it was explained that a study over at least a year's time would be necessary to confirm these estimated evaluations of the ponds.

The Dike Environment

Of 28 plants that were found growing on the dikes of the salt ponds, 21 of them are alien (not native to the area). For the most part these are plants that colonize disturbed areas, and that are able to successfully compete for space against native species by virtue of their modifications for enduring drought, their high reproductive rates, and in most cases by an annual (single growing season) life style. That three-fourths of these plants are adapted to the man-made dike environment tells us, in effect, that their presence is more the result of human intervention in the area than of any inherent biological richness of this particular habitat. This situation contrasts clearly with that of the salt marsh, where the entire habitat is dominated by native plants such as Cordgrass and Pickleweed. Transition plants found between marsh and dike - such as Marsh Grindelia, Fat Hen, and Alkali Heath - are native to California as well. Unlike many of the aliens, these natives represent stable forms whose long-term presence in the region has allowed them to integrate into complex ecological associations; as an example, Marsh Grindelia is a valuable forage plant for many insects, such as bees and butterflies, and also for seed-eating birds. For such reasons, as well as for their historical significance, the native plants must be regarded as important and valuable members of the natural community.

In our area certain waterbirds - avocets, Black-necked Stilts, Forster's Terns, and Snowy Plovers - frequently nest on dikes; and from a regional standpoint, several Caspian Tern nesting colonies on salt pond dikes in San Francisco Bay are important ones in North America. Whether for nesting or for roosting, one main reason that dikes are useful for waterfowl is because of their isolation. Cogswell (1973) believes that such areas, protected from disturbance by humans, dogs, motor vehicles, and the like, are one of the most critical habitat features for probing shorebirds in a metropolitan area.

TYPICAL SLOUGH - SALT POND LEVEE CROSS SECTION¹

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Ecological Overview

In the last analysis, the planning area's salt pond-dike system is something of a biological anomaly. The levees, power lines, and concentrations of brine underscore the highly altered nature of this environment, which has been described as "an intricate and fascinating system, a part of the largest solar evaporation plant complex in the world, and a colorful and important segment of the industrial community of the San Francisco Bay Region." As a setting for life, the value of this habitat can be exceedingly variable, ranging from barren, salt-encrusted margins of some of the ponds to spectacular displays of pelicans, egrets, and herons that can be found in season - at the right places. The areas on and around the dikes are home to a curious sequence of high-adopted plants that live under conditions which are prohibitive to the vast majority of members of the plant kingdom.

Besides serving as a wildlife habitat, salt pond areas have several other values that extend beyond the limitations of salt production. They support compatible commercial enterprises like brine shrimp production and marketing of bait fish. Waterfowling leases are an additional area of economic and recreational interest; in our area, duck hunters visit Leslie Salt Company ponds as well as the gun club ponds to the east of them.

MINOR MISCELLANEOUS HABITATS

Limited acreages of two other habitat types occur in the planning area: diked dry areas and freshwater ponds. Because they play relatively minor roles in the overall ecological pitcure, they will be treated briefly here.

Dry Diked Areas and Dumps

About 1,700 acres of planning area terrain are presently diked off and relatively dry. Since some of this area is composed of previous salt ponds, relatively high salinity can be a limiting environmental factor. For this reason and because of their aridity, Harvey (1973) considers these areas to be particularly low in ecological value since they lack much life; but he notes that, like low-value salt ponds, they serve as open-space areas that do not contribute greatly to air pollution and do not restrict air movement - thus are ecologically more valuable in their present state than they would be if urbanized.

Of some interest is the dump at the end of West Winton Avenue, which belongs to this general habitat type. As a rule, sanitary fills tend to smell bad and are unsightly; in addition, rainfall-leaching (and flood-leaching) in dump areas can result in seepage of polluted water and contamination of the environment. Despite these detrimental impacts, however, considerable wildlife may be attracted to disposal sites. While sanitary fills are never balanced ecosystems - vegetation cannot find a foothold in an active site - the fill does contribute a supporting food niche to adjacent habitats. In particular, hordes of gulls are commonplace - up to 13,000 of these birds have been reported in winter at the Winton Avenue site.

Seasonal Freshwater Ponds and Related Habitats

Limited amounts of shallow freshwater habitat are present in the planning area, the exact acreage varying with the time of year. This important, non-saline aquatic element is provided primarily by gun club ponds, the oxidation ponds of the sewage treatment plant, and winter floodplain accumulations. Freshwater habitats in general - ponds, marshes, or others - often contain a variety of green plants which, in turn, support a diverse pyramid of life, from aquatic micro-organisms to the larger, more conspicuous forms.

"Upland" Areas

In addition to its other major habitats, the Hayward shoreline planning area contains over two thousand acres of land which have been collectively termed "upland" terrain. These uplands occupy an irregular strip along the northeastern boundary of the planning area behind the mudflats, salt marshes and salt ponds; essentially they are part of the extensive "bay plain" region upon which San Lorenzo, Hayward, and Alvarado have been built. They include land now in residential or industrial use (not discussed here) and also grassy or weedy land which now lies fallow. Much of the area is underlain by a substratum which is too high - in some cases only by a matter of a few feet - for tide flooding. While parts of it may be flooded by winter rains, the land is comparatively dry. Salt or brackish water often lies only a short distance below ground level, so that deep-rooted plants do not grow well. Prolonged exposure to sun and wind are other limiting physical elements of the fallow upland habitat. In terms of component vegetation the open upland areas closely resemble the dikes, except that many of the native salt-tolerant species may be absent. As on the dikes, several important non-native grass species are joined by a diverse group of other non-native herbaceous plants, resulting in a 'weedy' groundcover that extends beyond the fields and pastures to re-invade the fringes of adjacent developed areas.

Fields and other undeveloped upland areas are capable of providing habitat for an interesting variety of animals. A wide variety of insects are found here. Reptiles include the Western Fence Lizard (Sceloporus occidentalis) and the Gopher Snake (Pituophis catenifer). A large proportion of the planning area's 'land bird' species are associated with relatively undeveloped upland habitats, and a number of water birds sometimes find their way into the area as well. Common mammals to be expected include, among other, Black-tailed Jack Rabbits (Lepus californicus), Gophers (Thomomys bottae), California Ground Squirrels (Citellus beecheyi), and California Meadow Mice (Microtus californicus). In the uplands, as elsewhere, an interlocking web of life binds many of these forms together.

Isolated Hills

Near the southern boundary of the planning area a pair of small hills rise conspicuously above the bay plain. Physiographically these are a northern extension of the Coyote Hills, and the most prominent of the two, known as Turk Island, attains a maximum elevation of only 116 feet above sea level. Even so, this difference in height, slope, and substrata - and perhaps in human land use - is sufficient to produce a marked change in the vegetation of these areas and to permit many wildflowers and other plants to flourish on these low hills that may be absent or uncommon elsewhere in the planning area.

For the most part, the plants of these hills are quite typical of grasslands throughout the coast ranges of central California and are therefore not actually rare or endangered species. But in the larger sense, the isolated nature of the hills places them in an ecological situation which - in its undeveloped state - is quite uncommon along the shore of San Francisco Bay. Well over forty different kinds of plants are found on or at the foot of the hills. In a vegetational sense, then, the hills should be ranked among the richest and most diverse of habitats to be found in the planning area.

Planning Implications

In the Hayward Shoreline area are major habitats that are more valuable than others. The salt marsh is most valuable, followed by open water, mudflats, and some salt ponds. Upland areas and dry diked areas rank lowest.

From every ecological standpoint, the small patches of salt marsh at the end of the Alameda Flood Control channel should remain inviolate. Because of the dependence of several rare species on this specific habitat (including the Clapper Rail, a subspecies of Song Sparrow, and possibly the Salt Marsh Harvest Mouse) and because of the extremely high productivity of its biological system, the existing salt marsh areas should definitely be retained.

Other suitable shoreline areas (such as some low-salinity salt ponds) should be encouraged to revert to this habitat form.

Other areas exposed to tidal action - the mudflats and open waters - should be exempted from further development. They are necessary for the support of large, attractive migratory waterfowl populations, and they are instrumental in the circulation of nutrients upon which the bay's fishery depends.