Explanation of Boundary Determination for the

Priority Project Area Map for the

Central Valley Project Conservation Program and the

CVPIA Habitat Restoration Program

I.Definition and Purpose

The Central Valley Project Conservation Program (CVPCP)/CVPIA Habitat Restoration Program 

(HRP) Priority Project Area Map depicts a general geographical area where current and future

Program conservation actions will be directed. The map illustrates the relationship of the Central 

Valley Project (CVP) to species and habitats in and around CVP facilities and Service Areas and the 

most current CVP Consolidated Place of Use boundary.

The central purpose of the map is to provide conservation action proponents with guidance related 

to locations deemed important for recovery and protection of CVP impacted species, in particular 

for project applicants during annual solicitation of proposals

While the map does correlate past and ongoing impacts of the CVP with species and habitats, it is 

not intended to be a comprehensive depiction of all areas historically impacted by the CVP, either 

directly or indirectly, nor is it meant to illustrate areas impacted by implementation of the Central 

Valley Project Improvement Act (CVPIA). The “Priority Project Area,” therefore, represents a 

project area where the relationship between past, ongoing, and future CVP impacts –in relation to 

species’ needs – is clear.

A single map was chosen for both the CVPCP and HRP, though some differences in program

requirements exist. As specified in Fish and Wildlife Service (Service) biological opinions, the 

CVPCP addresses past, ongoing, and future impacts of the project, while the HRP (established under 

section 3406 (b)(1) “other” of the CVPIA) is meant to address historical impacts of the CVP (prior to 

establishment of the Act, 1992). It was determined, however, that given the large degree of 

geographic overlap, creation of two separate maps would not be warranted and may confuse project

proponents.

II.General Criteria

Determining the Priority Project Area boundary was accomplished using three basic criteria: 1) 

existing and past CVP Consolidated Place of Use, 2) priority habitats impacted by the CVP (as 

identified in existing biological opinions and “critical needs” analysis related to CVP contracts and 

operations), and 3) U.S. Forest Service (USFS) Ecological subregion (Section and Subsection) 

boundaries that could be associated with CVP impacted habitats as a way of “enclosing” the project 

area.

In developing the map, areas were divided into quadrants to simplify the process. The general 

mapping criteria are described below, followed by more detailed information regarding 
inclusion of habitats and subregions within each quadrant.

1) CVP Consolidated Place of UseU. The place of use is the area authorized by the California State 

Water Resources Control Board to be entitled to water service under Bureau of Reclamation 

(Reclamation) CVP water service contracts. Existing, and past, CVP place of use boundaries 

were encompassed to formulate the “core” project area, since place of use areas generally 

represent regions of direct and indirect CVP impacts, past and future.

2) Priority Habitats Impacted by the CVPU Habitats known to be impacted directly or indirectly by 

the CVP have been identified in biological opinions related to CVP contract renewals and 

operations. These habitats have also been specified during annual priority-setting meetings with 

Service and Reclamation managers, as needs and priorities are updated. These habitats are 

indicated below. A shortage of serpentine and gabbro soil habitat mapping information precluded 

depiction of this habitat type on the map, though key areas have been included in the project area 

boundary.

Serpentine soil and associated habitats supporting endemic species, such as the bay checkerspot 

butterfly and serpentine plants, in Santa Clara County

Grassland, alkali sink, and alkali scrub habitat in the Central Valley

Vernal pool habitat throughout the Central Valley

Gabbro soil chaparral habitat in El Dorado County

Riparian, aquatic (including wetlands) and associated habitat mosaics (including oak woodlands) 

in the Central Valley and associated foothills

3) USFS Ecological Subregions of California. U Ecological subregions are defined in The Ecological 

Subregions of California, Section and Subsection Descriptions (USFS, Pacific Southwest 

Region, 1998 online). Elaborate descriptions of these sections and subsections can be obtained 

by consulting the USFS website. For mapping purposes, a section encompassing the above 

priority habitats was included, as well as a subsection boundary that had a biological connection

(overlapping species/habitats) with priority habitats. For the most part, subsection boundaries 

were a function of lower elevation, foothill communities associated with the Central Valley 

floor.

III. Mapping Quadrants

For practical purposes, the Priority Project Area Map was broken into four areas (quadrants). 

This was done to allow mappers to focus more narrowly on the ecological relationships between 

priority habitat types, CVP consolidated place of use boundaries, and USFS ecoregion contour 

lines. The following are general descriptions of the area encompassed by a quadrant, and the 

USFS ecoregions associated with priority habitats and CVP Place of Use, which were selected

for inclusion. Locating actual ecoregion contour lines (section and subsections) can be 

accomplished through accessing the USFS website.
1. Southwest Quadrant

This quadrant includes all of Contra Costa and Alameda counties, most of Santa Clara and San 

Benito counties, and portions of San Mateo, Santa Cruz, and Monterey counties. It also includes 

the western portions of San Joaquin, Stanislaus, Merced, Fresno, Kings, and Kern counties. 

Additionally it includes the southeastern portion of San Luis Obispo County in order to 

encompass the Carrizo Plain National Monument, and address critical needs of CVP-impacted 

species that utilize the Monument area and are associated with habitats of the Central Valley 

floor. The quadrant terminates to the south at the northern boundaries of Ventura and Santa 

Barbara counties. For this quadrant, CVP priority habitats include:

Central Valley grassland, alkali sink and alkali shrub

Central Valley vernal pools

Riparian, aquatic (wetlands) and associated upland, including oak woodlands

Serpentine soil and associated species – for this quadrant, this is defined as habitat for the bay 

checkerspot butterfly.

Eastern Contra Costa County

The Great Valley, Sierra Nevada Foothills, Central California Coast Ranges, and Central 

California Coast ecological sections encompass CVP Consolidated Place of Use boundaries and 

the above five priority habitat areas. These sections include numerous subsections that were

utilized as mapping boundaries. A brief description of these sections and subsections is as 

follows:

a) Great Valley (Section 262A). This section contains the alluvial plains of the San Joaquin 

Valley. It includes the habitat types listed above, and many CVP-impacted special status 

species. All USFS subsections of the Great Valley section in the Southwest quadrant are 

included in the project area. Predominant potential communities relevant to the proposal 

action area include the California annual grassland series, purple needlegrass series, valley 

oak series, vernal pools and wetland communities, blue oak series, allscale series and

saltgrass series.

b) Sierra Nevada Foothills (Section M261F). This section includes the riparian, aquatic 

(wetlands) and associated upland habitat types. The USFS subsection is:

i) San Emigdio Mountains (subsection M261Fe). This subsection is located in western 

Kern County. The predominant natural plant community is the blue oak series, with

ponderosa pine series and Jeffrey pine series at higher elevations. Also, there are some 

needlegrass grasslands series, canyon live oak series on steep canyon slopes, chamise 

series and mixed chaparral shrublands on shallow and rocky soils, and valley oak series 

in valleys.

c) Central California Coast Ranges (Section M262A). This section includes Central Valley 

grassland, alkali sink and alkali shrub, and the riparian, and aquatic (wetlands) and associated 

upland habitat types. The USFS subsections are:
i) Carrizo Plain (subsection M262Ai). The predominant natural plant communities are the 

California annual grassland series, needlegrass grasslands, saltgrass series, and emergent 

aquatic communities.

ii) Caliente Range – Cuyama Valley (M262Aj). The predominant natural plant 

communities are the blue oak series, needlegrass grasslands, chamise series on shallow 

soils, and California annual grassland series around Cuyama Valley. Around Cuyama 

Valley, the allscale series is present on salty soils, and the iodine bush series is present 

on very salty soils. The California juniper series is present on the south side of Cuyama

Valley.

iii) Temblor Range (M262Ak). Relevant plant communities are the blue oak series, 

California juniper series, needlegrass grasslands, chamise series, and California annual 

grassland series.

iv) Kettleman Hills and Valleys (M262Ag). The predominant natural plant community 

is the California annual grassland series.

v) Eastern Hills (M262Ad). The predominant natural plant community is needlegrass 

grasslands. There is some blue oak series on north-facing slopes in wetter areas, and 

some chamise series on shallow soils. The valley oak series is common in valleys 

along the San Andreas fault zone.

vi) Diablo Range (M262Ac). The predominant natural plant communities are the blue oak 

series and, on shallow soils, the chamise series. There is the leather oak series on 

serpentine soils, and some mixed chaparral shrublands. The Sargent cypress series is 

present, but sparse, on serpentine soils. Also, there are some black oak and mixed 

conifer series on north-facing slopes at higher elevations, and the Jeffrey pine series on 

serpentine soils on San Benito Mountain.

vii) Western Diablo Range (M262Ab). The predominant natural plant communities are the 

blue oak series on south-facing slopes, and the coast live oak series on north-facing 

slopes. There is some chamise series on shallow soils, and some live oak chaparral 

shrublands on shallow soils at higher elevations and on north-facing slopes. The Valley 

oak series and needlegrass grasslands are common in valleys. Black oak series and 

mixed conifer series are present, but not extensive, on some north-facing slopes at 

higher elevations.

viii) Fremont-Livermore Hills and Valleys (M262Aa). The predominant natural plant 

community is needlegrass grasslands in the hills around Livermore Valley and in the 

hills northeast of the Santa Clara Valley. The blue oak series and needlegrass

grasslands occur on south-facing slopes, and the coast live oak series on north-facing 

slopes. The valley oak and California sycamore series are common plant communities 

on recent alluvial plainCs.

d) Central California Coast (Section 261A). Predominant potential communities of this section

include the blue oak series, purple needlegrass series, coast live oak series, chamise series, 

valley oak series, and California sagebrush series. It includes the Central Valley grassland, 
alkali sink and alkali shrub, riparian, aquatic (wetlands) and associated upland, and the 

serpentine soils and associated species habitat types. The USFS subsections are:

i) Santa Clara Valley (subsection 261Ae). The predominant natural plant communities are 

the valley oak series, and the California oatgrass series or needlegrass grasslands. The 

coast live oak series, needlegrass grasslands, and blue oak series occur on hills and 

terraces.

ii) Leeward Hills (subsection 261Ag). The predominant natural plant communities are the 

coast live oak series and California bay series on north-facing slopes, the blue oak series 

on south-facing slopes, and the chamise series on shallow soils.

iii) Watsonville Plain-Salinas Valley (subsection 261Ah). The predominant natural plant 

communities are the valley oak series and needlegrass grasslands in the Salinas Valley,

and the coast live oak series and California oatgrass series on the Watsonville Plain. 

There are cottonwood woodlands in riparian areas along the Salinas River. Dunes 

support a succession of plant communities, from bare dune through herbaceous 

communities, and the coyote brush series to California sagebrush-black sage series on 

stabilized dunes on the southeast side of Monterey Bay. There is some pickleweed 

series in estuaries.

iv) East Bay Terraces and Alluvium (subsection 261Ad). The predominant natural plant 

communities are the coast live oak series and California oatgrass series, or 

needlegrass grasslands on alluvial CplainsC.

v) East Bay Hills-Mt. Diablo (subsection 261Ac). The predominant natural plant 

communities are the coast live oak series in the East Bay hills, both the coast live oak 

series and blue oak series on Mt. Diablo, and the valley oak series on alluvial plains. 

The chamise series is extensive on shallow soils on Mt. Diablo, and the usual natural 

plant community on vertisols is needlegrass grassland. The California sagebrush series 

is present on shallow soils on south-facing slopes in the East Bay hills.

2. Southeast Quadrant

This quadrant includes the eastern portions San Joaquin, Stanislaus, Merced, Fresno, Kings, and 

central Kern counties. It also includes the western portions of Calaveras, Tuolumne, Mariposa, 

Madera, and Tulare counties. The quadrant terminates to the south at the northern boundaries of 

Ventura and Los Angeles counties. For this quadrant, CVP priority habitats include:

Central Valley grassland, alkali sink and alkali shrub

Central Valley vernal pools

Riparian, aquatic (wetlands) and associated upland, including oak woodlands

The Great Valley and the Sierra Nevada Foothills ecological sections encompass CVP 

Consolidated Place of Use boundaries and the above three priority habitat areas. These sections 

include numerous subsections utilized as mapping boundaries. A brief description of these 

sections and subsections is as follows:
a) Great Valley (Section 262A). This section contains the alluvial plains of the San Joaquin 

Valley. Predominant potential natural communities include the purple needlegrass series, 

valley oak series, vernal pools and wetland communities, blue oak series, allscale series and 

saltgrass series. It includes the CVP Place of Use, the three habitat types listed above, and 

most of the CVP-impacted special status species.

b) Sierra Nevada Foothills (Section M261F). Predominant potential natural communities 

include the blue oak series, needlegrass grasslands, chamise series, mixed chaparral series, 

foothill pine series, and valley oak series. This section includes the riparian, aquatic 

(wetlands) and associated upland habitat series. 

All USFS subsections of the Great Valley section in the Southeast quadrant are included in the 

project area. The reason for including these subsections is that they have scattered riparian areas 

which are linked to the Central Valley floor. These riparian areas provide corridors and linkages 

for high priority species addressed by the programs. The USFS subsections are:

i) Lower Granitic Foothills (subsection M261 Fc). The predominant natural plant 

community is the blue oak series. Also, there are some of the needlegrass grasslands

series, chamise series on shallow and rocky soils, and valley oak series in valleys.

ii) Southern Granitic Foothills (subsection M261Fd). The predominant natural plant 

community is the blue oak series. Also, there are some needlegrass grasslands, chamise 

series on shallow and rocky soils, and valley oak series in valleys.

One area of the Southern Granitic Foothill habitat in the southeastern part of the quadrant was 

eliminated from the project area. This is a valley in the interior of the Sierra Nevada Mountains 

surrounded by Sierra Nevada montane habitat. It shares the same habitat type as the foothills, but

is too far removed from the Central Valley floor.

3. Northeast Quadrant

This mapping area includes central portions of Shasta County to the north, portions of eastern 

Tehama County, and western portions of Butte, Yuba, Nevada, Placer, El Dorado, and Amador 

counties, extending south through Sacramento County and the Central Valley floor. For this 

quadrant, CVP priority habitats include:

Central Valley vernal pools

Riparian, aquatic (wetlands) and associated upland, including oak woodlands

Gabbro soils chaparral habitat in El Dorado County

The Great Valley and the Sierra Nevada Foothills sections encompass CVP Consolidated Place 

of Use boundaries and the above three priority habitat areas. The subsections, the Tuscan 

Flows and Lower Foothills Metamorphic Belt, were used to determine outer boundaries. A 

brief description of these sections and subsections is as follows:

a) Great Valley (Section 262A). This section includes the Central Valley vernal pools, riparian, 
aquatic (wetlands) and associated upland series. Predominant potential communities relevant 

to the proposal action area include the California annual grassland series, purple needlegrass 

series, valley oak series, vernal pools and wetland communities, blue oak series, allscale 

series, and saltgrass series.

b) Sierra Nevada Foothills (Section M261F) – This section includes the Central Valley 

vernal pools, riparian, aquatic (wetlands) and associated upland, and the gabbro soils 

chaparral habitat in El Dorado County habitat types. Predominant potential natural 

communities include the blue oak series, needlegrass grasslands, chamise series, mixed 

chaparral series, foothill pine series and valley oak series. The USFS subsections are:

i) Tuscan Flows (Section 261 Fa). The predominant natural plant community is the blue 

oak series. Needlegrass grasslands predominate on vertisols and shallow soils. Northern 

basalt flow and northern volcanic mudflow vernal pool habitats occur in this subsection.

ii) Lower Foothills Metamorphic Belt (Subsection M261Fb). The predominant natural 

plant community is the blue oak series. Also, there are some needlegrass grasslands

series, chamise series on shallow and rocky soils, and valley oak series in valleys.

4. Northwest Quadrant

This quadrant includes portions of Trinity and western Shasta counties; Central Tehama County;

eastern portions of Glenn, Colusa and Yolo counties; and all of Sutter County, south to the northern 

boundary of Solano County. Solano County is not included in the project area since it is covered 

under a separate conservation program. Additional counties include the northern portion of San 

Joaquin and Contra Costa counties, and northwest portions of Alameda County. For this quadrant, 

CVP priority habitats include:

Central Valley vernal pools

Riparian, aquatic (wetlands) and associated upland, including oak woodlands

The Great Valley, Central California Coast, Northern California Interior Coast Ranges, and 

Klamath Mountains ecological sections encompass CVP Consolidated Place of Use boundaries and 

the above two priority habitat areas. These sections included numerous subsections that were

utilized as mapping boundaries. A brief description of these sections and subsections is as follows:

a) Great Valley (Section 262A). This section includes the two habitat types listed above. All 

USFS subsections of the Great Valley section in the Northwest Quadrant are included in the 

project area. Predominant potential communities relevant to the priority project area include 

the California annual grassland series, purple needlegrass series, valley oak series, vernal 

pools and wetland communities, blue oak series, and the allscale series and saltgrass series.

b) Northern California Interior Coast Ranges (Section M261C). Predominant potential 

natural communities include the blue oak series, chamise series, purple needlegrass series,

and foothill pine series. This section includes the riparian, aquatic (wetlands) and 

associated upland and Central Valley vernal pools habitat types. The USFS subsections 

are:

i) Tehama Terraces (Subsection M261Cb). The predominant natural plant community is the 
blue oak series. The needlegrass grasslands series predominates on some fine-textured 

alfisols, and northern claypan vernal pools are common.

ii) Dunnigan Hills (Subsection M261Cc). The predominant natural plant community is the 

needlegrass grasslands series. The blue oak series is present, but not common, on soils 

other than vertisols.

c) Klamath Mountains. Predominant potential natural communities are conifers, oaks, and 

chaparral. This section includes the riparian, aquatic (wetlands) and associated upland

habitats, including oak woodlands series. The USFS subsection is:

i) Eastern Klamath Mountains (Subsection M261Ai). Almost all of the area is in this 

subregion. The predominant natural plant communities are mixed conifer series, 

Douglas fir-ponderosa pine series, and ponderosa pine series. Blue oak and mixed 

chaparral communities occur on south-facing slopes at lower elevations. The canyon 

live oak series is common on very steep rocky slopes with stony soils. The white fir 

series occurs at higher elevations. The elevation range is from about 700 feet adjacent 

to the Great Valley, up to 6,252 feet. Small amounts of four other subsections also

occur. All are dominated by conifers and mostly at high elevations not appropriate for 

consideration by the CVPCP/HRP.