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Chapter 2 North Coast Hydrologic Region

51 inches per year. Relatively little snow is in this region, and 

it usually stays on the ground only a short time at elevations 

of 4,000 feet or higher. As a result of the abundant rainfall, 

the average annual runoff for the rivers of this region is about 

29 million acre-feet per year, which is the largest volume 

compared to all other hydrologic regions of California. 

Population

The population of the entire North Coast region was about 

644,000 in year 2000, which is less than 2 percent of 

California’s total population. More than half of this region’s 

population lives in the southern part, primarily in Santa Rosa 

and the surrounding communities of Rohnert Park, Windsor, 

and Healdsburg along the Russian River watershed. Urban 

growth in the Santa Rosa area, 147,500 people in year 2000, 

is heavily influenced by the overall urban expansion of the 

adjacent San Francisco Bay region. Other smaller communities 

in the northern portions of this region include Eureka, 26,000 

people in 2000; Ukiah, 15,500; Arcata, 16,600; Crescent 

City, 7,300; and Yreka, 7,200.

When compared with the 1990 regional population of 

571,750, the 644,000 in 2000 represents a growth rate of 

12.6 percent over the 10 years, which is slightly lower that 

the statewide growth rate of nearly 14 percent over the same 

period. Projections today indicate that the regional population is expected to grow to about 895,000 by year 2030, 

which represents a 39 percent increase from year 2000 

totals. Figure 2-2 provides a graphical depiction of the North 

Coast region’s total population from year 1960 through year 

2000, with current projections to year 2030. More than half 

of this projected growth is anticipated to occur in the Santa 

Rosa region, as urban populations from the San Francisco 

Bay area continue to expand north. Population increases in 

the rural communities in the northern half of this region are 

projected to grow more slowly.

Setting

The North Coast Hydrologic Region encompasses redwood 

forests, inland mountain valleys, and the arid Modoc Plateau. 

The region includes all or large portions of Modoc, Siskiyou, 

Del Norte, Trinity, Humboldt, Mendocino, Lake, and Sonoma 

counties (Figure 2-1). It also includes small areas of Shasta, 

Tehama, Glenn, Colusa, and Marin counties. The region 

includes the Pacific Ocean coastline from Tomales Bay to the 

Oregon border, and then extends east along the border to the 

Goose Lake Basin. This region covers roughly 19,500 square 

miles, or more than 12 percent of California’s land area. Most 

of the region is mountainous and rugged. The mountain crests, 

which form the eastern boundary of the region, are about 

6,000 feet elevation with a few peaks higher than 8,000 

feet. Only 13 percent of the land is classified as valleys or 

mesas, and more than half of that is in the higher northeastern 

part of the region in the upper Klamath River Basin. 

Climate

Weather conditions and temperatures vary dramatically 

from the cooler coastal areas to the arid inland valleys in 

Siskiyou and Modoc counties. In the western coastal portion 

of this region, average temperatures are moderated by the 

influence of the Pacific Ocean and range from highs in the 

mid-80s in the summer to lows in the mid-30s during the 

winter. In the inland regions of Siskiyou and Modoc counties, temperatures are more variable, where summer high 

temperatures usually reach the 100-degree mark and winter 

low temperatures are often in the low-30-degree range. 

Heavy rainfall in the coastal mountain ranges makes the 

North Coast region the most water-abundant area of California, producing about 41 percent of the state’s total natural 

runoff. Average annual precipitation varies from more than 

100 inches in the north coast mountains of Del Norte County 

to less than 15 inches in the Lost River drainage area of 

Modoc County. Region-wide, average precipitation is about 

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Land Use

Forest and rangeland represent about 98 percent of this 

region’s land area. Much of the region is identified as national 

forests, state and national parks, under the jurisdiction of the 

federal Bureau of Land Management, and American Indian 

lands such as the Hoopa Valley and Round Mountain reservations. The major land uses in the North Coast region consist 

of timber production, agriculture, fish and wildlife management, parks, recreational areas, and open space. However, 

in recent years the timber industry has declined as a result of 

timber over-cutting, economic issues, and the expansion of 

environmental regulations.

Vacationers, boaters, anglers, and sightseers are attracted to 

the region’s 400 miles of scenic ocean shoreline, including 

nearby forests with more than half of California’s redwoods. 

The inland regions are mountainous and include 10 wilderness areas run by the U.S. Forest Service. More than 40 state 

parks, numerous Forest Service campgrounds, the Smith 

River National Recreation Area and the Redwood National 

Park are within this hydrologic region. It is an area of rugged 

natural beauty with some of the most renowned fishing in 

North America. 

Climate, soils, water supply, and remoteness from markets are 

factors that limit the types of agricultural crops that can be 

grown in the North Coast region. In the inland valley areas, 

there is more irrigable land than can be irrigated with existing 

water. The agricultural trend in the past decade has been one 

of land consolidation and the conversion of prime agricultural 

land to urban growth. This trend is a result of low crop values, 

the lack of additional inexpensive surface water, and the ability 

to use only the most economically developable groundwater.

Irrigated agriculture in the North Coast region uses most of the 

region’s developed water supplies. Irrigation today accounts 

for about 81 percent of the region’s water use, while municipal 

The North Coast region encompasses redwood forests, inland mountain valleys, and the arid Modoc Plateau. The region covers roughly 19,500 square miles, 

or more than 12 percent of California’s land area. (DWR Photo)

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and industrial use is about 19 percent. About 326,600 acres, 

or about 2 percent of the region, is irrigated. Of that, 225,900 

acres are in the Upper Klamath River Basin where the main 

irrigated crops are pasture and alfalfa, grain, and potatoes. 

The highest value crops in the region are the substantial acres of 

grapes and orchards in the Russian River Basin and ornamental 

fl owers, including bulbs, in Del Norte County.

The total acreage of fruit and nut orchards has decreased over 

the past several decades. For example, in Sonoma County, 

orchards declined from 20,000 acres in 1971 to fewer than 

3,500 acres in 2001. However, the amount of irrigation water 

used on orchards did not decrease in the same proportion 

because many of the apple, prune, and walnut orchards taken 

out of production were not irrigated. As the acreage of orchards 

declined, the acreage planted in vineyards increased. Most of 

the newer vineyards use drip irrigation systems for plant irrigation, but overhead sprinklers are also used for frost protection 

in the spring and for post-harvest irrigation in the fall. 

The North Coast Hydrologic Region also contains roughly 280 

dairy farms with 60,000 milk cows, according to the 2002 

Census of Agriculture. The majority of these dairy farms are in 

Humboldt County (140 farms) and Sonoma County (110 farms).

Many of the region’s watersheds support threatened and 

endangered species of plants and animals, and many North 

Coast streams and rivers support anadromous fi sh runs of 

salmon and steelhead trout. The principal reaches of the 

Klamath, Eel, and Smith rivers have been designated wild 

and scenic under federal and State law and therefore are 

protected from additional large-scale water development. 

Water Supply and Use

Many of the smaller communities and rural areas in the North

Coast region are generally supplied by small local surface 

water and groundwater systems. Larger water supply projects 

in this region include the U.S. Bureau of Reclamation’s Klamath Project, the U. S. Army Corps of Engineers’ Russian River 

Project (Lake Mendocino and Lake Sonoma), and the Humboldt 

Bay Municipal Water District’s Ruth Reservoir, which serves 

coastal communities from Eureka to McKinleyville. Because 

the Upper Klamath River watershed is in both California and 

Oregon, the federal Klamath Project includes water supply 

facilities in both states. Facilities within the California portion 

include Clear Lake Reservoir for water supply, Tule Lake and 

Lower Klamath Lake as waterfowl refuges, and Iron Gate 

Reservoir as a hydroelectric facility of Pacifi c Power and Light 

Figure 2-2 North Coast Hydrologic Region population

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

1960 1970 1980 1990 2000 2010 2020 2030

Data from California Department of Finance provide decadal population from 1960 to 2000 and population projection for 2030 

for the North Coast region.

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Company. The primary water supply facilities on the Oregon 

side are Gerber Reservoir and Upper Klamath Lake. The Klamath Project is the largest agricultural irrigation project in the 

region, and supplies water to about 240,000 acres, of which 

62 percent is in Oregon and 38 percent is in California. To 

maintain adequate instream fishery flows for the lower Klamath 

River, water releases must be coordinated among the various 

reservoirs operated by different agencies within both states.

Two of the largest water supply reservoirs in the North Coast 

region are the U.S. Bureau of Reclamation’s 2.437 million 

acre-foot Trinity Lake on the Trinity River, and the U.S. Corps 

of Engineer’s 380,000 acre-foot Lake Sonoma in the Russian 

River watershed. These facilities provide water for instream 

flows, recreation, hydropower, and water supply purposes. 

Water from Trinity Lake is exported from the North Coast 

region to the Sacramento River region through the U.S. Bureau 

of Reclamation’s Clear Creek Tunnel. Lake Sonoma is operated to provide flood control and instream flows in the Lower 

Russian River in Sonoma County. Another intrabasin water 

transfer system known as the Potter Valley Project has been in 

existence since 1908 and diverts water from the upper reaches 

of the Eel River at Cape Horn Dam through a tunnel to the East 

Fork Russian River upstream from Lake Mendocino. The water 

stored behind Coyote Dam (Lake Mendocino, built in 1958) 

is used to meet instream flow requirements, as well as urban 

and agricultural needs in the lower Russian River watershed 

and the Santa Rosa area.

Groundwater development is sporadic throughout the mountainous areas of the region, and wells are generally along the 

valleys of rivers and streams. As described in “California’s 

Groundwater” (California Department of Water Resources 

Bulletin 118-03), there are very few significant aquifers in the 

coastal mountains that are capable of providing reliable water. 

In the coastal areas, most groundwater is developed from shallow wells that are typically installed in the sand and gravel 

beds adjacent to the region’s rivers. Significant groundwater 

basins do exist in the upper Klamath River valley along the 

border with Oregon and also in the southern tip of this region 

underlying the Santa Rosa area.

The principal developed uses of environmental water occur in 

the Lower Klamath Lake, Tule Lake, and Clear Lake National 

Wildlife Refuges, and the Butte Valley and Shasta Valley 

Wildlife Areas. In Butte Valley, most of the water for wildlife 

comes from about 3,000 acre-feet of groundwater. As a result 

of the passage of both federal and State wild and scenic rivers 

acts in 1968 and 1972, many of the major rivers in the North 

Coast region have been preserved to maintain their free-flowing character and provide for environmental uses. Most of 

the Eel, Klamath, Trinity and Smith rivers are designated as 

wild and scenic, which preserves these river resources and 

protects them from new water development. On the Trinity 

River, efforts to restore the fishery led to a federal Record of 

Decision in year 2000 to increase the fishery flow releases 

from Trinity Lake. After several years of legal challenges, this 

decision was upheld by a July 2004 federal court decision. 

The water allocated to downstream fishery flows is now being 

increased from the previous 340,000 acre-feet per year, to 

a new schedule that ranges between 368,600 acre-feet in a 

critically dry year to more than 700,000 acre-feet per year in 

a wet water year. Biologists and Central Valley Project operators are still working on the development of daily, weekly and 

monthly water release schedules that will make the best use of 

these new water allocations.

The water balance tables and the narrative discussion at 

the end of this chapter provide a detailed summary of the 

actual region-wide water supplies and water uses from years 

1998, 2000, and 2001 for the entire North Coast region. 

Figure 2-3 summarizes the dedicated and developed urban, 

agricultural and environmental water uses in the region for 

1998, 2000, and 2001. The figure also provides a graphical presentation of all of the water supply sources that are 

used to meet the developed water uses within this hydrologic 

region for these three years. As shown on the first graph, the 

volume of water dedicated to wild and scenic rivers, called 

“statutory required outflows,” is the largest component of 

dedicated water uses in the region. The information presented in Table 2-1 at the end of the chapter also indicates 

that the volume of water exported to other regions is generally greater than all the water consumptively used for urban, 

agriculture and wildlife refuges within the North Coast region. 

State of the Region

The North Coast region generally has the most abundant 

water resources of any region of the State. The high volumes of 

precipitation and natural river runoff are a key component for 

most of the beneficial uses of its water bodies, including commercial and recreational fishing, shellfish harvesting, urban 

and agricultural use, and recreation. Many of the region’s forests and watersheds support threatened and endangered species of plants and animals, and the major rivers and streams 

contain significant anadromous fishery resources. This region 

also features important coastal resources, including Bodega 

Harbor and Humboldt Bay, and many small estuaries. 

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Thousand Acre-Feet

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1998 2000 2001

Wild & Scenic

Rivers

Instream Flow

Managed

Wetlands

Irrigated

Agriculture

Urban

Figure 2-3 North Coast water balance for water years 1998, 2000, 2001

Thousand Acre-Feet

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

1998 2000 2001

Dedicated

Environ

Reuse &

Recycle

Ground Water

Federal

Projects

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in amount and relative proportions of water delivered to North Coast region’s urban and 

agricultural sectors and water dedicated to the environment (applied water, top chart), where the water came from, and how 

much was reused among sectors (dedicated water supplies, bottom chart).

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Challenges

The region faces many water quality and water supply challenges. The North Coast Regional Water Quality Control 

Board’s water quality priorities highlight the need for control of 

nonpoint source runoff from logging, rural roads, agriculture, 

and urban areas. In fact, sediment, temperature, and nutrients 

are the primary focus of the RWQCB’s 303(d) list of impaired 

water bodies. Along the coast, nonpoint-source pollution can 

cause microbial contamination of shellfish growing areas, 

especially oysters. Much of the region is characterized by 

rugged, steep, forested lands, with highly erodable, loosely 

consolidated soils; taken together with wildfires, extensive 

timber harvesting, and heavy precipitation primarily in the 

form of rain, the watershed is highly susceptible to erosion 

and landslides. Such heavy runoff in turn causes stream sedimentation that impacts habitat for spawning and rearing of 

anadromous fish. Channel modifications and water diversions 

have radically changed water-quality conditions in many 

water bodies in the region, reducing natural flows that dilute 

contaminant concentrations and lessen their impacts. In the 

southern portion of the region, the development of new hillside 

vineyards is an increasing source of erosion and pesticides. 

Fisheries can be adversely affected by a number of factors 

related to both water quality and water quantity. The Eel, 

Mad, Trinity, Klamath and Russian rivers, as well as many 

other streams, suffer from sedimentation, which can smother 

salmonid spawning areas. The North Coast region’s basin 

plan sets turbidity restrictions to control erosion impacts from 

logging and related activities, such as road building. Timber 

harvests can also decrease the canopy shading rivers and 

streams, thereby increasing water temperatures to levels that 

are detrimental to cold water fisheries. The basin plan also 

specifically establishes temperature objectives for the Trinity 

River, in which reduced flows have disrupted temperature and 

physical cues for anadromous fish runs. Because of water 

diversions, summer temperatures in the Trinity as well as the 

Klamath can be lethal to salmonids. Fisheries can be further 

affected by the lack of woody debris for pool habitat and 

sediment metering. 

The North Coast RWQCB’s basin plan requires tertiary treatment of wastewater discharges to the Russian River, a major 

source of domestic water, and establishes limits on bacteriological contamination of shellfish-growing areas along the 

coast. The plan also prohibits or strictly limits waste discharges 

to the Klamath, Trinity, Smith, Mad, and Eel rivers, as well as 

estuaries and other coastal waters. Nonpoint source runoff, 

especially after heavy precipitation, has resulted in contamination and closure of shellfish harvesting beds in Humboldt 

Bay. In the lower Russian River watershed storm water runoff 

also might be contributing to high ammonia and low dissolved 

oxygen levels in Laguna de Santa Rosa, which is threatening 

aquatic life. Mercury in fish tissue is a water quality concern 

in Lakes Pillsbury, Mendocino, and Sonoma; a health advisory 

for mercury has been issued for Lake Pillsbury. 

Groundwater quality problems in the North Coast region 

include contamination from seawater intrusion and nitrates 

in shallow coastal groundwater aquifers; high total dissolved 

solids and alkalinity in groundwater associated with the lake 

sediments of the Modoc Plateau basins; and iron, boron, 

and manganese in the inland groundwater basins of Mendocino and Sonoma counties. Septic tank failures in western 

Sonoma County, at Monte Rio and Camp Meeker, and along 

the Trinity below Lewiston Dam, are a concern because of 

potential impacts to groundwater wells and recreational 

water quality.

Other water quality concerns include the impacts of boating 

fuel constituents such as MTBE to recreational water use at 

Trinity, Lewiston, and Ruth lakes. Abandoned mines, forest 

herbicide application, and historical discharge of wood 

treatment chemicals at lumber mills, including Sierra Pacific 

Industries near Arcata and Trinity River Lumber Company in 

Weaverville, also are regional issues of concern. Of note, 

according to the 305(b) report, only the Russian River Basin 

has a long-term water quality data set in this region, which is 

necessary to evaluate quality changes over time.

Even though the North Coast region produces a substantial 

share of California’s surface water runoff, only about 10 

percent of this runoff occurs in the summer and water supplies 

are limited throughout much of the area. Small surface-water 

supply projects generally have limited carryover capacity that 

cannot supply adequate water during extended months of low 

rainfall. The drinking water for many of the communities on 

the North Coast, such as Klamath, Smith River, Crescent City, 

and most of the Humboldt Bay area, is supplied by Ranney 

collectors (horizontal wells adjacent to or under the bed of 

a stream). Erosion is undercutting some of these collectors, 

such as those in the Mad River supplying the Humboldt Bay 

Municipal Water District (which serves Eureka, Arcata, and 

McKinleyville). As such, these “wells” may actually be under 

the direct influence of surface water, which would then require 

filtration. The city of Willits has had chronic problems with 

turbidity, taste, and odor with water from Morris Reservoir, 

and high arsenic, iron, and manganese levels in its well 

supply. Organic chemical contamination has closed municipal 

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wells in the cities of Sebastopol and Santa Rosa. The town 

of Mendocino typifies the problems related to groundwater 

development in the shallow marine terrace aquifers; surveys 

in the mid-1980s indicate about 10 percent of wells go dry 

every year and up to 40 percent go dry during droughts. 

The Klamath River Basin is an interstate watershed with 

surface storage facilities in both California and Oregon and 

competing water needs for agriculture, Indian tribal rights, 

waterfowl refuges, and endangered fish. The primary water 

storage facilities belong to the federal Klamath Project, which 

is operated by the U.S. Bureau of Reclamation, in conjunction with other dams and diversion structures operated by 

local irrigation districts, wildlife management agencies, and 

electric power companies. In 2001, the lack of rainfall generated a severe drought, which aggravated water disputes and 

caused harsh effects to agriculture, waterfowl refuges and 

the downstream fisheries. The endangered fish populations 

include listed species such as the Lost River and shortnose 

suckers, coho salmon, and steelhead trout. During 2001, the 

U.S. Bureau of Reclamation was able to deliver only about 

75,000 acre-feet of water to agriculture in California, which 

is about 25 percent of normal. In the Tule Lake and Lower 

Klamath Lake subbasins, this translated to a drought disaster 

for both agriculture and the wildlife refuges. In 2002, about 

33,000 adult salmon died due to water quality and quantity 

problems while trying to swim up the Klamath. 

Federal agencies have taken a lead role in conducting 

studies and developing proposals to resolve the competing 

water needs in the Klamath Basin, with assistance from state 

agencies in Oregon and California, and several local governments and interest groups. The U.S. Bureau of Reclamation is 

developing a new Klamath Project Operations Plan intended 

to establish specific allocation procedures to best meet the 

needs of agriculture, fishery restoration per the Endangered 

Species Act, waterfowl refuges, and tribal water rights. The 

U.S. Geological Survey has initiated a four-phase Klamath 

Basin groundwater study to document water levels, water 

quality, and groundwater flow patterns; and to identify 

potential opportunities for future groundwater conjunctive 

use. The U.S. Natural Resources Conservation Service has 

developed an adaptive management program that allocates 

federal funds for agricultural conservation programs, fish and 

wildlife habitat, water quality improvements, and water storage improvements, which are intended to increase water use 

efficiencies and achieve long-term reductions in total water 

use. Other federal agencies in the Klamath Basin Working 

Group include the U.S. Forest Service, the Fish and Wildlife 

Service, the Bureau of Land Management, and the National 

Marine Fisheries Service. Many of these programs and studies 

will take several years to develop and implement, so the overall 

ability to successfully meet all competing water needs will not 

be known for several years. In the meantime, below-normal 

water supply conditions during the past three years continue 

to aggravate the water management issues, disputes, and 

negative effects to basin resources.

As part of the efforts to restore the Trinity River fishery, the Secretary of the Interior in December 2000 approved a significant 

change in use of Trinity River Basin water. As part of an effort 

to restore Trinity River fish habitat, the river’s instream flows 

were increased from 340,000 acre-feet per year (roughly 25 

percent of average annual flow at the Central Valley Project 

diversion point on the Trinity River) to an average of 595,000 

acre-feet per year. This decision, which would reduce the 

amount of water available for export from the Trinity River 

to the Central Valley, was challenged by water and power 

interests in U.S. District Court in 2001. On July 13, 2004, the 

9th U.S. Circuit Court of Appeals overturned the injunction 

imposed by the district court, and ruled that the original year 

2000 Record of Decision was adequate. The water allocated 

to downstream fish flows is now being increased to the new 

flow schedule, which ranges from a minimum of 368,600 

acre-feet in a critically dry year up to 815,000 acre-feet in 

an extremely wet year.

The Eel River and its tributaries are the largest river system 

draining to the coast of Humboldt County, and it is characterized by significant water quality problems during winter storm 

events due to massive sediment loads from unstable soils. The 

Eel River is also host to Humboldt County’s largest fisheries of 

salmon and steelhead, which depend on access to upstream 

tributaries for spawning. The only major water storage in the 

upper reaches of the Eel River is the Potter Valley Project, which 

consists of Lake Pillsbury and a downstream diversion dam and 

tunnel to the Russian River. The project was originally built in 

1908 by Snow Mountain Water and Power Company. Lake 

Pillsbury was constructed in 1922 for hydropower production, and the project was acquired by Pacific Gas and Electric 

Company in 1930.

In recent years fishery interest groups have argued that the 

amount of water diverted to the Russian River has adversely 

affected salmon and steelhead in the Eel River. The water needs 

of the Eel River fishery have been evaluated and disputed 

during the recent Federal Energy Regulatory Commission 

hydropower license amendment proceeding of the Potter 

Valley Project. In June 2004, FERC approved PG&E’s relicense 

amendment of the Potter Valley Project and its associated water 

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diversions to the Russian River. However, fishery groups are 

litigating the FERC decision, so the future distribution of project 

water between the Eel and Russian rivers is not yet resolved.

Accomplishments

In early 1998, the city of Santa Rosa selected an alternative plan 

to recharge depleted geothermal fields in the Geysers area with 

treated wastewater as part of its long-term wastewater-recycling 

program. Under this alternative, the Santa Rosa Subregional 

Sewage System will pump about 11-million gallons per day of 

treated wastewater to the Geysers for injection into the steam 

fields. This amount is a little less than half the flow the treatment system is expected to produce when finished. The project 

is intended to eliminate weather-related problems of the city’s 

disposal system and minimize treated wastewater discharges 

into the Russian River.

The communities around Humboldt Bay support programs 

intended to achieve the dual goals of flood control and habitat 

enhancement. The region is committed to restoring the natural 

functioning of urban streams and wetlands. The city of Arcata has 

many programs to acquire conservation easements and deeds 

to wetlands, for the re-establishment of a natural floodplain for 

storm water management, and for the restoration of fish and 

wildlife habitat. In the past 10 years, Arcata has collaborated 

with government agencies, nonprofit organizations, community 

groups, and schools for development of these restoration activities, and has spent millions of dollars on programs. Additional 

financial support has been obtained through grants from the 

California Department of Water Resources, Department of Fish 

and Game, the Wildlife Conservation Board, and the U.S. Fish 

and Wildlife Service. 

The Russian River Action Plan, first prepared in 1997, was 

updated by Sonoma County Water Agency in 2003 and provides a regional assessment of ongoing efforts to restore the 

salmonid fishery and improve the riparian habitat in the Russian 

River watershed. The plan describes 17 current and pending 

restoration activities, followed by an extensive list of additional 

habitat restoration projects that are in need of funding. In 1997, 

the National Marine Fisheries Service listed steelhead trout as 

threatened and in 2002 listed coho salmon as endangered along 

part of the Central California coast that includes the Russian River 

Basin. The Sonoma County Water Agency, the U.S. Army Corps 

of Engineers, and the National Marine Fisheries Service signed 

an agreement to establish a framework for consultation under 

Section 7 of the Endangered Species Act. Under that agreement, 

the Army Corps and the Sonoma County agency jointly review 

and coordinate information on their respective Russian River 

activities to determine effects to critical salmonid habitat. The 

Eel-Russian River Commission, composed of county supervisors 

from Humboldt, Mendocino, and Sonoma counties, also provides a regional forum for agencies and groups to stay informed 

about projects and issues affecting the Eel and Russian rivers.

Relationship with Other Regions

As shown on the regional map (see Figure 2-1) the Klamath 

River Basin straddles the border with Oregon, such that water 

from the upper basin flows into Oregon and eventually returns 

to California above Iron Gate Reservoir. On the Oregon side 

of this interstate basin, two surface water diversions export 

an average of 29,600 acre-feet per year from Klamath River 

tributaries into the Rogue River system in Oregon. The Klamath 

River Basin also receives a small amount of imported water 

(about 2,000 acre-feet per year) from the upper reaches of the 

Sacramento River Hydrologic Region through a canal called 

the North Fork Ditch. 

The North Coast region exports a large volume of water from 

the upper reaches of the Trinity River into the Sacramento 

River region through the US Bureau of Reclamation’s Central 

Valley Project at Lewiston Dam and the Clear Creek Tunnel. 

For 1998, 2000, and 2001, the Trinity River exports were 

851,000 acre-feet per year, 1.11 million acre-feet per year, 

and 669,000 acre-feet per year, respectively. In future years 

these Trinity River exports are likely to be reduced due to the 

increased instream flows established for the Trinity River fishery. Elsewhere, a smaller regional export of roughly 33,000 

acre-feet per year is transported from the lower Russian River 

into the northern portion of the San Francisco Bay region 

through the Sonoma-Petaluma Aqueduct, to supply communities in northern Marin County and southern Sonoma County. 

Looking to the Future

When compared to the more developed regions of the state, 

urban and agricultural water use in the North Coast region use 

a relatively small part of the total available water. However, 

localized water supply problems are expected to continue 

for communities with limited surface water and groundwater, 

particularly during extended droughts. While significant water 

supplies exist throughout most of the North Coast region, 

the ability to acquire funding to upgrade and expand water 

systems is a major problem for the rural communities.

Along the coast, the Humboldt Bay Municipal Water District 

system might expand to serve the Trinidad-Moonstone area, 

which is experiencing local water deficiencies. The EurekaEE-RM-PET-100 C0MMENT 01A
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Arcata area may undergo construction of a regional water 

treatment plant and is investigating groundwater development 

as an alternative source, which would not require the same 

level of water treatment. 

Crescent City has an adequate supply from the Smith River but 

needs to increase system transmission and storage capacity 

and might build a new water treatment facility. The city of Rio 

Dell might also begin construction of a surface water treatment 

facility. Ranney wells will be installed in the Eel River as a 

primary water supply for Rio Dell. Trinity County Waterworks 

District No. 1, which serves the town of Hayfork from the 800 

acre-foot Ewing Reservoir, has plans to enlarge the reservoir 

and expand its surface water system. 

In the Klamath River Basin, the U.S. Bureau of Reclamation is 

leading efforts to balance water needs between the historical 

agricultural uses of the Klamath Project, the instream needs of 

endangered fish, as well as other system water uses. The recent 

dry hydrologic conditions have intensified these issues, and 

federal funding was approved in 2002 to provide relief through 

the development of conservation programs and the availability 

of new groundwater. The U.S. Bureau of Reclamation is continuing to update the Klamath Project long-term operations plan, 

but difficult issues have delayed its completion. The Klamath 

River Compact Commission also provides a forum for discussions on management of interstate water resources between 

Oregon, California, and the federal agencies, and promotes 

intergovernmental cooperation on water allocation issues. A few 

additional groundwater wells are likely to be constructed to augment irrigation supplies in the Butte Valley and Tule Lake areas. 

Pressure for additional groundwater development in areas like 

Scott and Shasta valleys will be greater since the 2002 listing 

of the coho salmon. The new listing, along with stricter applications of California Department of Fish and Game instream 

regulations, will reduce the supplies available for irrigation from 

existing water developments and from natural runoff.

The lower Russian River watershed and the adjoining Santa 

Rosa area are projected to experience the most significant urban 

growth for any part of the North Coast Hydrologic Region. This 

growth will continue to stress the available water and accentuate 

the need balance urban water uses with environmental water 

needs. The Sonoma County Water Agency has a central role in 

maximizing the use of existing water supplies, and is actively 

developing conservation, water recycling, and groundwater 

conjunctive use. The Sonoma County Water Agency is also 

restoring and preserving the Russian River fishery and habitat 

and is the lead agency for developing and implementing a 

Russian River Action Plan.

Restoration and protection of salmonid habitat will continue 

to be a prominent fishery issue for all of the major coastal 

rivers. The federal listing of coho salmon and steelhead under 

the Endangered Species Act and the State listing of the coho 

salmon generate additional regulatory requirements that 

affect all surface water uses on these rivers. The California 

Department of Fish and Game has prepared a coho salmon 

Recovery Plan to guide actions directed at the recovery of this 

species. Existing and planned water projects will need to be 

operated in ways that do not affect the fishery, which might 

alter methods and schedules for water diversions, hydropower 

operations, and wastewater discharges. Surface water quality 

issues such as sediment loads, nutrients, and warm water can 

also affect the fishery, and these fall under the jurisdiction of 

the North Coast RWQCB, which is developing basin plans to 

address water quality problems and protect the coastal rivers. 

Regional Planning

The forum and focus of regional planning activities varies 

significantly from north to south across the North Coast region 

because of the diversity of water issues and the involved water 

agencies. In the far north interstate Klamath River watershed, 

much of the planning is being done by federal agencies such 

as the U.S. Bureau of Reclamation, the Natural Resources 

Conservation Service, and the U.S. Fish and Wildlife Service, 

among others. These federal agencies are working to balance 

the needs of the federal Klamath Project with water for fish, 

tribal interests, and interests of communities affected by the 

federal project. Planning and issue resolution for the Trinity 

River also have a significant federal lead role because of the 

federal Central Valley Project at Trinity and Lewiston lakes. 

In general, many of the Northern California counties lack 

funding at the level available to federal agencies to conduct 

regional planning.

In the central portion of the region, the communities and water 

issues in Humboldt, Trinity, and Mendocino counties tend to 

be organized at the local or county levels, partly because 

these areas are geographically separated from other developed regions. Planning activities of Humboldt Bay Municipal 

Water District and the Humboldt County general plan update 

are one of the primary forums for regional planning for the 

Arcata and Eureka areas. The Mendocino Council of Governments and the Mendocino Community Services District 

are among the lead water planning agencies for the county, 

which includes Ukiah and portions of the upper Russian River 

wine country.

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2 10 Volume 3 Regional Reports

Sonoma County is the southernmost county in the North Coast 

Hydrologic Region, and water planning is closely associated 

with those of the adjoining San Francisco Bay region. Water 

planning is strongly focused on meeting the urban needs 

of Santa Rosa and the surrounding communities served by 

Sonoma County Water Agency. The agency coordinates with 

and is a member of several San Francisco Bay area regional 

planning groups, such as the Bay Area Water Agencies 

Coalition that provides significant direction and guidance for 

regional planning. Much of Sonoma County regional planning also focuses on the competing uses of the Russian River, 

which is the largest river in this part of the North Coast region. 

The Russian River Action Plan has been updated by Sonoma 

County Water Agency, as a coordinated effort among federal, 

State, and local agencies to protect and restore salmonid 

fishery populations and habitat. 

The State agency with the most significant influence on regional 

water planning activities in the North Coast region is the North 

Coast RWQCB. Although headquartered in Santa Rosa, this 

agency has key responsibilities for surface water quality and 

regulations for all of the rivers in the region. The board oversees 

several water quality programs and issues related to timber 

operations, vineyard runoff, nonpoint source pollution, the 

development of total maximum daily load limits, and the development of water quality objectives for individual basin plans. 

Water Portfolios for Water Years 1998, 

2000, and 2001

The tables in this chapter present actual information about the 

water supplies and uses for the North Coast Hydrologic Region 

for the three selected years. Water year 1998 was a wet year 

for this region, with annual precipitation at 154 percent of 

average, while the statewide annual precipitation was 171 

percent of average. Year 2000 represents normal hydrologic 

conditions with annual precipitation at 98 percent of average 

for the North Coast region. Year 2001 reflected drier water year 

conditions with annual precipitation at 60 percent of average. 

For comparison, statewide average precipitation in year 2001 

was 72 percent of normal. 

Table 2-1 provides detailed information about the total water 

supplies available to this region for these three years from 

precipitation, imports, and groundwater, and also summarizes 

the uses of all of the water supplies. As shown in this table, the 

largest component of overall water use for this region is by 

evapotranspiration from the forest lands (native vegetation). 

The second largest component of water use consists of the river 

flows into the ocean from designated wild and scenic rivers, 

labeled as “statutory outflow to salt sinks.” The North Coast 

region has the highest total volume of water that is used by 

natural forests and the river outflows, compared to any of the 

other regions of California. Table 2-1 also indicates that water 

exports to other regions are generally greater than the volume 

of water that is consumed for agricultural and urban purposes 

within this region. 

A more detailed tabulation of the portion of the total available 

water that is dedicated to urban, agricultural and environmental 

purposes is presented in Table 2-2. Because most of the North 

Coast region is largely undeveloped, dedicated environmental 

water uses for wild and scenic rivers are a larger component 

of the total dedicated water uses in this region. Less than 10 

percent of the dedicated water is used for urban and agricultural purposes within this region. The section at the bottom of 

Table 2-2 also provides detailed information about the sources 

of the dedicated water supplies, which are primarily from surface water. Although groundwater is an important source of 

supply for many small, rural communities, the total amount of 

groundwater used in the region is small compared to surface 

water use.

More detailed information about how available supplies are 

distributed and used on a region-wide basis is shown in Table 

2-3 and the companion water portfolio flow diagrams (Figures 

2-4 and 2-5). 

 

Selected References

Water Quality Control Plan, Regional Water Quality 

Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board 

2002 California 305(b) Report on Water Quality, State Water 

Resources Control Board 

Bulletin 118 (Draft), California’s Groundwater, Update 2003, 

Department of Water Resources 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, California 

Coastal Commission, January 2000 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

Del Norte, Mendocino, and Siskiyou counties 

Mendocino County Russian River Flood Control and Water 

 Conservation Improvement District

EE-RM-PET-100 C0MMENT 01A
Chapter 2 North Coast Hydrologic Region 2 11

California Water Plan Update 2005

Water Entering the Region

Precipitation 79,216 50,755 31,254

 Inflow from Oregon 2,105 1,498 988

 Inflow from Colorado River 0 0 0

 Imports from Other Regions 2 2 2

 Total 81,323 52,255 32,244

Water Leaving the Region 

Consumptive Use of Applied Water * 646 791 647

 (Ag, M&I, Wetlands) 

 Outflow to Oregon 184 114 66

 Exports to Other Regions 883 1,144 703

 Statutory Required Outflow to Salt Sink 32,348 18,763 8,021

 Additional Outflow to Salt Sink 115 125 122

 Evaporation, Evapotranspiration of Native 

 Vegetation, Groundwater Subsurface Outflows, 46,491 31,592 23,323

 Natural and Incidental Runoff, Ag Effective 

 Precipitation & Other Outflows 

 Total 80,667 52,529 32,882

Storage Changes in the Region

 [+] Water added to storage

 [-] Water removed from storage 

 Change in Surface Reservoir Storage 703 -246 -491

 Change in Groundwater Storage ** -47 -28 -147

 Total 656 -274 -638

Applied Water * (compare with Consumptive Use) 1,166 1,353 1,018

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

 calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

1998 (154%) 2000 (98%) 2001 (60%)

Table 2-1 North Coast Hydrologic Region water balance summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

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2 12 Volume 3 Regional Reports

Table 2-2 North Coast Hydrologic Region water use and distribution of dedicated supplies - TAF

 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

DEDICATED WATER SUPPLIES

Urban

Large Landscape 11.0 12.4 12.7 

Commercial 17.1 17.2 17.5 

Industrial 30.2 31.7 31.1 

Energy Production 0.0 0.0 0.0 

Residential - Interior 42.7 44.1 43.3 

Residential - Exterior 38.9 44.6 44.8 

Evapotranspiration of Applied Water 41.2 41.2 45.9 45.9 47.7 47.7

E&ET and Deep Perc to Salt Sink 0.2 0.2 0.2 0.2 0.2 0.2

Outflow 76.3 76.3 80.8 80.8 79.5 79.5

Conveyance Applied Water 0.0 0.0 0.0 

Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

GW Recharge Applied Water 0.0 0.0 0.0 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Urban Use 139.9 117.7 117.7 150.0 126.9 126.9 149.4 127.4 127.4

Agriculture

On-Farm Applied Water 634.6 778.9 614.6 

Evapotranspiration of Applied Water 449.2 449.2 551.1 551.1 444.1 444.1

E&ET and Deep Perc to Salt Sink 29.6 29.6 33.5 33.5 26.4 26.4

Outflow 41.4 35.4 47.0 40.1 48.4 41.3

Conveyance Applied Water 24.0 27.5 17.9 

Conveyance Evaporation & ETAW 6.9 6.9 7.1 7.1 4.2 4.2

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 2.0 2.0 2.0 2.0 0.0 0.0

GW Recharge Applied Water 0.0 0.0 0.0 

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

 Total Agricultural Use 658.6 529.1 523.1 806.4 640.7 633.8 632.5 523.1 516.0

Environmental

Instream

 Applied Water 1,445.3 1,444.5 1,473.5 

 Outflow 1,425.1 1,425.1 1,441.9 1,441.9 1,473.5 1,473.5

Wild & Scenic

 Applied Water 30,923.0 17,321.1 6,547.6 

 Outflow 30,923.0 30,923.0 17,321.1 17,321.1 6,547.6 6,547.6

Required Delta Outflow

 Applied Water 0.0 0.0 0.0 

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 391.4 424.4 254.3 

 Evapotranspiration of Applied Water 155.7 155.7 194.4 194.4 155.3 155.3

 E&ET and Deep Perc to Salt Sink 0.4 0.4 0.4 0.4 0.1 0.1

 Outflow 111.0 111.0 115.4 115.4 67.9 67.9

 Conveyance Applied Water 0.0 0.0 0.0 

 Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Total Managed Wetlands Use 391.4 267.1 267.1 424.4 310.2 310.2 254.3 223.3 223.3

 Total Environmental Use 32,759.7 32,615.2 32,615.2 19,190.0 19,073.2 19,073.2 8,275.4 8,244.4 8,244.4

 

 TOTAL USE AND OUTFLOW 33,558.2 33,262.0 33,256.0 20,146.4 19,840.8 19,833.9 9,057.3 8,894.9 8,887.8

 

Surface Water

 Local Deliveries 537.9 537.9 534.2 592.7 592.7 588.6 340.6 340.6 336.5

 Local Imported Deliveries 2.0 2.0 2.0 3.1 3.1 3.1 17.8 17.8 17.6

 Colorado River Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 CVP Base and Project Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Other Federal Deliveries 334.5 334.5 332.2 408.7 408.7 405.9 238.2 238.2 235.4

 SWP Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 Required Environmental Instream Flow 32,187.9 32,187.9 32,187.9 18,583.6 18,583.6 18,583.6 7,933.7 7,933.7 7,933.7

Groundwater

 Net Withdrawal 187.7 187.7 187.7 240.7 240.7 240.7 352.5 352.5 352.5

 Deep Percolation of Surface and GW 76.6 94.2 100.2 

Reuse/Recycle

 Reuse Surface Water 219.6 211.4 62.2 

 Recycled Water 12.0 12.0 12.0 12.0 12.0 12.0 12.1 12.1 12.1

TOTAL SUPPLIES 33,558.2 33,262.0 33,256.0 20,146.4 19,840.8 19,833.9 9,057.3 8,894.9 8,887.8

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 

EE-RM-PET-100 C0MMENT 01A
Chapter 2 North Coast Hydrologic Region 2 13

California Water Plan Update 2005

Water Portfolios

North Coast Hydrologic Region

EE-RM-PET-100 C0MMENT 01A
California Water Plan Update 2005

2 14 Volume 3 Regional Reports

 ID North Coast North Coast North Coast

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries - - -

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon 2,104.5 1,498.0 988.0

 b Inflow From Mexico - - -

 5 Precipitation 79,216.3 50,755.1 31,254.4

 6a Runoff - Natural 53,812.0 N/A N/A

 b Runoff - Incidental N/A N/A N/A

 7 Total Groundwater Natural Recharge N/A N/A N/A

 8 Groundwater Subsurface Inflow N/A N/A

 9 Local Deliveries 537.9 592.7 340.6

 10 Local Imports 2.0 3.1 17.8

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries - - -

 12 Other Federal Deliveries 334.5 408.7 238.2

 13 State Water Project Deliveries - - -

 14a Water Transfers - Regional - - -

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water 1,445.3 1,444.5 1,473.5

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag - - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag 5.3 6.4 4.9

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture 11.7 11.7 11.7

 b Recycled Water - Urban 0.3 0.3 0.4

 c Recycled Water - Groundwater - - -

 20a Return Flow to Developed Supply - Ag 6.0 6.9 7.1

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag 46.9 61.2 72.2

 b Deep Percolation of Applied Water - Wetlands 1.2 1.3 0.7

 c Deep Percolation of Applied Water - Urban 18.7 19.7 18.5

 22a Reuse of Return Flows within Region - Ag 67.5 86.1 23.5

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S 143.3 115.5 30.3

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S - - -

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions N/A N/A N/A

 26 Surface Water in Storage - Beg of Yr 2,236.3 2,740.7 2,495.0

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 264.3 334.9 452.7

 23 Groundwater Subsurface Outflow N/A N/A N/A

 30 Surface Water Storage - End of Yr 2,938.8 2,495.0 2,003.9

 31 Groundwater Recharge-Contract Banking - - -

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation N/A N/A N/A

 b Evaporation and Evapotranspiration from Unirrigated Ag N/A N/A N/A

 35a Evaporation from Lakes 38.9 45.2 42.4

 b Evaporation from Reservoirs 167.5 181.3 162.7

 36 Ag Effective Precipitation on Irrigated Lands 271.1 183.2 144.3

 37 Agricultural Water Use 634.6 778.9 614.6

 38 Managed Wetlands Water Use 391.4 424.4 254.3

 39a Urban Residential Use - Single Family - Interior 29.4 30.4 29.1

 b Urban Residential Use - Single Family - Exterior 35.2 40.8 40.9

 c Urban Residential Use - Multi-family - Interior 13.3 13.7 14.2

 d Urban Residential Use - Multi-family - Exterior 3.7 3.8 3.9

 40 Urban Commercial Use 17.1 17.2 17.5

 41 Urban Industrial Use 30.2 31.7 31.1

 42 Urban Large Landscape 11.0 12.4 12.7

 43 Urban Energy Production - - 0

 44 Instream Flow 1425.1 1441.9 1473.5

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers 30923 17321.1 6547.6

 47a Evapotranspiration of Applied Water - Ag 449.2 551.1 444.1

 b Evapotranspiration of Applied Water - Managed Wetlands 155.7 194.4 155.3

 c Evapotranspiration of Applied Water - Urban 41.2 45.9 47.7

 48 Evaporation and Evapotranspiration from Urban Wastewater 0.2 0.2 0.2

 49 Return Flows Evaporation and Evapotranspiration - Ag 29.6 33.5 26.4

 50 Urban Waste Water Produced 75.8 79.8 78.6

 51a Conveyance Evaporation and Evapotranspiration - Urban - - -

 b Conveyance Evaporation and Evapotranspiration - Ag 6.9 7.1 4.2

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands 0.4 0.4 0.1

 d Conveyance Outflow to Mexico N/A N/A -

 52a Return Flows to Salt Sink - Ag 37.4 42.1 41.3

 b Return Flows to Salt Sink - Urban 76.3 80.8 79.5

 c Return Flows to Salt Sink - Wetlands 1.7 1.7 1.5

 53 Remaining Natural Runoff - Flows to Salt Sink 32348.1 18763 8021.1

 54a Outflow to Nevada - - -

 b Outflow to Oregon 183.7 113.7 66.4

 c Outflow to Mexico - - -

 55 Regional Imports 2.0 2.0 2.0

 56 Regional Exports 883.4 1143.5 702.5

 59 Groundwater Net Change in Storage -46.9 -28.4 -146.8

 60 Surface Water Net Change in Storage 702.5 -245.7 -491.1

 61 Surface Water Total Available Storage 3,779.9 3,779.9 3,779.9

 

 Inflows Outflows Green number signifies included in summary boxes 

Table 2-3 North Coast water portfolios (TAF)

EE-RM-PET-100 C0MMENT 01A
Chapter 2 North Coast Hydrologic Region

Figure 2-4 North Coast region - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 2-3, key components of the flow diagram are shown as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of the table’s flow diagram components; color indicates whether the component is water input, output, or summary.

52

Volume 3 Regional Reports 2 15

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
SUMMARY

OUTFLOWS

INFLOWS

Figure 2-5 North Coast region - schematic flow diagram

In schematic of Table 2-3, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates whether component is water input, output, or summary. 

Blank boxes are flow diagram components not relevant to the region. 

WILD & SCENIC RIVERS NET 

USE:

RUNOFF:

NATURAL: 

INCIDENTAL: 

PRECIPITATION: TOTAL STREAM 

FLOW: 

Sum of Known 

Quantities

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

INFLOW FROM 

OREGON:

LOCAL IMPORTED 

DELIVERIES:

LOCAL 

DELIVERIES:

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

OTHER FEDERAL 

DELIVERIES:

WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL: 

TRANSFERS:

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

 Sum of known quantities

GW EXTRACTIONS:

CONTRACT BANKS: 

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

TOTAL 

RECYCLED WATER: 

AG:

URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

AG & WETLANDS 

RETURN FLOWS:

RETURN FLOWS TO SALT 

SINKS:

AG:

WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

OUTFLOW TO OREGON: 

DEEP PERC OF APPLIED 

WATER: 

AG:

WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES: 

RESERVOIRS: 

E & ET FROM: 

NATIVE VEGETATION: 

UNIRRIGATED AG: 

RELEASES FOR 

INSTREAM USE: 

DIRECT 

DIVERSIONS:

CONVEYANCE E & ET: 

URBAN:

AG: 

WETLANDS:

CONVEYANCE RETURN 

FLOWS:

URBAN:

AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN:

AG:

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN :

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING: 

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

OTHER REGIONAL 

TRANSFER OUT: 

REGIONAL 

TRANSFER IN: 

INSTREAM NET USE: 

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN:

AG: 

WETLANDS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

1

2

5

4

3

55

6

13

11

19

12

10

9

7

20

21

45

29

26

30

35

39 to 43

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

TOTAL GROUNDWATER NATURAL RECHARGE: 

162 Chapter 2 North Coast Hydrologic Region Volume 3 Regional Reports

California Water Plan Update 2005

EE-RM-PET-100 C0MMENT 01A
Chapter 3 San Francisco Bay Hydrologic Region 

Volume 3 

EE-RM-PET-100 C0MMENT 01A
Chapter 3 San Francisco Bay Hydrologic Region 3 i

California Water Plan Update 2005

Chapter 3 San Francisco Bay Hydrologic Region

Contents

Chapter 3 San Francisco Bay Hydrologic Region .......................................................................................................3-1

Setting ................................ 3-1

Land Use ............................ 3-1

Population and Water Use ... 3-1

Water Supplies .................... 3-2

 Groundwater .................. 3-2

 Recycled Water ............... 3-3

 Role of Conservation ....... 3-3

Water Quality ..................... 3-3

Wetlands and Watershed Management ................................................................................................................3-6

State of the Region .............. 3-6

 Water Supply Reliability .. 3-7

 Water Conservation and Recycling ...................................................................................................................3-8

 Surface Storage .............. 3-8

 Desalination ................... 3-8

 Environmental Water Quality ...........................................................................................................................3-9

 Drinking Water Quality ... 3-9

 Wetlands and Watershed Management ..........................................................................................................3-10

Looking to the Future ......... 3-13

 Water Quality ............... 3-13

 Wetlands and Watershed ..............................................................................................................................3-15

Water Portfolios for Water Years 1998, 2000, and 2001 .....................................................................................3-15

Selected References ........... 3-15

Boxes

Box 3-1 Acronyms Used in San Francisco Bay Hydrologic Region ...............................................................................3-4

Box 3-2 Bay Area Water Agencies Forum .................................................................................................................3-6

Box 3-3 Ongoing Planning Organizations ..............................................................................................................3-12

Figures

Figure 3-1 San Francisco Bay Hydrologic Region ......................................................................................................3-ii

Figure 3-2 San Francisco Bay Hydrologic Region population ......................................................................................3-3

Figure 3-3 San Francisco Bay region water balance for water years 1998, 2000, 2001 (2 bar charts) ..........................3-5

Figure 3-4 San Francisco Bay region - illustrated water flow diagram .......................................................................3-19

Figure 3-5 San Francisco Bay region - schematic flow diagram ................................................................................3-20

Tables

Table 3-1 Sources of surface water imported .............................................................................................................3-4

Table 3-2 San Francisco Bay Hydrologic Region water balance summary ..................................................................3-14

Table 3-3 San Francisco Bay region water use and distribution of dedicated supplies .................................................3-16

Table 3-4 San Francisco Bay region water portfolios ................................................................................................3-18

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California Water Plan Update 2005

NAPA

SOLANO

CONTRA

COSTA

ALAMEDA

SANTA

CLARA

SAN

MATEO

MARIN

SAN

FRANCISCO

Some Statistics

 Area - 4,506 square miles (2.8% of State)

 Average annual precipitation - 25.4 inches

 Year 2000 population - 6,105,650

 2030 population projection - 7,857,360

 Total reservoir storage capacity - 746 TAF

 2000 irrigated crop area - 70,300 acres

.

.

.

.

.

.

Flow in TAF

1998

597

2000

629

2001

625

San Joaquin River Region

Contra Costa Canal

Mokelumne Aqueduct

Hetch Hetchy Aqueduct

South Bay Aqueduct (SWP)

Flow in TAF

1998

66

2000

89

2001

133

Central Coast Region

San Felipe Unit CVP

Flow in TAF

1998

32

2000

33

2001

34

North Coast Region

Sonoma Petaluma Aqueduct

Flow in TAF

1998

69

2000

72

2001

80

Sacramento River Region

Putah South Canal,

North Bay Aqueduct (SWP)

Vallejo Permit Water

Figure 3-1 San Francisco Bay Hydrologic Region

The San Francisco Bay Hydrologic Region includes the San Francisco and Suisun bays and Suisun Marsh and their drainage areas. Arrows

indicate annual flows entering and leaving the region for water years 1998, 2000, and 2001. 

Flow in TAF

1998

52,665

2000

21,751

2001

9,455

Outflow to Ocean*

*Outflow to Ocean includes Wild and Scenic Rivers, regulated flows, and estimated wastewater outflows.

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California Water Plan Update 2005

Chapter 3 San Francisco Bay Hydrologic Region

Land Use

Portions of the region are highly urbanized and include 

the San Francisco, Oakland, and San Jose metropolitan 

areas. Agricultural acreage occurs mostly in the north and 

northeast in Napa, Marin, Sonoma, and Solano counties. 

Santa Clara and Alameda counties also have significant 

agricultural acreage at the edge of the urban development. 

The predominant crops are grapes along with fruit and nut 

trees, hay production, and dairy and livestock operations. 

In the area along the ocean coastline south of the Golden 

Gate, more than half of the irrigated acres are in high-value 

specialty crops, such as artichokes, strawberries, or flowers. 

Population and Water Use

The bay region is a heavily urbanized region. From California 

Department of Finance figures, the total population of this 

hydrologic region in year 2000 was 6,106,000, with approximately half of the people residing in Alameda and Santa Clara 

counties. The Association of Bay Area Governments projects 

that even with the implementation of “Smart Growth” policies 

by local government, the nine counties that include the bay 

region will add 2 million people, 750,000 households and 

create 1.5 million jobs by year 2030. Figure 3-2 provides 

a graphical depiction of the San Francisco Bay hydrologic 

region’s total population from year 1960 through year 2000, 

with current projections to year 2030. Water use in the bay 

region is predominantly urban with more than 50 percent of the 

use residential. There are also numerous industrial users around 

the bay. Agricultural water use is a much smaller percentage 

of total water use in this region compared to other inland 

regions, such as the Sacramento River region, San Joaquin 

River region, and the Tulare Lake region. For example, in the 

San Francisco Bay region part of the Santa Clara Valley Water 

District service area, agricultural use is less than one percent 

of total water use of 383,000 acre-feet per year. However 

SCVWD does deliver about 29,000 acre-feet of agricultural 

water to customers in the Central Coast Hydrologic Region. 

Setting

The San Francisco Bay Hydrologic Region, which occupies 

parts of nine counties, extends from southern Santa Clara 

County north to Tomales Bay in Marin County, and inland 

to the confluence of the Sacramento and San Joaquin rivers 

near Collinsville (Figure 3-1). The eastern boundary follows 

the crest of the Coast Range, the highest peaks of which are 

more than 3,000 feet above sea level. Streams in the region 

flow into the bay-estuary or to the Pacific Ocean. The climate 

within the region varies significantly from west to east. Coastal 

areas are typically cool and often foggy, and inland valleys are 

warmer with a Mediterranean-like climate. Rainfall amounts 

vary among subregions and can be highly influenced by 

vegetative cover and marine influences. Although there are 

several small reservoirs and groundwater basins throughout 

this region, the primary water supplies are imported from 

other regions of the state.

The bay region boasts significant Pacific Coast marshes such 

as Pescadero marsh and Tomales Bay marshes as well as San 

Francisco Bay itself. San Francisco Bay is an estuary with a 

deep central channel, broad mudflats, and fringing marsh. 

The bay is commonly divided in to the South, Central, and 

North Bay. The North Bay is more brackish while the South and 

Central bays are more marine dominated. Suisun Marsh in 

between the North Bay and the Delta is the largest contiguous 

brackish water marsh remaining on the west coast of North 

America, providing more than 10 percent of California’s 

remaining wetlands.

The combined flows of the Sacramento and San Joaquin 

watersheds flow through the Delta and into the San Francisco 

Bay. Delta outflow interacts with tides to determine how far salt 

water intrudes from the ocean into the San Francisco Bay Estuary. The resulting salinity gradients influence the distribution 

of many estuarine fishes and invertebrates as well as plants, 

birds, and animals in wetlands areas. Delta outflow varies with 

hydrology, reservoir releases, and diversions upstream.

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Figure 3-1; provides a graphical presentation of all of the water

supply sources that are used to meet the developed water uses 

within this hydrologic region for years 1998, 2000, and 2001. 

Water Supplies

In the early 1900s, local water agencies developed significant 

imported water supplies from the Mokelumne and Tuolumne 

rivers to meet the anticipated demands. At the same time, local 

reservoirs and watersheds were being developed to capture 

surface supplies, to recharge the groundwater basins, and to 

act as terminal reservoirs for the larger projects. Later, State 

and federal water projects brought water to the northern, 

eastern, and southern parts of the region through a number of 

canals. Table 3-1 shows the sources of surface water imported. 

As additional information, Figure 3-3 presents bar charts that 

summarize all of the dedicated and developed urban, agricultural and environmental water uses and supplies within this 

hydrologic region for years 1998, 2000 and 2001.

Groundwater

Local groundwater accounts for only about 5 percent of the 

region’s average water year supply. The more heavily used 

basins include the Santa Clara Valley, Livermore Valley, Westside, Niles Cone, Napa-Sonoma Valley, and Petaluma Valley 

groundwater basins. For agencies like SCVWD, Alameda 

County Water District (ACWD), and Alameda County Flood 

Control and Water Conservation District-Zone 7 (Zone 7), 

groundwater is a critically important local supply that helps 

offset dependence on imported water supplies. (See Box 3-

1 for list of acronyms used in this chapter.) Conjunctive use 

programs have also been implemented by these agencies to 

optimize the use of groundwater and surface water resources, 

and water quality programs are in place to monitor and protect groundwater quality. Throughout the region additional 

groundwater resources continue to be investigated and developed to expand the role of conjunctive use programs.

Portions of the San Francisco Bay Region are highly urbanized and include the San Francisco (skyline in photo above), Oakland, and San Jose metropolitan 

areas. Agricult

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California Water Plan Update 2005

Recycled Water

Recycled water in the bay region is used in a full spectrum 

of applications, including landscape irrigation, industrial 

cooling, agricultural needs and as a supply to the areas 

many wetlands. Currently, nearly 50-million gallons per day 

of recycled water is produced in the bay region, and future 

planned projects have the potential to increase this amount 

to 100 mgd by the year 2020.

Role of Conservation

Urban water districts in the bay region generally are signatories 

to the Memorandum of Understanding Regarding Urban Water 

Conservation in California (MOU) that commits them to make a 

good faith effort to implement Best Management Practices (BMPs). 

In 2001, the California Urban Water Agencies issued a report 

that projected net water savings for the bay region based on 

implementation of the MOU at about 105,000 acre-feet. These 

numbers are being updated and revised by the CALFED Bay-Delta 

Water Use Efficiency Program as part of its planning process. 

The seven agencies that participate in the Bay Area Water 

Agencies Coalition—SCVWD, ACWD, Zone 7, San Francisco Public Utilities Commission (SFPUC), Contra Costa 

Water District (CCWD), East Bay Municipal Utilities District 

(EBMUD), and Bay Area Water Supply and Conservation 

Agency (BAWSCA)—recently completed a study on conservation advancement that showed that as a whole, their members 

had reduced the per capita water use by 16 percent since 

1986 and decreased total water use by 1.4 percent despite 

a 17 percent increase in population served during the same 

period. Individual agency results varied around these numbers. 

Water Quality

The San Francisco Bay Hydrologic Region is centered on the 

San Francisco Estuary and its water quality. The estuary’s 

immediate watershed is highly urbanized, resulting in contaminant loads from both point and nonpoint sources, as 

well as pollutants from the Napa, Petaluma, and Guadalupe 

rivers, the Sacramento-San Joaquin Delta, and the Central 

Valley. Bay Area residents generally receive good quality 

drinking water that varies by source and treatment. Sources 

range from high quality Hetch Hetchy and Mokelumne River 

supplies, local surface and groundwater, and variable-quality 

Delta water. Utilities that depend on the Delta for all or part 

of their domestic water supplies do meet the current drinking 

water standards, although they remain concerned about issues 

such as microbial contamination, salinity, and organic carbon. 

Figure 3-2 San Francisco Bay Hydrologic Region population 

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

9,000,000

1960 1970 1980 1990 2000 2010 2020 2030

Data from the California Department of Finance provide decadal population from 1960 to 2000 and population projection for 2030 for 

the San Francisco region.

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Box 3-1 Acronyms Used in the San Francisco Bay Regional Report

ACWD Alameda County Water District

BAWSCA Bay Area Water Supply and Conservation 

Agency 

BACWA Bay Area Clean Water Agencies

bay region San Francisco Bay Region

BMPs Best Management Practices

CALFED State and Federal Bay- Delta Authority

CCMP Comprehensive Conservation and 

Management Plan 

CCWD Contra Costa Water District 

CVP Central Valley Project

EBMUD East Bay Municipal Utility District 

mgd million gallons per day

MMWD Marin Municipal Water District 

MOU Memorandum of Understanding Regarding 

Urban Water Conservation in California 

SCVWD Santa Clara Valley Water District 

SCWA Sonoma County Water Agency

SFPUC San Francisco Public Utilities Commission

SIP Seismic Improvement Program

SMPA Suisun Marsh Preservation Agreement

SLLPIP San Luis Low Point Improvement Project 

SWP State Water Project

Zone 7 Alameda County Flood Control and Water 

Conservation District-Zone 7

Table 3-1 Sources of surface water imported

 Water Water source Operator Counties Served Water supplied to the Bay

 Conveyance Region via facility in 2000

 Facility 

Hetch Hetchy Tuolumne SFPUC San Francisco, San 

Aqueduct River Mateo, Alameda, and 259 TAF (29%)

Santa Clara counties 

Mokelumne Mokelumne EBMUD Alameda, Contra Costa

Aqueduct River counties 206 TAF (23%)

South Bay Delta DWR Alameda, 119 TAF (13%) Aqueduct (SWP) Santa Clara counties 

Contra Costa Western Delta CCWD/ Contra Costa County 117 TAF (13%) Canal CVP

San Felipe Unit Delta via San USBR Santa Clara County 89 TAF (10%) Luis Reservoir (CVP) 

North Bay Northern DWR Solano, Napa counties 36 TAF (4%) Aqueduct Delta (SWP)

Putah South Lake USBR Solano County 35 TAF (4%) Canal Berryessa

Sonoma Russian River SCWA Sonoma County 

33 TAF (4%) Petaluma

Aqueduct

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California Water Plan Update 2005

Figure 3-3 San Francisco Bay region water balance for water years 1998, 2000, 2001

0

200

400

600

800

1,000

1,200

1,400

1998 2000 2001

Thousand Acre-Feet

Instream Flow

Managed

Wetlands

Irrigated

Agriculture

Urban

0

200

400

600

800

1,000

1,200

1,400

1998 2000 2001

Thousand Acre-Feet

Reuse &

Recycle

Ground Water

State Project

Federal

Projects

Local Projects

Dedicated Water Supplies

Applied Water Uses

Three years show a marked change in amount and relative proportions of water delivered to San Francisco region’s urban and agricultural 

sectors and water dedicated to the environment (applied water, top chart), where the water came from, and how much water was reused 

among sectors (dedicated water supplies, bottom chart).

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Delta water constitutes about one-third of the domestic water 

in the bay region.

Wetlands and Watershed Management

The San Francisco Bay is one of the most modified estuaries in 

the United States. The topography, ebb and flow of the tides, 

patterns of freshwater inflows locally and from the Delta, and 

the availability and types of sediment have all been altered. 

Many new species of plants and animals have been introduced. 

These exotic and invasive species, such as the Chinese mitten 

crab and Asian clam, threaten to undermine the estuary’s food 

web and alter its ecosystem. 

Water quality has also changed over time. The character of the 

wetlands around the bay has changed dramatically. Over 75 

percent of the bay’s historical wetlands have been lost or altered 

through a variety of land use changes around the bay including filling for urban and industrial uses and the construction of 

dikes for agricultural uses. There used to be 190,000 acres of 

tidal marsh; now there are 40,000 acres with only 16,000 of 

these having been tidal marsh historically. Tidal flats have been 

reduced from 50,000 acres to 29,000 acres due to bay fill, 

erosion, tidal marsh evolution, and other factors. The total area 

covered by the bay at high tide was historically about 516,000 

acres. Now the bay covers about 327,000 acres at high tide. 

There are about 500 species of fish and wildlife associated with 

the bay lands, 20 of which are now threatened or endangered.

In recent decades, filling of the bay has slowed significantly 

due to regulatory changes and the creation of the Bay Conservation and Development Commission, a State agency 

charged with permitting activities along the shore of the bay. 

State of the Region

Some of the major water related challenges facing the San 

Francisco Bay region include improving water supply reliability 

to sustain water supplies in drought periods and other emergency 

outages, maintaining and improving drinking water quality 

across the region by continuing to meet and exceed current and 

anticipated drinking water quality standards and protecting 

drinking water sources, and improving the ecosystem health of 

San Francisco Bay. Other challenges include linking local land 

use planning with water system planning and improving water 

management planning on a regional level.

Many projects and programs are already under way to address 

these needs. However, the various parties concerned with waterrelated issues in the bay region are increasingly recognizing that 

there is also a need to develop solutions on a more collaborative 

regional or subregional basis (Box 3-2 Bay Area Water Agency 

Forums). Some of the longstanding regional planning efforts 

within the bay region are described in this section, including 

projects under way to improve water supply reliability, water 

quality and ecosystem restoration through regional partnerships. 

In addition, some of the newer water management and drinking 

water quality regional planning initiatives are described in the 

next section, “Looking to the Future.”

Box 3-2 Bay Area Water Agency Forums

ABAG-CALFED Task Force. Regional body of elected officials from local government and water districts, staff, and 

nongovernmental organizations that was formed to link planning for water supply and water supply reliability, 

water quality, and environmental protection for the Bay; support the objectives of the CALFED Record of Decision; 

and explore opportunities to improve regional cooperation. 

Bay Area Water Agencies Forum (formerly known as the Six Agencies Group). First convened in 2000 to provide a 

regular opportunity for water agency policymakers to discuss regional water policy issues and explore cooperative 

approaches to improving the quality and reliability of Bay Area water supplies. 

Bay Area Water Agencies Coalition. Established in 2002 to provide a forum and a framework for water agency 

general managers to discuss water management planning issues and coordinate projects and programs to improve 

water supply reliability and water quality. 

Northern California Salinity Coalition. Created in 2003 to advance the interests of the eight member water agencies in 

the development of local and regional efforts that will use desalination or salinity management technologies, 

practices, and approaches to improve water supply reliability for coalition members and to reduce salinity-related 

problems affecting the water supplies of the member agencies.

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California Water Plan Update 2005

Water Supply Reliability

Generally, water districts in the San Francisco Bay region 

have sufficient supplies to meet the needs of their customers 

in normal water years now and for some time into the future. 

The major water supply reliability challenges occur during 

droughts and other emergencies. Currently, during drought 

periods, locally developed water supplies are very limited, and 

imported water supplies can be short of water users needs. 

This problem is expected to worsen over time as the region’s 

urban use grows and because these imported supplies may 

be more at risk due to various other factors. For example, 

area of origin communities outside the San Francisco Bay 

region will also need more water as they grow. Water could 

be reallocated for environmental needs or Delta outflow and 

operational requirements could change, affecting the San 

Francisco Bay regions’ imported water supply. 

Some examples of future shortfall estimates are:

• Using year 2020 demand projections, SCVWD estimates 

a shortfall of approximately 66,000 acre-feet in a very 

dry year ( a repeat of 1977 drought conditions), or 

approximately 15 percent of the projected demand. 

• EBMUD, without the Freeport Project, could face projected 

dry period customer rationing of 68 percent based on 

2020 projected demand. With the proposed intake from 

the Sacramento River at Freeport, rationing would be 

reduced to 28 percent during dry periods.

The exact magnitude of drought year shortfalls and the best 

water management tools to be used to address them are 

controversial. Each district has different assumptions and 

policies that guide their planning. Different systems rely on 

water from different watersheds, so even the definition of a 

drought for planning purposes varies somewhat. However, 

drought supply reliability will continue to be a major challenge 

for water supply planning in the bay region.

The region is also prone to major earthquakes and other natural disasters that could damage and interrupt water delivery. 

Critical seismic reliability upgrades are required for some 

facilities that cross or are located on any of the three active 

earthquake fault systems (that is, San Andreas, Hayward, and 

Calaveras faults). According to SFPUC, a major earthquake 

could disrupt water supplies for up to 60 days in its system, 

which serves 2.4 million people in the bay region. In other 

areas, significant progress has already been made on seismic 

vulnerability but challenges remain. 

Each water district has plans under way to address these 

drought shortfalls and to ensure that their systems will provide 

a certain level of water service in the event of an earthquake 

or natural disaster. Details such as future projected water 

demands, supplies, and planned capital expenditures can be 

found in each district’s plans. However, there are no statistics 

that summarize the current and future expenditures planned 

region-wide or the amount of water expected to be developed 

for droughts or the expected performance region-wide in the 

event of a seismic event. This is the type of information that may 

become available through integrated resources planning. 

Some examples of projects under way to address future reliability needs are described in the following sections. In addition to the example projects listed here, there are numerous 

other efforts under way.

Seismic Vulnerability and Drought Supply Planning

• SFPUC is implementing a $4.3 billion capital improvement 

program to replace or repair aging facilities, provide 

seismic upgrades and improve water supply reliability. 

• EBMUD is nearing completion of a 10-year seismic 

improvement program. The program is a $189 million 

program to improve post-earthquake firefighting capability and water service within the EBMUD service area. 

• Zone 7 is updating its Well Master Plan so that it can more 

readily rely on groundwater to meet its normal demands if a 

seismic event disrupts the imported water delivery system.

• SCVWD is implementing and updating its integrated water 

resources plan to address water supply shortfalls and preparing a comprehensive water utility infrastructure management program to address seismic and security hazards. 

• CCWD recently completed the major components of its 

$120 million Seismic Reliability Improvements program, 

including a 21-mile Multi-purpose Pipeline, a new pumping plant at its Mallard Slough Intake, interties, and 

seismic valves. These facilities improve reliability and 

fire-fighting flows after a major earthquake. 

Groundwater

• ACWD, SCVWD, and Zone 7 have implemented conjunctive use programs within their service areas to optimize 

the combined use of groundwater and surface water 

resources. Objectives of these programs include the 

prevention of groundwater overdraft and subsidence, the 

prevention of salt water intrusion, and the development 

of an emergency groundwater storage supply.

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• To ensure that the quality of local groundwater supplies is 

not degraded, bay region water agencies actively monitor 

water quality and have implemented several groundwater 

protection measures.

• To date, the CALFED Bay-Delta Program has invested $2.4 

million in eight local groundwater projects in areas like 

Santa Clara County.

• Solano County Water Agency, ACWD, SCVWD, and 

Zone 7 have entered into agreements with groundwater 

banks outside the region. Currently 425,000 acre-feet of 

water is stored under these programs, as an additional 

water supply for droughts. Other Bay Area agencies are 

studying the potential of out-of-region groundwater banking options, as well as new conjunctive use programs. 

Conveyance and Interconnections

• EBMUD, in conjunction with the Sacramento County 

Water Agency, is preparing preliminary design documents to divert water from the Sacramento River to reduce 

customer rationing during multi-year droughts (Freeport 

Project).

• A 40-mgd intertie between the SCVWD system and the 

SFPUC system was completed recently in the City of Milpitas. EBMUD and SFPUC are also constructing another 

30-mgd treated water intertie between their systems.

• Studies are under way on the San Luis Low Point Improvement Project to address water quality and conveyance 

issues for South Bay water users and to improve the 

reliability of water supplies from San Luis Reservoir for 

the customers of the San Felipe Unit of the Central Valley 

Project including SCVWD. Additional details on the 

SLLPIP including schedule and budget can be found in 

the CALFED Bay-Delta Program Plan for the Conveyance 

Program.

Water Conservation and Recycling

Many different wastewater reclamation/recycling projects 

are under way in the Bay Region, and others are in the 

planning and environmental documentation stages. The Bay 

Area Regional Water Recycling Program (BARWRP) Water 

Recycling Project Master Plan, prepared in 1999, analyzed 

recycling for the counties of San Francisco, San Mateo, Santa 

Clara, Alameda and Contra Costa and developed a plan to 

achieve 125,000 acre-feet/year of water recycling over the 

next 10 years. 

BARWRP also had a number of recommendations to make 

regional reclamation and recycling projects more implementable including increasing public acceptance and dealing 

with environmental impacts regionally. Many of the nearterm recycling projects identified in the plan are now being 

developed, some through the use of $43 million in Bay-Delta 

program funding. BARWRP members are reviewing progress 

and updating program objectives and recommendations. A 

similar coordinated water recycling program is under way in 

the northern portion of the San Francisco Bay region.

Water conservation is generally included as a component of 

each water agency’s planning programs. Agencies are actively 

involved in implementing water conservation measures and 

raising public awareness about the need to conserve water 

supplies through more efficient practices. Water conservation 

efforts are helping to reduce water demands and conserve the 

bay region’s water supplies. To date, the CALFED Bay-Delta 

Program has invested over $15 million in 35 local water 

conservation programs.

Surface Storage

Water agencies are also studying several surface storage projects within the region and in other regions to help with drought 

relief, emergency storage, and water quality management. 

Some of the surface water storage projects under consideration 

in the region include expansion of Calaveras, Pacheco, and Los 

Vaqueros reservoirs. Calaveras Reservoir expansion is being 

studied as part of the CALFED Bay Area Water Quality and 

Supply Reliability Program to provide water supply reliability 

to SFPUC customers and potential regional partners in the Bay 

Area. Los Vaqueros expansion is being evaluated as part of the 

CALFED Program. This project is being studied both as a way 

to improve drought supply reliability and water quality for the 

Bay Region, and to provide environmental benefits to the BayDelta. Studies of the potential for expansion of Los Vaqueros are 

under way. Additional details on the schedule and budget for 

this project can be found in the CALFED Bay-Delta Program Plan 

for Storage. Expansion of Pacheco Reservoir is being considered 

by CALFED as an alternative under the SLLPIP. Additional information on this project can be found in the CALFED Bay-Delta 

Program Plan for Conveyance.

Desalination

With recent advances in technology, several water agencies in 

the Bay Region are investigating desalinization as a source to 

improve water supply reliability. Marin Municipal Water District is proposing a major new desalination project for Marin 

County using water from San Rafael Bay. EBMUD, CCWD, 

SCVWD and SFPUC are conducting a joint feasibility study for 

a desalinization plant to serve the Bay Region as an emergency 

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California Water Plan Update 2005

or dry-year supply. ACWD has built a brackish water desalination plant to produce potable water from brackish water taken 

from local aquifers.

Environmental Water Quality

The San Francisco Bay/Delta Estuary is the main focus of water 

quality issues in this region. Water and sediment in the estuary 

meet quality guidelines for most contaminants, with constituents in water meeting toxicity and chemical guidelines about 

87 percent of the time. Sediment concentrations, though, are 

more problematic, due to legacy pollutants, with only about 60 

percent of the sediment samples meeting chemical guidelines 

and passing toxicity tests. Over time, estuary water quality has 

significantly improved, for instance, with fewer toxic episodes 

and decreased silver concentrations in the south bay. Implementation of secondary treatment of domestic wastewater has 

dramatically improved the quality, especially the oxygen content, 

of the San Francisco Estuary, as has the reduction in the use of 

organophosphate pesticides. 

Major water quality issues include control of storm water, urban, 

and construction site runoff, as well as runoff and discharges 

from the vast Central Valley and Delta watershed. Legacy pollutants, such as polychlorinated biphenyls (PCBs) and mercury, 

contaminate fish in the estuary. Other water quality concerns 

include copper and nickel in the South Bay, selenium from 

Contra Costa refineries, erosion from vineyards in Napa and 

Sonoma valleys, pesticides in urban creeks generally, and 

toxicity of water and especially sediment. Habitat in the Suisun 

Marsh is threatened by increasing sedimentation. Exotic and 

invasive species, such as the Chinese mitten crab and Asian 

clam, threaten to undermine the estuary’s food web and alter 

its ecosystem. Because San Francisco Bay has several active 

seaports, discharge of ballast water and vessel wastes and 

maintenance dredging and disposal of contaminated sediments 

are water quality concerns. New contaminants are emerging 

that may be causing impacts to the aquatic ecosystem, including PBDEs (polybrominated diphenyl ethers), pyrethroid insecticides, and compounds from pharmaceuticals and personal 

care products.

The bay acts as a sediment repository, so persistent, sedimentbound contaminants, such as mercury, dioxins, PCBs, and 

organochlorine pesticides have accumulated over time. These 

compounds also bioaccumulate in the food chain, causing contamination of bay fish and endangering their consumers, including humans and wildlife. Happily, new inputs of the persistent 

sediment contaminants in the estuary are controlled as the use 

of most organochlorine pesticides and PCBs are banned, and 

the concentrations in the sediments and in organisms appear 

to be declining. The San Francisco Regional Water Quality 

Control Board is developing new regulatory requirements to 

address the mercury sources to the estuary, most significantly, 

the New Almaden mine, as well as the thousands of abandoned 

mercury and gold mine tailings in the Central Valley watershed. 

Mercury contamination in rstuary fish, such as the striped 

bass, has remained high for more than 30 years. Wetland 

restoration could increase mercury methylation processes and 

cause higher contamination in fish. State and federal agencies, 

working through the CALFED Bay Delta Program and other 

organizations, have funded a number of studies to determine 

potential effects of restoration and explore management actions 

that would decrease methyl mercury production and bioaccumulation. 

Since 1993, the San Francisco Regional Monitoring Program 

has been providing monitoring, and evaluation of the monitoring results, on water, sediment, and fish contamination issues 

in the bay. The annual conference and publication “Pulse of the 

Estuary” is produced by the San Francisco Estuary Institute and 

summarizes what is known about the estuary’s water quality 

issues. In addition to the mercury research mentioned previously, the CALFED Bay Delta Program has funded $10 million in 

projects related to water quality in the bay, including watershed 

management, pesticide use reduction, and toxicity studies. 

Outside of the San Francisco Estuary, Tomales Bay is one of 

only four commercial shellfish growing areas on the entire west 

coast. Some of the coastal watersheds of Marin and San Mateo 

counties provide important habitat for listed species of coho 

salmon and steelhead. Sediment threatens water quality and 

habitat in Bolinas Lagoon, the only wetland on the West Coast 

designated as a Wetland of International Significance by the 

U.S. Fish and Wildlife Service. 

Drinking Water Quality

The quality of domestic water supplies in the San Francisco Bay 

Region is generally excellent, but does vary by source of supply 

and method of water treatment. For instance, the source water 

quality of SFPUC’s Tuolumne River supply, EBMUD’s Mokelumne 

River supply, and local surface and groundwater supplies is generally better than that of water diverted from the Sacramento-San 

Joaquin Delta. However, even with a high quality water source, 

San Francisco recently implemented chloramine disinfection of 

drinking water, in order to reduce disinfection byproducts. In 

the CCWD service area, the storage of higher quality Delta 

water in Los Vaqueros Reservoir, as well as the implementation 

of advanced water treatment systems, has significantly improved 

water quality in that area.

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3 10 Volume 3 Regional Reports

Utilities that divert and deliver water from the Sacramento–San 

Joaquin Delta are pursuing a range of projects to protect and 

improve the quality of the water, including storing Delta water 

when it has relatively good quality, managing the watersheds, blending water from different sources, and applying 

advanced water treatment technology. For example, CCWD 

is continuing to work with local and regional agencies and 

CALFED to improve its source water quality. Projects include 

using CALFED funding to relocate agricultural drains and to 

line portions of the Contra Costa Canal that may be impacted 

by poor quality local groundwater. Utilities in Solano County 

use water blending methods to combine high quality local 

surface water with Delta water of variable quality from the 

North Bay Aqueduct. SCVWD, ACWD, and Zone 7 utilize a 

diversified portfolio of water sources, including Delta water, 

Hetch Hetchy supplies, local surface water, and groundwater. 

Starting in 2002, the SVCWD initiated major renovations 

to each of its three regional water treatment plants in order 

to provide higher quality drinking water to the residents of 

Santa Clara County. When these projects are completed in 

year 2010, the systems will switch from the current method 

of disinfection by chlorination to the use of ozone technology 

for water disinfection. 

The CALFED Bay-Delta Program has funded several efforts 

to improve water quality in the region, including the feasibility of expanding Los Vaqueros Reservoir and the San Luis 

Low Point Improvement Project (previously discussed under 

“Surface Storage” and “Water Supply Reliability/Conveyance,” respectively). The Bay Area Water Quality and Supply 

Reliability project is evaluating a broad array of cooperative 

regional projects to benefit ACWD, Zone 7, SFPUC, CCWD, 

SCVWD, EBMUD, and the Bay Area Water Supply and Conservation Agency (BAWSCA - representing the 28 wholesale 

water customers of the SFPUC). Some of the regional project 

concepts being considered in this study include the expansion of storage in Calaveras and Los Vaqueros reservoirs, 

additional recycling, additional conservation beyond existing 

urban BMPs, and desalination.

In general, groundwater quality throughout most of the region 

is suitable for most urban and agricultural uses with only local 

impairments, such as leaking underground storage tanks. 

Groundwater in the Livermore Valley and Niles Cone (southern Alameda County) basins has high levels of total dissolved 

solids, chloride, boron, and hardness; such that both Zone 

7 and ACWD are implementing wellhead demineralization 

projects to improve the quality of this groundwater supply. 

In the Santa Clara Valley region, some of the underlying 

groundwater supplies are threatened by pollutants from 

various industrial activities and historical agriculture. SCVWD 

works to protect the quality of these supplies by aggressively 

responding to pollution threats such as MTBE, PCE, TCE, and 

prechlorate. These pollution threats are individually identified 

and evaluated in order to prevent or mitigate groundwater 

contamination. Elsewhere, groundwater in Petaluma Valley 

and the Gilroy-Hollister Valley has high levels of nitrate, which 

adversely impacts the ability to use domestic wells for drinking 

water purposes. Groundwater recharge projects and the use of 

imported water have effectively halted land subsidence in most 

areas, and have successfully stopped or reversed seawater 

intrusion into aquifers around the bay.

Wetlands and Watershed Management

Although there are serious problems facing San Francisco 

Bay, its wetlands, and watershed, there has been a concerted 

effort over the last 20 years to restore the Bay. Some of the 

major planning and implementation efforts are described here. 

Expenditures to date on ecosystem restoration include $32 

million in Bay-Delta Program funding, along with significant 

local, state and federal funding. 

The Comprehensive Conservation and Management Plan, 

completed by the San Francisco Estuary Project in 1993, 

presents a blueprint of 145 specific actions to restore and 

maintain the chemical, physical, and biological integrity of 

the bay and Delta. The CCMP has been implemented over 

time by a wide variety of local, state and federal partners 

including the CALFED Bay-Delta Program. The Estuary Project 

regularly updates the priorities for CCMP implementation and 

prepares a report on the state of the estuary. In addition, the 

Estuary Project prepares Bay-Delta Report card that identifies 

many of the restoration projects under way to track progress 

implementing the CCMP. The most recent list of priorities 

identified by Estuary Project is:

• Reduce the impact of invasive species on the estuary 

through prevention, control, eradication, and education.

• Expand, restore, and protect bay and Delta wetlands and 

contiguous habitats. (These two items were both identified 

as top priorities.)

• Protect and restore watersheds, including promoting creek 

restoration, throughout the estuary.

• Create “incentives” that motivate governments, landowners, businesses and communities to protect and restore 

the estuary.

• Minimize or eliminate pollution of the estuary from all 

sources.

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California Water Plan Update 2005

• Increase public interaction with the estuary’s natural 

resources, encourage stewardship, and promote the 

values ecological processes provide to human activities 

and the effects of human activities on them.

• Continue, sustain, and expand the regional monitoring 

program to address all key CCMP issues including pollution;, wetlands including mitigation measures, watersheds, 

dredging, and sediment transport, biological resources, 

land use and flows and integrate scientific monitoring 

results into management and regulatory actions.

• Promulgate baseline inflow standards for San Francisco, 

San Pablo, and Suisun bays to protect and restore the 

estuary.

The Baylands Ecosystem Habitat Goals Report, prepared by 

the Habitat Goals Project in 1999, is a guide for restoring 

and improving the bay lands and adjacent habitats of the San 

Francisco Estuary. It provides recommendations for the kinds, 

amounts, and distribution of wetlands and related habitats 

that are needed to sustain diverse and healthy communities 

of fish and wildlife resource in the Bay. The CCMP originally 

identified the need for these types of habitat goals. The recommendations are being implemented over time through 

voluntary restoration efforts that include many local, state 

and federal partners.

The Implementation Strategy for The San Francisco Bay Joint 

Venture, prepared in 2001, identifies actions in the Habitat 

Goals Report that are consistent with the Joint Venture’s objectives. The State and federal partners in the Joint Venture are 

implementing these actions.

State, federal, and local governments, landowners, and nonprofit agencies have been working cooperatively to restore the 

San Francisco Bay estuary for a number of years in conjunction 

with these and other planning processes. Because the restoration and watershed management projects around the bay are 

so numerous, each one is not listed individually. Additional 

information can be found on websites for groups active in 

restoration such as the San Francisco Bay Joint Venture (www.

sfbayjv.org/), the Wetlands Regional Monitoring Program’s 

Wetlands Tracker (www.wrmp.org) or the Estuary Project’s 

Report Card (www.abag.ca.gov/bayarea/sfep.org). A few of 

the largest efforts are described here.

The Napa Sonoma Marsh Project is joint State, federal, and 

local project to restore 10,000 acres of wetlands and associated habitats within the former Cargill salt pond complex in 

the North Bay. It includes habitat restoration, beneficial use 

of recycled water, and improved water quality in the Napa 

River and the bay. The Bel Marin Keys and Hamilton Airfield 

projects will collectively restore over 2,400 acres of diked 

historical wetlands in the North Bay along the Marin County 

shoreline. These three projects, along with many smaller North 

Bay projects, will provide significant restoration of wetlands 

and associated uplands. In 2003, the State of California and 

the federal government approved the purchase and restoration of 15,100 acres of Cargill’s salt ponds in the South San 

Francisco Bay. 

Acquisition of the South Bay salt ponds provides an opportunity for landscape-level wetlands restoration, improving the 

physical, chemical, and biological health of the San Francisco 

Bay. The South Bay Salt Pond Restoration Project will integrate 

restoration with flood management, while also providing for 

public access, wildlife-oriented recreation, and education 

opportunities. The project will restore and enhance a mosaic of 

wetlands, creating a vibrant ecosystem. Restored tidal marshes 

will provide critical habitat for the endangered California 

clapper rail and the salt marsh harvest mouse. Large marsh 

areas with extensive channel systems will also provide habitat 

for fish and other aquatic life and haul out areas for harbor 

seals. In addition, the restored tidal marshes will help filter 

out and eliminate pollutants. Many of the ponds will remain 

as managed ponds and be enhanced to maximize their use 

as feeding and resting habitat for migratory shorebirds and 

waterfowl traveling on the Pacific Flyway. 

Flood management will be integrated with restoration planning, to ensure flood protection for local communities. Where 

feasible, flood capacities of local creeks, flood control channels, and rivers will be increased by widening the mouths of 

the waterways and reestablishing connections to historical 

floodplains. As ponds are opened to the tide, levees between 

the newly created tidal marsh and local communities will need 

to be built or enhanced to provide flood protection. 

The acquisition of such a large area of open space in the 

South Bay will allow for the provision of public access, wildlife-oriented recreation, and education opportunities, to be 

planned concurrently with restoration and flood management. 

Public uses could include creation of Bay Trail segments for 

biking and hiking, and provision of hunting and angling 

opportunities, bird watching, environmental education, and 

other recreational opportunities. 

In the Suisun Marsh, the Suisun Marsh Charter Group was 

formed in 2001 to resolve issues including recovery of 

endangered species, amendment of the Suisun Marsh PresEE-RM-PET-100 C0MMENT 01A
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3 12 Volume 3 Regional Reports

ervation Agreement (SMPA), issuance of a U.S. Army Corps 

of Engineers Regional General Permit, and implementation 

of a Suisun Marsh Levee Program. The Charter Group was 

charged with developing and analyzing a plan for the Suisun 

Marsh that would outline the actions necessary to preserve 

and enhance managed seasonal wetlands, restore tidal 

marsh habitat, implement a comprehensive levee protection/improvement program, and protect ecosystem and 

drinking water quality, consistent with the CALFED Bay-Delta 

Program’s goals and objectives. The proposed Suisun Marsh 

Plan would balance the goals and objectives of the Bay-Delta 

Program, SMPA, federal and State Endangered Species Acts, 

and other management and restoration programs within the 

Suisun Marsh in a manner that is responsive to the concerns 

of all stakeholders and is based upon voluntary participation 

by private landowners. The proposed Suisun Marsh Plan also 

would provide for simultaneous protections and enhancement 

of: (1) The Pacific Flyway and existing wildlife values in managed wetlands, (2) endangered species, (3) tidal marshes and 

other ecosystems, and (4) water quality, including, but not 

limited to the maintenance and improvement of levees.

Restoration efforts focused on the upper watershed lands 

above the baylands are also under way. A wide variety of local 

groups and agencies have watershed management initiatives 

under way. These are aimed at controlling pollution at the 

source, identifying contaminants of concern, and protecting 

watershed habitat. These are usually multi-objective efforts to 

address needs such as flood control, storm water management, habitat restoration, recreation, and open space. Local 

government agency and region-wide efforts are under way to 

control storm water runoff to Bay Region waterways, to initiate 

innovative land use development and agricultural practices 

and to improve wastewater discharges—leading to higher 

water quality for human and livestock consumption.

The Santa Clara Basin Watershed Management Initiative 

(SCBWMI) is one example of a collaborative, stakeholder 

driven effort among representatives from regional and local 

public agencies; civic, environmental, resource conservation 

and agricultural groups; professional and trade organizations; business and industrial sectors; and the general public, 

to protect and enhance the Santa Clara Basin watershed, 

creating a sustainable future for the community and the 

environment. The State Watershed Task Force recognized 

the SCBWMI as one of the top 10 watershed partnerships in 

California through Assembly Bill 2117. Its successes include 

the adoption of achievable and protective numeric standards 

for copper and nickel for lower South San Francisco Bay, 

adoption of wastewater discharge permits and multi-year 

stream maintenance permits, watershed education and outreach programs and collaborative efforts to address linkages 

between watershed management, flood protection and other 

land use and development activities.

Box 3-3 Ongoing Planning Organizations

• The Association of Bay Area Governments (ABAG) CALFED Task Force

• Bay Area Water Agencies Coalition (BAWAC) 

• Bay Area Wetlands Restoration Program 

• Bay Area Regional Water Recycling Program (BARWRP)

• Fish Passage Improvement Program 

• San Francisco Estuary Institute 

• Audubon Society – S.F. Bay Restoration Program 

• S.F. Bay Area Pollution Prevention Group (BAPPG)

• Bay Area Stormwater Management Agencies Association (BASMAA) 

• Bay Area Clean Water Agencies (BACWA) 

• San Francisco Bay Conservation and Development Commission (BCDC) 

• San Francisco Estuary Project (SFEP)

• SF Bay Area Regional Water Quality Control Board (RWQCB) – SF Bay Basin Plan

• Northern California Salinity Coalition (NCSC)

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California Water Plan Update 2005

Looking to the Future

The San Francisco Bay Hydrologic Region is home to a multitude of planning organizations that seek to identify future 

trends and the challenges that accompany them (Box 3-3 

Ongoing Planning Organizations). These groups are working 

on issues of land use, housing, environmental quality, and 

economic development, wetlands, water reliability, watershed 

management, groundwater management, water quality, fisheries, and ecosystem restoration. 

Most, if not all, of the water supply agencies in the bay region 

have undergone integrated water resource planning processes 

involving stakeholders in their regions including local land use 

planners and are implementing the adopted strategies to improve 

water supply reliability. These strategies call for the implementation of a diverse portfolio of water management actions including: conservation, recycling, desalination, conjunctive use, dry 

year transfers, banking, and storage development. 

Many local governments are now routinely evaluating or 

considering water supply plans as they conduct their land use 

planning through cooperative efforts with the agencies responsible for water supply. However, until recently, integrated water 

management planning has not been coordinated among the 

various subregions of the bay region and has not systematically combined water supply reliability, water quality, storm 

water and wastewater management, and environmental restoration planning together. A number of regional associations, 

including BAWAC, North Bay water districts, and BACWA 

are working under a Letter of Mutual Understandings that 

sets up a planning framework to develop such an integrated 

regional water management plan for the entire nine-county 

Bay Area. Parties involved in developing the report sections 

focusing on water supply and drinking water quality expect 

it to be completed by winter 2006 while efforts to compile 

other sections of the report will continue. 

This effort to develop a broad based multi-regional integrated 

water management plan for the nine-county bay region is very 

broad in its vision and scope. Although some of the regional 

agencies and organizations responsible for various aspects of 

water management have not been able to participate, others 

have joined BAWAC in this effort. 

These efforts at integrating regional water management and 

planning can benefit the bay region in many ways by facilitating implementation of innovative, cost-effective and efficient 

multi-objectives water management solutions. For instance, 

by demonstrating how recycling and water use efficiency are 

being incorporated, they can increase public support for the 

plan as a whole. Through an integrated plan, the Bay Region 

may also better compete for funding from broader sources 

such as state bond funds or federal appropriations. Some of 

the largest projects in the region will likely require multiple 

agencies to agree to participate and finance the effort. These 

types of regional agreements may be more easily reached 

with regional planning.

Efforts to develop a regional approach to water management 

can also benefit the state. As regional water management 

planning moves forward, regional information on current 

conditions and future planning is expected to become more 

readily available. This regional information will complement 

the information being developed for future California water 

plans and will be an important part of measuring the performance of the CALFED Bay-Delta Program at meeting water 

quality and supply reliability goals. It will also help the State 

and federal governments target expenditures at the highest 

priority regional needs.

Future bay region regional profiles are expected to incorporate information from integrated regional water management 

plans (IRWMP). The focus of the integrated regional water 

management plan within the San Francisco Bay Hydrologic 

Region covers the nine Bay Area counties. Areas outside 

the hydrologic boundary are developing separate plans. 

Proposition 50, Chapter 8 provides funds to assist agencies 

in developing the IRWMPs. Implementation proposals were 

submitted in July 2005 for projects that are part of the water 

supply–water quality section of the draft IRWMP.

Water Quality

Bay region water agencies have made significant investments in programs and projects to actively protect municipal 

water quality including facility upgrades, advanced treatment 

methods, watershed monitoring, groundwater monitoring and 

protection, demineralization projects, and nonpoint water 

source evaluations. More monitoring and studies are needed to 

determine the effects of contaminants, including the emerging 

contaminants, on the aquatic ecosystem of the San Francisco 

Bay. As the population continues to grow in the Bay Area, the 

control of storm water runoff, particularly from urban areas, 

will need to be improved in order to reduce contaminant loads 

to the estuary. Stricter regulatory requirements are being developed to address the major bay contaminants such as PCBs and 

mercury. However, even if all the sources of these contaminants 

were abated, it would take a very long time before sediment 

contaminants were reduced by degradation, transport to the 

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3 14 Volume 3 Regional Reports

 1998 (188%) 2000 (109%) 2001 (81%)

Water Entering the Region 

 Precipitation 11,438 6,644 4,908

 Inflow from Oregon/Mexico 0 0 0

 Inflow from Colorado River 0 0 0

 Imports from Other Regions *** 764 823 872

 Total 12,202 7,467 5,780

Water Leaving the Region 

 Consumptive Use of Applied Water *

 (Ag, M&I, Wetlands) 363 394 415

 Outflow to Oregon/Nevada/Mexico 0 0 0

 Exports to Other Regions 0 0 0

 Required Outflow to Salt Sink 23 22 20

 Additional Outflow to Salt Sink 664 727 759

 Evaporation, Evapotranspiration of Native 

Vegetation, Groundwater Subsurface Outflows, 11,146 6,234 4,795

Natural and Incidental Runoff, Ag Effective 

Precipitation & Other Outflows

Total 12,196 7,377 5,989

Storage Changes in the Region

 [+] Water added to storage

 [−] Water removed from storage 

 Change in Surface Reservoir Storage 76 -25 -56

 Change in Groundwater Storage ** -70 115 -153

Total 6 90 -209

Applied Water * (compare with Consumptive Use) 1,060 1,158 1,214

*Footnote for applied water

Consumptive use is the amount of applied water used and no longer available as a source of supply. Applied water is 

 greater than consumptive use because it includes consumptive use, reuse, and outflows. 

**Footnote for change in Groundwater Storage

Change in Groundwater Storage is based upon best available information. Basins in the north part of the 

state (North Coast, San Francisco, Sacramento River and North Lahontan regions and parts of Central 

 Coast and San Joaquin River regions) have been modeled – spring 1997 to spring 1998 for the 1998 

 water year and spring 1999 to spring 2000 for the 2000 water year. All other regions and year 2001 were 

calculated using the following equation: 

GW change in storage =

 intentional recharge + deep percolation of applied water + conveyance deep percolation - withdrawals

This equation does not include the unknown factors such as natural recharge and subsurface inflow and outflow.

 Water Year (Percent of Normal Precipitation) 

Table 3-2 San Francisco Bay Hydrologic Region Water Balance Summary - TAF

Water Entering the Region – Water Leaving the Region = Storage Changes in Region

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California Water Plan Update 2005

ocean or atmosphere, or burial under new sediment deposits. 

Continued monitoring is needed to evaluate the effectiveness of 

management actions, detect long-term trends and investigate 

emerging issues from new contaminants.

Wetlands and Watershed

With the large scale wetlands restoration under way around the 

bay, there will need to be ongoing monitoring and adaptive management to ensure that projects are meeting environmental objectives and integrating well with other water management objectives. 

 

Water Portfolios for Water Years 1998, 

2000, and 2001

The following tables present actual information about the 

water supplies and uses for the San Francisco Bay Hydrologic 

Region. Water year 1998 was a wet year for this region, with 

annual precipitation at 188 percent of average, while the 

statewide annual precipitation was 171 percent of average. 

Year 2000 represents nearly normal hydrologic conditions 

with annual precipitation at 109 percent of average for the 

San Francisco Bay region, and year 2001 reflected drier water 

year conditions with annual precipitation at 81 percent of 

average. For comparison, statewide average precipitation in 

year 2001 was 72 percent of normal. Table 3-3 provides more 

detailed information about the total water supplies available 

to this region for these three specific years from precipitation, 

imports and groundwater, and also summarizes the uses of 

all of the water supplies. The three-year Water Portfolio table, 

Table 3-4, and companion Water Portfolio flow diagrams, 

Figures 3-4 and 3-5, provide more detailed information about 

how the available water supplies are distributed and used 

throughout this region.

Table 3-3 presents the portion of the total available water 

that is dedicated to urban, agricultural and environmental 

purposes. Because most of the San Francisco Bay region is 

largely urbanized, more than 85 percent of the developed 

water is supplied for urban use. By comparison, agricultural 

use consumes roughly 10 percent of the developed water 

supply and instream flows and managed wetlands use only 2 

to 3 percent of the total dedicated water supply in this region. 

Table 3-3 also provides detailed information about the sources 

of the developed water supplies, which are primarily from 

surface water systems. For the years 1998, 2000 and 2001, 

this table shows that more than 65 percent of the region’s 

developed water supplies were imported from other hydrologic 

regions of the state.

Selected References

Water Quality Control Plan, Regional Water Quality Control Board 

Watershed Management Initiative Chapter, Regional Water 

Quality Control Board 

2002 California 305(b) Report on Water Quality, State Water 

 Resources Control Board 

Bulletin 118, California’s Groundwater, Update 2003, Department of Water Resources 

Nonpoint Source Program Strategy and Implementation Plan, 

1998-2013, State Water Resources Control Board, 

California Coastal Commission, January 2000 

Strategic Plan, State Water Resources Control Board, Regional 

Water Quality Control Boards, November 15, 2001 

“2003 Pulse of the Estuary,” San Francisco Estuary Institute

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 Applied Net Depletion Applied Net Depletion Applied Net Depletion

Water Use Water Use Water Use Water Use Water Use Water Use

1998 2000 2001

WATER USE

Urban

Large Landscape 83.7 90.8 94.6

Commercial 206.4 223.2 233.0 

Industrial 59.4 63.5 66.1

Energy Production 0.0 0.0 0.0

Residential - Interior 291.6 315.4 329.4 

Residential - Exterior 322.8 350.6 365.4 

Evapotranspiration of Applied Water 290.7 290.7 306.9 306.9 320.0 320.0

E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Outflow 632.8 632.8 692.7 692.7 722.6 722.6

Conveyance Applied Water 12.4 12.2 11.2

Conveyance Evaporation & ETAW 6.2 6.2 6.1 6.1 5.6 5.6

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 6.2 6.2 6.1 6.1 5.6 5.6

GW Recharge Applied Water 14.4 13.6 10.4

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

Total Urban Use 990.7 935.9 935.9 1,069.3 1,011.8 1,011.8 1,110.1 1,053.8 1,053.8

Agriculture

On-Farm Applied Water 90.1 108.3 119.2 

Evapotranspiration of Applied Water 69.4 69.4 83.7 83.7 91.8 91.8

E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Outflow 20.7 20.7 24.6 24.6 27.4 27.4

Conveyance Applied Water 1.4 1.4 1.2

Conveyance Evaporation & ETAW 0.7 0.7 0.7 0.7 0.6 0.6

Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

Conveyance Outflow 0.7 0.7 0.7 0.7 0.6 0.6

GW Recharge Applied Water 0.0 0.0 0.0

GW Recharge Evap + Evapotranspiration 0.0 0.0 0.0 0.0 0.0 0.0

Total Agricultural Use 91.5 91.5 91.5 109.7 109.7 109.7 120.4 120.4 120.4

Environmental

Instream

 Applied Water 23.1 21.5 20.0 

 Outflow 23.1 23.1 21.5 21.5 20.0 20.0

Wild & Scenic

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Required Delta Outflow

 Applied Water 0.0 0.0 0.0

 Outflow 0.0 0.0 0.0 0.0 0.0 0.0

Managed Wetlands

 Habitat Applied Water 6.2 6.2 6.2

 Evapotranspiration of Applied Water 3.1 3.1 3.1 3.1 3.1 3.1

 E&ET and Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Outflow 3.1 3.1 3.1 3.1 3.1 3.1

 Conveyance Applied Water 0.0 0.0 0.0

 Conveyance Evaporation & ETAW 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Deep Perc to Salt Sink 0.0 0.0 0.0 0.0 0.0 0.0

 Conveyance Outflow 0.0 0.0 0.0 0.0 0.0 0.0

 Total Managed Wetlands Use 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2 6.2

Total Environmental Use 29.3 29.3 29.3 27.7 27.7 27.7 26.2 26.2 26.2

TOTAL USE AND OUTFLOW 1,111.5 1,056.7 1,056.7 1,206.7 1,149.2 1,149.2 1,256.7 1,200.4 1,200.4

 DEDICATED WATER SUPPLIES 

Surface Water

 Local Deliveries 273.7 273.7 273.7 244.0 244.0 244.0 216.4 216.4 216.4

 Local Imported Deliveries 501.2 501.2 501.2 502.9 502.9 502.9 529.8 529.8 529.8

 Colorado River Deliveries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

 CVP Base and Project Deliveries 104.7 104.7 104.7 108.6 108.6 108.6 109.4 109.4 109.4

 Other Federal Deliveries 37.7 37.7 37.7 34.5 34.5 34.5 37.5 37.5 37.5

 SWP Deliveries 134.2 134.2 134.2 155.0 155.0 155.0 121.3 121.3 121.3

 Required Environmental Instream Flow 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Groundwater

 Net Withdrawal -17.2 -17.2 -17.2 81.8 81.8 81.8 163.6 163.6 163.6

 Deep Percolation of Surface and GW 54.8 57.5 56.3 

Reuse/Recycle 

 Reuse Surface Water 0.0 0.0 0.0

 Recycled Water 22.4 22.4 22.4 22.4 22.4 22.4 22.4 22.4 22.4

TOTAL SUPPLIES 1,111.5 1,056.7 1,056.7 1,206.7 1,149.2 1,149.2 1,256.7 1,200.4 1,200.4

Balance = Use - Supplies 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Table 3-3 San Francisco Bay Region Water Use and Distribution of Dedicated Supplies- TAF 

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California Water Plan Update 2005

Water Portfolios

San Francisco Bay Hydrologic Region

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Table 3-4 San Francisco Bay region water portfolios (TAF) 

 ID San Francisco San Francisco San Francisco

Number: Flow Diagram Component (see legend) 1998 2000 2001

 1 Colorado River Deliveries - - -

 2 Total Desalination - - -

 3 Water from Refineries - - -

 4a Inflow From Oregon - - -

 b Inflow From Mexico - - -

 5 Precipitation 11,438.0 6,643.7 4,908.0

 6a Runoff - Natural 

 b Runoff - Incidental 

 7 Total Groundwater Natural Recharge 

 8 Groundwater Subsurface Inflow N/A

 9 Local Deliveries 273.7 244.0 216.4

 10 Local Imports 501.2 502.9 529.8

 11a Central Valley Project :: Base Deliveries - - -

 b Central Valley Project :: Project Deliveries 104.7 108.6 109.4

 12 Other Federal Deliveries 37.7 34.5 37.5

 13 State Water Project Deliveries 134.2 155.0 121.3

 14a Water Transfers - Regional 1.0 1.0 0.2

 b Water Transfers - Imported - - -

 15a Releases for Delta Outflow - CVP 

 b Releases for Delta Outflow - SWP 

 c Instream Flow Applied Water 23.1 21.5 20.0

 16 Environmental Water Account Releases - - -

 17a Conveyance Return Flows to Developed Supply - Urban - - -

 b Conveyance Return Flows to Developed Supply - Ag - - -

 c Conveyance Return Flows to Developed Supply - Managed Wetlands - - -

 18a Conveyance Seepage - Urban - - -

 b Conveyance Seepage - Ag - - -

 c Conveyance Seepage - Managed Wetlands - - -

 19a Recycled Water - Agriculture 10.5 10.3 10.3

 b Recycled Water - Urban 5.7 5.9 5.9

 c Recycled Water - Groundwater 6.2 6.2 6.2

 20a Return Flow to Developed Supply - Ag - - -

 b Return Flow to Developed Supply - Wetlands - - -

 c Return Flow to Developed Supply - Urban - - -

 21a Deep Percolation of Applied Water - Ag - - -

 b Deep Percolation of Applied Water - Wetlands - - -

 c Deep Percolation of Applied Water - Urban 40.4 43.9 45.9

 22a Reuse of Return Flows within Region - Ag - - -

 b Reuse of Return Flows within Region - Wetlands, Instream, W&S - - -

 24a Return Flow for Delta Outflow - Ag - - -

 b Return Flow for Delta Outflow - Wetlands, Instream, W&S - - -

 c Return Flow for Delta Outflow - Urban Wastewater - - -

 25 Direct Diversions 

 26 Surface Water in Storage - Beg of Yr 491.3 530.5 505.7

 27 Groundwater Extractions - Banked - - -

 28 Groundwater Extractions - Adjudicated - - -

 29 Groundwater Extractions - Unadjudicated 37.6 139.3 219.9

 23 Groundwater Subsurface Outflow N/A N/A N/A

 30 Surface Water Storage - End of Yr 567.6 505.7 449.4

 31 Groundwater Recharge-Contract Banking - - -

 32 Groundwater Recharge-Adjudicated Basins - - -

 33 Groundwater Recharge-Unadjudicated Basins - - -

 34a Evaporation and Evapotranspiration from Native Vegetation 

 b Evaporation and Evapotranspiration from Unirrigated Ag 

 35a Evaporation from Lakes 10.1 10.1 9.8

 b Evaporation from Reservoirs 104.4 103.4 98.8

 36 Ag Effective Precipitation on Irrigated Lands 35.4 36.2 34.1

 37 Agricultural Water Use 90.1 108.3 119.2

 38 Managed Wetlands Water Use 6.2 6.2 6.2

 39a Urban Residential Use - Single Family - Interior 120.3 130.4 135.9

 b Urban Residential Use - Single Family - Exterior 280.0 304.3 317.0

 c Urban Residential Use - Multi-family - Interior 171.3 185.0 193.5

 d Urban Residential Use - Multi-family - Exterior 42.8 46.3 48.4

 40 Urban Commercial Use 206.4 223.2 233.0

 41 Urban Industrial Use 59.4 63.5 66.1

 42 Urban Large Landscape 83.7 90.8 94.6

 43 Urban Energy Production - - -

 44 Instream Flow 23.1 21.5 20

 45 Required Delta Outflow - - -

 46 Wild and Scenic Rivers - - -

 47a Evapotranspiration of Applied Water - Ag 69.4 83.7 91.8

 b Evapotranspiration of Applied Water - Managed Wetlands 3.1 3.1 3.1

 c Evapotranspiration of Applied Water - Urban 290.7 306.9 320

 48 Evaporation and Evapotranspiration from Urban Wastewater - - -

 49 Return Flows Evaporation and Evapotranspiration - Ag - - -

 50 Urban Waste Water Produced 560 605 631.5

 51a Conveyance Evaporation and Evapotranspiration - Urban 6.2 6.1 5.6

 b Conveyance Evaporation and Evapotranspiration - Ag 0.7 0.7 0.6

 c Conveyance Evaporation and Evapotranspiration - Managed Wetlands - - -

 d Conveyance Outflow to Mexico 

 52a Return Flows to Salt Sink - Ag 21.4 25.3 28

 b Return Flows to Salt Sink - Urban 639 698.8 728.2

 c Return Flows to Salt Sink - Wetlands 3.1 3.1 3.1

 53 Remaining Natural Runoff - Flows to Salt Sink 23.1 21.5 20

 54a Outflow to Nevada - - -

 b Outflow to Oregon - - -

 c Outflow to Mexico - - -

 55 Regional Imports 763.8 822.9 871.1

 56 Regional Exports 0.0 0.0 0.0

 59 Groundwater Net Change in Storage -70.4 114.5 -153.2

 60 Surface Water Net Change in Storage 76.3 -24.8 -56.3

 61 Surface Water Total Available Storage 746.1 746.1 746.1

 

Inflows Outflows Green number signifies included in summary boxes 

 

EE-RM-PET-100 C0MMENT 01A
Figure 3-4 San Francisco Bay region - illustrated water flow diagram

INFLOWS

SUMMARY

OUTFLOWS

8

15a,b

21

27

31

45

48

51

5

6

46

14 16

33

28

29

32

39- 43

59

50

18

9

51

34

47b

38

35

51

26

30

60

61

11

12

13

15c

54

56

7

1

4

55

10 44

36

47a

49

51

37

17

20

47c

22

25 24

31

23

2

3

52

53

19

In this illustration of Table 3-4, key components of the flow diagram are shown as characteristic elements of the hydrologic cycle. Circled numbers correspond to the identification number of the table’s flow diagram components; its color indicates whether the component is water input, output, or summary.

52

Volume 3 Regional Reports Chapter 3 San Francisco Bay Hydrologic Region 3 19

California Water Plan Update 2005

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SUMMARY

OUTFLOWS

INFLOWS

Figure 3-5 San Francisco Bay region - schematic flow diagram 

6

39to 43

In schematic of Table 3-4, key components of the flow diagram are shown as boxes and connectors in a flow chart. Circled numbers correspond to the identification number of flow diagram components in the table; box color indicates whether component is water input, output, or summary. 

Blank boxes are flow diagram components not relevant to the region. 

RUNOFF:

NATURAL: INCIDENTAL: 

PRECIPITATION: TOTAL STREAM 

FLOW: 

AG EFFECTIVE 

PRECIPITATION ON 

IRRIGATED LANDS: 

LOCAL IMPORTED 

DELIVERIES:

LOCAL

DELIVERIES:

CVP PROJECT 

DELIVERIES:

OTHER FEDERAL 

DELIVERIES:

SWP DELIVERIES: WATER DEPOSITS: 

SURFACE WATER: 

GROUNDWATER: 

RECYL & DESAL:

TRANSFERS:

TOTAL GROUNDWATER NATURAL RECHARGE: 

GROUNDWATER CHANGE IN STORAGE: 

BANKED:

ADJUDICATED: 

UNADJUDICATED: 

GW EXTRACTIONS:

CONTRACT BANKS:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

EVAPOTRANSPIRATION 

OF APPLIED WATER: 

AG:

WETLANDS:

URBAN:

WATER USE (APPLIED): 

AGRICULTURAL: 

WETLANDS:

URBAN:

RECYCLED WATER: 

AG: URBAN:

GW: 

URBAN

WASTEWATER 

PRODUCED:

INCIDENTAL E & ET 

AG RETURN FLOWS: 

RETURN FLOWS TO SALT 

SINKS:

AG: WETLANDS:

URBAN:

REMAINING NATURAL 

RUNOFF

FLOW TO SALT SINKS: 

DEEP PERC OF APPLIED 

WATER: 

AG: WETLANDS:

URBAN:

RETURN FLOW TO 

DEVELOPED

SUPPLY: 

AG:

WETLANDS:

URBAN:

EVAP FROM: 

LAKES:

RESERVOIRS:

E & ET FROM:

NATIVE VEGETATION: 

UNIRRIGATED AG: 

RELEASES FOR 

INSTREAM USE: 

WATER 

TRANSFERS:

REGIONAL:

CONVEYANCE E&ET, 

RETURN FLOWS, & 

SEEPAGE:

URBAN: AG:

WETLANDS:

CONVEYANCE E & ET: 

URBAN: AG:

WETLANDS:

CONVEYANCE RETURN 

FLOWS:

URBAN: AG:

WETLANDS:

CONVEYANCE SEEPAGE: 

URBAN: AG:

WETLANDS:

RETURN FLOW FOR 

DELTA OUTFLOW: 

AG:

WETLANDS:

URBAN : 

EVAPORATION AND EVAPOTRANSPIRATION OF APPLIED WATER, 

PRECIPITATION AND CONVEYANCE: 

GW RECHARGE:

CONTRACT BANKING:

ADJUDICATED BASINS: 

UNADJUDICATED BASINS: 

TO E & ET: 

SUBSURFACE GW 

INFLOW: 

SUBSURFACE 

GROUNDWATER 

OUTFLOW: 

OTHER REGIONAL 

TRANSFER OUT: 

REGIONAL

TRANSFER IN: 

INSTREAM NET USE:

AG & WETLANDS 

RETURN FLOWS:

SURFACE WATER IN 

STORAGE: 

 Beg of Yr: 

End of Yr: 

DIRECT 

DIVERSIONS:

Service Area

Return 

Flow within

Return of

Required Instream 

Flows

Return of

Required Wild & 

Scenic Flows

1

2

5

4

3

55

13

11

19

12

10

9

20

21

45

29

26

30

35

37

38

53

54

46

14

34 36

28

52

16

24

17

18

25

47

50

49

48

27

31

32

33

23

8

15C

15A

15B

56

44

16

51

22

TOTAL GROUNDWATER NATURAL RECHARGE: 

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3 20 Chapter 3 San Francisco Bay Hydrologic Region Volume 3 Regional Reports

California Water Plan Update 2005

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Chapter 4 Central Coast Hydrologic Region 

Volume 3 

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i4

California Water Plan Update 2005

Chapter 4 Central Coast Hydrologic Region

Chapter 4 Central Coast Hydrologic Region

Contents

Chapter 4 Central Coast Hydrologic Region ..............................................................................................................4-1

Setting ................................ 4-1

Climate ............................... 4-1

Population .......................... 4-3

Land Use ............................ 4-4

Water Supply and Use ......... 4-5

State of the Region .............. 4-7

 Challenges ..................... 4-7

 Accomplishments ............ 4-9

Relationship with Other Regions .........................................................................................................................4-10

Looking to the Future ......... 4-11

Regional Planning ............. 4-11

Water Portfolios for Water Years 1998, 2000, and 2001 .....................................................................................4-11

 Water Year 1998 .......... 4-11

 Water Year 2000 .......... 4-12

 Water Year 2001 .......... 4-14

Selected References ........... 4-15

Box

Box 4-1 Ongoing Planning Efforts ..........................................................................................................................4-11

Figures

Figure 4-1 Central Coast Hydrologic Region (map) ....................................................................................................4-ii

Figure 4-2 Central Coast Hydrologic Region population .............................................................................................4-3

Figure 4-3 Central Coast region water balance for water years 1998, 2000, 2001 (2 bar charts) .................................4-6

Figure 4-4 Central Coast region - illustrated water flow diagram ..............................................................................4-19

Figure 4-5 Central Coast region - schematic flow diagram .......................................................................................4-20

Tables

Table 4-1 Central Coast Hydrologic Region water balance summary ...........................................................................4-8

Table 4-2 Central Coast region water use and distribution of dedicated supplies ........................................................4-13

Table 4-3 Central Coast region water portfolios .......................................................................................................4-18

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