California's average annual water supplies are generally adequate for today's average annual demands. However, during drought, present supplies are insufficient to meet present demands, as illustrated by the 2.7-maf shortage shown in the 1990 level drought scenario under D-1485 criteria for Delta supplies. In the 1991 and 1992 drought years, shortages caused urban mandatory water conservation (rationing), agricultural land fallowing and crop shifts, reductions in environmental flows, and short-term water transfers. As shown in the California Water Budget, Table ES-7, and in the California Water Balance, Figure ES-9, water shortages exist today.
As a result of altered water project operations to comply with biological opinions and the CVPIA, supplies for areas of the State relying on Delta exports are becoming more unreliable. EPA's (and other) proposed water quality standards could also reduce total water supply for urban and agricultural use by a range of 500,000 af to 1 maf in average years and 2 to 3 maf in drought years. While these amounts do not include potential reductions in Delta exports due to "take limits" under the biological opinions, they basically fall within the 1- to 3-maf range for proposed additional environmental demands. Such uncertainty of water supply delivery and reliability will continue until issues involving the Delta and other long-term environmental water management concerns are resolved.
Water managers are looking into a wide variety of management actions to supplement, improve, and make better use of existing resources. The single most important one will be solving key issues in the Delta. Some options for addressing the shortages and improving California's supply reliability are summarized here. After presenting the options, some local water supply and management issues (detailed in Volume II of the bulletin) are highlighted.
Bulletin 160-93 presents both long-term and short-term supply augmentation and demand management options for meeting future needs. Included are short-term drought management options (demand reduction through urban rationing programs or water transfers that reallocate existing supplies through use of reserve supplies and agricultural land fallowing programs) and long-term demand management and supply augmentation options (increased water conservation, agricultural land retirement, additional waste water recycling, benefits of a long-term Delta solution, more conjunctive use programs, and additional south-of-the-Delta storage facilities). Future water management options are presented in two levels to better reflect the status of investigations required to implement them. Table ES-8 shows Level I demand management options, and Table ES-9 lists Level I water supply options.
If all Level I options were implemented, there would still be a potential shortfall in annual supplies of about 2.1 to 4.1 maf in average years and 2.9 to 4.9 maf in drought years by 2020 that must be made up by Level II water supply augmentation and demand management programs. Table ES-10 shows California's water supplies with Level I water management programs. Table ES-11 lists Level II water management options.
After accounting for future reductions of 1.3 maf in net water demand resulting from implementation of urban Best Management Practices, agricultural Efficient Water Management Practices, and after accounting for another 100,000-af reduction due to future land retirement, forecasted 2020 net demand totals roughly 65.7 maf in average years and 55.3 maf in drought years. These demand amounts could increase by 1 to 3 maf, depending on the ultimate outcome of the CVPIA, the biological opinions, and other actions being taken to protect Delta water quality or threatened species.
By 2020, without additional facilities and improved water management, annual shortages of 3.7 to 5.7 maf could occur during average years, again depending on the outcome of various actions discussed in Chapter 1. Average year shortages are considered chronic and indicate the need for implementing long-term water supply augmentation and demand management measures to improve water service reliability. Similarly, by year 2020, annual drought year shortages could increase to 7.0 to 9.0 maf under D-1485 criteria, also indicating the need for long-term measures in addition to short-term drought management measures.
Water shortages would vary from region to region and sector to sector. For example, the South Coast Region's population is expected to increase to over 25 million people by 2020, requiring an additional 1.8 maf of water each year. Population growth and increased demand, combined with a possibility of reduced supplies from the Colorado River, mean that the South Coast Region's annual shortages for 2020 could amount to 400,000 af in average years and 1 maf in drought years. All told, forecasted shortages will be larger if solutions to complex Delta problems are not found, proposed local water management programs are not implemented, and additional facilities for the SWP are not constructed.
Local surface water development includes direct stream diversions as well as supplies in local storage facilities. As a result of economic, environmental, and regulatory obstacles, local agencies are finding it difficult to undertake new water projects to meet their needs where supply shortfalls exist or are forecasted. Thus, many local and regional water agencies are advocating or implementing incentive programs for water conservation to reduce demand where such programs are cost effective. Implementation of urban Best Management Practices and agricultural Efficient Water Management Practices will reduce demands in the future, and reductions caused by these practices were incorporated into Bulletin 160-93 water demand forecasts to 2020. Following are highlights of some local water supply issues covered in Volume II of the bulletin.
In the North Coast Region, a number of smaller communities have continuing water supply reliability problems, often related to the lack of economic base to support water management and development costs. Small communities along the coast, such as Moonstone, Smith River, and Klamath, either experience chronic water shortages or have supplies inadequate to meet projected growth. Water use is already low due to conservation, so most of these problems will have to be solved by either constructing or upgrading community water systems.
In the San Francisco Bay Region, Marin Municipal Water District has relied, in part, on imported supply from Sonoma County Water Agency and extensive conservation efforts by its customers to ensure adequate supplies throughout the recent drought. Under 2025 demand conditions, without supplemental supplies, the district estimates a 40-percent deficiency once every 10 years. To improve reliability, MMWD has negotiated an agreement with SCWA to import an additional 10,000 af. This supplemental supply, in conjunction with the district's water conservation and water management plans, should limit water shortages to about 10 percent once every 10 years.
Imported supplies by the City of San Francisco, Santa Clara Valley Water District, and East Bay Municipal Utilities District also suffered deficiencies during the recent drought. During 1991, the City of San Francisco was able to reduce expected rationing from 45 to 25 percent through purchases of 50,000 af from the 1991 State Drought Water Bank and 20,000 af from Placer County Water Agency. Customers were still required to reduce indoor use by 10 percent and outdoor use by 60 percent. During 1989-91, Santa Clara Valley Water District was able to get through with 25 percent rationing by purchasing 69,000 af from Yuba County, 14,000 af from Placer County and 20,000 af from the State Drought Water Bank.
Water supplies in much of the Central Coast Region are greatly dependent upon the region's ground water basins; the storage in these basins is small and fluctuates from year to year. Since ground water and limited local surface supplies are its primary source of water, the region is vulnerable to droughts. As ground water extractions exceed ground water replenishment, several of the region's coastal aquifers are in overdraft, allowing sea water intrusion. The recent drought required many communities in the region to implement stringent water conservation programs. The cities of Santa Barbara and Morro Bay constructed sea water desalination plants to improve their water service reliability.
The South Coast Region is home to more than one half of the State's population, 16 million people. The region's population is expected to increase to more than 25 million people by 2020. Such growth poses several critical water supply difficulties, most notably increased demand with limited ability to increase supply. Further, imports from Mono Lake tributaries, Owens Valley, and the Colorado River will be reduced and limits placed on Delta exports could further reduce water service reliability in the South Coast Region. MWDSC has several programs in progress to improve its water delivery and supply capability, including the construction of Domenigoni Valley Reservoir, and supports improved Delta transfer capabilities to improve reliability of its SWP supplies.
Court ordered restrictions on diversion from the Mono Basin and Owens Valley in the South Lahontan Region have reduced the amount of water the City of Los Angeles can receive. These restrictions affect South Coast Region supplies while improving the reliability of supplies for meeting environmental needs in the South Lahontan Region.
Sacramento River Region water users are concerned about protecting their area's ground water resources from export. Organized ground water management efforts in the region are currently under way in Butte, Colusa, Glenn, Shasta, Tehama, and Yolo counties. Also, several foothill areas that rely heavily on ground water are finding those supplies limited. With many people relocating to these areas, concern about ground water availability and the potential for its contamination is increasing.
Flood protection is another major concern for the region, especially along the Sacramento and American rivers near Sacramento. In 1991, the U.S. Army Corps of Engineers completed a feasibility report and environmental documentation for a flood detention dam at the Auburn site in combination with levee modification along the lower American River to increase flood protection for the Sacramento area. The report, however, generated much controversy over whether Auburn Dam should be a flood detention only (dry dam) or multipurpose dam.
Foothill areas of both the San Joaquin River and Tulare Lake regions share the Sacramento River Region's problem of limited water supplies. Major concerns for this region's agricultural community are agricultural drainage disposal and treatment costs and potential reduction of imported supplies. CVP supplies will be reduced by the CVPIA, and both the CVP and SWP supplies are affected by ESA biological opinions and other actions proposed to protect Delta water quality and fisheries. Ground water overdraft in these regions will most likely increase because formerly-available surface supplies that recharged ground water basins may not return to former amounts.
In the North Lahontan Region years of disputes over the waters of the Truckee and Carson rivers led to the 1990 enactment of the Truckee-Carson-Pyramid Lake Water Rights Settlement Act. This federal act makes an interstate allocation of the rivers between California and Nevada, provides for the settlement of certain Native American water rights claims, and provides for water supplies for specified environmental purposes in Nevada. The act allocates to California: 23,000 af annually in the Lake Tahoe Basin, 32,000 af annually in the Truckee River Basin below Lake Tahoe, and allocations corresponding to existing water uses in the Carson River Basin. Provisions of the Settlement Act, including the interstate water allocations, will not take effect until several conditions are met, including negotiation of the Truckee River Operating Agreement required by the act.
Water exports from the South Lahontan Region have been the subject of litigation since the early 1970s. In 1972, the County of Inyo sued the City of Los Angeles claiming that increased ground water pumping for export was harming the Owens Valley. Consequently, the City of Los Angeles and Inyo County implemented enhancement projects to mitigate the impacts of ground water pumping. In 1989, the parties reached agreement on the long-term ground water management plan for Owens Valley and the EIR was accepted by the court.
Another long standing issue is the Los Angeles Department of Water and Power diversions from Mono Lake tributaries and the impact of these diversions on the lake level. As a result of extensive litigation between the City of Los Angeles and a number of environmental groups, LADWP is now prohibited by court order from diverting from the tributaries until the lake level stabilizes. SWRCB concluded Mono lake water rights hearings in February 1994. A draft decision regarding lake levels and stream flows on the four tributaries is expected in late 1994. The Mono-Owens system provided 17 percent of LADWP's water supply and 1.5 percent of its hydroelectric energy supply. Replacement water and energy are being sought. One source of replacement water will be four water reclamation projects to be funded by the Environmental Water Fund, which was created by the Legislature in 1989 to fund projects mutually agreed upon by LADWP and the Mono Lake Committee.
The Colorado River Region faces increasingly difficult
issues involving water quality. In the late 1960s, 1970s, and early 1980s,
the Salton Sea suffered from high water levels caused by increased agricultural
runoff, treated urban waste water, and above average rainfall. In 1984, the
State Water Resources Control Board adopted Water Right Decision 1600, which
required Imperial Irrigation District to prepare a conservation plan and take
other steps to improve its delivery system. Following a 1988 SWRCB order, IID
implemented a program with funds provided by MWDSC to conserve water. The sea
level has stabilized somewhat during recent years, due in part, to IID's conservation
measures. The Salton Sea dilemma illustrates the complexity and opportunities
for cooperative solutions of water management issues in California.
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