The reliability of water supplies in each of California's ten major hydrologic regions depends on the climate, geography, patterns of water use specific to each region, the abundance of local supplies, and in some cases the availability of imported supplies. California's water supply network is a sophisticated system with many interconnections, giving local and regional water planners a wide array of options from which to meet needs. If a region cannot manage water demand through demand management actions or find sufficient water supplies within its borders, it often goes beyond those borders and imports water from, or shares water with, other regions. Conjunctive use, water banking, water marketing, conservation, water recycling, and conventional supply augmentation projects are all options that can be employed individually or collectively because of supply network flexibility.
Whenever a region looks outside of its borders for water supply augmentation, statewide water management and integrated resource planning come into the picture. Depending on the package of options chosen, one region's actions can affect another region's supplies. The statewide planning process involves assessing trends in each region's water demand and quantifying the cumulative effects of each region's demand and use patterns on statewide supplies. It basically parallels the planning process at the local and regional levels. By working through a statewide planning process, the magnitude of both intraregional and interregional effects can be analyzed. However, in a number of circumstances, measures that would be taken to manage demand, to increase supplies, and to improve water service reliability are local decisions. These decisions must weigh the cost of increased reliability with the economic, environmental, and social costs of expected shortages.
Planners at the local and regional levels face the same increasingly difficult issues that statewide planners face: the pressures of a continually growing population on existing supplies, more stringent regulatory requirements, environmental consequences of developing new sources of supply, and the increasing costs of implementing new programs or projects. To plan for long-term water supply reliability, these planners must examine an increasingly wide array of supply augmentation and demand reduction options to determine the best courses of action for meeting water service needs. Such options are generally evaluated using the water service reliability planning approach outlined below. This chapter also summarizes Level I and Level II water management options for enhancing water supply reliability.
Water service planners now evaluate demand management options in much the same way that supply augmentation options were evaluated in traditional benefit/cost analyses completed for many of the State's existing major water supply facilities. For the California Water Plan Update, future long-term demand management options are those that go beyond the actions included in urban Best Management Practices or agricultural Efficient Water Management Practices. (See Chapters 6 and 7 for a discussion of BMPs and EWMPs.) These long-term options also go beyond retiring unproductive agricultural land. The costs of demand management or supply augmentation options to reduce the frequency and severity of shortages are now high enough that planners must also look more carefully at the costs of unreliability to make the best possible estimate of the net benefit of taking specific actions, hence the term "reliability planning." Reliability is a measure of a water service system's expected success in managing drought shortages.
The objective of reliability planning is to determine the most effective way of achieving an additional increment of reliability at the least cost and to ascertain whether the benefits, in terms of avoided shortage#related costs and losses, justify the costs of adding that increment. Reliability planning requires information about: (1) the expected frequency and severity of shortages; (2) how additional water management measures are likely to affect that frequency and severity of shortages; and (3) how available contingency measures can reduce the impact of shortages when they occur. The approach also uses information about the costs and losses associated with shortages of varying severity and duration as well as the costs of long-term and contingency water management options. Outlined below are the principles on which water service reliability planning is based:
Plans based on these principles are more likely to achieve the best balance between the costs of increasing reliability and the benefits of reducing the frequency and severity of shortages.
Surface and ground water reservoirs provide for water supply reliability through carryover storage. The success of these facilities in ensuring water availability depends on a number of factors, including storage capacity, precipitation, use in previous years, and forecasted use in future years. Use in previous years is a function of demand and decisions made by operators of the reservoir facilities. When water project planners and operators choose to restrict reservoir releases or ground water pumping to reduce the risk of shortages in the future, the cost of imposing a shortage in the current year is traded against the expected cost of future shortages. They use records of historic hydrologic conditions and trends to forecast future conditions and base their decisions about the amounts and timing of releases on these predictions.
In addition to climate, other factors that can cause water supply shortages are earthquakes, chemical spills, and energy outages at treatment and pumping facilities. Planners should also include the probability of catastrophic outages when using the reliability planning approach.
Reliability planning, used in conjunction with the Least Cost Planning process, offers water managers the best opportunity to identify how to integrate demand management and supply augmentation options into their planning process in the most productive and justifiable manner. The use of this planning process to evaluate alternative water management plans for enhancing an existing system's reliability involves the following steps:
Water management programs for the SWP, the East Bay Municipal Water District, and the Metropolitan Water District of Southern California are examples of programs based on this planning process. (See the SWP and Local Water Management Programs sections under Level I Reliability Enhancement Options.)
Figure 11-1 shows the basic concept of how the alternative plans are compared, and an optimal plan for increasing water service reliability is identified. Each of the alternative water management plans that have been analyzed using the least-cost process are arrayed according to their water management costs. Plan 1 represents existing conditions (no additional water management actions). In this example, the least-cost plan is Plan 8. Water management expenditures lower than those in Plan 8 would expose the local area to higher shortage-related costs and losses than would be necessary. Water management expenditures higher than those of Plan 8 do not "pay for themselves" in terms of reduced shortage-related costs and losses.
California's increasing urban and environmental water needs require that existing supplies be more efficiently managed while programs are developed and implemented to provide for future water supply needs. Water management plans by State and local agencies can increase reliability through long-term or contingency measures, or both. Long-term measures reduce the expected frequency and severity of shortages, and contingency measures reduce the impacts of shortages when they occur. Three pieces of legislation were enacted to encourage agencies to develop plans based on all available water management options: the Urban Water Management Planning Act of 1983; the Agricultural Water Management Planning Act of 1986; and the Water Shortage Contingency Planning Act of 1991. (See Chapter 2, Institutional Framework.) Under the auspices of these acts, DWR is working with local agencies in developing those plans.
Demand management and water supply augmentation options for meeting California's water needs to 2020 are summarized below. They are broken down into long-term and short-term demand management measures, available to water agencies to meet average and drought year needs, and long-term water supply management options. The future water management programs are presented in two levels to better reflect the status of investigations required to implement them.
The following sections describe Level I options in detail; Level II options are described in general conceptual terms. The options are ordered according to whether they reduce demands or augment supplies at the statewide, regional, or local level. Options for solving complex problems in the Delta and improving Delta water quality for urban water purveyors are discussed in Chapter 10, The Sacramento-San Joaquin Delta.
Demand management options discussed here are water management actions designed to permanently reduce demand for water (water conservation and land retirement). Table 11-1 shows demand reductions possible from Level I demand management programs.
Water Conservation. Californians began recognizing and acting on the need for demand management through water conservation during the 1976-77 drought. Since then, much attention has been focused on plans, programs, and measures to encourage more efficient use of water. The latest of such programs are: Best Management Practices, as adopted by over 100 major urban water agencies and environmental groups, and Efficient Water Management Practices under consideration for agricultural water conservation and management. (See Chapter 6, Urban Water Use, or Chapter 7, Agricultural Water Use.) The widespread acceptance of BMPs virtually assures that they will become the industry standard for water conservation programs. As urban water costs increase, urban users will have a strong incentive to accelerate implementation of BMPs. Accepted future BMPs (measures that are accepted by urban agencies for future implementation) are expected to reduce future urban water demands by about 10 percent; this would result in an annual 1.3 maf reduction in urban applied water by 2020 and a reduction in depletions of approximately 0.9 maf. These amounts are in addition to an estimated 0.4 maf annual savings resulting from conservation measures put in place between 1980 and 1990.
Increases in agricultural water use efficiency and other EWMPs will reduce future agricultural applied water demands. These measures could result in an annual agricultural applied water reduction of about 0.7 maf by 2020 (from 1990 level), which would result in an annual depletion reduction of roughly 0.3 maf. However, it should be noted that where both surface and ground water are used, increased agricultural water use efficiency may decrease ground water recharge and thus reduce sustainable yield.
Water savings from conservation have been accounted for in projections of agricultural and urban water demand. New water conservation measures will undoubtedly be suggested and evaluated in the future. (See Level II options.) However, as water use continues to become more efficient, water agencies will lose some flexibility to deal with shortages during droughts.
Land Retirement. Land retirement will take place in parts of the San Joaquin Valley where drainage disposal has been a problem and where continued cultivation of some marginal lands will not be feasible. A Management Plan for Agricultural Subsurface Drainage and Related Problems on the Westside San Joaquin Valley, September 1990, evaluated the drainage problems in the San Joaquin Valley and recommended a plan of action to resolve the drainage problems on the west side of the valley through the year 2040. The recommendations included source control (water conservation), reuse of drainage water, and land retirement. For this water plan update, and for the purpose of agricultural water demand calculations, it was assumed that source control and land retirement recommendations would be implemented. The 1990 report suggests 45,000 acres of land on the westside of the San Joaquin Valley could be out of production by 2020 and about 70,000 acres by 2040. These amounts are accounted for in agricultural acreage projections. The net water demand reduction resulting from land retirement could be about 0.13 maf. To facilitate this option, the Central Valley Project Improvement Act provides federal authority and possible sources of funding for land retirement. At the State level, the San Joaquin Valley Drainage Relief Act provides DWR with authority to undertake a program of retiring lands with drainage problems.
Water Transfers. Year-to-year water transfers can augment a water agency's long-term annual supplies to improve the water service reliability for the receiving area. Such transfers have been going on since early this century as evidenced by the construction of several major intrastate transfer facilities described in Chapter 3. The 1987-92 drought caused some water agencies and individuals to begin looking at the potential of a water transfers market to meet water needs by augmenting long-term supplies as well as short-term drought supplies. (Long-term transfers are ones that can augment a year-to-year supply of a water-short area, while short-term drought water transfers can take place by either long-term or spot market agreements.) However, areas looking to the water transfer market for long-term supplies need an element of predictability. Uncertainties of Delta transfer capabilities now and in the foreseeable future make it difficult to predict transfer capability of the system.
The State Drought Water Bank experience was a good indication that obstacles to market-based water transfers can be overcome. However, as more and more willing buyers and sellers got together, problems in completing such deals became more apparent. In response to such problems, the California Legislature has enacted and the Governor has signed several pieces of legislation that should facilitate market#based water transfers. Additional market-based water transfer legislation continues to be introduced with the hopes of further removing impediments to such transfers. The CVPIA is an example of federal legislation that will help facilitate water transfers in California, particularly those involving federal supplies.
In some source areas of transfer supplies, such as the upper Sacramento Valley, there is concern that the health of local economies and environment are at risk if long-term water transfers are allowed. The same concerns have also been expressed in areas where the source supply is imported but is allowed to be resold in the transfer market. To address these concerns, long-term water transfers must be treated as any other water management option and be planned with a thorough investigative analysis, including alternatives, third-party impacts, and environmental documentation in accordance with CEQA. A good example of a recent long-term transfer that underwent this type of process is the long-term (permanent) year-to-year transfer of 12,700 af of State Water Project entitlement supply from Devils Den Water District, on the west side of the San Joaquin Valley, to Castaic Lake Water Agency, in the South Coast Region.
There is only one long-term water transfer agreement far enough along in its development to be considered a Level I option. This transfer would be made possible by an agreement recently negotiated between the Metropolitan Water District of Southern California and the Imperial Irrigation District. In 1988, Public Law 100-675 was enacted authorizing the lining of a portion of the All-American Canal and its Coachella branch. The act allowed the California water agencies with Colorado River water delivery contracts to fund the project in exchange for the water conserved in accordance with the provisions contained in their water delivery contracts and P.L. 100-675. USBR, Imperial Irrigation District, and MWDSC have been investigating possible alternatives for recovery of an estimated 68,000 af of seepage water through preparation of environmental documentation. In August 1993, the IID and Coachella Valley Water District boards of directors entered into an agreement with MWDSC relating to the concrete lining of 23 miles of the All-American Canal. The agreement is being negotiated among the parties. When the Secretary of the Interior issues a record of decision upon review of the final EIS/EIR, and when IID's, MWDSC's, CVWD's, and Palo Verde ID's boards approve entering into a construction funding agreement, this program can be implemented, and MWDSC's supplies could be enhanced by about 68,000 af per year.
Apart from the MWDSC-IID transfer agreement, there are no other future long-term, year-to-year water transfers far enough along in the planning process to be considered Level I options; thus, the California water budget in Chapter 12 does not include any provision for additional Level I, long-term, year-to-year water transfers. Such transfers and factors affecting their feasibility are considered as part of the Level II water management options.
Short-term demand management options are actions taken by water managers to reduce water demand during drought. For this report, the "drought year" scenario was defined as a water year when statewide water supplies equal the average supplies of 1990 and 1991. Drought management options (mandatory conservation and land fallowing) are implemented by water managers during drought years to ensure water service reliability for critical needs during drought. Critical needs include maintaining public health and safety, providing for industrial and commercial uses, preserving permanent crops such as trees and vines, saving high-investment crops such as cut flowers and nursery products, and ensuring the survival of fish and wildlife species.
Demand Reduction. For this water plan update, a shortage of 15 percent for the urban sector during a 1990 level drought is used as a drought contingency measure. The 15-percent level reflects the actual 1990 urban water use experience for areas in California impacted by moderate shortages. It was chosen as a management planning tool for drought periods to illustrate its potential as an option rather than as an action that could impose severe hardships on affected communities. Most of the urban areas which implemented special conservation programs during the recent drought achieved cutbacks at or above this level. However, it does not mean that every type of urban water user within an area had similar cutbacks. Generally, most business users had smaller cutbacks than residential users, reflecting local water agencies' actions to avoid or minimize adverse economic and employment impacts. DWR studies indicate that some individual sectors of local economies, such as the green industry, suffered substantial income and employment losses in 1991. (The "green industry" includes nurseries, self-employed gardeners, landscapers, and landscape-related businesses.) However, from a statewide perspective, a shortage of 15 percent, based on the 1990#91 drought experience, is considered manageable at the 1990 level for drought events which would occur about once every 20 years.
As more conservation measures such as BMPs are developed and implemented in the future, a 15-percent shortage criterion will become more difficult to implement because of the increased efficiency in overall urban water use. These increases in efficiency mean that current drought contingency measures will be less productive in the future because opportunities to further reduce or eliminate water use (for example, putting displacement bags in more toilet tanks or installing more low-flow shower heads), for the most part, will have been exhausted. Consequently, smaller water supply shortages can result in greater adverse impacts. By 2020, the 1990 level of 15 percent would be reduced to a 10-percent voluntary or mandatory shortage criterion for urban applied water use, while implementing urban BMPs would reduce water demand by 10 percent for a total demand reduction of 20 percent in 2020 during drought years. Potential future measures, such as urban rationing programs and changing water price rate structures, while not mandated by the State, are assumed to be implemented during drought periods to attain the overall 10-percent cutback.
This demand management option is considered a Level I program because it generally doesn't require extensive investigations to implement. However, many water agencies object to this being a Level I option because prudent planning already requires that agencies thoroughly investigate the costs of shortages and reduce or eliminate such shortages based on their water conservation plans, supply availability, and other relevant factors. Figure 11-2 shows the relationship between drought contingency measures and BMPs. Urban demand reductions from drought contingency measures could be about 1.2 maf in drought years by 2020. However, such programs will vary from region to region depending on each region's water service reliability needs. During less frequently occurring and more severe droughts (that is, an event that occurs once every 100 years), much greater shortages could occur, causing substantial economic impacts to urban and agricultural areas and impacts on fish and wildlife.
Short-Term Water Transfers. Short-term water transfers can be an expedient means of alleviating the most severe impacts of water shortages during drought. Such transfers generally reallocate existing supply and can enhance water service reliability in the areas receiving transfers. These transfers can be temporary transfers with short-term agreements or drought transfers with long-term agreements. Temporary transfers are generally interim supply measures taken until long-term measures can be implemented to improve water service reliability. The following sections describe short-term water transfers and potential land fallowing and water bank operations.
Table 11-2 shows major short-term transfers between water purveyors in recent years. Transfers between water projects for operational reasons are not included. Much of the transferred water was from reserve supplies or was replaced by alternative sources (such as ground water), and had little, if any, adverse economic effect on the source areas.
Some water transfers benefit fish and wildlife. Refuge managers can use water transfers to augment their supplies. Table 11-3 shows major water transfers for environmental uses in recent years.
MWDSC is looking to water conservation and land fallowing programs through long-term agreements for short-term drought transfers to increase Colorado River supplies. Through a variety of irrigation management measures, there is a potential for conservation and transfer of 0.2 maf from the Colorado River Region to the South Coast Region.
In recent years, MWDSC and other water agencies have been actively negotiating to secure additional supplies through short-term water transfer agreements to enhance reliability of their water supplies. Following are some examples of such transfers:
Land fallowing and water bank operations are another option under short-term water transfers during periods of drought. The State Drought Water Bank began in 1991. During the first year of operation, it purchased 820,000 af. About 50 percent of the water came from land fallowing (420,000 af), followed by ground water exchange (258,000 af) and stored water reserves (142,000 af). Operations were short-term (one# year drought supply) for areas with critical needs as determined by State Drought Water Bank criteria. Since overall statewide water supply and water service reliability was not improved for the long-term, the drought water bank is considered a contingency or drought management supply option.
The Department of Water Resources is considering making the State Drought Water Bank a permanent water transfer program available for future drought management. A draft program EIR was published in January 1993, and after public review, a final EIR was released in November 1993. The EIR reports DWR's experiences in running the 1991 and 1992 drought water banks and evaluates potential environmental impacts associated with different categories of transfers. Figure 11-3 shows the categories of sources and allocations under the 1991 and 1992 drought water banks. Table 11-4 shows 1991 and 1992 drought water bank purchases and allocations. The program EIR only discusses a State-run drought water bank involving short-term transfers during supply shortages or drought periods over the next five to ten years. Judging from the 1991 and 1992 experience, the operation of a drought water bank in the future could probably reallocate 600,000 af of supplies during droughts.
In October 1993, the State Water Contractors negotiated a Short-Term Water Purchase Agreement with DWR to purchase options to buy 9,000 to 14,000 af of water from the San Joaquin Valley area in 1994. To minimize environmental impacts in the Delta, no water was to be purchased from sources north of the Delta. The agreement was primarily to test a process for buying and exercising options in the new climate of regulations and requirements to protect threatened aquatic species in the Delta. Due to the onset of a dry spring in 1994, the SWC requested that a direct water purchase of 73,000 af be implemented, most of it from north of the Delta. The 1994 Drought Water Bank would allow DWR to purchase water on behalf of outside agencies and SWP contractors. On June 10, 1994, DWR opened the drought water bank with those agencies as well as with SWP contractors that will have a need for 93,000 af or more.
Water supply management options discussed here are those actions designed to augment supply in water-short areas of California. Table 11-5 shows the capacity and annual supply for statewide and local water supply management programs possible under Level I programs.
SWP Water Supply Augmentation. Presented below, in addition to a discussion about SWP reliability, are several statewide programs designed to augment SWP supplies. A water conveyance project, the Coastal Branch, Phase II, is also described. The water supply benefits of these programs are included in the Level I future supplies of the SWP presented in Chapter 12. However, it must be noted that fixing the Sacramento-San Joaquin Delta is integral to any statewide water management program. More information about the Delta and available options for solving complex Delta problems are presented in Chapter 10.
SWP supply reliability under D-1485 depends on demand for water in SWP service areas and delivery capability of the project. Delivery capability of the SWP varies based on water year type. Figure 11-4 shows the SWP delivery capability for year 2020 with existing and Level I water supply management programs under D-1485. In terms of "full service reliability," with existing facilities, the SWP will be able to meet its requirements of 4.2 maf about 20 percent of the time. Planned programs under D-1485 could enable the SWP to meet its requirements about 75 percent of the time. Table 11-6 shows SWP supplies for 1990 to 2020 with and without additional Level I programs.
To illustrate the impact of drought periods on SWP deliveries to agricultural and urban users, frequency diagrams are presented showing deliveries based on a 3.2-maf level of demand for 1990 and on a 4.2-maf level of demand for 2020 (Figure 11-5). These diagrams reflect the future reliability of the SWP with existing SWP facilities and with planned Level I water management programs. These analyses are based on D-1485 standards and show that, with planned Level I water management programs, the SWP could provide full service delivery to urban contractors about 80 percent of the time. Figure 11-6 compares future delivery capability of the SWP (with Level I programs) with EBMUD and MWDSC reliability objectives.
Various restrictions imposed on Delta exports limit the delivery capability of the SWP. Recent Endangered Species Act biological opinions for winter-run salmon and Delta smelt and the proposed federal EPA Bay-Delta standards place further operational constraints on Delta exports. Figure 11-7 illustrates CVP and SWP Delta capabilities under various Delta export restrictions for average and drought years. Export capabilities were computed for the 1990 level of development for: (1) pre-D-1485 SWRCB Bay-Delta Standards; (2) D-1485; (3) D-1485 with winter-run and Delta smelt biological opinions; and (4) D-1485 with winter-run and Delta smelt biological opinions and EPA-proposed Bay-Delta standards. Restrictions imposed by biological opinions for winter-run salmon and Delta smelt, and by the EPA's proposed Bay-Delta standards, could reduce delivery capabilities of SWP and CVP by about 1.1 and 1.6 maf for average and drought years respectively. The reduction of SWP and CVP delivery capabilities do not reflect reductions in exports that may result from take limits required by winter-run salmon and Delta smelt biological opinions. Delta export capabilities shown in Figure 11-7 are based on monthly operation studies and do not reflect additional outflow that may be required to provide substantial buffers so as not to violate the proposed EPA salinity standards (to provide for 95 percent compliance with EPA standards). If required, such buffers could potentially double water supply impacts.
Los Banos Grandes Facilities. In 1983, DWR initiated a comprehensive investigation of alternative offstream storage reservoirs south of the Delta. In 1984, after an initial examination of 18 sites, a DWR study recommended that Los Banos Grandes be investigated to determine the most cost-effective reservoir size and its engineering, economic, and environmental feasibility. The proposed facilities would be located on Los Banos Creek in western Merced County, southwest of Los Banos and about 5 miles upstream from the existing Los Banos Detention Dam (see Figure 11-8).
Based on the feasibility investigation, a 1.73-maf reservoir was selected as a technically feasible and cost-effective solution to help offset projected future SWP water shortages and to provide the highest net benefits to the SWP. However, due to the recent endangered species actions in the Delta, the feasibility of the project is being reassessed. The actual sizing and schedule is highly dependent on the selection of a long-term solution for resolving fishery issues and facilitating efficient water transfer through the Delta.
The project will require several permits and agreements which would be issued by various agencies including a Section 404 permit (Section 404 of the federal Clean Water Act), and a Final Biological Resources Mitigation Plan being developed with DFG and the U.S. Fish and Wildlife Service, among others, to address potential impacts on biological resources.
Los Banos Grandes facilities could augment SWP supplies by about 300,000 af in average years (under D-1485). Yield of LBG in drought years would be about 260,000 af. The schedule for the investigation of this project has been slowed down in order to coincide with the Bay-Delta Oversight Council process (see Chapter 12). Financing of LBG has also been a continuing concern for several of the SWP water contractors, primarily agricultural users, who are concerned that the cost may be too high for them to pay.
The Kern Water Bank, established under an agreement between DWR and the Kern County Water Agency, would take advantage of available opportunities to store and extract SWP water in the Kern County ground water basin. There are eight potential elements, or separate components, to the Kern Water Bank; seven will be sponsored by local water districts and the eighth element is DWR's Kern Fan Element. DWR is awaiting the analysis of future water supply impacts that may result from a long-term solution for resolving fishery issues and facilitating efficient water transfer through the Delta. For now, the planning program is focused on completion of a Habitat Conservation Plan, incidental-take permits for terrestrial aspects of the KFE, analysis of delayed implementation on the economic viability of the KFE, and analysis of reduced levels of water supply on project economics. Once the supply impacts are identified and it appears that adequate water is available, the KFE will be reassessed, final environmental documentation will be issued, and a program for further evaluation of local elements will be considered.
The Kern Fan Element Programmatic EIR was completed in 1986. The EIR proposed acquiring up to 46,000 acres for recharging, extracting, and storing SWP water in the Kern River Fan area. DWR acquired 20,000 acres for the bank in 1988. Initial studies indicate that the Kern Fan Element could be developed to store as much as 1 maf and contribute as much as 140,000 af per year to the SWP in drought years.
The seven local elements are in various stages of investigation. A feasibility study and a negative declaration for local project impacts are essentially complete for a local element sponsored by the Semitropic Water Storage District. Reconnaissance#level investigations for the six remaining elements are essentially completed. These six elements are sponsored by North Kern Water Storage District, Cawelo Water District, Kern County Water Agency Improvement District Number 4, Rosedale-Rio Bravo Water Storage District, Kern Delta Water District, and (jointly) Buena Vista Water Storage District and West Kern Water Storage District.
There is considerable variation in size and potential among the local elements. With a potential ground water storage capacity of more than 900,000 af and a proposed annual recharge capacity of about 114,000 af, the Semitropic Local Element is the largest of the local elements. Cawelo Water District has the smallest element proposed to date, with a ground water storage capacity of about 110,000 af and an annual recharge capacity of about 20,000 af. Taken together, the local elements have the potential to provide over 2 maf of ground water storage and a capability to store and extract about 370,000 af annually (under D-1485). When the Delta issues and their impacts on the water available for the local elements are better defined, planning investigations to examine the feasibility of the local elements of the KWB will resume.
In a 1990 demonstration program by DWR and Semitropic WSD, about 100,000 af of SWP supply was stored in the ground water basin underlying Semitropic WSD. In 1992, Semitropic WSD exchanged about 42,000 af by pumping ground water for local use and allowing a like amount of SWP entitlement water to be delivered to SWP contractors. After accounting for losses, a balance of about 50,000 af remains in ground water storage for later withdrawal. More recently, MWDSC and Semitropic WSD have agreed to an exchange program that is similar to the Semitropic element of the Kern Water Bank. This program would allow MWDSC to temporarily store a portion of its SWP entitlements for later withdrawal and delivery to MWDSC's service area, as described earlier in this chapter under Short-Term Demand Management Options. If MWDSC and Semitropic WSD decide to carry out a permanent and long-term water banking program, KWB local elements storage will shift from the SWP to a local MWDSC project.
Coastal Branch, Phase II. Anticipating future supplemental water supply needs, San Luis Obispo and Santa Barbara County Flood Control and Water Conservation districts signed contracts for SWP water deliveries in 1963. At the request of the two districts, construction of Coastal Branch, Phase II, and delivery of SWP water was deferred several times until 1986, when SLOCFCWCD and SBCFCWCD asked DWR to begin planning for Coastal Branch completion.
Water demand during the 1980s exceeded dependable water supplies by an average of 60,000 af per year in Santa Barbara County and by 61,000 af per year in San Luis Obispo County. In both San Luis Obispo and Santa Barbara counties, the lowering of ground water levels has resulted in overdraft conditions and deteriorating water quality. During the recent drought a number of communities in the two counties had severe water shortages. The Phase II aqueduct is designed to deliver 4,830 af per year of SWP water to San Luis Obispo County and 42,486 af per year to Santa Barbara County.
The Coastal Branch, Phase II, is planned as a 102-mile buried pipeline which will complete the Coastal Branch of the SWP (see Figure 11-9). The existing Phase I, a 15-mile canal from the California Aqueduct to Devils Den in northwestern Kern County, was completed in 1968. Under current plans, Phase II will start at Devils Den, traverse San Luis Obispo County, extend 14 miles into Santa Barbara County, and terminate on Vandenberg Air Force Base. Three pumping plants will lift the water approximately 1,500 feet to Polonio Pass where the water will be treated at a regional treatment plant, constructed and operated by the local water purveyors. There will be a power recovery plant east of the city of San Luis Obispo. A fourth pumping plant near Casmalia will lift the water approximately 400 feet over the Casmalia Hills to Tank 5, the terminus of Phase II. From there, local facilities will convey the water 42 miles to Lake Cachuma, which serves the south coastal area of Santa Barbara County.
Potential benefits of SWP water for the area include improved municipal and industrial water quality, improved ground water quality, reduced ground water overdraft, and increased reliability of urban water supplies. While this project increases supplies in the Central Coast Region, it only reallocates existing SWP supply capabilities of the California Aqueduct.
In June 1990, the Draft EIR for the Coastal Branch, Phase II, and the Mission Hills Extension (a local pipeline in Santa Barbara County) was released. The Final EIR was completed in May 1991 and the Notice of Determination was filed in July 1992. Construction began in late 1993 and is scheduled to be completed in early 1997.
CVP Supply Augmentation. Over the years, various projects have been studied for possible augmentation of CVP water supplies or improvement of water conveyance within the CVP service area. Examples include the Shasta Dam enlargement study and the San Joaquin Valley conveyance investigation described later in this chapter. Many of the CVP studies in recent years have focused on alternative strategies for managing existing water supplies, rather than development of new sources of supplies.
Recently, there has been a new mandate to investigate increasing CVP yield. The CVP Improvement Act directed the Secretary of the Interior to submit a plan to Congress by late 1995 for increasing the yield of the CVP by the amount of water dedicated for environmental purposes under the act. Methods of increasing yield can include nonstructural approaches such as water transfers and purchases, as well as structural measures such as modifications or additions to existing facilities (see CVP Level II options). The act further directs the secretary to develop and implement a plan for obtaining supplemental water supplies for fish and wildlife.
American River Flood Control (Auburn Dam). In 1991, the Army Corps of Engineers completed a Feasibility Report and environmental documentation for a 545,000-af flood detention dam at the Auburn Dam site which would provide 1-in-200-year flood protection for Sacramento and vicinity. The cost of the proposed 425-foot dam, along with the proposed levee improvements in the Natomas area of Sacramento, is estimated at $700 million. These improvements would provide about $134 million of flood protection benefits annually.
Although considered by Congress, the American River Flood Control Dam (which was not a water supply augmentation project) was not authorized in 1992. Congress expressed concerns in two areas: (1) that the environmental protections being proposed by the project were not fully documented, and (2) that the guarantees offered by the project's supporters were insufficient to ensure that the dam would not impact future water supply development at the Auburn site. Studies addressing these concerns could be presented to Congress before 1996. This Level I option would have flood control benefits for the Sacramento area. Current temporary reoperation of Folsom Dam to provide limited flood control improvements has reduced the water supply available from Folsom Reservoir. Implementing this option could increase CVP supplies to the extent that Folsom Reservoir could be operated based on its original flood control criteria.
Local Water Supply Augmentation. Existing local surface water projects were among the first projects developed to meet regional water needs. Currently, in an average year local agencies provide about 11.1 maf of annual supply, including 1.0 maf of imported water supply. Future local water projects and demand management programs will also play a major role in providing water supply reliability out to 2020. Local water development programs are expected to add an additional 0.2 maf to average year supplies and 0.6 maf to drought year supplies by 2020. The following is a brief description of some local projects currently under investigation. More detailed discussions of the local projects are presented in the regional chapters of Volume II.
Water Recycling. Water recycling for the 1990 level is based on evaluation of data presented in Water Recycling 2000, a September 1991 report by the State Water Conservation Coalition Reclamation/Reuse Task Force, a work group of the SWRCB's Bay-Delta proceedings, and information provided by local water and sanitation districts. Projected water recycling is based on the July 1993 survey, Future Water Recycling Potential, by the WateReuse Association of California and input from local water and sanitation districts.
The 1993 survey indicates that there is potential for accelerating the pace of water recycling in the future. However, current budgetary problems and the economic recession have had a negative impact on water recycling project development in the State. That report indicated that the State's goal of achieving and surpassing 1 maf of water recycling by year 2010 "is definitely within reach."
Additional water supply would be generated by water recycling where the outflow of water treatment plants would otherwise enter a salt sink or the Pacific Ocean. In the Central Valley, the outflow from waste water treatment plants is put into streams and ground water basins and is generally reused. Recycling of such outflow would not generate any new supply but would be a change in the waste water treatment and use process. In coastal regions recycled water would generally be considered as new water supply. In the areas where water supply contains high total dissolved solids, such as Colorado River water, the TDS of recycled water would be too high for direct use. Recycled water with high TDS could be used if desalination techniques were employed to improve it or by blending it with high-quality water. In the South Coast Region local water agencies are concerned that the lack of future adequate high-quality water for blending supplies or the cost of desalination of recycled water could affect the timing of future water recycling facilities by delaying their cost effective implementation until adequate good quality source water is available.
To estimate how much additional supply would be generated by Level I and Level II water recycling, a set of criteria was established. Total annual Level I water recycling for 2020 is projected to be about 1,321,000 af. This would contribute about 923,000 af of new water to the State Water Project supply. Table 11-7 shows 1990 and projections of total water recycling and new water supply by hydrologic region.
Ground Water Reclamation. High total dissolved solids and nitrate levels are the most common ground water quality problems. Ground water reclamation programs are designed to recover this degraded ground water. Currently, most of the ground water reclamation programs under consideration are located in Southern California (excluding ground water reclamation solely to remediate contamination at hazardous waste sites). Some of the polluted water must be treated, some can be blended with fresh water to meet water quality standards, and some can be applied untreated for landscape irrigation. Total annual contribution of ground water reclamation by year 2000 is about 90,000 af and is accounted for in evaluations of the South Coast Region's ground water supply.
El Dorado County Water Agency Water Program. The El Dorado County Water Agency is preparing a water resources development and management plan to meet the long-term needs of the local water districts within its jurisdiction. In May 1993, EDCWA certified a final Water Program EIR for the El Dorado Irrigation District Service Area.
Water demand for the EID service area is projected to increase from a 1990 level of 34,000 af to 60,000 af in 2020. EDCWA proposes to provide a long-term water supply to the EID service area by implementing a water management program that involves use of various combinations of water rights, water storage, and water conveyance facilities. The preferred alternative is a combination of the El Dorado Project, the Folsom Reservoir Project, the White Rock Project, and a diversion and conveyance project which would not provide any additional water supply. The El Dorado Project consists of securing water rights to certain direct diversion and storage amounts from the South Fork of the American River using PG&E's El Dorado Canal. The combined average supply from these rights could be up to 17,000 af per year.
The Folsom Reservoir Project involves recently enacted federal legislation (PL 101-514) designating 15,000 af of water stored in the CVP's Folsom Reservoir for municipal and industrial supply for EDCWA. EDCWA proposes to make this water supply available to both EID and Georgetown Divide Public Utility District. EID's portion of the Folsom Reservoir would be about 7,000 af and 6,000 af for average and drought years, respectively.
Other alternatives considered involve the construction of new dams and reservoirs. Such options would be more costly and involve greater environmental impacts. To a certain extent, the EDCWA approach relied on least-cost planning concepts, in that both structural and nonstructural options were evaluated on an equal basis.
Contra Costa Water District--Los Vaqueros Project. Water quality and reliability are the objectives of Contra Costa Water District's Los Vaqueros Project. The Environmental Impact Report for this $450-million project was certified in October 1993, and in April 1994, the Army Corps of Engineers issued a permit for the project under Section 404 of the Clean Water Act. The 100,000-af offstream reservoir near Byron would store high-quality Delta water during wet periods for blending with lesser quality Delta supplies in dry seasons. The reservoir is also designed to meet the district's need for storage in the event of an emergency, such as a temporary loss of Delta supplies.
The project includes a new supplemental Delta intake location, and conveyance and storage facilities necessary for project operations. The proposed reservoir would inundate about 1,400 acres along Kellogg Creek. The district purchased about 20,000 acres in the canyon along the creek, which would be used for open space and protected from future development. Careful land management would improve habitats for some rare and endangered species in the canyon. The Los Vaqueros Project would improve the reliability of the district's supplies but would not add any new water, as water for the project is provided by the CVP under an existing contract.
East Bay Municipal Utility District Water Supply Management Program. The East Bay Municipal Utility District is a multipurpose regional agency with water supply as a major function, serving an estimated 1.2 million people and industrial, commercial, and institutional water users in the East Bay region of the San Francisco Bay Area.
EBMUD forecasts its customer demand to increase from an average 1990 level of 246,000 af to 280,000 af in 2020. This projection includes demand reductions as a result of additional conservation and reclamation programs. It is projected that increased use of Mokelumne River water by senior water rights holders will decrease availability of Mokelumne River supply for EBMUD. With increases in customer demand and the projected increased use by senior water rights holders, and possible additional Mokelumne River fishery flow requirements, EBMUD projects a drought year shortage of 130,000 af per year by 2020. To address this deficiency, EBMUD has been studying a wide range of potential water management options to help meet its future water demands. These include: several additional conservation programs, water recycling programs, conjunctive use options on the lower Mokelumne River, use of its CVP contract for Folsom-South Canal water, and raising the height of Pardee Dam.
After several hearings and extensive evaluation, EBMUD's Board of Directors designated two of the six composite programs as preferred alternatives. The main element of each alternative is the use of ground water storage. One of the preferred alternatives (Alternative II) would store available surface water in an underground basin during wet years. During dry years, this water would either be: (1) used for agricultural irrigation in the lower Mokelumne River basin; or (2) pumped into aqueducts for use by EBMUD's customers. The conjunctive use element of this program would require cooperation of San Joaquin County where ground water storage is located. The other preferred alternative (Alternative IV) includes the same components mentioned above, plus a supplemental water supply from the American River. Rights to use of this supply are regulated by court order. American River water could be delivered to the Mokelumne aqueduct by a 16#mile pipeline tapping into the existing Folsom South Canal. EBMUD's proposed new water supply program specifies instream flows, reservoir operations, and hatchery operations and spawning habitat enhancements to improve fisheries in the Mokelumne River. The water supply benefit of this program is about 43,000 af in drought years. In October 1993, EBMUD's Board of Directors certified the WSMP final EIR and voted to focus planning efforts on the use of ground water storage in San Joaquin County. The Board directed EBMUD staff to continue working with San Joaquin County water interests regarding development of a joint conjunctive use project, with the option of using the District's contract with USBR for 150,000 af per year of American River water.
The District's need for water could change, depending on the outcome of various actions by federal agencies and the SWRCB Mokelumne River water rights hearing. Should any of these actions result in a significant increase in the District's water needs, the District would reexamine all the alternatives contained in the WSMP EIR for meeting the demand.
Monterey Peninsula Water Supply Project. To improve the reliability of water supplies in the Monterey Bay area, the Monterey Peninsula Water Management District has taken a number of actions including water conservation and water reclamation, and has investigated several other water development alternatives. Improvements to the system also are needed to provide water for municipal and industrial users as well as for environmental water needs of the area. Current supply is inadequate during drought years when shortages develop due to lack of adequate carryover storage facilities. The district has investigated 32 alternatives. The current preferred alternative is enlarging a dam and reservoir on the Carmel River. Enlarging Los Padres Reservoir to approximately 24,000 af could provide an average annual water supply of 22,000 af and a drought year supply of about 18,000 af to the Monterey Peninsula's water supply system.
The Metropolitan Water District of Southern California Water Management Programs. MWDSC supplies about 60 percent of the water delivered by its member agencies. These agencies, which cover all or part of six of California's most highly populated counties, serve over 15 million residents. MWDSC's major sources of supply are the SWP and the Colorado River. Ninety percent of the demand on MWDSC's supplies is from municipal and industrial users; the remaining demand is from agricultural users.
Population in MWDSC's service area is expected to increase from 14.8 million in 1990 to more than 22.7 million by 2020. In 1988, MWDSC began a preliminary effort to expand reservoir storage capacity to meet the projected water demands in its service area. Reservoir storage requirements were evaluated in a two-step process designed to establish the combined ground and surface storage needs and to determine the minimum surface storage needed. Three alternative sites for surface storage were selected, including the preferred alternative Domenigoni Valley in western Riverside County, based on the minimum reservoir storage need and a comparison of several sites.
The Domenigoni Valley Reservoir involves constructing two main embankments as well as a large roller-compacted concrete saddle dam as shown on Figure 11-10. The site is near the junction of the Colorado River Aqueduct, the San Diego Pipeline, and the terminus of the East Branch of the California Aqueduct. The reservoir, which could receive water from both the Colorado River and California aqueducts, will have a capacity of 800,000 af.
The reservoir would provide emergency storage, drought year storage, carryover storage, and seasonal storage and enhance operational reliability of MWDSC's system. It would also assist with ground water basin recharge as part of a regional conjunctive use program. Approximately 50 percent of the reservoir capacity would be allocated to emergency storage. The remainder would be used for seasonal regulation and to augment MWDSC supplies by 264,000 af per year during drought years. In October 1991, MWDSC certified the final Environmental Impact Report for the Domenigoni Valley Reservoir Project. The current MWDSC schedule indicates that the project would be operational by the end of this decade. However, it could take five or more years to fill the reservoir, so the full benefit of the reservoir may not be realized until after the year 2004.
Arvin-Edison--MWDSC Conjunctive Use Program is another supply augmentation program that MWDSC is investigating. The Arvin-Edison Water Storage District and MWDSC agreed on a complex conjunctive use program which allows Arvin-Edison to provide CVP entitlement water to MWDSC in dry years and use ground water pumped from previously stored ground water supplies made available by MWDSC from SWP supply in wet years. As originally envisioned, the project would have provided 93,000 af of drought year supply. However, recent actions to protect aquatic species in the Delta and implementation of the CVPIA have restricted operations in the Delta. Consequently, MWDSC and Arvin-Edison are currently reassessing the project.
MWDSC's Inland Feeder is a 45-mile-long conveyance facility which will bring supplemental SWP water supplies to Riverside, San Bernardino, San Diego, Orange, and Los Angeles counties. The facility would be intended to help MWDSC preserve operational reliability, optimize use of existing water resources, and meet increasingly stringent State and federal water quality standards through blending of supplies.
Pajaro Valley Water Authority Water Augmentation Program (San Felipe Extension). The Pajaro Valley Water Management Authority is analyzing whether or not to take water from the CVP's San Felipe Division. The proposed San Felipe extension would consist of a 22-mile pipeline from the Santa Clara Conduit to the Watsonville area which could supply a maximum of 19,900 af annually of CVP water for municipal and industrial, as well as agricultural, use in the Watsonville area. The San Felipe extension is a water conveyance rather than a water supply augmentation project. The supply for the project will come from reallocation of CVP supply pumped from the Delta.
City of San Luis Obispo-Salinas Reservoir. The City of San Luis Obispo has actively been pursuing the Salinas Reservoir Expansion Project to supplement its water supply. The project involves installation of spillway gates to increase the storage capacity of the existing reservoir by about 17,950 af--from about 23,840 af to 41,790 af--and the city's supplies would increase by about 1,650 af. The Environmental Impact Report for the project is expected to be certified in 1994.
Following is a brief discussion of demand management and supply augmentation concepts or projects which are not specifically quantified but, through some combination of actions, could fill the gap between supply and demand shown in the California water budget, Chapter 12. Plans for some of these projects are on hold for various reasons, including the need for a long-term solution to Delta problems, but work could be resumed at any time to help meet California's growing water needs. Some others, programs such as San Diego County Water Storage Project and Conjunctive Use Programs, are very active but are in the early stages of planning and further studies are needed to determine the water supply benefits of such programs. Table 11-8 summarizes Level II water management options.
Increased Agricultural Water Use Efficiency. A 73-percent
seasonal application efficiency is defined as a statewide target in Chapter
7 and has been supported by many irrigation experts in a variety of reports.
This coincides with the draft report On-Farm Practices prepared for
the Agricultural Task Force of the State Water Conservation Coalition. The
73-percent target efficiency relies on: (1) subtracting any effective precipitation
from the evapotranspiration requirement of the crop; (2) attaining an 80-percent
distribution uniformity; and (3) adding a very small leaching requirement.
This target assumes that all portions of farm fields will be fully irrigated.
The target efficiency considered an appropriate Level I option is shown by
the formula below.
SAE=[(ETAW + LR)/AW]=73%
where: SAE is the seasonal application efficiency; ETAW is the evapotranspiration minus effective precipitation; LR is leaching requirement; and AW is the applied water.
Level II agricultural demand reduction is based on a statewide agricultural irrigation efficiency of 75 percent. The feasibility of increasing agricultural irrigation efficiency over 73 percent should be further investigated because of potential reduction in yield due to under-irrigation, which may occur in part of each field. For example, Westlands Water District has estimated that irrigation efficiencies could reach 75 percent in their service area at an 80-percent distribution uniformity. However, approximately 12.5 percent of each field is under-irrigated using this formula according to Westlands Water District's Water Conservation Plan (July 1992). If under-irrigation of this magnitude is considered acceptable, an additional statewide annual reduction in applied water of approximately 300,000 af could be attained and considered as a Level II option. Reduction in depletion would occur only in areas from which outflow enters a saline sink such as the west side of the San Joaquin Valley and Imperial Valley. However, because irrigation efficiency in Imperial Valley and Westlands Water District has already reached 75 percent, this option will not reduce depletions. The positive or negative effects of reducing applied water would have to be evaluated on a case by case basis.
Increased Urban Water Use Efficiency. The Level I urban water conservation estimates were based on Best Management Practices, which included three landscape-related BMPs that were quantified and ultra-low-flush toilet replacement, among others. Two of the three landscape BMPs relied on the Model Water Efficient Landscape Ordinance developed by DWR. The criteria developed under this ordinance resulted in the following formula used to estimate the maximum applied water allowance in a landscape plan:
MAWA=[0.8(Eto) x LA]/CF
where: MAWA is the maximum applied water allowance; 0.8 is an ET adjustment factor based on an irrigation efficiency of 62.5 percent; Eto is the reference evapotranspiration of well watered pasture; LA is the landscaped area; and CF is a conversion factor to hundreds of cubic feet.
For a Level II option, an increase in irrigation efficiency of 5 percent should be investigated. The rationale behind this assumption is that this would parallel the increase in agricultural efficiency over the same period. If landscape irrigation efficiency is increased by 5 percent, an additional 220,000 af in applied water reduction would be realized. This amount would be commensurate with a 190,000-af reduction in net water use. Other potential Level II options that need further evaluation include: greater increases in landscape irrigation efficiencies; evapotranpiration reduction from xeriscaping; and horizontal axis washing machines.
Applied Water Reduction Due to Land Retirement. A Management Plan for Agricultural Subsurface Drainage and Related Problems on the Westside San Joaquin Valley (San Joaquin Valley Drainage Program, 1990) reported that many of the valley's water and drainage districts and individual growers had begun to take actions similar to those recommended in the report. Therefore, it was assumed in Chapter 6, Agricultural Water Use, that the source control (irrigation efficiency improvements) and land retirement elements of the recommended plan developed by the SJVDP would be implemented by 2020. Implementation of these two elements would result in an applied water reduction of 232,000 af by 2020. This was adopted in the Level I scenario and included in water demand projections.
The SJVDP report also suggested that if no portion of the recommended plan were implemented, applied water could be reduced by 1,040,000 af due to the abandonment of 460,000 acres of irrigated land by 2040. Assuming that the abandoned acreage increases linearly over time results in an estimate of 276,000 acres abandoned by 2020 and a reduction in applied water of 689,000 af if no portion of the plan were implemented. The analysis also assumed that approximately 20,000 af of source control would occur.
Therefore, to establish a Level II option scenario, it is assumed that the SJVDP recommended plan will be partially implemented by 2020, reflecting the status of various recommendations in the report, resulting in a potential applied water reduction of about 477,000 af from land abandonment and source control. This amount would correspond to a reduction in net water use of 390,000 af. Table 11-9 illustrates what could be available due to partial implementation of that preferred plan. However, more detailed analysis is required to determine whether the water would be used for other agricultural production in the region.
Water Transfers. Water transfers can augment an area's water supplies on a short- or long-term basis. Short-term transfers are generally either one-time spot market or long-term agreements for drought year supplies. Long-term annual transfers are generally designed to augment a water agency's year-to-year supplies over the long-term to improve the water service reliability for the receiving area. Such transfers have been going on since early this century as evidenced by the construction of several major intrastate transfer facilities (described in Chapter 3), and they are indeed the backbone of the State's long-existing water delivery system. However, the 1987-92 drought caused some water agencies and individuals to begin looking at the potential of a water transfers market to meet their needs by augmenting long-term supplies as well as short-term drought supplies.
There are currently physical limits to water transfers. Total usable transfer capacity of existing major conveyance facilities from the Delta, under D-1485, during drought years is about 1.4 maf per year. Level I drought water transfers from the Delta are estimated at 0.6 maf, resulting in a remaining Level II transfer potential of about 0.8 maf. (See Short-Term Water Transfers in the Level I--Reliability Enhancement Options section of this chapter.) The unused capacity of conveyance facilities is considerably less during average years when both projects would be able to export more of their own water. However, recent actions taken to protect fisheries in the Delta have considerably curtailed the pumping capability of the projects, resulting in increased limitations on the SWP and CVP facilities to convey or wheel transfer water. Drought year usable transfer capacity of the SWP and CVP at the 1990 level is estimated to be about 0.7 maf when projects are operated to comply with Delta smelt and winter-run chinook salmon 1993 biological opinion, as discussed in detail below. The primary sources of water for transfer have been ground water substitution, unallocated developed supply, and land fallowing. This section presents the factors affecting the feasibility of transferring water along with a general discussion of sources of water for transfer.
Ground water substitution makes surface irrigation water available for transfer by pumping an equivalent amount of ground water for use on irrigated lands. Local water districts usually coordinate ground water pumping with reduced surface water diversions by growers, although growers not affiliated with a local water district have also participated in ground water substitution contracts. Replacement pumping must be far enough from perennial streams, rivers, and Delta tributaries to not induce additional immediate percolation to ground water, thus reducing surface water supplies and negating the transfer.
Unallocated developed supply, which would have stayed in storage and possibly spilled in future years, can be available for transfer if the transferee obtains approval from the SWRCB and makes assurances that reregulation of reservoir operations will not adversely affect operations of the SWP or CVP. This is essential, because SWP and CVP facilities are used to transport most transferred water and must meet downstream water quality standards obligations in the Sacramento-San Joaquin Delta.
Temporary fallowing of irrigated crop land is the water transfer alternative with the most potential for providing short-term water supply during drought, thus improving water service reliability for areas receiving the water. By not planting a crop, or by withholding irrigation from a crop already planted, or by shifting from a high-water-using crop to a lower-water-using crop, growers are able to free up irrigation supplies for transfer. Since drainage water is normally used on other farms, or maintains wildlife habitat, the amount of water transferred is usually limited to the average consumptive use (evapotranspiration of applied water for specific crops) on the transferring farm, plus drainage if it goes to a saline sink.
Permanent fallowing or land retirement is a long-term transfer strategy similar to temporary fallowing. The most attractive agricultural land for this type of transfer is land with salinity problems, or of only marginal production. The 1992 Castaic Lake Water Agency transfer of Devil's Den Water District SWP supplies is a good example of permanent land retirement although the actual retirement of the land is still several years away.
Physical limitations to water transfers exist within the conveyance capability of the various water systems. The San Francisco Bay, the South Coast, the west side of the San Joaquin Valley, and the Tulare Lake regions are regions with water shortages, and these regions would likely be primary purchasers of water transfers. A key factor in water transfers to these regions is the Delta because the potential sellers of surplus water for interregional water transfers would primarily be in areas of surplus, such as the Sacramento River Region, and to a lesser degree, the San Joaquin River Region.
The following water transfer discussions involving the hub of California's water supply infrastructure, the Delta, are based on SWRCB D-1485 and project operations under winter-run salmon and Delta smelt criteria. Actions taken in 1992 and 1993 to protect fisheries in the Delta have already considerably reduced export capabilities.
Most major water transfer actions require participation of SWP or CVP as facilitator to convey the transferred water to the areas of need, and approval from the SWRCB to change the point of diversion and place of use. Availability of unused capacity of pumping plants and conveyance facilities is critical in determining the feasibility of wheeling water to the receiving agency, particularly for long-term fixed annual deliveries.
The CVP's Tracy Pumping Plant is generally used to almost full capacity to meet existing contractual commitments. However, during times of drought, there is unused CVP capacity which is considered in this analysis. The SWP's California Aqueduct capability is constrained at several critical locations which restrict excess capacity to convey transfer water. These constraints are Banks Pumping Plant, Reach 13 of the California Aqueduct upstream of Buena Vista Pumping Plant in the lower San Joaquin Valley, and Edmonston Pumping Plant, where water is pumped over the Tehachapi Mountains into the upper desert and South Coast Region.
Under D-1485, and the USCE permit (public notice 5820A, amended) with existing facilities, Banks Pumping Plant restricted capacity is about 6,400 cfs with limited additional capacity in winter and spring. The Banks Pumping Plant is physically capable of pumping approximately 10,300 cfs. With implementation of the proposed south Delta water management program and USCE pumping restrictions removed, Banks Pumping Plant capacity could increase to approximately 10,300 cfs under certain conditions. Edmonston Pumping Plant would then become the critical constraint in conveying water to the South Coast Region. Under endangered species operation criteria, constraints at Tracy and Banks pumping plants significantly reduce water transfer capabilities.
Two operation studies were evaluated to determine the unused capacity of SWP and CVP facilities for the 1990 level of development, with D-1485 and with endangered species criteria based on the 1993 Delta smelt and winter-run chinook salmon biological opinions. The "take limitations" criteria imposed by the opinions cannot be modeled and are not included in the analyses. Another set of studies was conducted to evaluate year 2020 usable transfer capacity of the conveyance systems with existing facilities and with Level I water management programs based on D-1485 criteria.
Table 11-10 shows annual SWP and CVP usable transfer capacity from Banks Pumping Plant to the South Coast and San Francisco Bay regions, based on D-1485 operating criteria. Unused CVP capacity at Tracy Pumping Plant and Delta Mendota Canal are also included in the analyses. Unused capacity of the projects is directly related to annual hydrologic variations and the demand for water in the SWP/CVP service areas. During drought periods when supplies are insufficient to meet demands and deficiencies are imposed on SWP and CVP water contractors, more unused capacity is available in the conveyance systems. In addition, as demands for water in SWP service areas increase and additional facilities are completed to meet contractual demands, unused capacity of the SWP decreases.
For the South Coast Region, the 1990 level of usable transfer capacities in drought and average years under D-1485 criteria are about 1.4 and 0.6 maf, respectively. By year 2020, with Level I water management programs, unused capacity of the projects will be reduced to 1.1 and 0.3 maf in drought and average years, respectively. Similar analyses conducted for the San Francisco Bay Region indicate that the combined usable transfer capacity of the SWP North and South Bay Aqueducts and the CVP San Felipe unit (Santa Clara Conduit) for the 1990 level varies from 0.3 to 0.2 maf for drought and average years respectively. By year 2020, with Level I water management programs, usable transfer capacity will be reduced slightly to 0.2 and 0.1 maf for drought and average years respectively.
Transfer capability from the South Delta shown for the San Francisco and South Coast regions was computed independently and is not additive. The Delta Pumping Plant's unused capacity is not adequate to convey enough water to fill the combined unused capacity of the aqueduct systems conveying water to the two regions. SWP and CVP usable transfer capability from the Delta to the San Francisco Bay Region is shown in Table 11-10.
Figure 11-11 compares the SWP and CVP water transfer capacity from the Delta to the South Coast Region under D-1485 and endangered species criteria. This figure shows that average and drought year usable transfer capacities of the SWP and CVP are reduced to about 0.3 and 0.7 maf, respectively, for the 1990 level when projects are operated under endangered species criteria for winter run salmon and Delta smelt, reflecting pumping curtailments resulting from endangered species biological opinions. Among the factors limiting Delta exports are reverse-flow criteria and take limitations. Usable transfer capabilities discussed here do not reflect pumping limitations due to take limits under the biological opinions.
Water transfers with source water from south of the Delta, for example the San Joaquin Region, would not have reverse-flow limitations, but would be subject to other pumping restrictions. If source water for transfer is from the San Joaquin River, an additional pumping of about 0.2 maf in drought years could be realized as shown in Figure 11-11. Therefore, the water transfer capabilities mentioned for through-Delta transfers are less than those for source water from south of the Delta. Thus, considering pumping limitations in the Delta and Edmonston Pumping Plant, an envelope of usable transfer capacity can be developed. The envelope for water transfers to the Southern California ranges from an upper limit of 1.4 maf (under SWRCB D-1485) to about 0.9 maf in drought years (under endangered species actions). Similarly, the average year Delta water transfer envelope for exports to Southern California would be about 0.3 to 0.6 maf under endangered species actions and SWRCB D-1485, respectively. None of these restrictions consider potential pumping curtailments at the Delta due to take limits imposed by biological opinions.
Other considerations that could impair water transfers include lack of willing buyers and sellers, potential third-party impacts, and timing of availability of unused capacity of the facilities. Figure 11-12 shows the monthly variation of unused capacity of the SWP and CVP, under D-1485 for the 1990 level, and indicates that unused capacity of conveyance facilities is extremely limited from May through July when demand for water is high and SWP and CVP pumping is limited by D-1485 criteria. Therefore, most long-term water transfers are limited to those agencies that have re-regulation and storage capabilities that can be operated to take advantage of timing of available transfer capability. However, short-term drought year transfers, such as Drought Water Bank transfers, can use unused SWP/CVP storage (nonproject contractors may have a lower priority for storage) and re-regulation capabilities to facilitate transfer of water to agencies without storage capacity.
Water Rights Law is paramount in any discussion about water transfer. Virtually all of California's developed surface water is committed under riparian or appropriative water rights. Water rights laws and institutional constraints constrain the ability to make water transfers. Statutes governing California water rights are generally administered by the SWRCB . Water transfers lasting more than a year generally require the water right holder to petition the SWRCB for approval. There are different procedures for temporary (one-year) and permanent (long-term) transfers.
The Central Valley Project Improvement Act permits water districts and individuals receiving CVP water to transfer that supply to any other individual or entity subject to conditions specified in the Act, and subject to a federal approval process. The transfer must be approved by the affected district if the amount of the proposed transfer would exceed 20 percent of a district's CVP contract amount.
Transfers carried out in accordance with the Act must meet the conditions specified therein, and must comply with relevant State and federal laws such as CEQA, NEPA, and the State and federal Endangered Species Acts. Transfers must also comply with USBR's interim Guidelines for Water Transfers and must eventually comply with long-term water transfer rules and regulations when they are promulgated. The restrictions contained in the guidelines apply in particular to transfers of project water, rather than to transfers of water rights settlement water conveyed by the CVP. Given the restrictions placed on transfers of project water, it is likely that transfers of water rights settlement water may constitute much of the total CVP#related supply being made available for transfer. The CVP Improvement Act also contains provisions allowing use of project facilities to carry out water banking programs, including banking programs for fish and wildlife.
Delta Outflow Requirements are another factor affecting water transfers. Minimum water quality standards for the Delta are set by the SWRCB and the SWP and CVP must be operated to meet those standards. Presently, Delta outflow is maintained by either limiting exports or increasing releases from upstream reservoirs. Since most transfers of water originating in the Sacramento Region must be conveyed through either the SWP or CVP Delta facilities, transfers must conform to existing and future Delta outflow requirements.
Threatened and Endangered Species must also be considered when discussing water transfers. Potential impacts of transfers on listed species must be evaluated under the State and federal Endangered Species Acts. CVP/SWP pumping from the Delta is currently restricted to protect listed species. The lack of Delta transfer capacity rather than the general availability of supply may be a common occurrence.
Environmental Impacts of a water transfer are another factor to consider. The quantity and timing of reservoir releases are very important and can have significant impact upon instream fish flows. Careful consideration and coordination with DFG is required. For example, the Drought Water Bank water was transferred later in the year to minimize impacts upon chinook salmon and Delta smelt. However, conjunctive use programs can have a positive effect on aquatic resources by using ground water for irrigation during dry years, thereby reducing direct pumping from the river which results in fewer fish being taken through unscreened intakes.
Not all negative impacts on wildlife can be eliminated. Land fallowing has some negative impact on wildlife habitat, by cutting off some food sources, vegetation for cover, and nesting. Any future fallowing contracts are expected to contain provisions to minimize these impacts. Water transfers also can substantially reduce surface flows to waterfowl areas which are depended on to provide habitat for migrating and resident birds using cultivated crops as food and nesting sources.
Impacts on Transferring Area are important. Two concerns with water transfers involve the impacts on local ground water levels and impacts on local tax revenues and economies. For example, those issues arose during the 1991 Drought Water Bank due to the replacement of transferred surface water with ground water, sale of pumped ground water, and the fallowing of more than 150,000 acres.
Review and evaluation of ground water data indicate little impact on ground water levels from the State Water Bank transfers that took place in 1991 and 1992. Monitoring programs have been established in areas where such ground water pumping took place. Approximately 100 wells, part of DWR's usual semi#annual monitoring program in Butte, Colusa, and southern Glenn counties, were monitored monthly during the transfer and subsequent recovery periods. The monitoring program did not indicate any significant impact on the ground water basins in these counties as the result of ground water pumping for the State Drought Water Bank. Local concerns regarding future water transfers will be assessed through expanded ground water monitoring similar to those implemented as part of the 1991 and 1992 Drought Water Bank programs.
Transfer from agricultural water use to urban use is a concern because many agricultural areas are considered more economically vulnerable than urban areas. Although not all water transfers from land fallowing go to urban areas, urban areas have a relatively higher ability and willingness to pay for water during shortages, which makes them the likely recipients of water transfers to shore up water service reliability.
The economic health of farm communities is tied to the farm activity within their spheres of influence. For many local businesses, the goods and services furnished to farmers is a major part of their income. If farm production declines, whether because of drought, government programs, or crop land fallowing for water transfers, a ripple effect happens in the local economy. These supporting businesses will likely see less sales income, and if there is less business income, employees may be terminated or asked to work fewer hours, reducing the amount of salaries paid. In turn, the employees spend less money in the community, and another round of adverse impacts results.
Any resulting unemployment can be an additional burden on local governmental and private agencies that provide services to unemployed and indigent people. Compounding this problem is the likelihood that, due to the aforementioned decline in business activity, these same agencies will be facing revenue cutbacks from falling tax income and fewer charitable contributions. However, payments for the transferred water, water surcharges, and controls on land fallowing can be used to mitigate these impacts. For example, the 1991 State Drought Water Bank experience showed that many farmers used water sales income to make improvements to their land, providing jobs and income within the local area. Restricting the percentage and frequency of land fallowed within any one area can allow affected communities to avoid much of the potential permanent economic or social damage.
Level II supply management options discussed here are those actions that could augment supplies in water-short areas of California. Table 11-8 also shows statewide and local water supply management programs under Level II options.
SWP Water Supply Augmentation. The following conjunctive use options offer potential means to further enhance the SWP reliability. These are not, by any means, meant to be all-inclusive; other options could also be identified and investigated in the future for augmenting SWP supplies.
Conjunctive use of surface and ground water supplies can be an efficient means of augmenting supplies to help meet California's future water needs. Conjunctive use is the operation of a ground water basin in coordination with a surface water supply system to optimize the combined yield. A surface water storage and conveyance system is used to recharge a ground water basin, either directly or indirectly, during wet years to provide storage of water that can be used during dry years. Several conjunctive use programs are under study in the State today.
Currently, DWR, USBR, and local agencies are conducting planning studies for the Stanislaus River Basin and Calaveras River Water Use Program. The Stockton East Water District and the Central San Joaquin Water Conservation District have contracted for 155,000 af from New Melones Reservoir, a CVP facility on the Stanislaus River. The two districts propose to divert their contract water from the Stanislaus River during wet, above-average, and average years. During below-average, dry, and critical years the agencies would pump ground water to meet their needs and release their contract water down the Stanislaus River to provide increased flows for fish, water quality improvement in the south Delta channels, and increased yield to the SWP. The ground water basin would be replenished during wet years. A draft EIR/EIS is scheduled for release by fall 1994. Currently the effects of proposed Delta water quality and flow standards, implementation of the CVPIA, and Delta smelt and winter-run salmon biological opinions on this program are being evaluated.
DWR has also started investigations to identify conjunctive use projects in the Sacramento Valley which could further supplement SWP supplies. Initial studies are focused in eastern Yolo County, Butte County, and southern Sutter County. Other areas could be studied in the future, as agreements are reached with local agencies. Sacramento Valley conjunctive use programs could potentially augment drought year SWP supplies by as much as 100,000 af annually by the year 2000. These conjunctive use programs are in the early planning stages, and their yields are not included in SWP future supplies. (For more details about conjunctive use programs, see Chapter 4, Ground Water Supplies.)
Red Bank Project. The project, about 20 miles west of Red Bluff, would consist of two storage reservoirs, Dippingvat on the South Fork of Cottonwood Creek and Schoenfield on Red Bank Creek. The combined storage would be about 354,000 af and could produce an estimated 40,000 af of water supply benefit annually. The estimated cost of this project is $209 million. The project would provide increased water supply reliability for the SWP, increased flood protection along Cottonwood Creek and the Sacramento River, recreational opportunity, and anadromous fish restoration. The project is essentially on hold because of the uncertainty of Delta transfer facilities and escalating SWP costs.
Westside Sacramento Valley Storage and Conveyance Concept. This concept was first presented in Bulletin 3, The California Water Plan, published in 1957. The Westside storage and conveyance facilities, as envisioned by CH2M Hill Engineering, would tie together Shasta, Clair Engle, and Oroville reservoirs and some proposed offstream reservoirs on the west side of the Sacramento Valley and would be operated for multiple uses including flood control, environmental, and water supply. A number of sites on the west side of the Sacramento Valley have been investigated for offstream reservoirs, including, among others, various sites on Cottonwood Creek, Stony Creek, Red Bank Creek, and Sites Reservoir (west of Maxwell). Under this option, a portion of the Sacramento River flood flows would be diverted and stored in offstream reservoirs for later use, thus reducing flood flows downstream.
A conveyance facility originating above Keswick Dam on the Sacramento River would convey water along the west side of the Sacramento Valley, and could be extended to Clifton Court Forebay in the South Delta. Anderson-Cottonwood Canal, Tehama-Colusa Canal, Glenn-Colusa Canal, Corning Canal, and a number of smaller Sacramento River diverters could be supplied by the Westside Canal. Under this option, Red Bluff Diversion Dam and major pumping plants and diversions along the Sacramento River could be removed, providing a free-flowing river from Keswick to the Delta. A cross-valley conveyance facility could also connect the Oroville complex with the Westside facility, to convey SWP water to the Banks Pumping Plant. The facility could deliver over 3 maf of CVP water to Sacramento Valley service areas, eliminating over 300 unscreened diversions along the Sacramento River. If the canal were extended to the Clifton Court Forebay, it would replace the isolated facility discussed in Chapter 10 (see Figure 11-13).
This option could greatly reduce the impact of diversions on the Sacramento River fishery; would improve conditions for Sacramento River fish migrations, thus enhancing the recovery of the winter-run chinook salmon; would begin the restoration of the Delta by reducing direct diversions and pumping from the Delta; and would provide additional water supply and good quality water for urban users.
CVP Water Supply Augmentation. The following options summarize the programs that could be investigated in the future or have been studied in the past, but are on hold for a variety of reasons. These programs could be reevaluated at any time to augment CVP supplies.
Central Valley Project Improvement Act Studies. This effort to identify elements of new yield totaling 800,000 af is just beginning, and no specifics are available.
Shasta Lake Enlargement. Both the USBR and DWR have studied enlarging Shasta Lake. Prior planning efforts looked at increasing the storage capacity by approximately 9.7 maf to a total capacity of 14.25 maf. This would require raising the existing dam approximately 213 feet. The enlargement would increase the firm yield to the SWP and CVP by 1.45 maf annually, and would cost about $4.5 billion. The enlargement would also provide instream flows for fish, increased flood protection on the Sacramento River, and provide greater amounts of dependable hydroelectric energy.
Some of the issues surrounding Shasta Dam enlargement are the inundation of significant cultural sites, environmental impacts, and relocations of I-5 and the Southern Pacific Railroad. Because of these issues and the high capital cost of construction, this project has been deferred indefinitely.
Clair Engle Lake Enlargement. An alternative to the Shasta Lake enlargement is enlarging Clair Engle Lake by raising Trinity Dam. The capital cost of this project would be less than the Shasta Lake Enlargement because of lower relocation costs. This option would raise Trinity Dam by about 200 feet to increase reservoir storage by about 4.8 maf (see Figure 11-13).
As envisioned by Harza Engineering Company, unregulated flood flows from the Sacramento River would be pumped to Clair Engle Lake through a pump/generation facility. Water would then be released to Shasta Reservoir to meet water needs during the dry season. Enlarging Clair Engle Lake would have a water supply benefit of about 700,000 af per year. Production of hydroelectric power during on-peak periods could provide revenues to help finance the project. The environmental impacts have not been identified.
Mid-Valley Canal.The USBR investigated options to provide supplemental water supplies to the east side of the San Joaquin Valley to improve the ground water overdraft problem. A Report on the San Joaquin Valley Conveyance Investigation, released in June 1990, identified the Mid#Valley Canal as the best option to develop a long-term solution to the valley overdraft problem.
The San Joaquin Valley Conveyance Investigation involves issues and activities affecting CVP water yield and project management. These include fish agreements and negotiations, the CVP Improvement Act of 1992, Delta point of diversion and rediversion under CVP water rights, consolidated place of use for CVP water rights, cross-Delta facilities, conveyance capacity south of the Delta, and the CVP water contracting program.
Because these unresolved issues will have an impact on the availability of a supplemental water supply for the canal, further work has been deferred on the San Joaquin Valley Conveyance Investigation.
Folsom South Canal Extension. Folsom South Canal originates at Nimbus Dam on the American River and extends southward toward San Joaquin County. The original plan was for a 68.8-mile-long canal, terminating about 20 miles southeast of the City of Stockton to deliver American River water to agricultural and urban contractors. The first two reaches of the canal were completed in 1973 to a point just south of State Highway 104. Construction of the three remaining reaches, a total of 42.1 miles, has been suspended pending completion and consideration of alternative studies.
American River Water Resources Investigation. A five-year study of water needs and water supply alternatives in the American River Watershed and adjacent counties began in 1991. The study is governed by a memorandum of agreement between USBR and the Sacramento Metropolitan Water Authority. Costs are shared on a fifty-fifty basis. Other local cost-sharing partners include the American River Authority, Sacramento County Water Agency, and San Joaquin County Flood Control and Water Conservation District. DWR is represented at the executive and management level and provides in-kind services. The study area includes portions of El Dorado, Placer, Sacramento, San Joaquin, and Sutter counties. The results of this study will be coordinated with early stages of design of the American River Flood Control Project, if authorized by Congress.
This study, under the leadership of the USBR, will evaluate alternatives for supplying unmet water demands in the study area. Included as alternatives are water transfers, conjunctive use, water conservation, and development of additional water supplies on the American River and other rivers in the study area. The feasibility report and environmental documentation for this study should be completed in 1996.
Local Water Supply Augmentation. Several possibilities for augmenting local water supplies are discussed below.
Gray Water Use. Gray water use could help reduce the demand for potable fresh water over the long term. Most households produce between 24 and 36 gallons of gray water per person per day. Many population centers in California are located in areas where the climate requires landscape irrigation at least seven months of the year, so gray water could replace potable water during that time span. Gray water would generally only be practical in larger lots where adequate side clearances can be maintained for subsurface irrigation fields.
A more substantial use of gray water in residential areas would require major investments in plumbing and may not be practical for existing housing. The expected population increase between 1990 and 2020 is about 19 million people. If half of these people live in single-family dwellings in new housing with gray water plumbing, the potential for gray water use, at 30 gallons per person per day, could be about 180,000 af of water in 2020.
Water Recycling. The WateReuse Association of California conducted a Survey for Future Water Recycling Potential (final report, July 1993). The survey indicates that there is potential for accelerating the pace of water recycling in the future. Statewide total water recycling could increase to about 1,691,000 af per year and create about 1,293,000 af of new water supply (see Table 11-7).
Level I total water recycling was estimated to be 1,321,000 af, producing about 923,000 af of new supply. The remainder would be Level II water recycling. Therefore, there is a potential for 370,000 af of additional water recycling per year by 2020, which should be investigated under Level II options.
Water Desalting. Engineers and scientists have been working on economical ways to desalt water for the last fifty years. The major limitation of desalting has been its high cost, much of which is directly related to high energy requirements. A recent, principal development is the availability of relatively low cost desalting systems for reclaiming brackish (low-salinity) ground water (ground water reclamation) and for recycling municipal water. Both ground water reclamation and desalting of recycled municipal water are being successfully practiced in California and are projected to grow. The cost of desalting using these systems can range from $300 to $500 per acre-foot (plus other costs of treatment in the case of water recycling). Ground water reclamation is discussed in this chapter under Level I--Reliability Enhancement Options.
Sea water desalting costs from $900 to $2,000 per acre-foot; additional costs are required to convey the water to the place of use. With few exceptions, the combined costs are greater than obtaining water from most other sources. However, sea water desalting can be a feasible option for coastal communities that are relatively far from the statewide water distribution system and have limited water supplies. Because of such circumstances, sea water desalting plants have been constructed in the City of Avalon (Santa Catalina Island) and the Cities of Santa Barbara and Morro Bay in the Central Coast Region. Sea water desalting plants can be designed to operate only during droughts to improve water supply reliability. They can also be downsized and operated continuously in conjunction with ground water (reducing ground water pumping during wet periods and providing more ground water supplies for drought periods). The reliability of supply is very high, although at a generally higher cost.
Future desalting programs depend on several factors including the success of pilot projects, the determination of environmental requirements for concentrate disposal and, most importantly, the availability and cost of other sources of supply. Table 11-11 shows current and potential desalting volumes by type of desalting. Because of its relatively high costs and uncertain future, desalting is considered a Level II option for future water supply. Its use is not likely to be widespread and, therefore, is not included in water supply projections and the water budget in this report. The potential desalting water supply production shown in Table 11-11 was derived from various feasibility studies in the last five years, and the amounts represent a potential for Level II future supply as other water sources become unavailable or too costly. The increasing potential for sea water desalting represents future additions of desalting systems to existing power plants during refurbishment and repowering projects. This combination of power generation and desalting is generally the most cost-effective form for sea water desalting facilities. Metropolitan Water District of Southern California and San Diego County Water Authority, in conjunction with San Diego Gas and Electric Company, are among the utilities considering such projects.
Reuse of Brackish Agricultural Drainage Water. Agricultural drainage is reused extensively throughout the State. As drainage water is reused, its salinity can be increased to a level that prohibits further reuse for most crops. Some salt-tolerant crops can be grown with a portion of applied water having a relatively high concentration of dissolved solids. Fresh water use might be reduced by substituting brackish agricultural drainage water or brackish shallow ground water for irrigation during the mid- and late growing season. Using drainage water for irrigation of some salt-tolerant crops was studied and discussed in the San Joaquin Valley Drainage Program report, A Management Plan for Agricultural Subsurface Drainage and Related Problems on the Westside San Joaquin Valley.
The primary concern in long-term use of brackish drainage water for irrigation is the impact of salt accumulation on the integrity and productivity of the soil. Before a decision can be made about large-scale reuse of brackish agricultural drainage water for irrigation, field-sized pilot experiments should be conducted during the next decade to examine the impact of salt accumulation on soil and the feasibility of commercial farming with brackish water.
Local Conjunctive Use Programs. Local agencies are also considering conjunctive use of surface and ground water supplies to enhance reliability of their supplies. Calleguas Municipal Water District, through a cooperative agreement with MWDSC, is pursuing the development of a large-scale conjunctive use project in the North Las Posas Basin in Ventura County. This project could provide storage of up to 300,000 af of imported water. When available, water would be injected into the ground water basin and subsequently recovered as demand dictates.
San Diego County Water Authority Water Resources Plan and Emergency Water Storage Project. The San Diego County Water Authority has recently completed a Water Resources Plan which identifies future water demands, reviews water supply options, and recommends a preferred mix of future supplies. This preferred mix will guide the authority in securing adequate water supplies to meet future demands. The plan includes the development of an additional 85,000 af of local supplies by 2010. These supplies include sources such as water recycling, ground water development, and brackish water desalination. Also, an estimated 70,000 af per year of conservation resulting from implementation of urban BMPs is included in the plan. Currently the authority receives less than ten percent of its average water supply from local sources, or about 60,000 af per year.
The county relies on water imported from MWDSC via the California and the Colorado River aqueducts. However, the imported water supply pipelines cross three major earthquake faults and the flood-prone San Luis Rey River. Currently, San Diego County's 105,000 af of emergency storage is considered inadequate. The latest population growth projections indicate that the county will need as much as 100,000 af in increased storage capacity by 2030. The SDCWA is also studying to determine the best method for meeting the county's emergency water storage needs; the project's goal is to provide sufficient water storage capacity so the county can endure up to a six-month supply interruption without severe economic and environmental damage.
The objective of the current study is to identify combinations of various elements that are capable of meeting the requirements for emergency storage. Each system alternative may be composed of any or all of the following elements: construction of new or enlargement of existing surface reservoirs, emergency reoperation of existing reservoirs, and new pipeline facilities. There are currently thirteen primary storage systems being considered, including expansion and reoperation of San Vicente Reservoir, reoperation of El Capitan Reservoir, and potential construction of Mossa Canyon, Geujito Valley, or Olivenhain reservoirs. The reoperation scenario consists of reconfiguring and enlarging the existing distribution system so that pipelines can shift water among the existing reservoirs in the county.
The reservoir sites and reoperation of existing facilities can be combined in many different systems to meet the county's emergency storage needs. The study review process is designed to select the least environmentally damaging, most practicable system alternatives.
Santa Clara Valley Water District Investigation. Santa Clara Valley Water District is currently investigating various ways of providing additional drought year supplies for its service area. Investigations include increased water conservation programs (to reduce demand), water reclamation, permanent water transfers, and additional long-term storage. Existing facilities and contracts can meet current and future demands during average years through the year 2020. Additional supplies are needed to meet the district's demand during drought periods. Projected drought year deficiencies are approximately 125,000 af annually.
Other Water Management and Supply Augmentation Options. Other options
could include watershed management, local rainfall collection and storage,
and ground water recharge with storm water. Potential water supply management
benefits from implementing watershed management in national forests could be
about 100,000 af statewide. There is also some potential for watershed management
on lands other than those owned by the U.S. Forest Service. Small local rainfall
collection and storage facilities are used for water supplies in remote areas,
such as Point Reyes Lighthouse, and in Southern California to fill fire-fighting
water tanks on ridge tops. Supply from this option is relatively expensive.
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