The Southern California Comprehensive Water Reclamation and Reuse Study , for example, provides a comprehensive assessment of existing reuse and reuse potential in Southern California.The following is a review of key moments in history that changed water policy, from passage of water rights legislation to the voter approval of the State Water Project . Although there are other significant events, however, they are not deemed as relevant and significant to this research and hence are not included. As shown in Figure 2-5, the first Colorado River delivery was made to the farmlands of the Imperial Valley was in 1901 and the major compact agreement was signed in 1922, designating specific allocation to the upper and lower Colorado basins for all seven states . The Central Valley Project and State Water Project were authorized for construction in 1933 and 1951 respectively. In 1973, the first State Water Project delivery was made to Southern California and the Federal Safe Drinking Water Act was passed in 1974 setting the first ever standard for drinking water throughout the country.
In 1998-2003,plastic seedling pots the Colorado Quantification Settlement Agreement was reached between California and other Colorado River Basin states and the Federal Government. As a result of this agreement, California received its allocation of 4.4 MAF which still serves as the state’s allotted water share even until today. Many state agencies are involved with California water management as shown in Table 2-3. While overlapping responsibilities might occur in terms of broad objectives, generally, there is not duplication of functions. Most agencies focus on a specific subset of water management, for example, the State Water Resources Control Board and the Department of Water Resources are the two leading water management agencies. They have mandated water supply objectives, however, their roles differ greatly. DWR focus on water delivery, water supply planning, and infrastructure development, while SWRCB is more of a regulatory body, managing water rights and water quality permitting . These roles are complementary and often require the two agencies to work in concert to address water management at the state level. The management of California water systems consists of three main components: water supply, water quality, and flood control.
Most agencies involved in one or more of these components also have responsibilities for scientific activities and monitoring and administering financial assistance for local water infrastructure. For example, several financial assistance programs attempt to jointly address water quality and water supply needs at the local levels, thereby providing more comprehensive local water supply reliability. Other state agencies not listed may be involved with water management as part of their greater mission . At the federal level, most agencies have distinct roles, for example, the United States Environmental Protection Agency focuses on water quality, while the United States Bureau of Reclamation focuses on water supply. However, these roles can overlap and potentially duplicate state efforts, for example, both state and federal entities estimate the state’s water supply resources, although the state has a more comprehensive role through the efforts of DWR. At the local and tribal levels, most entities play multiple roles including both water supply and water quality ones. Local entities can be both regulated and regulatory entities, receiving permits from state agencies for water quality while in return regulating their constituents to meet those permitting requirements as shown on Table 2-4. In some respects, these roles may duplicate those of state and federal efforts. For example, federal, state and local water agencies may each be independently investigating the development of new water supply sources to potentially serve the same region of the state. Water regions defined by DWR and SWRCB are similar but not identical.
SWRCB works in conjunction with nine semiautonomous regional boards while the DWR divides the state into ten hydrological regions governed from Sacramento headquarters. Although, some activities of DWR and SWRCB require coordination among regions and between the two state agencies, their differences in regional definitions can pose a challenge for implementing programs, planning or accounting for California water resources. Figure 2-6 shows the difference in regional boundaries between DWR and SWRCB.The Federal government holds the most water rights in the state with over 112 MAF of water rights mainly for delivery through the federal Central Valley Project. Second to this area are the water rights held by Imperial Irrigation District serving mainly farms in the Colorado River region. Water rights exceed actual total water volume availability on almost all river systems of the state. This is partly because water may be reused as it runs off farms or may be returned to the river after use for a non-consumptive purpose such as energy production. In some cases, water rights are oversubscribed and exceed actual water availability .As described above, California’s water supplies originate from many sources including local surface water projects, groundwater, inter-regional surface water deliveries such as State Water Project, Colorado River imports, treated wastewater, and natural stream flow. In 2005, DWR estimated that California used about 40.2 million acre-feet of water. Of this amount, roughly 78% was used by the agricultural sector, while the remaining 22% was used by urban users. Table 2-5 shows historical estimates of urban water use published by DWR for the years 1972 to 2005.
Urban water appears to have grown along with the state’s population . Water declined during the drought in the 1990’s, but appears to have rebounded. Per capita urban water use does not appear to have changed significantly over time . From 2000 to 2005, per capita water use averaged 229 gallons per capita per day. The data appear to show that statewide average per capita urban water use has changed little over time over the period from 1972 to 2005 . Compare to the year 2000, a typical water year, total water supply of 43.1 MAF was used to supply agricultural and urban sectors. Figure 2-11 shows the proportions of water use by each sector and the corresponding non-stream supply for California for this year. Almost 80% of non-environmental water supply is used by the agricultural sector,container size for raspberries and more than half of the urban use is by households. One third of all supply originated from local sources and another third is from groundwater and reuse. The remaining third came from the big water management projects – the State Water Project, the Central Valley Project and the Colorado River. Figure 2-12 shows a graphic that illustrates the significant movement of water across the state. The figure shows that about a quarter of the water that flows into the Bay-Delta region from the Sacramento and San Joaquin Rivers and other tributaries is diverted from the Bay-Delta region for distribution throughout the southern portion of the state. Much of the supply exported from the Bay-Delta is delivered to agricultural regions in the southern Central Valley, supplementing their surface water and groundwater supplies . The remaining Bay-Delta exports are delivered via the California Aqueduct to urban regions along the Central Coast and to Southern California. Southern California also imports substantial water supply from the Colorado river to supplement its local resources. Water and energy are inseparable. The two resources are inextricably entwined. Energy is needed to pump, treat, transport, heat, cool and recycle water. Likewise, the force of falling water turns the turbines that generate hydroelectric electricity, and most thermal power plants are dependent on water for cooling . In California, concurrent demands for energy and water usage have continued to rise. As a result, the need to plan and implement efficient technologies and using alternative sources are critical to the success of California’s future.
Water usage for energy generation in California varies greatly, depending on the primary energy source, conversion technologies, and cooling technologies used. Figure 2-13 illustrate the state’s typical water use cycle. Water is first extracted from a source. It is then transported to water treatment facilities and distributed to end users. What happens during end use depends on whether water is for agricultural or urban use. Wastewater from urban uses is collected, treated and discharged back to the environment, where it might become a source for someone else. Energy is required in all stages of the water use cycle. It is difficult to measure the amount of water-related energy that is actually consumed. Figure 2-14 indicate the total water-related energy consumption used in California at approximately 19% of all electricity and 32% of all natural gas generated in the state in the year 2005 . Due to significant variations in energy used to convey water supplies form one place to another, the average energy intensity of water use cycle in Southern California is much greater than in Northern California. This is due to the fact that Southern California imports about 50% of its water from the Colorado River and from the State Water Project . Each of these supply sources is more energy intensive than any single source of water supply used in Northern California . Table 2-6 illustrates the combined energy intensity of the water use cycle for urban communities in Northern and Southern California. By and large, California’s reservoirs and water delivery systems were designed and operated based on historical hydrology. However, with climate change, this mode of traditional operation may no longer be valid . When it comes to climate impacts in the next 20- 50 years, “utility planners will have to grapple with many of them prospectively rather than as phenomena that are already observable” . According to DWR, temperatures across California has risen one degree Fahrenheit on average. This increase in temperature has decreased the spring snow pack in the Sierra Nevada Mountains by about 10 percent which is equivalent to a reduction of 1.5 million acre-feet of water. Seasonal snowpack in the Sierra Nevada has always been the largest surface water storage for the state. Sea level along the California’s coast has also risen by about 7 inches . Climatology experts advise that the warming of air temperatures may cause our normal precipitation to shift from snow to rain. This would lead to serious reduction in the amount of snowpack, an important natural reservoir for storing water in the winter and supply California with water in the spring snowmelt. Figure 2-16 provides an estimate of the average reduction in snowmelt water content based on rising temperatures. California water planners further suggest that more changes are expected to come as we head towards the year 2050 and beyond. Some of those changes may include another rise in mean temperature by 1.5 degrees Fahrenheit which may decrease the Sierra Nevada snowpack further to 25 percent, a near storage volume of about 3.8 million acre-feet. Figure 2-17 provides an estimate of the snowmelt reduction based on projected future temperatures. Figure 2-18 shows the increased in flood events as recorded by DWR from 1910 to 2000. Climate change is already having a profound effect on California’s water systems as evidenced by the changes in snowpack storage, river flows, and sea levels. Scientific studies show these changes will increase stress on the water systems in the future. Because some levels of the climate change is inevitable, California water systems must be adaptable to change . The impacts of these changes will gradually increase during this century and beyond. California needs to plan for water system modifications that adapt to the impacts of climate change. Figure 2-19 shows a possible global sea level rise of 4 to 6 inches by mid-century. Higher sea levels will increase the salinity in the Delta, disrupting the freshwater supply and quality that many Californians traditionally rely on. While California’s urban water use has grown steadily with population, some areas of the state have succeeded in lowering per capita water use. For example, in 2011, urban water use in Los Angeles was 123 gpcd, among the lowest in the state . A Study by DeOreo et al. 2011 found that more than half of California water use for single-family residences was for outdoor uses. DWR 2011 also reported that residences account for about two-thirds of urban water use. In 2005, residential use accounted for an estimated 66% of total urban water use in California. Water planners believe that this number can be curtailed with improvements in water-use efficiency and conservation by means of rebates and incentives. Water agencies and utilities are also encouraged to implement conservation and efficiency programs, termed best management practices, outlined in the of California Urban Water Conservation Council’s Memorandum of Understanding .