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2015 URBAN WATER MANAGEMENT PLAN <br />Turnback pool water is Table A water that has been allocated to SWP contractors that has exceeded their <br />demands. This water can then be purchased by another contractor depending on its availability. <br />SWP Delta exports are the water supplies that are transferred directly to SWP contractors or to San Luis <br />Reservoir storage south of the Delta via the Harvey O. Banks pumping plant. Estimated average annual <br />Delta exports and SWP Table A water deliveries have generally decreased since 2005, when Delta <br />export regulations affecting SWP pumping operations became more restrictive due to the Biops. A <br />summary of SWP water deliveries from the years 2005 and 2013 is summarized in Table 3 -1. <br />Table 3 -1: Metropolitan Colorado River Aqueduct. Program Capabilities <br />The following factors affect the ability to estimate existing and future water delivery reliability: <br />• Water availability at the source: Availability depends on the amount and timing of rain and snow that <br />fall in any given year. Generally, during a single dry year or two, surface and groundwater storage <br />can supply most water deliveries, but multiple dry years can result in critically low water reserves. <br />• Water rights with priority over the SWP: Water users with prior water rights are assigned higher <br />priority in DWR's modeling of the SWP's water delivery reliability, even ahead of SWP Table A water. <br />• Climate change: mean temperatures are predicted to vary more significantly than previously <br />expected. This change in climate is anticipated to bring warmer winter storms that result in less <br />snowfall at lower elevations, reducing total snowpack. From historical data, DWR projects that by <br />2050, the Sierra snowpack will be reduced from its historical average by 25 to 40 percent. Increased <br />precipitation as rain could result in a larger number of "rain -on- snow" events, causing snow to melt <br />earlier in the year and over fewer days than historically, affecting the availability of water for pumping <br />by the SWP during summer. <br />• Regulatory restrictions on SWP Delta exports due to the Biops to protect special- status species such <br />as delta smelt and spring- and winter -run Chinook salmon. Restrictions on SWP operations imposed <br />by state and federal agencies contribute substantially to the challenge of accurately determining the <br />SW P's water delivery reliability in any given year. <br />• Ongoing environmental and policy planning efforts: the California WaterFix involves water delivery <br />improvements that could reduce salinity levels by diverting a greater amount of lower salinity <br />Sacramento water to the South Delta export pumps. The EcoRestore Program aims to restore at <br />least 30,000 acres of Delta habitat, and plans to be well on the way to meeting that goal by the year <br />2020. <br />arcadis.com Bill 4U 3 -6 <br />