Item 28 - Urban Water Management Plan and Water Shortage Contingency Plan

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Santa Ana 2020 Urban Water Management Plan arcadis.com 6-14 Table 6-4: Retail: Groundwater Volume Pumped DWR Submittal Table 6-1 Retail: Groundwater Volume Pumped Supplier does not pump groundwater. The supplier will not complete the table below. All or part of the groundwater described below is desalinated. Groundwater Type Location or Basin Name 2016 2017 2018 2019 2020 Alluvial Basin Orange County Groundwater Basin 24,722 24,357 21,327 25,505 25,591 TOTAL 24,722 24,357 21,327 25,505 25,591 NOTES: Source: MWDOC, 2020 6.3.2 Basin Characteristics The OC Basin underlies the northerly half of Orange County beneath broad lowlands. The OC Basin, managed by OCWD, covers an area of approximately 350 square miles, bordered by the Coyote and Chino Hills to the north, the Santa Ana Mountains to the northeast, and the Pacific Ocean to the southwest. The OC Basin boundary extends to the Orange County-Los Angeles Line to the northwest, where groundwater flows across the county line into the Central Groundwater Basin of Los Angeles County. A map of the OC Basin is shown on Figure 6-2. The total thickness of sedimentary rocks in the OC Basin is over 20,000 feet, with only the upper 2,000 to 4,000 feet containing fresh water. The OC Basin’s full volume is approximately 66 MAF. There are three major aquifer systems that have been subdivided by OCWD, the Shallow Aquifer System, the Principal Aquifer System, and the Deep Aquifer System. These three aquifer systems are hydraulically connected as groundwater is able to flow between each other through intervening aquitards or discontinuities in the aquitards. The Shallow Aquifer system occurs from the surface to approximately 250 feet below ground surface. Most of the groundwater from this aquifer system is pumped by small water systems for industrial and agricultural use. The Principal Aquifer system occurs at depths between 200 and 1,300 feet below ground surface. Over 90% of groundwater production is from wells that are screened within the Principal Aquifer system. Only a minor amount of groundwater is pumped from the Deep Aquifer system, which underlies the Principal Aquifer system and is up to 2,000 feet deep in the center of the OC Basin. Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of manmade chemicals that includes perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). PFAS compounds were once commonly used in many products including, among many others, stain- and water-repellent fabrics, nonstick products (e.g., Teflon), polishes, waxes, paints, cleaning products, and fire-fighting foams.