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WATER RESOURCES TECHNICAL REPORT• In the UAS, water level declines could potentially interfere with pumping operations atthe Forebay spreading grounds.The potential groundwater level declines were evaluated for four Phase 2 scenarios (2a, 2b,2c, and 2c2), which included groundwater recovered at the following locations: the UWCDEl Rio wellfield (several UAS wells), the City Water Yard (two LAS wells, five UAS wells),and at the City Blending Station No. 3 (three UAS wells). These scenarios consisted of thefollowing extractions:Extraction Scenarios to Assess Groundwater Level Declines from Groundwater Recovery (AFY)Extraction Area Scenario 2a Scenario 2b Scenario 2c Scenario 2c2UWCD El Rio Wellfield 3,857 20% 15,429 80% 5,092 20% 10,183 40%City Water Yard 15,429 80% 3,857 20% 20,366 80% 5,092 20%City Blending Station No. 3 — — — 10,183 40%Total 19,286 19,286 25,458 25,458All groundwater recovery is from UAS wells, except for 500 AFY recovered from each of the two City WaterYard LAS wells (Nos. 20 and 21) for each of the Phase 2 scenarios.Best management practices are described below to minimize the potential to:• Induce brief periods of coastal landward flow in the UAS during extended, drierclimatic periods.• Increase of the moderate potential for landward flow that exists in the LAS, particularlyduring drier years and in the fall when water levels are seasonally low.• Interfere with pumping operations at the Forebay spreading grounds.Reducing the Potential for Coastal Landward Flow in the UASAs previously described, all Phase 2 scenarios incrementally increased the potential toinduce brief periods of coastal landward flow during extended, drier climatic periods. Asseen on the hydrograph for coastal well 05G02 (Figure 2-29), however, the periods whengroundwater levels are below sea level are infrequent and brief, occurring during extended,drier periods. In general, groundwater should be recovered further inland to minimizewater level declines at the coastline, as supported by the following observations from thesimulations:• For Scenarios 2a and 2b (recovery of 19,286 AFY), the water level declines along thecoastline were similar, between 5 and 10 feet, but were slightly higher for Scenario 2a,which included more recovery at the City Water Yard (located closer to the ocean) thanat the UWCD El Rio wellfield (located further away from the ocean).• For Scenarios 2c and 2c2 (recovery of 25,458 AFY), the water level declines along thecoastline were higher for Scenario 2c, which included most recovery (80 percent) at theCity Water Yard (located closer the ocean), compared to Scenario 2c2, which includedmost recovery (80 percent) equally split between the UWCD El Rio wellfield and theCity Water Yard (located further away from the ocean.W112003002SCO LW1458.DOC/ 033390002 99