14 ATTACHMENT 1 EXHIBIT A - Laserfiche WebLink

Chapter 6 Water Supply Characterization THE CITY OF PLE ASANTON water via its streams or arroyos ("in -stream recharge" or "artificial recharge") for storage in the Main Basin, began supplying treated surface water to customers to augment groundwater supplies, and regulating municipal pumping by other users. Figure 6-4 shows Zone 7's total annual artificial recharge amounts, pumping amounts, and their cumulative net impacts to operational storage from the 1974 water year to the 2020 water year. Zone 7's operational policy is to maintain the balance between the combination of natural and artificial recharge and withdrawal or pumping to maintain groundwater levels above the emergency reserve storage. Zone 7 has generally been able to pump as much groundwater as it has needed to over the last five years; however, during the recent drought, decreases in groundwater elevation did noticeably affect the production of certain wells. Zone 7 is continuing to study the groundwater basin and developing new tools (such as an improved groundwater model) to better understand the levels of groundwater extraction possible under various conditions and contributing factors such as groundwater connectivity, spatial distribution of groundwater in the Main Basin, and others. Since 1974, Zone 7 has artificially recharged over 67,000 AF more water than it has pumped, helping to offset demands and keeping the Main Basin's groundwater levels above the historical lows. Between 1974 and 2007 Zone 7 had artificially recharged approximately 70,000 AF more than it had pumped during that same time; however, since 2007, Zone 7 has artificially recharged about 3,000 AF less than it has pumped, primarily due to construction work on the SBA, recent drought conditions, and lower -than -average SWP allocations over that same time period. Overall net groundwater storage remains significantly above historical lows, as shown on Figure 6-3. Zone 7 plans to augment its current groundwater in -stream recharge capacity with off -stream recharge using the future Chain of Lakes. 80,000 iiiiiiiiiiiiZone 7 Recharge (Supply) Zone 7 Pumping I Demand) 70,000 — _Cumulative Zane 7 Supply/Demand 60,000 50,000 40,000 30,000 w w 4 W 20,000 10,0 -10,000 Since 1974 Zone 7 has artificially recharged / 67,095 AF more than it has pumped 0,000 n n n tr tr tr m m m m m m m m m m O� m O O O O O W W O O O O O O O O O O r r N m m m m rn rn rn rn m rn rn rn rn rn m m m m m rn rn rn m m w rn o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 .......... N N N N N N N WATER YEAR Figure 6-4. Artificial Recharge, Pumping, and Net Cumulative Impacts to Operational Storage WEST YOST 6-12 City of Pleasanton 2020 Urban Water Management Plan N-680-60-20-04-WP-R-680-2020UWMP May 2021