14 ATTACHMENT 1 EXHIBIT A - Laserfiche WebLink

Chapter 6 Water Supply Characterization 6.2.2 Groundwater THE CITY OF PL£ASANTON This section describes the Livermore Valley Groundwater Basin and Zone 7's Groundwater Management Plan', which is used to manage the basin. Each year, Zone 7 prepares an Annual Report for the Groundwater Management Program. A copy of the Executive Summary of the 2019 Water Year Annual Report is provided in Appendix H. The City owns and operates three active groundwater wells in the Main Basin, which is a portion of the Livermore Valley Groundwater Basin. The City's groundwater resource is described below. 6.2.2.1 Groundwater Basin Description Zone 7 has managed local surface water and groundwater resources for beneficial uses in the Livermore Valley Groundwater Basin (Basin) for more than 50 years. Consistent with its management responsibilities, duties, and powers, Zone 7 is designated in the 2014 Sustainable Groundwater Management Act (SGMA) as the exclusive Groundwater Sustainability Agency (GSA) within its jurisdictional boundaries. As defined in DWR Bulletin 118 Update 2003 (California's Groundwater), the Basin (DWR Basin 2-10, shown on Figure 6-2) covers 69,600 acres (109 square miles), extending from the Pleasanton Ridge east to the Altamont Hills and from the Livermore Uplands north to the Tassajara Uplands. The Basin is not adjudicated, and DWR has identified it as medium priority; Basin 2-10 is not identified as either in overdraft or expected to be in overdraft. Surface drainage features include Arroyo Valle, Arroyo Mocho, and Arroyo Las Positas as principal streams, with Alamo Creek, South San Ramon Creek and Tassajara Creek as minor streams. All streams converge on the west side of the basin to form Arroyo de la Laguna, which flows south and joins Alameda Creek in Sunol Valley and ultimately drains to the San Francisco Bay. Some geologic structures restrict the lateral movement of groundwater, but the general groundwater gradient is from east to west, towards Arroyo de la Laguna, and from north to south along South San Ramon Creek and Arroyo de la Laguna. The entire floor of the Livermore Valley and portions of the upland areas on all sides of the valley overlie groundwater -bearing materials. The materials are mostly continental deposits from alluvial fans, outwash plains, and lakes. They include valley -fill materials, the Livermore Formation, and the Tassajara Formation. Under most conditions, the valley -fill and Livermore Formation yield adequate to large quantities of groundwater to all types of wells, with the larger supply wells being in the Main Basin. The Main Basin is composed of the Castle, Bernal, Amador, and Mocho II sub -basins, with an estimated total storage capacity of 254,000 AF. 4 Jones & Stokes, 2005. Groundwater Management Plan for Livermore-Amador Valley Groundwater Basin. httiD://www.zone7water.com/index.iDhiD/36-public/content/79-F-roundwater-manaFement-plan WEST YOST N-680-60-20-04-WP-R-680-2020UWMP 6-8 City of Pleasanton 2020 Urban Water Management Plan May 2021