14 ATTACHMENT 1 EXHIBIT A - Laserfiche WebLink

Chapter 6 Water Supply Characterization THE CITY OF PL£ASANTON Nitrates and salinity have historically been the primary water quality constituents -of -concern in wastewater and recycled water, but nitrates have become less of a concern since 1995, when the LWRP and DSRSD's RWTF, two wastewater treatment facilities in the area feeding into recycled water facilities, reduced nitrates in their effluent. Salinity is addressed by the SMP, as discussed above. In 2015, Zone 7 completed a Nutrient Management Plan (NMP)', which provides an assessment of the existing and future groundwater nutrient concentrations relative to the current and planned expansion of recycled water projects and future development in the Livermore Valley. The NMP also presents planned actions for addressing positive nutrient loads and high groundwater nitrate concentrations in localized Areas of Concern where the use of septic systems is the predominant method for sewage disposal. The NMP was prepared as a supplement to the SMP; together, they are a Salt and Nutrient Management Plan, which has been incorporated into the GMP and Alternative GSP. Under the Toxic Sites Surveillance Program, Zone 7 documents and tracks polluted sites across the groundwater basin that pose a potential threat to drinking water and interfaces with lead agencies to ensure that the Main Basin is protected. Information is gathered from state, county, and local agencies, as well as from Zone 7's well permitting program and the SWRCB's GeoTracker website and compiled in a GIS database. In general, there are two types of spills potentially threatening the Livermore Valley Groundwater Basin: petroleum-based fuel products and industrial chemical contaminants. In the 2020 water year, Zone 7 tracked the progress of 56 active sites where contamination has been detected in groundwater or is threatening groundwater. More details on the affected sites and their remediation can be found in the annual report.' 6.2.2.2.5 Land Surface Elevation Monitoring Program Previously, Zone 7's Land Surface Elevation Monitoring Program involved contracting with a licensed land surveyor to measure land surface elevations within the Main Basin boundary twice per year. The program included a network of approximately 40 elevation benchmarks encompassing Zone 7's production wellfields and spanning the Bernal and Amador Subareas within the Main Basin. In the 2016 water year, Zone 7 contracted with TRE Altamira (TRE) to evaluate Interferometric Synthetic Aperture Radar (InSAR) as an alternative to land surveying for subsidence monitoring. TRE analyzed InSAR data from three different satellites over a 24 -year period (from 1992 to 2016) which included approximately 120 satellite images with between 415 and 1,202 measuring points per square mile. Each measuring point contains a deformation time series, including cumulative displacement, average deformation rate, acceleration, and seasonal amplitude. The study results correlated well with topographic surface measurements taken by land surveys within the same time period. An added benefit of the InSAR dataset was that it included a larger area (i.e., the entire Main Basin) than the land surveying. Starting in the 2019 water year, Zone 7 retired the land surveying program and transitioned to InSAR for monitoring land subsidence. In general, observed land surface elevation changes between September 2018 7 Zone 7 Water Agency, 2015. Nutrient Management Plan — Livermore Valley Groundwater Basin. httio://www.zone7water.com/imaFes/iodf docs/F-roundwater/nmio-2015 final.lodf 8 Zone 7 Water Agency, 2020. Annual Report for the Sustainable Groundwater Management Program, 2019 Water Year (October 2018-2019), Livermore Valley Groundwater Basin. httios://www.zone7water.com/36-public/content/76-jzroundwater-manaizement-iorojzram-annual-report WEST YOST N-680-60-20-04-WP-R-680-2020UWMP 6-14 City of Pleasanton 2020 Urban Water Management Plan May 2021