14 ATTACHMENT 1 EXHIBIT B - Laserfiche WebLink

Zone 7 Water Agency Executive Summary Chromium The minimum threshold for total Cr in groundwater is < 0.050 mg/L which matches the State's MCL. No total Cr detections exceeded this threshold in any municipal supply wells or lower aquifer monitoring wells in 2019 WY. Total Cr above 0.050 mg/L was detected in one upper aquifer monitoring well (0.063 mg/L in monitoring well 3S/2E 12C 4) located in the Fringe Subarea -Northeast. This is consistent with previous years. PFAS PFAS are a large group of human -made substances that do not occur naturally in the environment and are classified by the Environmental Protection Agency (EPA) as "contaminants of emerging concern". While there are no current federal or California State limits (e.g., Maximum Contaminant Levels [MCLS]) for any PFAS compounds, in December 2019, the EPA published draft screening levels of 40 parts per trillion (ppt) and Preliminary Remediation goals (PRGs) of 70 ppt for PFOS and/or PFOA (combined or individually) for groundwater that is a current or potential source of drinking water. In addition to the California State Water Resources Control Board Division of Drinking Water (DDW)-required quarterly monitoring of the municipal wells, Zone 7 sampled and tested several other monitoring program wells for PFAS to determine if PFAS contamination is widespread. Only one of Zone 7's municipal wells, Mocho Well No. 1 (i.e., 3S/1E 9M 2), had PFOS concentrations (78 to 90 ppt) that exceeded DDW's recommended Response Level of 70 ppt. Several monitoring wells also had exceedances and additional testing is underway. More detailed results of Zone 7's Groundwater Quality Monitoring Program can be found in Section 7, Groundwater Quality. A description of Zone 7's management actions regarding groundwater basin quality can be found in Section 13, Water Quality Sustainability. ES.2.5. Subsidence Up through the 2018 WY, Zone 7 contracted with a licensed land surveyor to measure the land surface elevations of approximately 40 benchmarks that extended from bedrock outside of the Main Basin to the vicinity of Zone 7's production wellfields. In 2016, Zone 7 contracted with TRE Canada, Inc. (TRE) to evaluate Interferometric Synthetic Aperture Radar (InSAR) as an alternative to land surveying for subsidence monitoring. Starting in 2019, Zone 7 is now using InSAR instead of the land surveys for analyzing land subsidence. For the 2019 WY, Zone 7 contracted with TRE Altamira to acquire satellite data collected between the 2016 WY and the 2019 WY to perform an InSAR study for the Livermore Valley. For this study, TRE increased the coverage area to include most of the Livermore Valley Groundwater Basin area, including the entire Main Basin and most of the Fridge and Upland Areas. The study indicated that there continues to be no inelastic (permanent) deformation between the 2016 and 2019 water years; just seasonal and cyclical surface elevation fluctuations that correlate with groundwater elevation fluctuations. These "elastic" fluctuations generally have been + or - 0.07 ft per cycle; and less than 0.03 ft of net change during the 2019 WY. The results are presented in Section 8, Land Surface Elevation. Annual Report for the Sustainable March 2020 Groundwater Management Program 2019 WY ES -11