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ekienvironment & water The calculated gradient magnitude in the vicinity of LAA A23 was 0.0016 and the gradient azimuth was 260 degrees.The Spring 2023 gradient magnitude increased by 0.0013 and azimuth changed by -85 degrees relative to Fall 2022 (Table 4). Recycled water was last applied to LAA A23 on 24 September 2009. Therefore, changes in the calculated gradient beneath LAA A23 are due to factors other than irrigation with recycled water (for example, seasonal conditions and the corresponding changes in Mossdale area groundwater levels). Beneath the CLSP area, the water levels in the monitoring wells increased about 6.48 feet on average between Fall 2022 and Spring 2023 (Table 3). The inferred groundwater flow direction in Spring 2023 is generally away from the San Joaquin River toward the southeast, whereas groundwater flow in Fall 2022 was generally northeast from CLSP-3 towards CLSP-1. The calculated gradient in the vicinity of LAA A36 was 0.0007 and the gradient azimuth was 150 degrees. The Spring 2023 gradient magnitude increased by 0.0004 and the azimuth changed by 150 degrees relative to Fall 2022 (Table 4). Beneath River Islands, the water levels in monitoring wells increased by about 5.86 feet on average between Fall 2022 and Spring 2023 monitoring events (Table 3). The measured water levels and calculated gradients appear to be influenced by irrigation of River Islands agricultural fields, San Joaquin River, Old River, Paradise Cut,the drainage ditch located north and northeast of the LAAs, and construction dewatering activities in the area of LAA A30 (Figure 3). In the northwestern part of River Islands (beneath LAAs A30 and A31) inferred groundwater flow is generally away from the drainage ditch and towards well MWR-28, similar to Fall 2022. The measured water levels near LAA A30 appear to be influenced by continued construction dewatering activities in the vicinity of MWR-12, MWR-27, and MWR-28.10 MWR-12 was dry during the Spring 2023 semiannual monitoring event; therefore, no gradient was calculated within the vicinity of LAA A30 (Table 4). The calculated gradient beneath LAA A31 was 0.0014 indicating the gradient magnitude decreased by 0.0004; however, the azimuth was very similar to Fall 2022, as it only changed by 10 degrees (Table 4). In the southeastern part of River Islands (beneath LAA A28), the inferred groundwater flow direction is away from Paradise Cut and towards well MWR-3 (Figure 3), which is consistent with most past monitoring events. The calculated gradient beneath LAA A28 was 0.0032 and the azimuth was 45 degrees, indicating a 0.0026 increase in the gradient magnitude and -5 degree change in azimuth relative to Fall 2022 (Table 4). Beneath the CTF Facility, water levels in the monitoring wells increased about 6.17 feet on average between Fall 2022 and Spring 2023 (Table 3). Between these two sampling events, approximately 372 acre-feet of recycled water was applied to 1313-1. The Spring 2023 gradient directions are away from PB-1,which is the same as Fall 2022 (Table 4). Groundwater elevation contours (Figure 3) and gradient calculations indicate that inferred horizontal groundwater flow is generally to the west and southwest beneath Pond S5 and former LAS-2. The calculated gradient beneath PB-1 was 0.0034 and the azimuth was 315 degrees, indicating the Spring 2023 gradient magnitude increased by 0.003 and the azimuth changed by io Construction dewatering around MWR-12, MWR-27 and MWR-28 started during the Fall 2021 Monitoring Event. City of Lathrop 10 13 July 2023 EKI 1390088.03