ARCHIVED REPORTS_2013 ANNUAL REPORT

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Nestle USA, Inc., Ripon, California March 26, 2014 2013 Annual Report and pumping rate. Groundwater in the Lower Aquifer flowed northwesterly throughout 2013 (Figure 5-1 through Figure 5-4). In January 2012, ECM implemented a long-term, high-resolution water level monitoring study using pressure transducers in select wells located near the WWTP lagoons/pond and the Stanislaus River (refer to Section 4.1 for more information). The results from the monitoring program indicate that groundwater levels in this area are relatively dynamic due to seasonal fluctuations in lagoon/pond recharge and river stage. In addition, groundwater discharges to the river during low stage (gaining stream) and is recharged by the river during high stage (losing stream). 2.2.2 INFLUENCE OF RIVER STAGE As confirmed by the high-resolution water level monitoring study, river stage is a major influence on groundwater flow in the Upper and Intermediate aquifers. Recharge from the river appears to be the primary cause for regional groundwater flow towards the north-northwest in these aquifers. The Lower Stanislaus River is controlled by reservoirs located in the foothills of the Sierra Nevada, east of the Site. The river receives most of its flow from late spring and early summer snowmelt. Flow released from the upstream dams is dictated by the lifecycles of aquatic species: the fall flow for attraction, spring pulse flow for outmigration cues in wet years, and sustained late-spring flows for outmigration. The U.S. Geological Survey maintains stage gauge (RIP), which is located on the south side of the river just east of Highway 99. The following chart shows RIP daily river stage elevation (North American Vertical Datum of 1988 (NAVD88), same as groundwater monitoring wells) for 2013. Stanislaus River @ RIP Stage Gauge 55 00 Z 50 a c 45 a� W d0 N 40 L W 35 1/1/13 4/2/13 7/2/13 10/1/13 1/1/14 Groundwater Level Monitoring Event River Stage 5