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Agreements with MWD and OCWD for Restoration of Local Recharge Sources from Invasive Dreissnid Mussels Study August 20, 2019 Page 2 Water District (OCWD) and Trussell Technologies to submit a proposal entitled "Restoration of Local Recharge Sources from Invasive Dreissenid Mussels" (Study). Ever since their discovery in Lake Mead in 2007, quagga mussels (Dreissena bugensis) have spread through MWD's Colorado River Aqueduct (CRA) as far south as Lake Skinner, near Temecula. As of December 2017, quagga mussels have been detected in 43 locations in California. To minimize the spread of quagga mussels, MWD chlorinates CRA water, starting at Copper Basin reservoir, close to the eastern end of the CRA, and at other locations, such as Lake Matthews. Despite this effort, quagga mussels have infested reservoirs used for capture of local runoff, as well as rivers, streams, and canals used to convey both local supplies and imported supplies to groundwater replenishment facilities. This is important because OCWD uses many of the same facilities to recharge imported water and local sources, such as stormwater. As a result, the presence of quagga mussels presents a barrier to the efficient use of these dual -use facilities and has affected the ability to maximize the capture and recharge of local supplies. This, in turn, affects the amount of water available to those that rely on the groundwater basin for water supplies. As an example, Irvine Lake, which is owned and operated by the Irvine Ranch Water District (IRWD), receives both imported CRA water and local storm flow. Downstream of Irvine Lake are OCWD's Santiago Basins which are gravel mines that were converted to groundwater replenishment facilities in the early 1990s. In the 1990s, water from Irvine Lake was discharged to Santiago Basins via Santiago Creek for groundwater replenishment. These deliveries are no longer possible due to the presence of the quagga mussel in Irvine Lake and the potential for infesting Santiago Creek and Santiago Basins. The City of Sana Ana is one of 19 major retailers in the OCWD service area, serving a population of over 334,000. As a groundwater producer in the OCWD service region, the City relies upon OCWD's management of the Orange County groundwater basin for three-quarters of its water supply. This Study is designed to examine ways to maximize the recharge of both imported and local supplies, which will, in turn, increase available water supplies to the City, and others that rely on the groundwater basin. The total cost of the Study is $245,592. On January 31, 2019, the City was notified that MWD authorized the proposal under the FSA Funding Program, which will cover half of the total Study cost. In addition to OCWD, other agencies contributing funding to the Study include the Water Replenishment District of Southern California, United Water Conservation District, the Main San Gabriel Watermaster, and the Central Basin Municipal Water District. The Study is slated to be completed by February 2021. As lead agency, the City will need to enter into two agreements. The first is with MWD (Exhibit 1) and the second is with OCWD (Exhibit 2). The City will receive invoices from OCWD and issue payments for the MWD share of the costs. Subsequently, City will submit invoices to MWD for reimbursement. MWD will not reimburse the City until it issues payments to OCWD. As a result, City funds.will be used to temporarily facilitate the transfer of funds between MWD and OCWD. At 20Ci-2