25B - METRO WATER DISTRICT FUTURE SUPPLY

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quagga mussels in the San Gabriel River that came from deliveries of MWD water. Although steps were taken to desiccate the river and prevent the spread of quagga mussels, it is possible that further infestations will occur and hamper the use of the San Gabriel River and associated spreading facilities for the capture and recharge of local storm water. In the Santa Clara River watershed, United Water Conservation District (UWCD) captures storm flows from the Piru Creek watershed in Lake Piru, as well as imports a small amount of SWP water from Pyramid Lake. UWCD then releases the stored water in late summer, recharging the downstream groundwater basins, including the coastal Oxnard Plain. When Lake Piru became infested with quagga mussels in late 2014, the California Department of Fish and Wildlife (CDFW) ordered UWCD to limit discharges to downstream recharge facilities, to limit the spread of quagga mussels. UWCD's downstream recharge facilities are the primary source for the cities of the Oxnard Plain, which are also served by MWD via its member agency Calleguas Municipal Water District (Calleguas). Groundwater has historically provided approximately half of the water for this portion of Calleguas' service area. Quagga mussel -induced limitations on UWCD's groundwater recharge will shift additional burden onto Calleguas and MWD. UWCD is currently working with CDFW, U.S. Fish and Wildlife, and National Marine Fisheries Service to develop an eradication plan for Lake Piru using EarthTec QZ that could potentially be implemented within the next few years. California Department of Fish and Wildlife Regulations The California Department of Fish and Wildlife (CDFW) has a mandate to prevent the spread of quagga mussels. As a result, CDFW requires the preparation of Dreissenid Mussel Monitoring, Response and Control Plans (Plan) for any facility that is impacted. Desiccation is the primary method of mitigating for quagga mussel infestations. Although desiccation can work for isolated spreading grounds, it is less feasible in rivers and streams and impossible in large reservoirs unless they can be fully drained. For OCWD, the Plan contains a requirement that OCWD use imported water for recharge only in basins that can be desiccated (dried out) for two weeks. In addition, these basins must be drained and dried prior to the storm season to prevent potential conveyance of quagga mussels -laden water to other basins or to the Santa Ana River. Moreover, one of the most effective recharge facilities, the Santa Ana River, cannot be fully utilized because it cannot be fully desiccated. These restrictions present a barrier to both the recharge of imported water and the capture of storm water, which reduces the recharge of local supplies and the overall efficiency of groundwater replenishment operations. The recharge of imported and storm water are considered together because OCWD, as with other entities, use their facilities for storage, conveyance and recharge of both sources of supply. The WRD has also been affected by the potential for infestations of waterways used to convey both imported and storm water by quagga mussels. The Los Angeles County Department of Public Works (LACDPW) owns the conveyance and spreading facilities used by WRD for the recharge of storm water, recycled water and imported water. Due to the potential for quagga mussel infestations, imported deliveries from the Colorado River have not been approved by City of Santa Ana 25 Agreement No. 189280 25B-28