Augmenting Water Resources with Reclaimed Water: The Case of Eastern Municipal Water District and Rancho California Water District

Eastern Municipal Water District (EMWD) operates five water reclamation facilities providing either secondary- or tertiary-treated water that is used for a variety of irrigation and landscape uses. Currently EMWD beneficially reuses approximately 55 percent of its reclaimed water. As a result of anticipated growth in population, water consumption, and reclaimed water generation, EMWD is interested in maximizing water reuse in order to curtail water demand and reliance on imported water supplies. It is anticipated that up to 16,000 acre-feet per year (AFY) of reclaimed water could be available in the future to implement water augmentation projects, beyond current water reuse rates.EMWD, in cooperation with Rancho California Water District (RCWD) evaluated four concept projects aimed at maximizing the use of reclaimed water to augment water supplies. The alternatives entail using highly treated reclaimed water for:Aquifer rechargeStorage in a surface reservoirDischarge of reclaimed water to Murrieta Creek to meet water rights flow requirements for downstream usersSupply of low-salinity reclaimed water to sensitive agricultural areasThe feasibility of these alternatives was evaluated in terms of technical, financial and regulatory aspects. The results of this evaluation were then incorporated into RCWD's Regional Integrated Resources Plan, which examined other supply and demand management opportunities to meet future needs in the region.The implementation of one or more of the conceptual projects evaluated will reduce the Districts' reliance on imported water in the future, thus providing environmental benefits from reduced water diversion. In addition, these projects would defer or reduce the need for additional imported water conveyance and treatment facilities to meet future water demands.