Increasing the Sustainable Yield of the Orange County Groundwater Basin with Managed Aquifer Recharge.

Abstract

The Orange County Water District (OCWD) has increased the sustainable yield of the Orange County Groundwater Basin (Basin) by developing a large managed aquifer recharge (MAR) system that utilizes multiple sources of water. The Basin is the primary water supply for 2.5 million people. The sources of recharge water have changed over time, shifting from imported water to advance-treated recycled water. Santa Ana River (SAR) supplies have also provided a significant source of recharge water. SAR water recharge is enhanced through a stormwater capture program in collaboration with the United States Army Corps of Engineers at Prado Dam. Forecast Informed Reservoir Operations is a promising new approach to increase the effectiveness of the stormwater capture program at Prado Dam. Investments in MAR has increased the Basin's sustainable yield three-fold. Over the last 50 years, increased pumping has been sustained by MAR so that Basin storage has remained within the target storage range. Groundwater supplies sustained by MAR are less expensive than the alternative water supply of imported water and also have a lower energy and greenhouse gas footprint than imported water supplies. By increasing the Basin's sustainable yield while reducing dependence on imported water, OCWD's MAR program continues to support the local economy by ensuring that residents and businesses have a reliable source of water.