Evaluation of Surface Water Augmentation at Lake Jennings

East County Advanced Water Purification Program (Program) is considering implementation of up to 58,670 cubic meters per day (15.5 million gallons per day) of potable reuse through surface water augmentation (SWA) at the Lake Jennings Reservoir in three phases. Determining the feasibility of using Lake Jennings under emerging California Division of Drinking Water SWA Regulations was important to verifying the future size and capacity of the Program. 3-D hydrodynamic modeling tested the viability of using Lake Jennings for receiving potable reuse water with utmost consideration to public health and safety. Modeling results demonstrated high dilution capability of Lake Jennings system even at low residence times. Lake Jennings is anticipated to operate at or above 4 months of residence time 99% of the time. Similarly, Lake Jennings would provide 100:1 dilution or higher 99.8% of the time. Therefore Phases 1 and 2 of the Program is a feasible SWA project.