Los Angeles County Department of Public Works, California, USA – Operating Groundwater Replenishment site receiving purified recycled water from ARC (Pico Rivera 1)
Groundwater has been pumped out of the Central and West Coast Basins for over 100 years, providing residents and businesses with a reliable and high quality source of water. Agencies such as Water Replenishment District must provide artificial replenishment and keep the groundwater basins balanced to avoid overdraft (more water taken out than going in). Spreading grounds are like ‘leaky lakes’ – they must be constructed in geologically suitable areas where surface water can soak down into the subsurface and recharge the aquifers in a groundwater basin.
Since the late 1930s, basins have been recharged with stormwater runoff; imported water was added in the 1950s and recycled water in the 1960s to supplement this natural source. Over time, recycled water amounts increased while imported water amounts decreased as the safety and reliability of the recycled water was proven through intensive sampling, monitoring and research efforts. Currently, about 35% of the replenishment water is stormwater and 65% is from recycled water. By replacing the need for new imported water to replenish the Central Groundwater Basin, the groundwater resources for the region are more sustainable and drought resilient.