Watermaster outlines basin recharge, drought risk and ‘pure water’ plan to Monrovia council

Kelly Gardner, executive officer of the Main San Gabriel Basin Watermaster, briefed the Monrovia City Council on April 1 about the basin’s recharge sources, recent rainfall shortfalls, basin operating targets and Watermaster programs to preserve groundwater supply.

Gardner described the San Gabriel Valley’s principal natural sources — runoff from the San Gabriel Mountains collected behind three dams (Cogswell, San Gabriel Dam and Morris Dam) and directed into spreading grounds — and explained how those features recharge the underlying groundwater that supplies roughly 80 percent of the region’s water through wells. She said imported water provides less than 20 percent of local deliveries but is an important element in managed recharge and drought buffering.

Key points presented - Dams and spreading grounds: Gardner explained that the three mountain dams hold water for flood control and to provide recharge, noting San Gabriel Dam’s approximate 44,000 acre‑foot capacity and that…