The Key Well for San Gabriel aquifer has dropped to the lowest level ever recorded for the San Gabriel Basin – 171 feet. This is particularly concerning for Arcadia and Monrovia as the cities – and nearly all of the San Gabriel Valley – rely on the Main San Gabriel Basin Aquifer for its water use.
Prior to this current low, the previous historic low was recorded in 2016 when the Key Well had dropped to 172.2 feet.
Advanced hydrogeological modeling has indicated that if the water level falls below 165 feet at the Key Well, then 10 percent of all production wells in the Main San Gabriel Basin will fail, and water production output will decrease by 30 percent. The data has also indicated that should the aquifer level fall below 165 feet, Monrovia’s water production capacity will be particularly impacted, given our location at the edge of the basin.
Staff at the City of Monrovia are assessing this new water issue and have been making plans to ensure greater water resiliency for the community. In particular, the two primary efforts the city has engaged include current efforts to site a new, deeper well to allow access to water in the aquifer, along with the development of plans to ensure the reliability and usability of directly imported water for the community from Metropolitan Water District.
In addition, on a regional basis, the staff has been coordinating with the Watermaster, who is anticipating the delivery of around 16,000 acre-feet of water (which is equivalent to around 2 feet of additional depth at the Key Well) from the Metropolitan Water District in the coming months.
Staff will continue monitoring this issue in greater detail during the next several months, and in the meantime, the city urges everyone to redouble water conservation efforts. A full suite of possible water saving options and tips can be found online.