Stormwater Capture and Environmental Disaster Averted – How Water Managers Reacted to Record-Breaking Rainfall in Los Angeles

Los Angeles, California experienced Record-breaking rainfall last week, which provided a boost for water managers busy capturing runoff to save for dry days ahead. The storm runoff swelled the Los Angeles River, but some agencies were able to capture billions of gallons of stormwater for future use. Meanwhile, some water managers were also grappling with the possibility of an environmental disaster caused by the heavy rainfall.

The Los Angeles County Public Works managed to capture 2.7 billion gallons of stormwater, enough to supply 65,600 residents with water for a year. Across Southern California, stormwater capture facilities were able to secure around 15,000 acre-feet, or approximately 4.9 billion gallons, to recharge into groundwater since Sunday night. This proactive measure is essential for preparing for future droughts in the face of extreme weather events.

However, the sheer volume of rain posed challenges for some agencies, such as the Las Virgenes Municipal Water District, whose treatment plant was overwhelmed by nearly 10 inches of rain. Officials had to work quickly to prevent raw sewage from being discharged into Santa Monica Bay at Surf Rider Beach, where partially treated wastewater was on the verge of overflowing. The rapid increase in water intake during the storm strained the functionality of the plant, putting the environment at risk of a potential disaster.

Amidst the urgent need to conserve rainfall for future use, facilities across the West are facing the reality that they were not designed for the most extreme rain events, which the region will continue to experience amidst a hotter and drier climate. While reservoirs across the state are well above average for this time of year, the coordination of flood control releases is crucial to make room for runoff from the recent storms.

In Los Angeles County, excess stormwater released from Pyramid Lake was being captured and stored downstream in Lake Piru for future water supply. This careful coordination between state and local water agencies is essential for maximizing the use of storm water releases. Overall, the challenges posed by extreme weather events highlight the need for proactive measures to capture, store, and manage water resources for future use in the face of a changing climate.