L.A.’s flood-control system survived epic storm. But it’s losing battle with climate change

Amid hammering rainfall, viscous mud flows and multiple state emergency declarations, Los Angeles County’s Byzantine flood control system has thus far absorbed near-record precipitation — a feat that officials say was made possible by extensive preparations, including the massive dredging of key debris basins and clearing of storm drains in areas deemed most susceptible to flooding.

But as the most intense period of rain passed into history Monday, the concern among local engineers and officials was whether flood infrastructure built over the last 100 years and based on 20th century hydrologic records can continue to keep up with increasingly frequent extreme weather events propelled by climate change.

“The system can handle multiple atmospheric rivers, as long as they have some spacing between them,” said Dena O’Dell, a spokeswoman for the U.S. Army Corps of Engineers. “When they are back-to-back without a break, the system could be tested.”