Get Full Government Meeting Transcripts, Videos, & Alerts Forever!
Get email alerts on the Storm Flood Drought topic
No spam. Unsubscribe anytime.
SFPUC: Flash storms overwhelmed catch basins but reservoirs and water supply are strong
Summary
SFPUC staff showed video and data on intense, short-duration storms that briefly overwhelmed catch basins and caused neighborhood flooding, and said reservoir storage is high, Calaveras releases have been used to lower levels and short- and long-term infrastructure options will be brought back to the commission.
San Francisco Public Utilities Commission staff on Wednesday described how a late-night flash storm produced very high short‑duration rainfall in parts of the city that overwhelmed local storm drains and flooded streets and garages, even as regional reservoirs sit at or above typical storage for this time of year.
Tommy Moala, Assistant General Manager for Wastewater, showed security‑camera footage from the Fifteenth and Wawona area that captured a ‘‘wall of water’’ moving across an intersection in minutes. Moala said crews deployed sandbags and flood barriers, and that catch basins and the sewer system were performing as designed but were overwhelmed by the storm—s intensity. "It's doing what it's doing," Moala said of catch basins, adding they "were overwhelmed" during the event. He reported localized damage — including flooded garages and streets — and said cleanup and restoration began the next morning.
Steve Ritchie, Assistant General Manager for Water, told commissioners that although the city is handling flooding impacts, overall water supply conditions are strong. He reported that Hetch Hetchy storage is near full, the water bank is full and Calaveras Reservoir was holding roughly 54,000 acre‑feet — above the Division of Safety of Dams— current operational restriction of about 33,000 acre‑feet. Ritchie said staff used the Calaveras cone valve and treated and released water to lower reservoir elevation while coordinating with Alameda County on downstream conditions.
Ritchie noted the recent three‑week period exceeded the previous wet‑year record in cumulative precipitation and said snowpack is above typical peak values for early April. He said state drought regulations are likely to remain in effect into May but added that the present abundance of water would limit any near‑term change to local drought management.
Commissioners asked about neighborhood impacts, particularly in Cayuga and Seventeenth & Folsom, and about longer‑term capacity improvements. Staff said they have identified short‑ and long‑term alternatives and will return in a few months with cost estimates and options for increasing system capacity. The commission also discussed the challenges of predicting highly localized flash events and the limits of deploying barriers in advance of such rapid storms.
The commission received the updates as informational items and directed staff to return with alternatives and cost estimates for both short‑term mitigations and long‑term infrastructure improvements.
