Pasadena advances underground stormwater capture project at Jefferson Park

Pasadena is moving forward with plans for an underground stormwater capture system at Jefferson Park aimed at intercepting polluted runoff from areas burned in the Eaton Fire and improving downstream water quality.

The city’s Department of Public Works is advancing the project through a feasibility study that would divert storm and dry-weather flows from the Sierra Bonita Drain into an underground infiltration gallery. The proposed system would be capable of storing approximately 3.5 acre-feet of runoff per storm and up to 38.5 acre-feet annually, with all dry-weather flows infiltrated into the Raymond Basin.

The project targets a 567-acre drainage area, much of it outside Pasadena city limits in unincorporated Los Angeles County, including areas affected by and downstream from the Eaton Fire. Pasadena has secured $441,000 for pre-design work, including Measure W Local Return funds and a grant supporting community outreach, though design and construction funding has not yet been identified.

In addition to the underground gallery, surface features under consideration include bioswales, vegetated infiltration basins and drywells designed to slow, treat and infiltrate runoff while reducing pollutants such as zinc, bacteria and trash. The project supports compliance with Pasadena’s Municipal Separate Storm Sewer System permit requirements and is one of 10 Priority 1 projects identified in the city’s 2022 Storm Drain Master Plan.

Craftwater Engineering is leading the feasibility study, with Dudek and Amigos de Los Rios supporting community outreach. Pre-design work began in December and is expected to wrap up by late summer, with a draft design concept anticipated in March and final study completion in June.