Vista Grande Drainage Basin Improvement Project

Storm related flooding particularly in the Vista Grande Watershed overflows from Daly City’s Vista Grande Canal and tunnel system resulting in property damage from uncontrolled runoff into Lake Merced during large storm events.  

The project will route stormwater from the Vista Grande Watershed through a gross particle screening device prior to diversion into Impound Lake and South Lake Merced. Some stormwater will also be diverted through a treatment wetland prior to diversion. 

In addition, some approved non-treated stormwater flows that meet certain water quality criteria would also be routed to South Lake Merced. As part of the Vista Grande Project, Daly City would expand the capacity of the Vista Grande tunnel in order to better manage conveyance of stormwater to the Pacific Ocean. These efforts would reduce uncontrolled overflows from the Vista Grande Canal into Lake Merced, while achieving a sustained increase in Lake Merced lake levels, improving storm water quality, and providing further restoration of the drainage basin's natural hydrology.