The Foster City Lagoon as a drainage detention basin is designed to withstand successfully a storm of 100 year return frequency, or a storm of such severity that it is likely to occur only once each century. The lagoon therefore provides maximum drainage security for Foster City. Stormwater collected throughout the City flows to the Foster City Lagoon. All storm water enters the storm drain system through curb inlets and catch basins, and drains into the lagoon from which it is pumped into the bay.
How well does the Foster City Lagoon system work as a drainage catch basin? During the El Niño rainstorms of 1997/98, which were very close to a 100-year frequency severity, the City of Foster City experienced no flooding while surrounding cities in San Mateo County experienced major drainage problems. Thanks to the effectiveness of its lagoon system, Foster City has never experienced major flooding.
It is unlawful to dispose of any substances that may contaminate the lagoon and storm water system or cause blockages of the storm drainage system. In the event of flooding due to a blockage of the storm drain system, contact the Foster City Streets Department.
Why do we adjust the lagoon levels seasonally?
Our primary reasons for seasonal adjustment are:
The City's Lagoon Management Plan sets standard lagoon water levels for winter and summer periods.
Around Mid-March, water in the lagoon is raised to summer operating levels. The water level will usually be maintained between one or two feet from the elevation 100, which is the design height of most lagoon bulkheads. The water level will be generally higher on weekends and holidays to accommodate recreational uses, and the water level will be lower mid-week. This is done to promote maximum water exchange in the lagoon.
In Mid-November, the lagoon level is lowered to prepare for frequent winter storms. If a major storm is forecast during summer, the levels will be lowered to accommodate the anticipated runoff.
©2017 City of Foster City
City Hall - 610 Foster City Blvd.
Foster City, CA 94404