Seal Slough

About

Seal Slough, also known as Marina Lagoon, is a narrow winding tidal channel through a tidal marsh in San Mateo and Foster City, California. This slough has been the object of a wetland restoration project in recent years to enhance habitat value. Dredging has been carried out in Seal Slough since at least 1954. When the original sewage treatment plant for the city of San Mateo was constructed in 1935, its discharge was directed to Seal Slough.

The marshy area through which Seal Slough meanders is a productive brackish wetland whose dominant flora is cordgrass. There are a number of significant wildlife features associated with Seal Slough, including use by the endangered California clapper rail. A tide gate near the mouth of Seal Slough regulates tidal influx from San Francisco Bay to Marina Lagoon; this flushing action is important to prevent population explosion of midges in the local area.