[4] When the original sewage treatment plant for the city of San Mateo was constructed in 1935, its discharge was directed to Seal Slough.

[6] 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.

Cordgrass and pickleweed habitats are among the most productive types in the state of California, in each case producing over five tons of organic material per acre per annum.

Cordgrass is also used for food and cover for a multiplicity of waterfowl, including the endangered California clapper rail, which species occurs in Seal Slough.

The Seal Slough mudflats also provide a feeding area at high tides for a variety of fishes including topsmelt, anchovy, bat ray, leopard shark, spiny dogfish, striped bass and longjaw mudsucker.

Colonies of Australian tubeworms (ficopomatus enigmaticus) were discovered on the support columns for SR 92 when the water level was lowered for maintenance.