- Seal Slough
Seal Slough is a narrow winding tidal channel through a tidal
marshin San Mateo and Foster City, California. [ [http://maps.google.com/?sll=37.57083,-122.29306&spn=0.05,0.05 Satellite Photo of Seal Slough in San Mateo and Foster City, California (Seal Slough is the westernmost winding channel.)] ] This slough has been the object of a wetlandrestoration project in recent years to enhance habitat value. [ [http://www.wetlandtracker.org/GISInfoCatalog/servlet/org.sfei.GISInfoCatalog.UserInterface?directive=viewproject&project_name=Seal+Slough Bay Area Wetland Tracker: Seal Slough, San Mateo, California] ] Dredginghas been carried out in Seal Slough since at least 1954. [ [http://sflib1.sfpl.org:82/search/dShips+D/dships+d/1,45,49,E/frameset&FF=dships+dredges&1,2, Historic Photo and Record of Dredging of Seal Slough] ] When the original wastewater treatmentplant for the city of San Mateo was constructed in 1935, its discharge was directed to Seal Slough. [ [http://www.ci.sanmateo.ca.us/dept/wwtp/faq.html City of San Mateo, California Official Website: Discussion of Wastewater Treatment Plant] ]
The marshy area through which Seal Slough meanders is a productive brackish wetland whose dominant
florais cordgrass. There are a number of significant wildlifefeatures associated with Seal Slough, including use by the endangered California Clapper Rail.T.E. Harvey, H.S. Shellhammer, C.M.Hogan, K.Wilson, G.W.Ball, V. Pfeifle et al., "Section 7 endangered species biological assessment for the proposed East Third Avenue widening project, city of San Mateo, San Mateo County", prepared by Earth Metrics Inc. for Caltransand the city of San Mateo, California (1980}] A tide gatenear the mouth of Seal Slough regulates tidal influx from San Francisco Bayto the Marina Lagoon; this flushing action is important to prevent population explosion of midges in the local area.
Seal Slough has a tidal exchange with San Francisco Bay on the eastern
shoreline of the city of San Mateo, approximately mid-way between Coyote Pointand the San Mateo Bridge. ["San Mateo Quadrangle Map, 7.5 Minute Series", U.S. Geological Survey, Washington, DC, 1956, photo-revised 1980] At its mouth there is a marshy area and an extent of bay mudextending approximately 700 meters northward into San Francisco Bay. Near the mouth area is situated the city of San Mateo Wastewater Treatment Plant and Bayside School. The course of the slough is highly tortuous as it winds easterly. Further along its course continuing eastward, single-family residential uses have encroached closely on its southern banks; in this middle reach it also passes close to and north of Parkside School. Further to the east it passes beside Lakeshore School before crossing under Hillsdale Boulevard and entering Foster City; beyond this point it is known as O'Neill Slough.
Much of the information regarding Seal slough was developed in a 1980 study, in which Caltrans and the city retained Earth Metrics to analyze impacts of a new
bridgeacross Seal Slough at East Third Avenue.T.E. Harvey, H.S. Shellhammer, C.M.Hogan, K.Wilson, G.W.Ball, V. Pfeifle et al., "Section 7 endangered species biological assessment for the proposed East Third Avenue widening project, city of relientk rocks face San Mateo, San Mateo County", prepared by Earth Metrics Inc. for Caltrans and the city of San Mateo, California (1980}] The most significant habitat area along Seal Slough is the tidal mouth, where there are three identified plant communityzones. The lowest zone is defined by the presence of mudflats and/or the dominant plant cordgrass, " distichlis" sp. The middle zone is characterized by the dominant plant pickleweed, " Salicornia" sp., and the upper zone, which is the most disturbed, is characterized by salt grass, "Distichlis spicata", and by peripheral halophytes (salt tolerant plants). The pickleweed community thrives primarily on the north banks of Seal Slough. 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. Further these plants supply the adjacent mudflats with detritusthat is the basis of estuarine food chains.
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. Other avafaunafound in this robust wetland include killdeer, mallards and the snowy egret. The Seal Slough mudflats also provide a feeding area at high tides for a variety of fishes including top smelt, anchovy, bat ray, leopard shark, spiny dogfish, striped bassand longjaw mudsucker.
Salt Marsh Harvest Mouse
* [http://www.ci.sanmateo.ca.us/dept/pubwks/lagoon2.html City of San Mateo: Description of Marina Lagoon and Seal Slough]
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