Lake Sammamish - Ecology and Conservation

Ecology and Conservation

Historically, runoff from the high precipitation in the lake's watershed (nearly twice the 35 inches that Seattle gets each year) was absorbed by the surrounding forests. Loose, sponge-like forest soils virtually eliminated runoff during winter storms and recharged groundwater aquifers which then released fresh water to streams in the dry summer months. With rapid urbanization the forests have been replaced by impervious surfaces—roofs, roads, parking lots—and stormwater runoffs have increased flooding. The stormwater runoff carries sediment loads and toxic pollutants into streams and ultimately the lake, which generally has a negative impact on lake water clarity as well as fishes and wildlife.

In May, 2010 the federal government asked the town of Sammamish to restrict development within 250 feet (76 m) from the lakeshore to protect local salmon and steelhead trout (Oncorhyncus mykiss) species. The report did not include Lake Sammamish kokanee salmon (Oncorhyncus nerka) among the species in trouble, although environmentalists and scientists said development along Lake Sammamish and tributary creeks have pushed the fish to the brink of extinction. Despite resistance to the report by the city of Sammamish, Issaquah already limits development within 200 feet (61 m) of the lake, Issaquah Creek and the East Fork of Issaquah Creek under the Shoreline Management Program. It is estimated that fewer than 100 Kokanee salmon remain in Lake Sammamish.