Three-Dimensional Eutrophication Model of Lake Washington, Washington State

Abstract

Abstract : Lake Washington is one of a system of three lakes located in northwestern Washington State (Figure 1 - 1). The lake provides a textbook example of eutrophication remediation through reduction of nutrient loads. The decline and recovery of the lake are the subject of a series of classic works by W. T. Edmondson, his students, and co-workers (Edmondson 1972; Edmondson and Lehman 1981; Edmondson 1991; Edmondson 1994). The description of the lake in this chapter is derived from these sources as well as from a Web site maintained by the King County Department of Natural Resources and Parks (http ://dnr/metrokc. gov/wlr/waterres/lakes/Monitor. htm). Lake Washington was formed at the end of an ice age roughly 12,000 years ago. Within historic times, the lake had one major inflow at its northern end, the Sammamish River, which drains Lake Sammamish. The outlet was the Black River at the southern end. The Black River flowed into the Cedar River, which led to Puget Sound. In 1916, a locked ship canal was constructed that connected Lake Washington with Puget Sound through Lake Union to the west. The level of Lake Washington was lowered by 3.3 m, and the Cedar River was converted from an outflow to an inflow. The major outflow was now through the Chittenden locks at the western end of Lake Union.