About the Sammamish River

The Sammamish River corridor runs 13 miles from Lake Sammamish to Lake Washington. It passes through rural and suburban communities and commercial, agricultural, and recreational areas.

Over the past few decades, the cities of Redmond, Woodinville, Bothell, and Kenmore have grown around the river. This growth has also brought more ways for people to walk, bike, fish, boat, float, picnic, gather, and play in the valley. Unfortunately, some of these new land uses have degraded the river. 

The Sammamish River is within the ancestral lands of Coast Salish People. Kokanee salmon, once an important local food source and cultural symbol to the Coast Salish, are nearly gone from the valley today. This is due to land use change and its impact on fish habitat.

Other fish species in the Sammamish River include Chinook salmon, which are protected by federal, state, and local laws. However, the Sammamish River has many problems that make it difficult for fish and wildlife to thrive. Straightening,  deepening of the river, and removal of vegetation have degraded the health of the river.

Kokanee salmon in Ebright Creek (Courtesy of Roger Tabor, USFWS).

Legacy of the Flood Project

The entire Sammamish River is a federal flood project called the Sammamish River Improvement Project (Flood Project). King County, as a service provider to the King County Flood Control District, maintains the Flood Project’s function. 

The purpose of the Flood Project was to reduce springtime flooding of the farmland that covered most of the Sammamish River valley. Upon completion of the project in 1964, the Corps of Engineers outlined rules for how King County should take care of the river and riverbanks.

Sammamish River mouth looking north, circa 1960-64. Courtesy of King County Archives.

The rules are intended to:  

• Reduce flood frequency and extent on agricultural land use, residences and public infrastructure. 
• Reduce springtime flooding around the lake. 
• Keep river flows adequate for fish passage in the summer when water levels are low. 
• Sustain the river’s use for navigation by small boats.  

Examples of maintenance activities defined by these rules are:  

• Maintaining flow conveyance between Lake Sammamish and the Sammamish River. 
• Mowing all vegetation on the banks. 
• Repairing areas of bank erosion or slumping.  
• Filling holes made by burrowing animals. 
• Removing sediment deposits (for example, sand and silt) on the riverbed. 

Maintaining the river today 

Many maintenance requirements are no longer practical because they impair water quality and damage habitat for protected Chinook salmon.  

The 2002 Sammamish River Corridor Action Plan was co-authored by the County and Corps of Engineers to promote environmental restoration. Many projects in the plan have been completed, but there is more work to do.