Upper Green River Subwatershed

Why is the Upper Green River Important to Salmon?

Photo of the Green River near the old townsite of Lester in the Upper Green River SubwatershedAlthough salmon do not currently have access to the Upper Green River subwatershed due to two dams downstream, this part of the watershed has some good habitat. Scientists think that if we can help the fish upstream and downstream past these dams -- which should be possible on a test basis by 2009 -- they will be able re-establish themselves in the Green River mainstem and major tributaries in this subwatershed.

Subwatershed Salmon Habitat Overview

The Upper Green River Subwatershed begins at River Mile 64.5, the location of modern-day Howard Hanson Dam and stretches 30 miles east the Cascade Crest. This subwatershed is home to the headwaters of the Green/Duwamish River.

The map below shows the Upper Green River subwatershed. View a map showing this subwatershed in relation to the rest of the watershed.

Map of Upper Green River Subwatershed showing land cover

Prior to 150 years ago, this part of the watershed was probably home to Chinook, coho, and steelhead salmon.

Since 1911, salmon access to this part of the watershed has been blocked by a water diversion dam at River Mile 61. The City of Tacoma constructed this dam to provide drinking water. While Tacoma has limited public access in a portion of this subwatershed to protect the drinking water supply, commercial timber harvest has occurred throughout this portion of the watershed.

This activity has altered many of the ecological processes and degraded much of the habitat. Roads and a railroad also have had an impact on the mainstem as described below. Currently, only the resident form of coastal cutthroat and some anadromous salmonids that have been transported around the dams (juvenile steelhead trout, Chinook and coho salmon, and adult winter steelhead trout) use this portion of the watershed.

Upper Green Subwatershed Facts

Human population: 0 (2009 estimate)

Primary land uses: commercial forestry (nearly 100%), municipal water supply, recreation

Mean annual discharge: about 1300 cubic feet per second at River Mile 64.5

Salmon species currently present:
resident cutthroat trout; also transported juvenile Chinook, juvenile coho, juvenile steelhead, and adult steelhead

Additional salmon species thought to be here historically: Chinook, coho, and bull trout

In 1962, Howard Hanson Dam (HHD), a flood control dam, was completed at River Mile 64.5, which is the downstream boundary of this sub-watershed. HHD also currently is a complete barrier to upstream and downstream adult migration. The large flood control dam and associated reservoir interrupts the natural flow of sediments and large woody debris to lower mainstem Green River reaches. It also chronically floods upstream habitat when the reservoir is full.

The Army Corps of Engineers and the City of Tacoma are working together to construct and operate fish passage facilities to make possible the safe migration of fish upstream and downstream past the two dams. Construction of the upstream fish passage facility by Tacoma Public Utilities was completed in 2005. Construction of the downstream fish passage facility by the Army Corps of Engineers should be complete by 2009.

Where the Fish Are in the Upper Green River Subwatershed

Fish distribution maps show where anadromous salmon and trout have been found or should be present.

Problems on the Mainstem Green River

While the two dams currently block upstream fish passage and Howard Hanson Dam severely hampers downstream passage, some salmon do reside in this reach and are affected by existing habitat conditions. When fish passage past the dams is completed in 2009, existing habitat conditions will affect salmon that are reintroduced to the area. These problems include:

Problems on Tributary Streams

Habitat Information

Additional information on the quality of habitat -- historical and current -- along Green River mainstem in this subwatershed is detailed in the Upper Green River Historical and Current Habitat Conditions Report (Adobe Acrobat 16 MB) published in June 2004.

Water quality information on this stretch of the Green River is available in two reports:

Project Solutions to These Problems

Planned projects in this subwatershed are proposed in the Salmon Habitat Plan.

Information on the status of individual projects also is tracked on the state's Lead Entity Habitat Work Schedule.

Local Governments in the Upper Green River Subwatershed

Follow the external links to learn what this jurisdiction is doing to improve habitat for salmon.
* Indicates that volunteer opportunities or other specific salmon related information are available on this site.

Other Organizations/Efforts in the Upper Green River Subwatershed

Howard Hanson Dam Additional Water Storage Project
This Army Corps of Engineers project includes raising the pool level of Howard Hanson Reservoir, constructing a fish passage facility for downstream salmon migration, and operation of the dam to provide more water for human water supply and instream flow for salmon. Also included are downstream habitat improvements consisting of introduction of spawning gravel and large woody debris into the river.

Howard Hanson Dam
Information on the Howard Hanson Dam, constructed in 1962 and operated by the U.S. Army Corps of Engineers for flood protection purposes.

Tacoma Water Operations on the Green River (Tacoma Public Utilities)
Tacoma Water serves more than 83,000 customers in the cities of Tacoma and University Place, plus portions of Puyallup and Pierce and South King counties. The majority of this water is taken from the Green River. Tacoma operates the diversion dam ("Headworks") at River Mile 61, which is located just below the Upper Green River subwatershed. Tacoma restricts public access to the western part of the Upper Green River subwatershed to protect its water supply.

Information Resources for the Upper Green River Subwatershed

Reconnaissance Assessment Report on the Green/Duwamish and Central Puget Sound Watershed
Comprehensive information on salmon habitat as of 2000. Includes detailed information on on salmon populations, conditions in specific subwatersheds and stream basins, and maps showing salmon habitat.

Green River Watershed Page - King County
Information about the Green/Duwamish River watershed.

Green River Hydrograph - U.S. Geological Survey
Interested in how much water is flowing in the Green River right now? This page provides current and historic data on flow for several locations on the Green River.