Emerging Coastal Network | Pacific Coast Watershed Partnership

Skagit River Watershed | Mt. Baker - Snoqualmie National Forest


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	Skagit Dungeness Lower Columbia Siuslaw Umpqua Coquille


	6th field HUC Maps:

	Skagit Dungeness Lower Columbia Siuslaw Umpqua Coquille

The Skagit river basin, draining 1.7 million areas, is the largest river system in the Puget Sound basin. It accounts for about 30% of the freshwater flowing into Puget Sound (Beamer et al. 2000). The headwaters are in the High Cascade Mountains in British Columbia. Annual precipitation averages from about 50 inches near the mouth of the Skagit River to over 140 inches on the ridge tops of the Cascade Mountains The surface geology in the headwaters of the Skagit basin is mostly Mesozoic and Paleozoic sedimentary rocks (Schuster 1992). The upper portion of the Skagit basin drains the High Cascades Mountains primarily comprised of Pre-Cretaceous and Pre-Tertiary metamorphic rock. The lower Skagit flows through a wide valley comprised primarily of glacially derived deposits. The uplands in the lower portions of the basin are mostly Mesozoic sedimentary or volcanic rock. The primary salmonids found in the Skagit system include: Chinook salmon, coho salmon, pink salmon, chum salmon, sockeye salmon, steelhead, cutthroat trout and bull trout/Dolly Varden. The major factors responsible for the decline of salmonids production in freshwater include: increased landslides from timber harvest and road building on unstable slopes, loss of floodplain and wetland habitat, dams which control river flows, nutrient enrichment and high levels of lead and copper.

The Skagit basin is the largest river system draining into Puget Sound, draining about 1.7 million acres (Kruckeberg 1991). Its headwaters are high in the High Cascade Mountains of British Columbia near Allison Pass about 35 miles north of the U.S./ Canadian border. The surface geology in the headwaters of the Skagit basin is mostly Mesozoic and Paleozoic sedimentary rocks. Annual precipitation averages up to 140 inches on the ridge tops and mountain peaks. Numerous tributaries drain glaciers. The majority of this portion of the valley is recreational, and includes considerable wilderness and National Parks in Canada and the United States.

The upper portion of the Skagit basin above Sauk River and below the headwaters drains the High Cascades Mountains primarily comprised of Pre-Cretaceous and Pre-Tertiary metamorphic rock. Again numerous tributaries drain glaciers. The annual precipitation is up to 140 inches on the ridge tops and peaks (Phillips 1965). The major landownership is U.S. Forest and National Park Service. Considerable portions of the basin are wilderness. However, three mainstem dams were constructed in this reach during the 1920's. Much of the stream network in this reach is not accessible to anadromous fish.

The lower Skagit flows through a wide valley comprised primarily of glacially derived deposits. The uplands in the lower portions of the basin are mostly Mesozoic sedimentary or volcanic rock. Precipitation is about 50 inches in the valley but increases rapidly in the higher areas. The streams in this portion of the basin are degraded. European settlement to the lower Skagit occurred late in the 1870's because of the large major jams which blocked the river. However, today the lowlands are highly developed urban/ agricultural areas, which high road densities in the riparian areas. The mainstem river is highly modified below Sedro-Woolley and over 70% of the tidal delta has been converted by diking, tide-gates, draining, and removal of beaver dams (Washington State Conservation Commission 2002).

In the lower portion of the basin many of the tributaries have poor water quality because of increased landslides from logging and road building on steep unstable slopes. Most of the upland areas in this portion of the basin are private timber lands or Forest Service. Also, riparian zones have been extensively logged and roads constructed resulting in elevated stream temperatures (Washington State Conservation Commission 2002).

The lower Skagit mainstem also has impaired water quality. The nutrient levels are elevated from agricultural/urban run off and water treatment facilities. The temperature and sediment regimes are also highly altered largely because of the tributary impacts.

The Skagit River was also historically the most productive basin for salmonids production in Puget Sound (Washington State Conservation Commission 2002). It is estimated that 30% of Puget Sound salmonids production is in the Skagit system. Salmonid species which occur in the basin include: Chinook, coho, chum, pink, and sockeye salmon and steelhead and cutthroat trout (SASSI 1992). The Skagit also has probably the largest bull trout/ Dolly Varden population in the Puget Sound. Most of these species also have numerous life-histories in the Skagit system.

Literature Cited:

Beamer, E., J. Sartori, and K. Larsen. 2000. Skagit Chinook Life History Study Progress Report #3. Skagit System Cooperative, La Conner WA. 19pp.

Phillips, E.L. 1965. Climate of Washington. Weather Bureau, U.S. Department of Commerce.

SASSI 1992. Washington State Salmon and Steelhead Stock Inventory.

Schuster, J.E. 1992. Geologic Map of Washington. Washington Department of Natural Resources.

Washington State Conservation Commission. 2002. Habitat Limiting Factors for the Skagit and Samish Basins (WRIA 3 and 4).