Clackamas River

Oregon

Mount Hood National Forest
16400 Champion Way
Sandy, Oregon 97055

Designated Reach: October 28, 1988. From Big Springs to Big Cliff.

Classification/Mileage: Scenic — 20.0 miles; Recreational — 27.0 miles; Total — 47.0 miles.

The Clackamas River is located to the west of the Cascade Range and to the south of the Columbia River Gorge. From its origins in the Olallie Lake Scenic Area, the river flows through the communities of Estacada, Barton and Carver and is an important water source for southern Clackamas County. The river joins the Willamette River at Oregon City. The designated portion of the river runs for 47 miles from Big Spring (headwaters area) to Big Cliff, just south of Estacada.

The Clackamas drainage incorporates portions of two major physiographic zones, the Cascade Mountain range and the Columbia Basin. The Clackamas is the only west-side Cascade river which flows northwest out of the mountains. This occurs because of a series of faults which line up in a diagonal across the state. Almost the entire river follows this major weakness in the underlying bedrock of the region. The Clackamas is the largest west-side Cascade river (in Oregon) primarily because the fault patterns provided a larger area for the watershed to develop. The headwaters of the Clackamas receive ample rainfall and snow with approximately 130 inches of precipitation a year. Rainfall in the lower reaches averages 60 inches a year. The climate is classified as temperate. The Clackamas River upstream from Big Cliff drains a watershed of approximately 666 square miles (640 square miles, excluding the South Fork Clackamas River). Major tributaries of the upper Clackamas River include the South Fork of the Clackamas, Fish Creek, Roaring River, Oak Grove Fork and Collawash River.

Streams and rivers in the Clackamas drainage have been subject to hydroelectric development, with power generation facilities located on the Oak Grove Fork and on the mainstem (in the designated corridor). Several dams are situated between Big Cliff and Oregon City.

The mean elevation of the watershed is 3,500 feet, corresponding approximately with the transition from a Douglas-fir and western hemlock forest to the higher elevation true fir and lodgepole pine forests. Elevations range from around 740 feet to 7,200 feet. Only two percent of the watershed area is above 5,000 feet elevation. Earthflows dominate the topography in much of the watershed, particularly within the Collawash River drainage and areas adjacent to the Clackamas River in the vicinity of Ripplebrook. Channel gradients are steep within the headwaters reaches, gradually becoming less steep moving downstream. Slope aspects are generally equally represented in the watershed, although the upper reaches of the mainstem above Big Bottom have more northerly exposures.

The designated river corridor is entirely within the Mt. Hood National Forest boundary and encompasses forested lands, wetlands and riparian areas and rock cliffs. Land uses within the corridor include recreation, transportation, hydroelectric energy generation and transmission, and fish and wildlife habitat. Timber harvest in the corridor has been a relatively minor land use in recent years. There is a one-mile stretch of river containing approximately 155 acres of privately owned land at Austin Hot Springs. There is one-half mile of shoreline, and 288 acres of land administered by the Bureau of Land Management.

The outstandingly remarkable values of the Clackamas River are recreation, fish, wildlife, history and vegetation.

Recreation Resources. The river offers a wide variety of recreation opportunities, including whitewater boating in close proximity to the Portland metropolitan area.

Fish. The Clackamas River provides necessary habitat for several anadromous fish species. It is the last significant run of wild late winter coho in the Columbia Basin, and it is also one of only two remaining runs of spring Chinook in the Willamette Basin. In addition, it supports a significant population of winter steelhead.

Wildlife. The Clackamas River also provides habitat for the federally threatened bald eagle and northern spotted owl, and it is potential habitat for the threatened peregrine falcon as well.

Vegetative Communities. Along the banks of this river are outstanding old-growth Douglas-fir forests.

Historic Resources. There is evidence that the Clackamas River had a significant role in both prehistoric and historic human use, and it played an important part in local and regional development.