Oak Grove Fork Clackamas River is a tributary of the

Clackamas River The Clackamas River is an approximately tributary of the Willamette River in northwestern Oregon, in the United States. Draining an area of about , the Clackamas flows through mostly forested and rugged mountainous terrain in its upper reaches, a ...

in the U.S. state of

Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

. From its headwaters in the

Warm Springs Indian Reservation The Warm Springs Indian Reservation consists of in north-central Oregon, in the United States, and is governed by the Confederated Tribes of Warm Springs. Tribes Three tribes form the confederation: the Wasco, Tenino (Warm Springs) and Pa ...

near

Abbot Pass Abbot Pass lies between Mount Lefroy and Mount Victoria, in the divide between the valleys of Lake O'Hara and Lake Louise. It was named for Philip Stanley Abbot who died in 1896 in an attempt to climb Mount Lefroy with Charles Fay, Charles ...

in the

Cascade Range The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, ...

, the river flows generally west through

Mount Hood National Forest The Mount Hood National Forest is a U.S. National Forest in the U.S. state of Oregon, located east of the city of Portland and the northern Willamette River valley. The Forest extends south from the Columbia River Gorge across more than of fore ...

Clackamas County Clackamas County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 421,401, making it Oregon's third-most populous county. Its county seat is Oregon City. The county was named after the Native ...

to the unincorporated community of Ripplebrook. Here it enters the main stem of the Clackamas River. Oak Grove Fork feeds

Timothy Lake Timothy Lake is a lake about southeast of Portland, Oregon, United States. It is in proximity to Clear Lake and an impoundment of the Oak Grove Fork Clackamas River. The compacted-earth Timothy Lake Dam was built by Portland General Electric in ...

and Lake Harriet, two artificial impoundments built along its course to control water flows to

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

plants.

Course

The Oak Grove Fork Clackamas River arises at an elevation of above

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...

and falls between source and mouth to an elevation of . The main stem begins in the Cascade Range near Abbot Pass, a mountain gap at , on the border between Clackamas County and

Wasco County Wasco County is one of the 36 counties in the U.S. state of Oregon. As of the 2020 census, the population was 25,213. Its county seat is The Dalles. The county is named for a local tribe of Native Americans, the Wasco, a Chinook tribe who ...

. Originating on the Warm Springs Indian Reservation, the river flows generally west about through the Mount Hood National Forest to the unincorporated community of Ripplebrook, where it joins the main stem of the Clackamas River. From its source, the river flows about through a

landform A landform is a natural or anthropogenic land feature on the solid surface of the Earth or other planetary body. Landforms together make up a given terrain, and their arrangement in the landscape is known as topography. Landforms include hills, ...

known as Big Meadows before leaving the reservation. Shortly thereafter, it crosses the

Pacific Crest Trail The Pacific Crest Trail (PCT), officially designated as the Pacific Crest National Scenic Trail, is a long-distance hiking and equestrian trail closely aligned with the highest portion of the Cascade and Sierra Nevada mountain ranges, which lie ...

, which follows the river from there to Timothy Lake. Oak Grove Fork then flows between the Clackamas Lake Campground and Clackamas Lake, which lies to the left of the river, before entering Timothy Lake about from the mouth. From here to Ripplebrook, Forest Road 57 follows the river. Campgrounds on the lake shore to the left include Oak Fork, Gone Creek, Hood View, and Pine Point. Meditation Point Campground lies on the opposite shore. While flowing through Timothy Lake, the elevation of which is above sea level, Oak Grove Fork receives Crater Creek, Cooper Creek, and Dinger Creek, all from the right. The river exits the lake via a

spillway A spillway is a structure used to provide the controlled release of water downstream from a dam or levee, typically into the riverbed of the dammed river itself. In the United Kingdom, they may be known as overflow channels. Spillways ensure tha ...

from the mouth. Just below the spillway, the river passes the USGS gauge station at Timothy Lake, then receives Anvil Creek from the right, Stone Creek from the left, Buck Creek from the right, Peavine Creek from the left, and Shellrock Creek and Cat Creek, both from the right, before reaching the USGS gauge above Lake Harriet. Lake Harriet Campground lies along the shore to the right. Flowing through the lake, the river receives Kelley Creek from the left, then exits the lake and receives Sam Creek from the left about from the mouth. Then the river receives Skunk Creek and Canyon Creek from the right, Butte Creek from the left, and Station Creek and Pint Creek, both from the right, before passing Ripplebrook, Ripplebrook Campground, the Ripplebrook Ranger Station and Heliport, and the southeastern terminus of

Oregon Route 224 Oregon Route 224 is a state highway which runs through some of Portland's southeastern suburbs and ends in the Cascades. Route description The northwestern terminus is an interchange with OR 99E in Milwaukie, a suburb of Portland. It contin ...

, which all lie to the right. Shortly thereafter, the river flows by Rainbow Campground, which lies to the left, and enters the Clackamas River about above its confluence with the Willamette River at Gladstone.

Discharge

The

United States Geological Survey The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, ...

monitors the flow of Oak Grove Fork at two stations, one below Timothy Lake, from the mouth, and the other above a

Portland General Electric Portland General Electric (PGE) is a Fortune 1000 public utility based in Portland, Oregon. It distributes electricity to customers in parts of Multnomah, Clackamas, Marion, Yamhill, Washington, and Polk counties - 44% of the inhabitants of O ...

(PGE) power plant intake, from the mouth. The average flow of the river at the Timothy Lake gauge is . This is from a

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, t ...

of . The maximum flow recorded there was on December 24, 1964, and the minimum flow was on September 23, 1968. At the power plant gauge, the average flow is from a drainage basin of . The maximum flow recorded there was on January 7, 1923, and the minimum flow was on August 16, 2004.

Fishing

The Oak Grove Fork has fishing for

Brook trout The brook trout (''Salvelinus fontinalis'') is a species of freshwater fish in the char genus ''Salvelinus'' of the salmon family Salmonidae. It is native to Eastern North America in the United States and Canada, but has been introduced elsewhere ...

(''Salvelinus fontinalis'') close to the Timothy Lake dam, wild

coastal cutthroat trout The coastal cutthroat trout (''Oncorhynchus clarkii clarkii''), also known as the sea-run cutthroat trout, blue-back trout or harvest trout, is one of the several subspecies of cutthroat trout found in Western North America. The coastal cutthroa ...

(''Oncorhynchus clarki clarkii''), and

Rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coasta ...

(''Oncorhynchus mykiss irideus'') further down, and

Brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

(''Salmo trutta'') close to Harriet Lake. All species respond well to flies or artificial baits. Only artificial lures and flies allowed on the Oak Grove Fork, with barbless hooks.

Hydroelectric dams

As part of its efforts to generate electricity from water power in the Clackamas River basin, PGE built a dam on the Oak Grove Fork in 1923. The company's power plant at Lake Harriet, created by the dam, began making electricity in 1924. To regulate flows on the Oak Grove Fork and on the mainstem Clackamas River, the company built a dam at Timothy Meadows, upstream of Harriet Lake, in 1956. The new dam formed Timothy Lake, a impoundment that doubles as a recreation site.

References

External links