Bull Run Lake is a

reservoir A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including contro ...

, an impoundment of the Bull Run River 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 ...

. Providing part of the primary drinking water supply for

Portland, Oregon Portland (, ) is a port city in the Pacific Northwest and the largest city in the U.S. state of Oregon. Situated at the confluence of the Willamette and Columbia rivers, Portland is the county seat of Multnomah County, the most populous co ...

, it rates highly as an oligotrophic lake, a very clean source of water. As of 1925, noted geographer Lewis A. McArthur described the lake as one of the two most important in the state (along with Crater Lake), supplying the drinking water for a third of the state's population. The lake basin receives more than of rain annually due to its location 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, ...

, about west of

Mount Hood Mount Hood is a potentially active stratovolcano in the Cascade Volcanic Arc. It was formed by a subduction zone on the Pacific coast and rests in the Pacific Northwest region of the United States. It is located about east-southeast of Portlan ...

. Public access to the area has been controlled since June 17, 1892, with the creation of the Bull Run Reserve by President Benjamin Harrison. Water from the reservoir first flowed into the Portland water system on January 2, 1895. President

Theodore Roosevelt Theodore Roosevelt Jr. ( ; October 27, 1858 – January 6, 1919), often referred to as Teddy or by his initials, T. R., was an American politician, statesman, soldier, conservationist, naturalist, historian, and writer who served as the 26t ...

restricted entry to all but government agents and water company employees and banned stock grazing on April 28, 1904. In 1915 a new timber and

rock fill dam Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...

raised the lake level about . At least two series of efforts were made between 1917 and 1925 to decrease lake seepage. In 1961 additional areas of seepage were sealed with clay, and the outlet dam was remodeled to contain gates at elevations of and . In 1994, concerns of outflow water temperature and its effect on fish populations led to regular careful measurements of the lake's thermocline characteristics and the inlet water temperature. Concrete pier blocks were installed to minimize the effect of water temperature shock on downstream aquatic life.

References

{{authority control Reservoirs in Oregon Lakes of Multnomah County, Oregon Lakes of Clackamas County, Oregon Mount Hood National Forest Buildings and structures in Multnomah County, Oregon Buildings and structures in Clackamas County, Oregon Protected areas of Clackamas County, Oregon Protected areas of Multnomah County, Oregon 1895 establishments in Oregon

See also

References