Cougar Dam
Encyclopedia
Cougar Dam is a 450 feet (137.2 m) tall rockfill hydroelectric dam
in the U.S. state of Oregon
. It has a gated concrete spillway
and a powerhouse with two turbines totaling 25 megawatts of electric power.
The dam impounds the South Fork of the McKenzie River
about 42 miles (67.6 km) east of Eugene, Oregon
, creating Cougar Reservoir
which has a storage capacity of 219000 acre.ft. The purpose of Cougar Dam is to provide flood risk management, hydropower, water quality improvement, irrigation, fish and wildlife habitat, recreation, storage, and navigation.
In 2005, the Willamette temperature control facility was constructed to help regulate the water temperature released to the river below Cougar Dam in an attempt to reduce the negative effects on salmon migration. To further help recover endangered salmon and bull trout
populations in the Willamette River Basin, the U.S. Army Corps of Engineers
constructed a fish collection and sorting facility on the South Fork McKenzie River below Cougar Dam which was completed in 2010. From 2003 to 2005, state-of-the-art turbine runners
were installed in the turbine-generator units at the Cougar powerhouse, and were designed to resist cavitation
and operate efficiently at very large head ranges.
to power two Kaplan turbines, an emergency spillway capable of a capacity of 76140 cuft/s, a regulating outlet, and a diversion tunnel. The diversion tunnel was built to divert the South Fork McKenzie River during the construction of Cougar Dam, and the tunnel was later closed with a concrete plug once the construction of the dam was complete.
migration and productivity. In the fall, the reservoir level is considerably lower and the warmer water from the surface enters the intakes and makes the river downstream unnaturally warm which causes salmon eggs to hatch several months too early. In order to help control the temperature of water discharged below the dam, the original intake tower was modified by adding a 302 feet (92 m) tall wet well. The wet well has three adjustable gates at various levels so that different temperature water can be mixed in the wet well to a desired temperature. The mixed water enters the existing regulating and penstock intakes. By controlling the temperature of the water released from the dam, the impacts on the McKenzie River are greatly reduced.
will be loaded on trucks and released into high-quality habitats above Cougar Dam in an effort to recover endangered salmon and bull trout populations.
, Quebec
, Canada
and the project was completed in March 2005. The project included physical model testing, new turbine runners, a major turbine overhaul, a generator rewind, and disassembly and reassembly of the units.
The problems with the runners for the turbines at Cougar powerhouse are associated with the cycle of large head changes of the Cougar Reservoir. Since Cougar Reservoir is built for flood control, the levels of the reservoir very greatly, causing the units to operate at heads between 400 and 438 ft (121.9 and 133.5 m) one third of the time and at heads between 270 and 310 ft (82.3 and 94.5 m) one fifth of the time.
In 2002, the Corps began lowering the level of the reservoir for the construction of a temperature control facility. The reservoir level was lowered to an elevation below the turbine intakes, which put the powerhouse out of service and provided an opportunity to overhaul the turbine-generator units.
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
in the U.S. state of Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. It has a gated concrete spillway
Spillway
A spillway is a structure used to provide the controlled release of flows from a dam or levee into a downstream area, typically being the river that was dammed. In the UK they may be known as overflow channels. Spillways release floods so that the water does not overtop and damage or even destroy...
and a powerhouse with two turbines totaling 25 megawatts of electric power.
The dam impounds the South Fork of the McKenzie River
McKenzie River
The McKenzie River is a tributary of the Willamette River in western Oregon in the United States. It drains part of the Cascade Range east of Eugene and flows into the southernmost end of the Willamette Valley. It is named for Donald MacKenzie, a Scottish Canadian fur trader...
about 42 miles (67.6 km) east of Eugene, Oregon
Eugene, Oregon
Eugene is the second largest city in the U.S. state of Oregon and the seat of Lane County. It is located at the south end of the Willamette Valley, at the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast.As of the 2010 U.S...
, creating Cougar Reservoir
Cougar Reservoir
Cougar Reservoir is a reservoir on the South Fork McKenzie River in the U.S. state of Oregon. It is located in Lane County. It was created in 1964 with the construction of the hydroelectric Cougar Dam....
which has a storage capacity of 219000 acre.ft. The purpose of Cougar Dam is to provide flood risk management, hydropower, water quality improvement, irrigation, fish and wildlife habitat, recreation, storage, and navigation.
In 2005, the Willamette temperature control facility was constructed to help regulate the water temperature released to the river below Cougar Dam in an attempt to reduce the negative effects on salmon migration. To further help recover endangered salmon and bull trout
Bull trout
The bull trout, Salvelinus confluentus, is a char of the family Salmonidae native to northwestern North America. Historically, S. confluentus has been known as the "Dolly Varden" , but was re-classified as a separate species in 1980. Bull trout are listed as a threatened species under the U.S....
populations in the Willamette River Basin, the U.S. Army Corps of Engineers
United States Army Corps of Engineers
The United States Army Corps of Engineers is a federal agency and a major Army command made up of some 38,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency...
constructed a fish collection and sorting facility on the South Fork McKenzie River below Cougar Dam which was completed in 2010. From 2003 to 2005, state-of-the-art turbine runners
Turbine
A turbine is a rotary engine that extracts energy from a fluid flow and converts it into useful work.The simplest turbines have one moving part, a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades, or the blades react to the flow, so that they move and...
were installed in the turbine-generator units at the Cougar powerhouse, and were designed to resist cavitation
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...
and operate efficiently at very large head ranges.
Background
Cougar Dam was completed in 1963 at a cost of $54.2 million and the two turbine units were completed in 1964. Cougar Dam is operated in coordination with Blue River Dam to control flooding, and since the completion of the dam, it is estimated that it prevented approximately $452 million in potential flood damages. The dam consists of a rock-fill embankment approximately 1500 feet (457.2 m) long, a penstockPenstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
to power two Kaplan turbines, an emergency spillway capable of a capacity of 76140 cuft/s, a regulating outlet, and a diversion tunnel. The diversion tunnel was built to divert the South Fork McKenzie River during the construction of Cougar Dam, and the tunnel was later closed with a concrete plug once the construction of the dam was complete.
Temperature control tower
The original intakes for the powerhouse and regulating outlet were deep and pulled water from the bottom of the reservoir which is much colder than the surface water. During the spring and summer, the release of unnaturally cold water into the McKenzie River reduces salmonSalmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
migration and productivity. In the fall, the reservoir level is considerably lower and the warmer water from the surface enters the intakes and makes the river downstream unnaturally warm which causes salmon eggs to hatch several months too early. In order to help control the temperature of water discharged below the dam, the original intake tower was modified by adding a 302 feet (92 m) tall wet well. The wet well has three adjustable gates at various levels so that different temperature water can be mixed in the wet well to a desired temperature. The mixed water enters the existing regulating and penstock intakes. By controlling the temperature of the water released from the dam, the impacts on the McKenzie River are greatly reduced.
Fish collection and sorting facility
When the Cougar Dam was originally constructed, it contained adult and juvenile fish passage facilities that helped fish move past the dam. However, fish no longer migrated to the facility, and it became ineffective. The Army Corps of Engineers decided to construct a new collection and sorting facility to collect, sort, and transport fish upstream and downstream of the dam. The new facility would cost $14.7 million and include a fish ladder, presort pool, sorting facility, and two pump structures for water supply. At the collection and sorting facility, adult salmon and bull troutBull trout
The bull trout, Salvelinus confluentus, is a char of the family Salmonidae native to northwestern North America. Historically, S. confluentus has been known as the "Dolly Varden" , but was re-classified as a separate species in 1980. Bull trout are listed as a threatened species under the U.S....
will be loaded on trucks and released into high-quality habitats above Cougar Dam in an effort to recover endangered salmon and bull trout populations.
Replacement of turbines
The runners from the two turbines in the Cougar powerhouse experienced significant cavitation damage during operation and by the 1980s they were in need of repair and had to be taken out of service four times a year for inspections and repair. In 1987, the U.S. Army Corps of Engineers installed replacement runners that were designed by Voith Siemens Hydro Power Generation. By 2000, the replacement runners were again experiencing cavitation problems and in need of repair. Repair of the runners would prove to be difficult because the runner blades are thin, making them difficult to weld, and the spacing between the blades is small which gives limited access to the damaged area. The U.S. Army Corps of Engineers realized that a state-of-the-art runner design was required and devised a turbine-generator rehabilitation program. Due to the technical challenges associated with the program, the Corps chose a best value procurement method for this project. In 2003, the contract was awarded to General Electric Hydro of MontrealMontreal
Montreal is a city in Canada. It is the largest city in the province of Quebec, the second-largest city in Canada and the seventh largest in North America...
, Quebec
Quebec
Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and the project was completed in March 2005. The project included physical model testing, new turbine runners, a major turbine overhaul, a generator rewind, and disassembly and reassembly of the units.
The problems with the runners for the turbines at Cougar powerhouse are associated with the cycle of large head changes of the Cougar Reservoir. Since Cougar Reservoir is built for flood control, the levels of the reservoir very greatly, causing the units to operate at heads between 400 and 438 ft (121.9 and 133.5 m) one third of the time and at heads between 270 and 310 ft (82.3 and 94.5 m) one fifth of the time.
In 2002, the Corps began lowering the level of the reservoir for the construction of a temperature control facility. The reservoir level was lowered to an elevation below the turbine intakes, which put the powerhouse out of service and provided an opportunity to overhaul the turbine-generator units.