Ochoco Reservoir (Crook)

Reachcode: 17070305009769 | Area: 969.6 acres | Shoreline: 8.9 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985)  Ochoco Reservoir is a large impoundment in Central Oregon, located on Ochoco Creek on the west slope of the Ochoco Mountains. The project was completed by the Ochoco Irrigation District in 1921 for the purpose of providing storage for the irrigation of agricultural lands in the Prineville area. In 1949, the dam was rehabilitated and enlarged by the Bureau of Reclamation. The reservoir now has a storage capacity of 46,500 acre feet at full pool and a surface area of 1100 acres, according to U.S. Bureau of Reclamation data. Approximately 19,500 acres are irrigated with the combined waters from Ochoco and Prineville Reservoirs. Inflow to the reservoir is from Ochoco Creek, Mill Creek, and some other small intermittent streams. Outflow is into Ochoco Creek and the Ochoco Feed Canal. The name Ochoco is used for several geographic features in Central Oregon and is said to be the name of a Snake or Paiute chief. Another version is that the chief was named for the stream because he lived nearby, and that the word "ochoco" is a local term for willows.

The drainage basin for the reservoir consists mainly of forest land within the Ochoco National Forest. The lower portion of the basin is mostly private rangeland, as is most of the shoreline. On the north shore is Ochoco Lake State Park with a resort, marina, camping areas, and picnic grounds. Recreational use is heavy and good rainbow trout fishing has been available in recent years. However, Ochoco Reservoir has a long history of fishery problems. It was treated in 1968 to remove scrapfish, and treated again in 1973. By 1974 the reservoir was back in production after being restocked. It is open all year and fish are caught at any season. Ice fishing is also popular in the winter.

The canyon walls near the dam are steep, but slopes are much more gentle at the upper (eastern) end of the reservoir where Ochoco Creek and Mill Creek enter. At the eastern end extensive mudflats are exposed when the reservoir is drawn-down and water level does fluctuate greatly throughout the year because of irrigation withdrawals. Accordingly, there are no extensive growths of macrophytes even in the shallow water. The concentrations of ions are fairly high because of the arid climate. During the summer there are extensive blooms of cyanophytes (Aphanizomenon flos-aquae) which drive up the pH of the water. The concentration of phosphorus is high and is partially responsible for the phytoplankton growth. Possible sources of nutrients are from animal wastes and fertilizers. Water transparency is limited because of the phytoplankton blooms and the presence of suspended inorganic sediment. The reservoir is eutrophic.

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The list below includes results of zebra and quagga mussels surveys conducted by the Center for Lakes and Reservoirs and other agencies. The results "non-detect" and "results pending" indicate that surveys for zebra and quagga mussels were conducted, but none were detected or results are pending. For more details on zebra and quagga mussel monitoring, please visit the Online Mussel Monitoring Map.

Date Status/Species Source
Aug. 1, 2013 non detect Portland State University
Sept. 14, 2012 non detect Portland State University
Sept. 13, 2012 non detect Portland State University
Aug. 22, 2012 non detect Portland State University
Sept. 14, 2010 results pending Oregon Dept of Fish and Wildlife
Aug. 13, 2010 results pending Portland State University
July 23, 2010 results pending Portland State University
No plant data available.
No photos available.

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