Unity Reservoir (Baker)

Reachcode: 17050202004614 | Area: 921.0 acres | Shoreline: 12.4 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985).  Unity Reservoir is the major component of the Burnt River Project, an irrigation complex built by the Bureau of Reclamation and operated by the local Burnt River Irrigation District. Unity Dam, completed in January 1939, impounds the flow of Burnt River and its tributaries and provides storage for nearly 26,000 acre-feet of water. Through its distribution system, the Project supplies supplemental water for the irrigation of about 16,000 acres in Baker County, land which formerly depended on the natural flow of the Burnt River. The drainage basin is mostly federal forest land within the Wallowa-Whitman National Forest. However, the lower reaches consist of more private land and about 80 percent of the shoreline of the reservoir is privately owned.

Although it was built for irrigation storage, Unity Reservoir is an important recreation site and receives over 30,000 visitor-use days per year. Rainbow trout are stocked and provide good angling. Coho salmon have also been stocked in past years, but with little success as they tend to migrate out of the reservoir. There is a nice state park on the shore which includes a picnic area, a boat ramp, and a small campground. At full pool, the maximum depth of the reservoir is about 50 feet; but for much of the year, especially in late summer and fall, it is much shallower because of irrigation withdrawals, and recreation activity is then limited.

The concentrations of major ions in the water are fairly high, characteristic of surface water in this semiarid region; calcium and sulfate concentrations are particularly high. Fine sediment on the bottom and sides of the reservoir is easily brought into suspension by wave action. Because of this fine inorganic sediment and the frequent changes in surface level, the reservoir is often turbid, noticeably reducing water transparency. During summer there is an intense bloom of Aphanizomenon, a blue-green alga, which further reduces transparency. The bloom is maintained by the high concentration of phosphorus, derived from the aforementioned sediment and from drainage basin runoff. The concentration of chlorophyl, also derived from the phytoplankton bloom, is high. The growth of Aphanizomenon also drives up the pH which is among the highest observed in the state. There is no evidence of nutrient enrichment from artificial sources; Unity Reservoir is naturally very eutrophic.

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
Sept. 7, 2010 non detect Oregon Dept of Fish and Wildlife
No plant data available.
No photos available.

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