Rock Creek Reservoir (255)
- Wasco County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) Rock Creek Reservoir is a small irrigation impoundment on the east slope of Mt. Hood just inside the eastern border of the Mt. Hood National Forest. It was developed in the 1940s with construction of a 50-foot high, earthfill dam on Rock Creek. The origin of the name Rock Creek is impossible to establish with certainty. There are at least fifty streams in Oregon with this name, bestowed by early residents with little concern for originality. This Rock Creek seems to have been named by one Joel Palmer who passed through the area in 1845. Surface inflow is from a drainage basin of about 17.5 square miles, a landscape supporting a forest of ponderosa pine. In addition to the inflow of Rock Creek, there is contribution from Wildcat Spring at the southwest end, and water is diverted from Gate Creek into the reservoir. Natural outflow is into Rock Creek, tributary to the White River which it joins about eight miles from the dam. Water is also diverted directly into the Rock Creek Ditch.
Although the drainage basin is within the National Forest boundaries, much of it is private land and about half the shoreline is also in private ownership. There is a private resort on the south shore and a Forest Service campground. The lake is stocked each year with rainbow trout and usually has good fishing for native rainbow trout also. No motorboats are allowed on the lake.
The mineral content of the water in Rock Creek Reservoir is moderate, somewhat above average for reservoirs in the Cascades. Total phosphorus concentration is average, but chlorophyl concentration is low. The reservoir is too shallow to allow an accurate measurement of the Secchi disk depth. The reservoir is mesotrophic.