- Union County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) Jubilee Lake (also known as Jubilee Meadows Reservoir) is a fairly new recreation reservoir in the Umatilla National Forest, a part of the state in which lakes are scarce. It is a cooperative effort between the Oregon Department of Fish and Wildlife and the U.S. Forest Service. A rock and earthfill dam was built across Motett Creek in 1968, and the Forest Service built the roads and a very nice campground. A three mile hiking trail around the lake has been designated a National Recreation Trail. First stocked in 1968 with rainbow trout, the lake and recreation area attracted over 25,000 visitors in the first year of existence, and this level of use has continued. The small contributing drainage basin is an area of steep slopes covered by a thick coniferous forest. In addition to Motett Creek, there are a few small intermittent streams that provide inflow to the lake during the snowmelt season.
The shape of the impoundment is typical of reservoirs; there are four separate shallow arms along the north side of the lake where the water backs up into Motett Creek and its tributaries. The deepest portion of the reservoir is confined to a small area just behind the dam. The water in the lake is low in mineral constituents, with some of the lowest values for alkalinity, conductivity and major ion concentrations among reservoirs in eastern Oregon. Water transparency is good, indicating mesotrophic conditions. The concentrations of chlorophyl and phosphorus are also characteristic of mesotrophic ecological conditions. The lake develops a relatively shallow thermocline (between 15 and 25 feet; 4.5 to 7.6 meters) in the summer, indicating that it is sheltered from strong winds. The bottom water stays very cold (39 degrees Fahrenheit; 4 decrees Celsius), a legacy of the cold winters at this altitude and location. The bottom water has been observed to be anoxic in late summer, a situation that usually occurs only in eutrophic lakes. In Jubilee Lake, the anoxia may result from the small volume of the hypolimnion, which occupies less than 10 percent of the bottom of the reservoir, and from the import of incompletely decomposed organic matter from the watershed.