Mann Lake is the largest of the shallow playa lakes in the northern part of the Alvord Valley in Harney County in the U.S. state of Oregon. The lake is a remnant of a larger Pleistocene lake that covered much of the valley, east of Steens Mountain. Fields–Denio Road runs along the east side of the lake.[2]
Inflow to Mann Lake comes from small, intermittent streams, mainly from Steens Mountain. The lake, which has no outlet, but loses water by evaporation, is hypereutrophic. An influx of cattle waste from nearby rangelands adds to the lake's natural eutrophic state. Large concentrations ofCladophora algae are common.[2]
The Bureau of Land Management operates the Mann Lake Recreation Site, about 100 miles (160 km) southeast of Burns by highway and unpaved road. The site has vault restrooms and boat ramps, but no other amenities. Recreation at or near the site includes fishing, camping, hiking, wildlife viewing, and amateur geology.[4]
Mann Lake, stocked with Lahontan cutthroat trout, has been called "one of the premiere trout fisheries in southeast Oregon".[5] Trout in the lake range in length from 12 to 20 inches (30 to 51 cm).[5] Fishing is restricted to artificial flies and lures.[5]
^Johnson, Daniel M.; Petersen, Richard R.; Lycan, D. Richard; Sweet, James W.; Neuhaus, Mark E., and Schaedel, Andrew L. (1985). Atlas of Oregon Lakes. Corvallis: Oregon State University Press. p. 232. ISBN0-87071-343-4.{{cite book}}: CS1 maint: multiple names: authors list (link)