- Wallowa County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) Minam Lake is located high in the Eagle Cap Wilderness at the head of the Lostine River. It is remarkable because of the fact that it has an outlet at either end. Minam River flows from the south end and Lostine River from the north. This unusual situation is due to the artificial modification of what was formerly a small natural lake. Early in this century a 14-foot high dam was constructed across the natural outlet to the south, thereby enlarging the lake and deflecting the drainage to the north. The purpose of creating the reservoir was to provide irrigation for agricultural lands in the Lostine Valley and to provide some water for domestic use. The meadow in which Minam Lake lies is a lovely site surrounded by the rugged peaks of the Wallowa Mountains. It is a favorite destination for wilderness travellers and there are several undeveloped campsites along the east shore of the lake. Fishing for brook trout is excellent from July through September.
The pre-existing natural lake was located near the center of the present enlarged lake. Accordingly, the maximum depth occurs where the natural lake was located, rather than near the face of the dam, as is typical of reservoirs. The lake develops a weak thermal stratification during the summer. Because of the high altitude (7370 feet), surface temperatures remain very cool (60 degrees Fahrenheit; 15 degrees Celsius). Water quality is excellent, and the concentration of chemical constituents is very low. Only the concentration of calcium ion exceeds a milligram per liter. Water transparency is excellent (26 feet; 8 meters) and the concentrations of chlorophyl and phosphorus are low. There is evidence of a limited amount of oxygen depletion in the hypolimnion. In summary, Minam Lake is distinctly oligotrophic.