- Klamath County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) Summit Lake, at an elevation of 5553 feet above sea level, is so named because it is situated very nearly on the divide between the Willamette River Basin and the Deschutes River Basin. The name was apparently first used in 1865 by B. J. Pengra and W. H. Odell while making a reconnaissance for the Oregon Central Military Road. A small drainage basin of about eight square miles contributes to the lake. There are no perennial surface streams in this terrain; inflow is by snowmelt runoff, direct precipitation, and subsurface seepage. Surface outflow is into Summit Creek which discharges into Crescent Lake four miles to the east. Vegetation cover is a coniferous forest, typical of the High Cascades at this elevation.
Because of the high elevation, access to Summit Lake is possible only three to four months a year. There is one Forest Service campground on the northwest shoreline. Recreational use of the lake is comparatively light, because many people use the campground as a base from which to reach other small lakes in the vicinity. Biological productivity in Summit Lake is low and fishing is only fair. Eastern brook trout are stocked, but are difficult for anglers to locate; rainbow trout are also stocked, and there is a small population of mackinaw.
The shape of the lake basin is rather complex with several deeper holes and some underwater ridges and hills. The shoreline is also highly indented, particularly along the northern shore, which is flanked by a relatively recent lava flow. Water in the lake is extremely low in concentrations of major ions, alkalinity, and conductivity. Concentrations of phosphorus and chlorophyl are also very low. All indicators identify this lake as ultraoligotrophic. The water is very transparent giving the lake the lovely turquoise color characteristic of very pure water.