- Klamath County)
(From Atlas of Oregon Lakes, Johnson et al. 1985) Island Lake is one of numerous small, alpine lakes situated at about 6000 feet elevation in the southern Oregon Cascades. It lies in the Sky Lakes Area, a de facto wilderness which straddles the Cascade crest and is administered jointly by the Rogue River National Forest and the Winema National Forest. The Area is currently under consideration for inclusion in The National Wilderness Preservation System. Such a designation for this idyllic region of 116,343 acres would insure the continuation of the wilderness characteristics that make it so appealing. The natural environment is beautiful: glaciers and volcanic activity have both left their marks clearly on the landscape. More than 200 water bodies, ranging from mere ponds to shallow lakes of 30 to 40 acres, are scattered across the terrain, all a legacy of the ice sheets that covered the mountains thousands of years ago. A number of volcanic peaks dominate the skyline. Vegetation in the area is that of a typical coniferous forest composed of a variety of species, including mountain hemlock, subalpine fir, and Engelmann spruce at higher elevations and species of pine at lower elevations.
Island Lake, named for the single large island in its center, is one of the largest lakes within the Sky Lakes Area. Like most of the others it is shallow; the average depth is less than 5 feet and the maximum depth is 21 feet. No surface inflow or outflow is reported, typical for this volcanic area where groundwater movement dominates. The lake lies just off the Pacific Crest Trail and thus receives frequent use by hikers. Fishing is excellent; fly fishing is the most popular form because of the large amount of shoal area. Eastern brook trout are the most common species and are stocked each year by the Oregon Department of Fish and Wildlife. Several good, unimproved campsites are found around the lake.
The concentrations of major ions, alkalinity, and conductivity in Island Lake are very low and indicate ultraoligotrophic conditions. However, biological indicators (chlorophyll and total phosphorus, for example) suggest the lake is oligotrophic. Apparently, the water is moderately enriched with phosphorus from the sediments, a situation not uncommon in shallow lakes, and the phytoplankton are able to reach a moderate density. This, in turn, supports a productive food chain resulting in good fishing. There is no evidence that human activity has either supplied phosphorus to the lake or adversely affected the water quality in any other way.