Cultus Lake (Deschutes)
Reachcode: 17070301000888 | Area: 1145.7 acres | Shoreline: 8.1 mi | View on Interactive Map
(From Atlas of Oregon Lakes, Johnson et al. 1985). Cultus Lake is a beautiful, natural lake located high on the east slope of the Cascades in the upper Deschutes River Basin. It is one of many popular recreation lakes accessible from the Cascade Lakes Highway, and is reached on a good paved road two miles west of the highway. The word "cultus" is used in many places in the Pacific Northwest. It is a Chinook jargon word, very expressive, meaning bad or apparently worthless. With regard to this pristine, unproductive lake, it probably referred to the poor fishing conditions that existed. Cultus Mountain, a symmetrical cone rising to an elevation of 6759 feet immediately to the south was doubtless named for the lake. Little Cultus Lake is on the south side of the mountain.
The drainage basin contributing to the lake is volcanic terrain with low to moderate slopes covered with a dense, mixed conifer forest. The entire area is within the Deschutes National Forest, much of it within the Three Sisters Wilderness. Ponderosa pine dominates in the lower elevations with more firs closer to the Cascade divide. In the forest on the north side of the lake is an extensive marsh area. Numerous small lakes are located in the drainage basin, the largest being Deer Lake to the south, Irish and Taylor Lakes near the summit, and Winopee Lake to the north. The area contributes surface inflow to Cultus Lake through a number of intermittent streams; the largest is Winopee Creek which enters through the marsh on the north side. There is also a substantial amount of subsurface seepage into the lake through the permeable volcanic terrain. Springs have been noted along both the south and north shorelines. Outflow is at the southeast end into Cultus Creek which enters Crane Prairie Reservoir about two miles downstream. The lake basin itself is long and narrow, about three miles long and one and one-half miles wide, oriented west to east, a typical shape for a lake basin scoured out by glacial activity. Maximum depths occur in the eastern end of the basin (maximum depth = 211 feet), while the western half of the lake is nowhere more than 125 feet deep. Both the eastern and western ends have shallow, sandy bottoms, creating very favorable swimming conditions. Otherwise the bottom is a mixture of coarse sand, muck, and organic detritus.
Vehicle access to Cultus Lake is limited from late October to late May each year due to snow-blocked roads. However, during the summer season it is a popular recreation site; water skiing and boating are particularly popular activities because it is one of the few lakes in the area without a speed limit on boats. Angling for rainbow trout is fair, and they are taken mostly by trolling. There are many white fish in the lake as well as a few mackinaw. A nice private resort with cabins, boats, and supplies is located near the outlet, and there are three good Forest Service campgrounds, two with boat launches. West Cultus Lake campground is accessible only by boat or trail. All have good swimming beaches.
Cultus Lake is ultraoligotrophic, with a recorded transparency of 56 feet (17.2 meters) on 8/20/81. The lack of any substantial amounts of phytoplankton or macrophytes similarly indicates ultraoligotrophic conditions. With respect to transparency and phytoplankton density, Cultus Lake is quite similar to Waldo Lake and Big Lake, two other large ultraoligotrophic lakes in the Cascades. However, the concentrations of major ions, the alkalinity, and the conductivity are appreciably higher in Cultus Lake, although still below average for Cascade lakes in general. The higher concentrations of major ions may be attributed to the swampy drainage on the north side of the lake through which Winopee Creek enters, or to subsurface springs which normally have high concentrations of major ions. Concentrations of phosphorus and chlorophyl are extremely low, consistent with the ultraoligotrophic state. The lake stratifies in summer, with the thermocline generally occurring at about 35 feet (11 meters).
In general, this ultraoligotrophic lake (as well as other similar lakes such as Waldo Lake and Big Lake) seems not to be adversely affected by the high amount of recreational activity. It is generally considered that ultraoligotrophic lakes are very sensitive to cultural influences, but several factors appear to be "absorbing" any perturbations to Cultus, Waldo, and Big Lakes. First, these lakes contain a very large volume of water that dilutes any elevated nutrient sources. Second, these lakes are in a sub-alpine environment, with only a very short "growing season", and the overall biological productivity is probably limited more by these physical factors than by nutrient availability. These observations have not been verified, but they seem quite likely. Future lake management efforts should address this possibility of physical limitations to accelerated eutrophication so that unnecessary attempts at controlling algal nutrients may be avoided.