Suttle Lake (Jefferson)

Reachcode: 17070301000834 | Area: 264.8 acres | Shoreline: 3.6 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985).  Suttle Lake is a very well known and heavily used lake on the east slope of the Cascade Range. It is easily seen by all travellers along U.S. Highway 20 about five miles east of Santiam Pass. The name Suttle is in honor of John Settle, one of the principals in the supervision and construction of the Willamette Valley and Cascade Mountain Military Wagon Road in the 1860s. It is said that while on the expedition Settle went hunting and found the lake which was named for him (although misspelled); he also found nearby Blue Lake.

Suttle Lake owes its existence to glaciation as do so many of the lakes in the Cascade Range. The valley of Lake Creek which contains the lake basin, is broad and easily recognizable as a glacial trough, sculpted during the Pleistocene Epoch when all the high mountain areas in Oregon were buried by ice. Terminal and lateral moraines impounded the headwater portions of Lake Creek. The shape of Suttle Lake reflects this origin; it is long and narrow, conforming to the symmetry of the glacial valley, and consists of a single deep basin with relatively steep sides. Much of the lake is deeper than 60 feet, yet the deepest point is only about 75 feet. This type of morphometry can be seen in other Oregon lakes formed by the impoundment of waters in glacial troughs. Odell is a good example in the Cascades, and Wallowa Lake in northeast Oregon is another dramatic example. Blue Lake, immediately up valley from Suttle Lake, was formed by volcanic activity in more recent geologic times.

The drainage basin of Suttle Lake is a densely forested region of steep slopes. Permeable volcanic rocks cover much of the basin and permit a substantial amount of ground water movement. Thus, a major source of water to the lake is subsurface seepage. The only permanent surface inflow to the lake is Link Creek from Blue Lake. A few small intermittent streams also contribute flow during the snowmelt season. Lake Creek, the outlet, eventually joins the Metolius River after flowing north through the Camp Sherman area. The shoreline of the lake is federal land and there are a number of Forest Service campgrounds and boat launching sites. This is an extremely popular outdoor recreation area in all seasons of the year. A hiking trail circles the lake and other trails head off to other small lakes in the area. A large private resort is located at the east end of the lake on land leased from the Forest Service, while Suttle Lake Lodge at the north end provides supplies and cabins. There are several other private resorts in the Suttle Lake-Blue Lake area, as well as a number of church camps. All sorts of water recreation opportunities exist: fishing, swimming, camping, picnicking, water-skiing and small boating. Fishing centers on kokanee, or land-locked blueback salmon, taken most successfully early in the season. Rainbow trout and brown trout are also taken, but in smaller numbers. Rainbow trout are stocked regularly by the Oregon Department of Fish and Wildlife. One end of Suttle Lake has a 10 mph speed limit for boats.

The bottom of Suttle Lake is composed of sand, gravel, and in deeper areas, muck. Most of the littoral areas are gravel and rock. Macrophytes are found along the periphery in a narrow zone between the 6 and 20 foot depths. However, they are not a problem and most of the lake is far too deep for macrophyte growth. The major ion chemistry is unexceptional, but the concentration of phosphorus is much higher than might be anticipated and promotes the active growth of planktonic algae, sometimes to bloom proportions. The lake has a history of algal blooms; Newcomb'(1941) reported a high abundance of phytoplankton. In general, high densities of diatoms occur throughout the year, but in summer and early fall the lake also has high densities of blue-green algae. In spring Asterionella formosa predominates; summer algae are mostly Fragilaria crotonesis and Anabaena species; in the fall, Stephanodiscus astrea is most common. In their 1978 study of Suttle Lake, the U.S. Ei T2 nmental Protection Agency in the National Eutrophication Survey reported Melosira, Dactylococcopsis, Anabaena, Stephanodiscus, Fragilaria, Chroomonas, and Cryptomonas as predominant algal species (E.P.A. 1978). Transparency of the water is reasonably good, but it may have been reduced somewhat in recent decades due to cultural activities in the area. Newcomb (1941) measured a Secchi disk depth of 35 feet (10.6 meters) in 1940; several studies in the early 1970s report values ranging from 14 to 16 feet (4.3 to 5.0 meters); and measurements in 1982 in this survey were 22 feet (6.7 meters) or lower. Although not conclusive, these limited data suggest a decline in water transparency concurrent with increased recreational use in recent decades.

The various indicators of trophic status are contradictory. Secchi disk measurements clearly suggest mesotrophic conditions, whereas the standing crop of algae clearly indicate eutrophic conditions. Other Cascade lakes also exhibit this apparent contradiction between water transparency and density of phytoplankton; for example, Odell Lake, Diamond Lake and Marion Lake. All four of these lakes have two attributes in common: (1) high phosphorus concentration, and (2) similar physiographic location, geologic origin, and morphometry. It may be that the long mountain winters limit biological productivity for most of the year; but during the short summer growing season, high phosphorus levels drive the lakes to a higher than expected trophic state. The blue-green algae which occur in the lake (Anabaena spp) are capable of nitrogen fixation. Bioassays (E.P.A. 1978) indicate that nitrogen limits algal growth in the lake, a reflection of the generous phosphorus supply. The source of the high phosphorus levels is debatable. It is certainly due in part to natural sources; however, the fact that the trophic state has increased in recent decades suggests contributions from the increased level of human activity around and on the lake (McHugh 1972). If this is so, the trend is likely to continue. The source(s) of the high nutrient levels should be determined and if cultural activities are responsible, the feasibility of various lake manipulations should be considered. A D.E.Q. study found high phosphate levels in Blue Lake close to its outlet, and the E.P.A. (1978) credited this outlet stream with 81.9 percent of the total phosphorus input. If the phosphate source can be located and eliminated, Suttle Lake should be a very good candidate for phosphorus inactivation (McHugh 1979). In summary, Suttle Lake would be classified as mesotrophic according to transparency data; however, the abundance of phosphorus and algae appear to be the overriding consideration and the lake is classified as eutrophic.