Trillium Lake (Clackamas)

Reachcode: 17080001017715 | Area: 62.4 acres | Shoreline: 1.9 mi | View on Interactive Map

(From Atlas of Oregon Lakes, Johnson et al. 1985)  Trillium Lake is a popular recreational lake located on the south slope of Mount Hood in the Salmon River drainage basin. It was originally a small seven acre water body named Mud Lake, the source of Mud Creek. About 1960 the present lake of about 57 acres was created by the damming of Mud Creek. It has been developed as a fishing lake through the combined efforts of the Isaac Walton League, the Forest Service, and the Oregon Department of Fish and Wildlife. A water-right certificate was issued for storage of 352.7 acre-feet for public fishing. Rainbow trout are planted yearly and is the species caught most commonly. The lake also supports brook trout and cutthroat trout.  All are stocked, as there is no opportunity for spawning. It is considered a good fly-fishing site because of all the shallow water.

A Forest Service campground and picnic area are maintained on the east shore of Trillium Lake; a boat ramp is available and only boats without motors are allowed. Proximity to the heavily travelled Oregon Highway 26 has meant heavy recreational use over the years and the area is also popular with cross-country skiers in winter. Trillium Lake is easily seen from the front porch of Timberline Lodge and for this reason is one of the more recognizable lakes in the state.

The lake is shallow and lies in a meadow that includes some swampy areas, although it is flanked by high, forested ridges. During the summer of 1977 the lake nearly dried up due to drought. There is a considerable growth of pond lilies and macrophytes in the shallow areas. In spite of the shallow depth the lake develops a definite thermal stratification in the summer because of its sheltered location. The water transparency is influenced by dissolved organic matter from the swampy portions of the drainage basin and by the presence of diatoms. The transparency is thus somewhat less than for most other Oregon Cascade lakes and indicates a mesotrophic state. The species of diatoms present in the water also indicate mesotrophic conditions. Lakes similar to Trillium (i.e. relatively shallow with a mud bottom) at lower elevations would typically be dominated by blue-green algae during the summer months. At the elevation of Trillium Lake, water temperatures are generally too low to encourage blue-green algal blooms. Dissolved organic matter, diatom growth and thermal stratification sometimes lead to a pronounced oxygen depletion in the hypolimnion.

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