Monon Lake (Jefferson)
Reachcode: 17070306002041 | Area: 94.3 acres | Shoreline: 2.7 mi | View on Interactive Map
(From Atlas of Oregon Lakes, Johnson et al. 1985) Monon Lake is one of countless mountain lakes and ponds in the Olallie Butte lake district north of Mt. Jefferson. Thick ice sheets occupied this part of the Cascade Range during the Pleistocene Epoch, carving and modifying the contours of the original volcanic terrain. As the ice finally melted about 10,000 years ago, only water was left to occupy the gentle but uneven landscape of rock basins and glacial moraines. The jumbled land has since been covered by a coniferous forest of hemlock, true fir, and pine; lakes, ponds, and wet meadows dot the area. There are few permanent streams; Monon Lake is fed chiefly by rain and melting snow, with only occasional inflow from two seasonal creeks.
In 1968 the Mt. Hood National Forest dedicated 14,238 acres as the Olallie Lake Scenic Area, to be managed primarily for back-country recreation and scenic preservation. The wooded shoreline of Monon Lake has been kept in an undeveloped condition, except for Skyline Road on the western shore. This road is usually closed by snow until June. Campgrounds are located nearby at Olallie Lake and at Breitenbush Lake to the south. An unimproved boat launch is available at Monon Lake, but parking is limited. As with other lakes in this area, no motors are allowed. Angling is considered good, mostly for stocked rainbows and a few brook trout. Monon Lake was named by a forest ranger because the word had a pleasing sound, although it is unknown whether the word actually has any meaning.
The lake consists of three interconnected basins: a large shallow basin making up most of the lake, a smaller but much deeper adjoining basin at the northeast end of the lake, and an isolated small basin connected to the main lake at the northwest end of the lake. The water in the lake is low in chemical constituents; concentrations of all the major ions, alkalinity and conductivity are among the lowest of any Oregon lakes. The concentration of phosphorus is also exceptionally low. The water is very transparent, and the lake bottom is visible even in the deepest part. Monon Lake is ultraoligotrophic.