Eel Lake
Eel Lake is a large, deep coastal lake south of the mouth of the Umpqua River. Eel Lake, Clear Lake to the north, and Tenmile Lakes to the south owe their existence to the same series of geological events as described by Cooper (1958). Tenmile Creek was the mainstem of a stream network that drained this entire region. Eel Creek and its tributary Clear Creek were two sources of Tenmile Creek. During a time of coastal submergence that accompanied post-glacial warming, the entire system went through a period of readjustment. The main valley and the lower courses of its tributary valleys were inundated. A bar of sand dunes formed across the river mouth and the ponded valley thus became a large lake with branches extending up the tributaries. As submergence continued the depth of the lake increased and arms extended farther upstream. At the same time, dunes along the shore north of Tenmile Creek were advancing inland and eventually entered broadside into the valley of Clear Creek, impounding its headwaters and forming what is now Clear Lake. As drainage from Clear Lake flowed into the Eel Creek valley a delta began to form that developed into a sand flat blocking off the upper portion of the valley. The resultant ponding gave rise to Eel Lake. The same process proceeded downstream to form North and South Tenmile Lakes. The primary inflows to the present day lake include Clear Creek, which originates in Clear Lake and passes through Lake Edna, and two unnamed tributaries that flow into the heads of the east and west arms of the lake.
The Lakeside Water District holds a small water right for municipal use of Eel Lake water, but the primary function of the lake is for recreation. Fishing is popular with native cutthroat trout, stocked rainbow trout, steelhead, coho salmon, smallmouth bass, and panfish present. A boat launch, picnicking, hiking trails and restrooms are provided at William M. Tugman State Park on the southwest shoreline.
Watershed Characteristics
Eel Lake is surrounded by steep timber covered slopes characteristic of the foothills of the Coast Range The majority of Eel Lake's watershed, 63%, consists of mainly coniferous forests. Most of the forest is relatively young. The remainder of the watershed includes non-forested vegetation (marshes and parkland), open water, and barren areas to the west (sand dunes). There are a few residential areas to the west of the lake, but most land is owned by logging interests. There are no homes on the lakeshore. Slopes are steep throughout the watershed. The mean slope is sixteen degrees, the highest among coastal lakes included in this survey. Elevations range from 16 to 228 meters above sea level. Rainfall averages 74 inches per year across the watershed, typical for the Oregon Coast Range area.
Morphometry
Nearly all the shoreline of Eel Lake drops precipitously to a flat bottom of over eighteen meters deep. The average depth is 12.5 meters. The deepest point measured of 20.9 meters lies in the middle of the southern section of the lake. Relief in the northern ends of both arms is not quite as dramatic. In these sections, extensive areas less than ten meters deep slope to a shoreline of marshes at the northern ends. Shoreline development, an index of the shape, is high as would be expected with a dendritic lake.
To log your "Found It" log, please send your answers to following questions to me and then post your log.
1. What shape does the lake take form?
2. Roughly how deep is the lake at the deepest point?
3. What is the lake primarly used for?