It is in proximity to Clear Lake and an impoundment of the Oak Grove Fork Clackamas River.

The compacted-earth Timothy Lake Dam was built by Portland General Electric in 1956 to regulate seasonal water flow to Lake Harriet downstream.

[3] The dam, 110 feet high and impounding 81,000 acre-feet, does not generate any hydroelectric power itself.

In the summer, the lake is a very popular destination for camping, boating, hiking, horseback riding, and mountain biking.

This Clackamas County, Oregon state location article is a stub.