Part of the Elk River Chain of Lakes — Upper Chain. The Sinclair River flows in from Six Mile Lake through the St. Clair Lake / Six Mile Lake Natural Area — over a mile of undeveloped protected shoreline, called the 'Amazon of the North' for its rich biodiversity. A quarter-mile segment of the Intermediate River flows out to Ellsworth Lake. Portage required between St. Clair and Ellsworth. Formerly known as Campbell Lake.
St. Clair Lake is a small (60 acres), pretty lake in the Upper Chain — long, narrow, and relatively undeveloped. Formerly known as Campbell Lake. The Sinclair River connects it to Six Mile Lake through the St. Clair Lake / Six Mile Lake Natural Area, a 255-acre preserve protected by the Grand Traverse Regional Land Conservancy and Little Traverse Conservancy. A local conservationist called it 'ecologically and aesthetically, there's no other place like it in the entire Chain of Lakes.'
The lake straddles Antrim and Charlevoix counties, with the town of Ellsworth at the western end. A portage across the road is required to reach Ellsworth Lake downstream. The natural area's undeveloped riverine habitat between St. Clair and Six Mile lakes is the ecological highlight — paddlers passing through it experience one of the last wild stretches of the chain.