 Loon Lake Dam impounds water at the headwaters of Gerle Creek which, prior to the dam, flowed intermittently through (natural) Loon and Pleasant Lakes.But most of the water now stored in Loon Lake Reservoir arrives from Buck Island Reservoir in the adjacent Rubicon River watershed by way of the Buck-Loon Tunnel.Nearby is Loon Lake Chalet, a popular winter recreation destination.