- Round Lake, like its larger neighbor Lacamas Lake, is a child of the Missoula Floods, a depression carved when ice dams collapsed somewhere in northern Montana over 12,000 years ago and swept down through the Columbia River valley. The floods were not a single event but occurred at least 40 times over a period of 2,000 years. A “Missoula boulder,” perhaps rafted down the cataclysmic spate on a floe of ice, sits at the south end of Round Lake…
