Rice Lake State Park is a state park of Minnesota, United States, just east of Owatonna. Park lands entirely surround Rice Lake, an important stopping point for migrating waterfowl. The lake covers 750acre with an average depth of 3ft.Natural historyThe park's bedrock is limestone laid down 500 million years ago as organic sediments settled to the bottom of a shallow sea that covered much of the Midwest. This limestone is entirely covered by glacial till deposited during a Pre-Illinoian glaciation about 400,000 years ago. As those glaciers were retreating, a block of ice broke off and remained embedded in the till. The ice melted, forming a kettle which became Rice Lake. 10,000 years ago the more recent Wisconsin glaciation missed Rice Lake, passing to the west of the park. Meltwater from that glacier eroded streambeds into the Kansan till.Rice Lake is the headwaters of the South Branch, Middle Fork of the Zumbro River. This east flowing stream was the lake's original outlet. After the Wisconsin glacier passed, the land to the west was lowered and a second outlet formed that flowed west into another watershed. This outlet feeds the Straight River, a tributary of the Cannon River.In historical times, Rice Lake may have been as much as 55ft deep, but has filled in considerably due to human influence and the process of eutrophication. Today, Rice Lake is ringed with marsh vegetation. The marshy, shallow nature of the lake, as well as its being the only large lake in the area, make it ideal for migrating waterfowl. Whistling swans, Canada and snow geese, diving ducks, western and pied-billed grebes, and black terns are frequent visitors.
