• Surface Area: 23,040 Acres
Lake Petenwell is a man-made lake in central Wisconsin, in Adams, Juneau, and Wood counties next to Castle Rock Lake. It covers over 23,000 acres and is 42 feet deep. Lake Petenwell is Wisconsin's second largest lake at 23,040 acres or approximately 36 square miles. It was created in 1948 by the Wisconsin River Power Company with the construction of a dam across the Wisconsin River near Necedah. It has a maximum depth of 42 feet and is used for skiing, sailing and fishing. Private lakefront property is very limited as most of the virgin shoreline is undeveloped forest. Wildlife includes wintering bald eagles. Game fish include walleye, northern pike, bass, panfish, and muskellunge.
The area around the lake has restaurants, a community theater, a golf course and two casinos.
Lake Petenwell has blue-green algae blooms in the summer, the toxicity of which is unknown. The algae, which exists naturally in most lakes, is magnified on Lake Petenwell as a result of industrial and agricultural sources upstream. The Wisconsin Department of Natural Resources has recommended that humans and pets not use the waterway for recreational use.