Big Creek Lake is a lake situated in the Big Creek State Park in Polk County, Iowa. The lake is situated two miles to the north of Polk City, spreads across 814 acres, and its mean depth is 17.3 feet (maximum 51 feet deep). The lake's purpose was to protect Polk City from floods. It was a part of the Saylorville project. It provides numerous recreational options including fishing, picnicking, swimming, boating, camping, and others.