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 (329 ha), and its mean depth is 17.3 feet (5.3 m). 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.