Flandrau State Park is a state park of Minnesota, United States, on the Cottonwood River adjacent to the city of New Ulm. Initially called Cottonwood River State Park, it was renamed in 1945 to honor Charles Eugene Flandrau, a leading citizen of early Minnesota who commanded defenses during the Battles of New Ulm in the Dakota War of 1862. The park was originally developed in the 1930s as a job creation project to provide a recreational reservoir.