The Saint Croix Flowage, also known as the Gordon-St. Croix Flowage, is a 1,912-acre drainage lake in Douglas County, Wisconsin. Created by a dam on the St. Croix River, it serves as the largest lake in Douglas County with a mean depth of 6.5 feet and a maximum depth of 28 feet. The flowage has a diverse ecosystem that supports a variety of fish species and recreational opportunities. The water body is characterized by abundant aquatic plant growth, with 98% of the surface area containing vegetation, much of it moderate to dense. The flowage has been dealing with invasive species challenges, particularly Eurasian watermilfoil (EWM) and curly-leaf pondweed (CLP). Wild rice can be found in portions of the flowage, adding to its ecological importance. Water clarity is moderate, with the lake classified as mesotrophic to slightly eutrophic. The flowage's watershed is primarily forested with wetlands, creating a relatively natural shoreline that supports diverse wildlife.