The Headwaters Lakes Project is located in Minnesota?s lake country. Campfires and sunsets and the peacefulness of the water make each day a special event. The dams were originally constructed of native materials (earthen embankments filled with puddled clay, and timber control structures) in the early 1880s, except Gull Lake, which was constructed in 1912, using concrete. Sandy Lake Dam had the northernmost navigational lock on the Mississippi River and was the site of an early trading post.