The country's largest artificial lake offers the perfect desert oasis.. In Short The damming of the Colorado River in 1935 resulted in the formation of Lake Mead over the course of three years. With almost 600 miles of shoreline, it's the largest artificial lake in America. The 1.5 million-acre recreation area welcomes millions of visitors annually. People come in droves in the summer to picnic, camp, boat, hike and fish. Visitors can enjoy boat tours or rent speedboats, jet skis and houseboats for their own use.