Fed by receding glaciers and Lake Agassiz 12,000 years ago, the Glacial River Warren carved today's Minnesota River valley. On the northern border of Burnsville, the Minnesota River winds through marshland and flood plains toward its confluence with the Mississippi. Most of the river is in the Minnesota Valley National Wildlife Refuge with fish, wildlife, and parkland managed collectively by the U.S. Fish and Wildlife Service and the Minnesota Department of Natural Resources. Burnsville also contains the Black Dog and Lower Minnesota River Watershed Districts managed by the Dakota County Soil and Water Conservation District.