- The Madison Wetland Management District marks the western edge of the tall grass or "true" prairie". Native areas in our eastern counties are dominated by tall warm season grasses. Grasslands in our western counties are dominated by cool season species.
The topography consists of rolling hills at the end of the Coyote des Prairies formation. A portion of the western counties lie within the James Basin, a glacially eroded valley which is drained by the James River. The District contains a great number of fine wetlands and numerous lakes.
The Sioux and Vermilion Rivers flow to the south through the District. Most of the wetlands and main rivers in the District were formed by glaciers during the Pleistocene era. Elevation ranges from 1400 to 2200 feet.
The Madison District is characterized by hot summers with highs in the 90's and humidity in the 50's. Winters are moderately cold with occasional lows of -20 degrees F. or colder. Winter snow accumulation in grass cover is typically 12 to 18 inches. Average annual precipitation ranges from 25 inches in the eastern counties to 23 inches at the west edge of the District.