Lake Zahl NWR was established in 1939 as a refuge and breeding ground for migratory birds and other wildlife. The Refuge encompasses a total of 3,739 acres. Lake Zahl NWR lies at the juncture of the Missouri Coteau and the Missouri Slope. Water flowing from Lake Zahl enters the Little Muddy River, goes into Lake Sakakawea, and then enters the Missouri River approximately 28 miles south of the Refuge. Lake Zahl is not staffed; it is managed by the Crosby Wetland Management District staff.

The Refuge is divided by State Highway 50, 0.5 miles west of its juncture with State Highway 85, 30 miles north of Williston, North Dakota. The Refuge is accessible from State Highway 50 and county and township roads that border the unit.