After conducting research, it appears that there is no boat ramp named McLean County in North Dakota. It is possible that the name may have been misspelled or it may be a local name for a boat ramp that is not widely known.

However, there are several boat ramps located in McLean County, North Dakota that service different bodies of water. For example, there is a boat ramp located on the eastern shore of Lake Sakakawea, which is a large reservoir along the Missouri River. This boat ramp is maintained by the US Army Corps of Engineers and is open to the public. It can accommodate a variety of watercraft, including small fishing boats, pontoons, and larger motorboats.

Another boat ramp in McLean County is located along the Knife River, which flows through the county and eventually empties into the Missouri River. This boat ramp is located in the town of Stanton and is also open to the public. It can accommodate small to medium-sized boats, including canoes, kayaks, and fishing boats.

Both of these boat ramps are relatively wide and can accommodate multiple boats at once. However, specific measurements of their width were not readily available.

In summary, while there may not be a boat ramp in McLean County named exactly "McLean County," there are several boat ramps in the area that service different bodies of water and permit a variety of watercraft.