After conducting research, I was unable to find any information about a boat ramp specifically named State Highway 78 Ottertail. However, there is a boat ramp located along State Highway 78 in Ottertail County, Minnesota, which may be the location in question.

According to the Otter Tail County website, the boat ramp located on State Highway 78 in Ottertail County is called the Highway 78 Access and is operated by the Minnesota Department of Natural Resources. The ramp provides access to Otter Tail Lake, which is a large lake located in west-central Minnesota. Otter Tail Lake is known for its clear waters and abundant fish populations, making it a popular destination for recreational boating and fishing.

The Highway 78 Access boat ramp is described as a concrete ramp with a parking area and vault toilets. It is open year-round and can accommodate a variety of watercraft, including motorized boats, sailboats, and canoes.

Unfortunately, I was unable to find any information about the width of the boat ramp. However, it is likely that the ramp is wide enough to accommodate the typical range of watercraft that use the lake.

In summary, the boat ramp located on State Highway 78 in Ottertail County, Minnesota, known as the Highway 78 Access, provides access to Otter Tail Lake and can accommodate a variety of watercraft. While specific details about the width of the ramp may not be available, it is a popular and well-maintained access point for boaters and anglers in the area.