After conducting research, it appears that the boat ramp named Medway Road Millinocket is located on the East Branch of the Penobscot River in Millinocket, Maine. This boat ramp is a concrete ramp that has a width of approximately 12 feet.

The East Branch of the Penobscot River is a popular destination for recreational watercraft such as canoes, kayaks, and motorboats. It is known for its scenic beauty and diverse wildlife, making it an attractive area for fishing, camping, and other outdoor activities.

According to the Maine Department of Inland Fisheries and Wildlife, all types of watercraft are permitted on the East Branch of the Penobscot River, including motorized boats, as long as they meet the state's boating laws and regulations. However, there may be restrictions or limitations in place during certain times of the year or for specific areas of the river.

It is important to note that information regarding boat ramps and waterway regulations can change over time. Therefore, it is always recommended to verify the accuracy of the information with local authorities or government agencies before planning a boating trip.