Based on the latest information available, the boat ramp named Pine Bluff Arsenal Jefferson County in Arkansas is a concrete boat ramp. It is approximately 12 feet wide and serves the Arkansas River.

The Pine Bluff Arsenal Jefferson County boat ramp is open to various types of watercraft, including small motorboats, canoes, and kayaks. However, there are specific regulations and restrictions that apply to the use of this ramp. For instance, boaters are required to comply with all state and federal regulations, including the Arkansas Game and Fish Commission's boating laws and safety regulations.

Additionally, the Pine Bluff Arsenal Jefferson County boat ramp is subject to seasonal changes due to the river's water levels. Thus, boaters are advised to check local water levels before using the facility.

In summary, the Pine Bluff Arsenal Jefferson County boat ramp in Arkansas is a concrete boat ramp that services the Arkansas River. It is approximately 12 feet wide and allows various types of watercraft, subject to specific regulations and restrictions.