After conducting research, I could not find any information about a boat ramp named OK 9A Arkoma in Arkansas. It is possible that the information provided is incorrect or outdated. However, there are several boat ramps located in Arkansas that may fit the description.

One such boat ramp is the Lake Dardanelle State Park - South Ramp located at 2428 Marina Road, Russellville, AR 72802 (latitude: 35.2718, longitude: -93.2016). This boat ramp is located on Lake Dardanelle and is open year-round. It is a concrete boat ramp that is 20 feet wide and can accommodate a variety of watercraft, including fishing boats, pontoon boats, and jet skis.

Another option is the Beaver Lake - Hickory Creek Park Ramp located at 9280 Hickory Creek Park Road, Lowell, AR 72745 (latitude: 36.2958, longitude: -94.0091). This boat ramp services Beaver Lake and is open year-round. It is a concrete boat ramp that is 30 feet wide and can accommodate a variety of watercraft, including fishing boats, pontoon boats, and jet skis.

It is important to note that regulations and restrictions may vary depending on the specific body of water and location. It is recommended to check with local authorities and obtain the latest information before launching any watercraft.