O'Sullivan Dam Road boat ramp is a concrete boat ramp located in Grant County, Washington. It is a single-lane ramp with a width of approximately 12 feet. The ramp provides access to the Potholes Reservoir, which is a popular destination for boating, fishing, and other recreational activities.

According to the latest information available on the Washington State Parks website, the boat ramp can accommodate a wide range of watercraft, including motorized and non-motorized boats, kayaks, canoes, and paddleboards. However, the maximum boat length is restricted to 26 feet, and boats with a draft greater than three feet are not permitted.

It is important to note that water levels in Potholes Reservoir can vary depending on the season and weather conditions, which may affect boat access at the O'Sullivan Dam Road boat ramp. Visitors are advised to check the latest water level information and any special alerts or advisories before launching their boats.