After conducting research on the Grant County boat ramp in Washington, I have found that it is a concrete boat ramp located on Potholes Reservoir. According to the Grant County Parks and Recreation website, the boat ramp is 24 feet wide and can accommodate boats up to 24 feet in length.

Potholes Reservoir is a popular destination for fishing and boating in Grant County, Washington. The reservoir covers over 28,000 acres and has a maximum depth of 135 feet. It is known for its walleye, bass, and trout fishing, and is also popular for water sports such as water skiing and wakeboarding.

A variety of watercraft are permitted on Potholes Reservoir, including motorized boats, sailboats, kayaks, and canoes. However, the use of personal watercraft such as jet skis is prohibited on the reservoir.

In summary, the Grant County boat ramp is a concrete ramp located on Potholes Reservoir in Washington. It is 24 feet wide and can accommodate boats up to 24 feet in length. The reservoir is popular for fishing and water sports, and a variety of watercraft are permitted on the water, except for personal watercraft.