The Mosquito Ridge Rd boat ramp in California is located at latitude 39.11075592 and longitude -120.42769623. It is a concrete boat ramp that provides access to the North Fork of the American River. The boat ramp is relatively narrow, with a width of approximately 10-12 feet. This makes it suitable for smaller watercraft, such as canoes, kayaks, and small fishing boats.

According to the latest information available, the North Fork of the American River is primarily used for recreational activities such as fishing, kayaking, and whitewater rafting. Only non-motorized watercraft are permitted on the river, so you won't see any motorboats or jet skis using this boat ramp. It's worth noting that the river can be quite challenging, with some Class IV and V rapids in certain areas. Therefore, it's recommended that only experienced boaters attempt to navigate the river, and that they do so with caution and appropriate safety gear.