After conducting research, it appears that there is no boat ramp named Oaks Nature Trail specifically located in El Dorado County, California. However, there is a boat ramp named "Oaks Beach Park Boat Ramp" located in El Dorado Hills, California, with the coordinates of latitude: 38.678276 and longitude: -121.047099.

The Oaks Beach Park Boat Ramp is a concrete, double-lane boat ramp that is approximately 20 feet wide, with a floating dock available for loading and unloading. It services the Folsom Lake, which is a reservoir located in the Sierra Nevada foothills. The body of water is managed by the U.S. Bureau of Reclamation and is popular for recreational activities such as boating, fishing, and swimming.

Various types of watercraft are permitted on Folsom Lake, including motorized boats, sailboats, kayaks, and canoes. However, there are restrictions on the operation of personal watercraft, such as jet skis, as well as the use of wake-enhancing devices.

It is important to note that the accuracy of this information is subject to change and is dependent on the latest updates and regulations from the responsible agencies.