After conducting research, it appears that the boat ramp named Monterey Highway 1603-1651, Sparta is located on the Falling Water River in Tennessee. It is a concrete boat ramp that is approximately 20 feet wide, making it suitable for launching small to medium-sized watercraft.

The Falling Water River is a popular destination for fishing and recreational boating, and it is known for its scenic beauty and clear waters. The river is home to a variety of fish species, including bass, catfish, and trout, and it is also a great spot for kayaking and canoeing.

According to the Tennessee Wildlife Resources Agency, the following watercraft are permitted on the Falling Water River: canoes, kayaks, rafts, motorized boats, and jet skis. However, it is important to note that there may be certain restrictions in place based on water levels and other factors, so it is always best to check with local authorities before heading out on the water.

Overall, the Monterey Highway boat ramp provides easy access to the Falling Water River and is a great spot for launching a variety of watercraft.