Onion Creek is a popular whitewater river run located in the state of Utah. The ideal streamflow range for this river is 200-700 cubic feet per second (cfs), with the best time to run the river being in the spring or early summer when snow melt provides the highest water levels. This class II-III river run has a total segment mileage of 8.5 miles, with the rapids and obstacles within the river varying in difficulty throughout the run.

The first 2.5 miles of the river are relatively mild with the class II rapids, while the remaining 6 miles of the river are more intense with a mix of class II-III rapids. Some of the specific rapids and obstacles on this river include Boulder Drop, Onion Falls, and Rocky Rapid. It is important to note that the difficulty of these rapids can vary depending on the water level.

To ensure safety while running Onion Creek, specific regulations have been put in place by the Bureau of Land Management. These regulations include the requirement of wearing personal flotation devices (PFDs) at all times while on the river, adhering to a strict leave-no-trace policy, and not camping or building any structures within 300 feet of the river. It is also important to note that the river can be closed during periods of high water or other hazardous conditions.

Overall, Onion Creek provides an exciting and challenging whitewater river run for experienced paddlers. It is important to check current water levels and regulations before attempting this run, and to always prioritize safety while on the river.