The Cooney Creek Headwaters to Mainstem run on the Whitewater River in Montana is a popular destination for whitewater enthusiasts. The ideal streamflow range for this segment is between 500 and 2,000 cubic feet per second (cfs), which typically occurs during the spring runoff season. The class rating for this section of the river is Class III-IV, making it best suited for experienced paddlers.

The segment mileage for this run is approximately 14 miles, with several notable rapids and obstacles along the way. The first significant rapid is called "The Notch," which requires precise maneuvering to navigate safely. Other notable rapids include "S-Turn," "Boxcar," and "Jaws." These rapids can be challenging, particularly at higher streamflows.

There are specific regulations in place for the Cooney Creek Headwaters to Mainstem run, including a permit requirement for commercial outfitters and a ban on camping within 300 feet of the river. Additionally, boaters are required to carry a Type III Personal Flotation Device (PFD) and a whistle, and motorized watercraft are not permitted on this section of the river.

Overall, the Cooney Creek Headwaters to Mainstem run on the Whitewater River in Montana offers a thrilling and challenging experience for experienced whitewater paddlers. However, it's important to check current streamflow conditions and adhere to all regulations to ensure a safe and enjoyable trip.