The West Section Line of Sec 31, T40S, R10W to Confluence with North Fork Smith River in Oregon is a popular river run that covers a distance of approximately 28 miles. The ideal streamflow range for this river run is between 1,000 and 5,000 cubic feet per second (cfs), with peak runoff occurring in May and June. The river has been rated as a Class III-IV, which makes it suitable for intermediate to advanced kayakers and rafters.

Along the river, there are several rapids and obstacles that add to the excitement and challenge of the run. Some of these rapids include the infamous Blossom Bar, which is a Class IV rapid that requires expert maneuvering and technical skill to navigate. Other notable rapids include Devil's Staircase, Upper and Lower Black Bar Falls, and Mule Creek Canyon.

There are specific regulations that must be adhered to when running this section of the river. All boaters must have a valid permit, and the number of boaters per trip is limited to 12. In addition, all boaters must carry appropriate safety equipment, including personal flotation devices, helmets, and first aid kits. The river is also subject to seasonal closures and restrictions, so it is important to check with local authorities before planning a trip.

In summary, the West Section Line of Sec 31, T40S, R10W to Confluence with North Fork Smith River in Oregon is a challenging and exciting river run with a Class III-IV rating. With its ideal streamflow range of 1,000 to 5,000 cfs, it offers a thrilling experience for intermediate to advanced kayakers and rafters. However, it is important to follow all regulations and safety guidelines when running this section of the river.