No Exit Rapids. Photo by Steve Van Beek.
After running the Mekong above the Man Wan Dam (24 37 19N, 100 26 55E) in 1995 and 1996, Earth Science Expeditions learned that the Chinese were building the Da Shao Shan Dam about 90 miles below the Man Wan Dam, so they ran this section in April, 1997 before it was flooded. The average gradient for the entire stretch was only 4' per mile, but for the first 40 miles it was only about 1' per mile (flat), so the team, with two 16' catarafts and three kayaks, knew the gradient had to increase. Within a few miles after the first Class 4 rapid, the nine person team encountered the damsite at 24 01 32N, 100 22 15E, only half way to the take-out (Jinggu-Lincang Bridge, 23 33 44N, 100 10 27E, 2600'). Just after they passed by the diversion tunnel, they encountered another Class 4, and eventually they encountered several more Class 4s plus one Class 5 (No Exit, where one raft flipped twice) at the spring discharge of about 25,000 cfs. Even though it rained a lot, at the relatively low elevation (put-in was about 3000') and low latitude, the weather was mild.
The Da Shao Shan Dam was completed and filled by 2004, and the Chinese are building two more dams below it, so this stretch is no longer runnable. See First Descent of Man Wan Gorge of the Mekong by Pete Winn, The Power of One by Steve Van Beek, and Bigger Than the Grand Canyon by Marion Softky for details.