According to AmericanWhitewater.Org
This fine playhole was first probed for its' fun potential back in the 80's with the big boats. At that time, many nasty swims occurred due to the nature of paddling in those long forgotten days. Today it is being played in by intermediate paddlers that have good rolls. Swims still occur here especially at the sticky levels. Although the 'dog makes its appearance below 12,000 cfs, it is generally not in its' prime till it is above 15000.
Dead-dog was named by a couple of Idaho paddlers who came out to play here, only to discover the broken, deceased carcass of a poor dog that got thrown off the bridge directly overhead. Pity for the dog, great name for this spot! Just remember that dead dogs can bite!
The hole is formed by the river flowing over an immense slab of rock near the second bridge abuttment. The hole is typically 15-20 feet wide or wider depending on flow and has a glassy smooth entrance with a high backwash. The eddy behind the hole is a self feeder right into the hole at certain levels, which makes wet exit and self rescue somewhat difficult at those sticky levels, but also provides an easy elevator ride back in for another go at it!
From surfer's left, the hole has its' apex and this is the sticky spot. The middle and right provide the most fun with the hole cresting into a wave on boater's right.
This was the site for Otter-Sports first rodeo in 1999. Due to the uneven nature of flows, it has been difficult to schedule another rodeo here. Some years, the 'dog never even gets to bare its' teeth!