This is a writeup about a potential hazard below Eye of the Needle. The hazard involved is an undercut rock that I do not believe sieves out. The rock is approximately 50 yards below the rapid on the river left bank, 5 to 10 feet before where the river makes a left hand turn.
I was leading a single raft trip after the 4th of July from Sandy Ford to the 76 bridge. We were 4 people in a 10.5' foot raft. I would describe myself as having extensive experience and another one of the paddlers as having significant experience. The remaining 2 paddlers were inexperienced. This was my 4th or 5th trip through this section of the river, but the highest I had paddled it at. We ran the rapids before Eye of the Needle without any issues.
During the approach to Eye, I had the raft in the middle of the river debating between running left or right of the rock that bisects the river. Upon deciding to run the right side, we were already too far to the right of the main line. I got the raft back into the main line directly above the main hole, but we were still sideways from the ferry and the raft flipped, ejecting everyone.
When I surfaced, 3 of us were on the right side of the raft, and the other two immediately swam into the eddy behind the rock that bisects the river and then to beach on the river right where another group of two rafts were at. At this point I swim to the raft to right it and get to shore. I reach the front of the raft 40' before the pool runs out into a class 2 rapid. I notice that one of the inexperienced paddlers, who is a weak swimmer, was trying to swim to the river left bank to get out. I begin yelling to swim to the beach, but at this point the person has been pulled into the undercut rock.
I look back to the beach to indicate for help, but the other group has already gotten into their rafts and begin ferrying to the rock. I swim to below the undercut rock, and extend my paddle to the trapped person. I used the rock adjacent to brace myself and then pull the swimmer out. We both climbed the bank directly below this rock. She was in the undercut for less than 15 seconds.
The next time I ran Eye of the Needle, I stopped below to inspect the rock. It has an entrance that is approximately 8 feet wide and goes back at least 7 to 8 feet, converging to a 2 foot wide gap at the back. At 2.1 foot, the undercut does not appear to be retentive nor sieve out, but I am not positive. At higher flows, a significant amount of water flows past/into this rock, making self rescue challenging.
This could have been easily avoided, by swimming and self rescuing immediately after the raft flip. The pool behind Eye of the Needle is sufficiently long enough. The hazards were not know before running the rapid and where to swim to was not conveyed to the group before running the rapid.
My recommendation is to inform everyone in your group, especially at high water, of the potential for entrapment on the river left side of Eye of the Needle and if swimming, to swim towards the right bank.