Thanks for posting that Chris - I ran my boat part way up that part of the river last weekend and the sounder showed 4'-6' of water along the dike at the north end of McSween. Although it's far too deep to wade or drive across, it may be deep enough for fish to run through. There were a couple of bar rods setup there.
I agree with lovetofish about not blaming the gravel extraction. The extraction out of Jespersen's was nowhere near that channel, nor anywhere near the upstream end of that channel. The gravel extraction was upstream (east) of Jespersen's. The river below the extraction: passes the slough at Jespersen's, runs past a large farm, then mainflow shifts north around a major point of land before this channel we're discussing ever starts. The start of the channel you've mentioned actually runs south-west from that point whereas the river flow would be tending north due to the obstructing point of land. If anything, I would say the extra flow causing this channel to deepen is being caused by the main channel (from Jespersen's to Harrison) becoming filled in and shallower. My soundings through the traditional main channel show it being a couple of feet shallower than last year. The river is moving.