I went past there two weekends ago. The John Day was not to off color ie:not mud brown. As for night fishing it gets hammered near the park so I would recommend looking for some holes some where else. I always wanted to try the backwater below the dam on the Oregon side at night. The area where the water comes in from the main river looks like it could be fun at night, and I have caught some channel cats in there in the past fishing for bass.
P.S. I went further up the Columbia river and fished for a couple hours with no takers. I think I was fishing to deep but who knows, beat the heck out of mowing the lawn.