On-stream packs

Typically, I bring a day-pack loaded with lunch, coffee supplies, water,
booze, etc and leave it stream side while I fish an area. When done with the
area, I go get the pack and move along to the next spot.

Anyone know of a good pack that will carry same but would be suitable to
wear on stream, to eliminate the return for the pack? I'd think it would
have to be water-proof (or close, anyway) and sit higher on the back to
avoid dragging in the water.

Thoughts?

Thanks,
Dan