Fish slower water, closer to shore, with bigger nymphs, or streamers. Bright colors arent neccesary, I usually go with black leeches, big dark stoneflies, etc. Find slow DEEP water next to a bank, and your in the money. I usually fish a slow 4 foot deep bank, and fish it about a rod length or less from shore. Some banks will differ and the best spot will be 10-15 feet out, but as long as it's slow, your in the fish. They won't be in riffle or chop water in dirty conditions (unless YOU can see more than a foot). That's my 2 cents..