I just got back from the river today. I read a story in the Yuma paper this morning about that. It talked about I think old rocket fuel or chemicals in the ground as well as maybe nitrate levels and waste levels being high...I'm not really sure what the chemicals were, but it said the Colorado River in places is higher than EPA standards. It even said they found traces in the lettuce grown in that area. A professor from the University discounted it though, saying that they've never found abnormally high levels in the water. Who knows....