A University of Idaho study on the Middle Snake River shows what a lot of people already know: The river is in trouble.
And there appears to be plenty of blame to spread around.Among the findings are the Snake carries nearly 70,000 tons of sediment per day by the time it reaches King Hill.
A typical fish hatchery dumps between 1 and 11/2 tons of nitrates and nitrites into the stream each day. By contrast, a typical irrigation return flow stream on the south side of the river produces only about 50 pounds of those chemicals.
The study was conducted between July 1990 and July 1991 and covered a 100-mile stretch between Milner Dam and King Hill.
Hydrologist Charles Brockway of the UI Kimberly Research Station said the water quality problem involves two materials: sediment and "nutrients" such as nitrates, nitrites and phosphorus. Nutrients help algae bloom and choke the oxygen out of the water.
Although many irrigators like to blame fish farmers for dumping nutrients into the Snake, Brockway said no one should be throwing stones.
For example, the typical return-flow stream from the south side of the river pumps about 60 pounds of phosphorus a day into the Snake, compared with the typical fish farmer's 100 pounds.
But at the height of the irrigation season, the typical return-flow stream drops 20 tons of sediment into the Snake each day, far more than the typical hatchery's peak of 31/2 tons.
South-side streams are higher in sediment than the northern ones because they contain more groundwater and surface water.
"It's not as though the fish hatcheries are the bad guys and everyone else is doing fine," Brock-way said. "Everybody's putting stuff in there. What we need to do is find out where the nutrients are coming from and then work toward a reasonable solution."