Economic Causes of Non-Point Pollution in the Boise River

to the river near Parma, which is a short distance from where the Boise River empties into the Snake River. By comparing measurements of nitrogen and phosphorus at Lucky Peak Dam (above Boise) with similar measurements at Parma, an estimate of pollution from both urban and rural sources along the river can be made. Contamination concentrations vary greatly with the level of stream flow because of the dilution effect. Stream flow varies greatly from year to year and within the year, depending upon the amount of runoff available from snowfall in the mountains. This complicates the analysis of the causes of non-point pollution, because high flows carry more pollutants (loads) but also have the effect of diluting pollution concentrations.