Concentrations of total nitrogen and phosphorous have not changed significantly from 1974 to 1991 at most sites, although there was a decrease in phosphorous concentrations near Dallas. Spatial variations in chemical concentrations in streams are related primarily to point sources and reservoirs. The largest nutrient concentrations occur downstream from Dallas, where streamflow is dominated by treated wastewater. The smallest concentrations occur just downstream from reservoirs, which act as sinks for nutrients. The largest concentrations of nitrate in ground water have been detected in samples from the Queen City and Nacatoch aquifers.
Concentrations tend to decrease with depth.