Algal blooms can be detrimental to fish and other aquatic organisms.
More than 96 percent of the total anthropogenic phosphorus input to the study area is in the form of commercial fertilizers and livestock manures. Phosphorus is naturally occurring and present in many clay soils in the study area. Phosphorus concentrations at the 11 Fixed Sites were primarily related to land use and secondarily related to clayey surficial deposits in the basin. Phosphorus concentrations in stream water at agricultural sites were considerably higher than at urban and forested sites during base flow conditions. Nitrate was detected in all 412 stream-water samples collected during the study.