EFFECT OF A POINT SOURCE INPUT ON STREAM NUTRIENT RETENTION

The effects of point-source inputs on nutrient retention in Spavinaw Creek in Oklahoma/Arkansas were investigated. Whole-system net nutrient retention was estimated, and smaller-scale experiments were conducted to examine the ability of sediments to remove nutrients from stream water. The Decatur wastewater-treatment plant discharges effluent into Columbia Hollow, a third-order tributary to Spavinaw Creek, and Columbia Hollow acts as a point-source input to Spavinaw Creek. Results indicated that soluble reactive phosphorus and nitrate nitrogen concentrations at the first site below Columbia Hollow were approximately 8 25 and 1.1 1.4 times greater, respectively, than above the tributary confluence, and the degree of enrichment decreased with increasing discharge. The degree of NO sub(3) N enrichment was more sensitive to changes in discharge than soluble reactive P, and the concentrations of both nutrients in Spavinaw Creek decreased exponentially with distance from Columbia Hollow. Above the point source, sediments exhibited little natural P buffering capacity. The wastewater-treatment plant was determined to be the likely contributor to anthropogenic eutrophication and other water-quality problems in the reservoir.