Phosphorus Loadings Associated with Housing in a Rural Watershed

Abstract

Phosphorus and biological indicator organisms were measured in a rural watershed to quantify housing and agricultural inputs to the drainage system. Total-P and orthophosphate-P (PO 4-P) were significantly higher downstream from intensive housing areas than at areas with lower housing density. Housing areas discharged 40% particulate-P and 53% PO 4-P while rural areas discharged 62 and 29%, respectively. On the average, rural housing contributed 2 g P/house/day which comprised 27% of the PO 4-P discharged from the study area. For the rural subwatersheds, phosphorus from agriculture was not differentiated from biogeochemical and precipitation inputs. Assuming all phosphorus arose from fertilizer application, total-P losses represented 3.5% of that applied while PO 4-P losses represented less than 1%. It was concluded that housing in rural areas contributes PO 4-P to nutrient enrichment of drainage systems and that measures to control rural erosion may reduce total-P load but increase the proportion ofPO 4-P.