University of Arkansas, Fayetteville Division of Agriculture


With the growing concern about elevated phosphorus (P) concentrations in regional lakes, rivers, and streams, it is essential to investigate factors contributing to P transport from the landscape. Phosphorus fluxes from nonpoint sources, particularly land applications of poultry litter and other animal manures, are closely related to the amount and production of surface runoff. Daily stream discharge and the software program, Base Flow Index (BFI), were used to estimate the amount and temporal patterns of surface runoff at different locations within the Illinois River Basin, including selected tributaries in northwest Arkansas and northeast Oklahoma. Daily streamflow data from nine U.S. Geological Survey discharge stations were imported into the BFI program to estimate base flow, where surface runoff was the difference between total streamflow and base flow. Surface runoff was found to be greatest during spring and winter (November-June), and least during the summer and early fall (July-October). Land on which poultry litter and other animal manures are applied during the summer and early fall when runoff is less could pose less risk of P transport, likely helping to minimize nonpoint source P loads introduced into the Illinois River.