The nutrient status or streams impacted by agriculture and silviculture is little known, especially in Oklahoma and Arkansas. USA. In this research we assessed the impact of nutrients on biofilms in the Glover River, Oklahoma, which drains a watershed impacted by poultry manure, clear-cutting, and forest fertilization. We used nutrient diffusing substrata with two independent measures of biomass and N:P ratios to assess N and P limitation in this stream during 1988–1990. The substrata data revealed limitation by N. However, N:P supply ratios indicated P limitation during 1990. The nutrient regime, turbidity and discharge changed radically during the study. Caution is advised in use of nutrient diffusing substrata in streams impacted by high turbidity and high discharge.