The scientific basis to measure impacts of non-point source pollution on streams is often lacking because insufficient information exists on upstream-downstream differences in nutrient concentrations. The primary purpose of this study was to establish patterns of concentrations of nitrate (NO3-) and soluble reactive P (SRP) in Peacheater Creek, Oklahoma, to provide a basis for selecting a station on the stream where monitoring might take place to evaluate impacts of Best Management Practices (BMP) to be installed on the watershed. In addition, chloride was used as a conservative tracer to assess the relative importance of factors that might reduce NO3concentrations. Samples were taken at base flow at five stations on six dates between September 1995 and May 1996. Downstream declines in NO3were attributed to dilution and biological activity, the former being more important downstream. SRP concentrations also declined downstream but occasionally were lowest upstream. The site farthest downstream would be the most important site to sample to assess the effects of BMP in this watershed.