Long-term stream chemistry concentrations and fluxes: Small watershed proportional samples in the Andrews Experimental Forest

Analyses of stream water chemistry were initiated in 1968 in two small watersheds and expanded over time to all gaged basins. Composite water samples are collected at stream gaging sites over three week periods, in proportion to the amount of streamflow, and analyzed at Cooperative Chemical Analytical Lab (CCAL). Fluxes are calculated using concentrations and flow. The original objective was to examine the nutrient budgets for small watersheds and to evaluate changes in average concentrations and fluxes following timber harvest. Unharvested reference watersheds are also monitored. The study has evolved into a general monitoring effort for stream water chemistry. This study is conducted in conjunction with Andrew's precipitation chemistry (CP002) and the U.S. National Atmospheric Deposition Program (NADP)