This study examined the effects of acid mine drainage on two ecosystem-level processes, primary production and detrital processing. Primary production was measured in two un-impacted and three heavily impacted streams, using the single-station open-system method. The daily rate of gross primary production was higher at the reference sites than the impacted sites, but the difference was not statistically significant. Detrital processing rates were determined in nine streams, varying in degree of AMD-impact, by placing sycamore and silver maple leaf packs in each of the study streams and retrieving them after 4 days, and 4, 8, and12 weeks. In each of the study streams, silver maple leaf breakdown was faster than sycamore. The percentage final AFDM was significantly higher in the impacted and moderately impacted sites versus un-impacted sites. Both sycamore and silver maple leaves had slower breakdown rates in AMD-impacted sites, but only the silver maple breakdown was significantly different.