Based on studies in the 1980s linking stream water quality (acidification) and atmospheric acid deposition, the GRSM initiated a long-term continuous water quality monitoring program in the early 1990s. The current sampling design consists of two parts: 1) detailed long-term hydrologic and water quality monitoring; and 2) a Park-widestream survey designed to characterize water quality under base-flow conditions throughout the GRSM.&nbsp. Park-wide stream survey (also called Long-term Synoptic Stream Water Quality Monitoring) began in October 1993 to monitor water quality in GRSM streams, and simultaneously assess possible correlations between GRSM water chemistry and atmospheric sources of acid-generating pollutants. Five NDW hydrological stations were installed to monitor the potential effects of long-term acid deposition. These stations include: wet precipitation (open site, OS), throughfall (TF), soil water from lysimeters, and two streamlets (southeast, SE; and northeast, NE sites). This monitoring design provides a means to assess impacts from acidic deposition, both wet and dry deposition (OS, TF sites), effects of soil biogeochemical processes on pollutant fate and transport, and stream acidification response based on levels of atmospheric acid inputs to the watershed.