Direct/delayed response project: Predicting future long-term effects of acidic deposition on surface water chemistry



In 1984 the U.S. Environmental Protection Agency, as part of the National Acid Precipitation Assessment Program, initiated a project to estimate potential future effects of acidic deposition on the chemistry of lakes and streams. This project, the Direct/Delayed Response Project (DDRP), has focused its attention on surface waters in regions of the eastern U.S. thought to be most vulnerable to effects of acidic deposition. The project hascombined regional surface water chemistrydata gathered by EPA's National Surface Water Survey with a unique regional watershed and soil survey under take n within the DDRP.The project is applying a variety of analyses, including the use of three independently derived watershed models of acidic deposition effects. This article describes the design of the DDRP and presents some of its preliminary products.