The Watershed Manipulation Project (WMP) was implemented by EPA to: identify and quantify the relative importance of various processes in controlling surface water acidification with particular emphasis on the role of sulfate adsorption and base cation supply in the long-term watershed response to acidic deposition; assess the quantitative and qualitative watershed response to various levels of acidic deposition; and evaluate the assumptions that underlie the Direct/Delayed Response Project (DDRP) models and their ability to predict short-term watershed responses to experimental manipulation. These objectives will be achieved through a series of experiments at various spatial and temporal scales ranging from laboratory, plot, hillslope, and catchment manipulations. The document presents the rationale for these hypotheses, their importance for WMP objectives, the probability of a conclusive outcome, and the decision criteria that will be used, and in general terms, the experimental approach.

"Jeffrey J. Lee, project officer." "February 1991."