The U.S. Geological Survey and the Massachusetts Department of Fish and Game, Division of Ecological Restoration, collaborated to collect baseline information on the quantity and quality of sediment impounded behind selected dams in Massachusetts, including sediment thickness and the occurrence of contaminants potentially toxic to benthic organisms. The thicknesses of impounded sediments were measured, and cores of sediment were collected from 32 impoundments in 2004 and 2005. Cores were chemically analyzed, and concentrations of 32 inorganic elements and 108 organic compounds were quantified. Sediment thicknesses varied considerably among the 32 impoundments, with an average thickness of 3.7 feet. Estimated volumes also varied greatly, ranging from 100,000 cubic feet to 81 million cubic feet. Concentrations of toxic contaminants as well as the number of contaminants detected above analytical quantification levels (also known as laboratory reporting levels) varied greatly among sampling locations. Based on measured contaminant concentrations and comparison to published screening thresholds, bottom sediments were predicted to be toxic to bottom-dwelling (benthic) organisms in slightly under 30 percent of the impoundments sampled. Statistically significant relations were found between several of the contaminants and individual indicators of urban land use and industrial activity in the upstream drainage areas of the impoundments. However, models developed to estimate contaminant concentrations at unsampled sites from upstream landscape characteristics had low predictive power, consistent with the long and complex land-use history that is typical of many drainage areas in Massachusetts.

The NPDES Storm Water Sampling Guidance Document provides a comprehensive description of basic sampling requirements for NPDES storm water discharge permit applications and offers procedural guidance on how to conduct sampling. Many of the procedures in this manual are also applicable to the sampling requirements contained in NPDES storm water permits. Topics covered include background information and a summary of permit application requirements, the fundamentals of sampling (including obtaining flow data, handling samples, and sending them to the lab), analytical considerations, regulatory flexibility regarding storm water sampling, and health and safety considerations. This book will be a cornerstone of NPDES compliance for wastewater treatment plant managers and supervisors, consultants, laboratories, lab managers and chemists, regulators, current NPDES permit holders, and anyone applying for an NPDES permit.