Download or read book An Assessment of Water Quality Impacts of Maintenance Dredging on the Upper Mississippi River in 1978 written by Dennis D. Anderson and published by . This book was released on 1981 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1978, the St. Paul District, Corps of Engineers, monitored five dredging operations at various locations on the Upper Mississippi River, including three hydraulic dredging operations and two mechanical (clamshell) dredging operations. All five studies were conducted in areas with relatively coarse sediments. Overall, with the methods used for disposal of the dredged material at the five sites studied, no major degradation of water quality was evidenced for either the mechanical (clamshell) or hydraulic dredging and disposal operations. Bottom sediment samples from many historical dredging sites were analyzed for bulk chemistry, particle size distribution, and settleability. Frequency of dredging at a site did not appear to be a major factor in determining the degree of contamination. High levels of contaminants were closely associated with the finer sediments. Sites in and immediately downstream of the Twin Cities metropolitan area contained the most contaminated sediments.