Water Quality Survey of the Mississippi River at Dubuque Iowa prepared for the Iowa Department of Environmental Quality by the University of Iowa Hygienic Laboratory, September 26, 1974

(1978) Water Quality Survey of the Mississippi River at Dubuque Iowa prepared for the Iowa Department of Environmental Quality by the University of Iowa Hygienic Laboratory, September 26, 1974. University of Iowa

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Abstract

In September of 1971, the Limnology Division of the State Hygienic Laboratory conducted a water quality survey of the Mississippi River in the Dubuque area. The results of this study, which are contained in the State Hygienic Laboratory's Report #72-18, indicated fairly heavy contamination of the Iowa side of the river below Dubuque which was attributable to the operation of the Dubuque Sewage Treatment Plant. In view of these results, their public health implications, the value of the resource involved, and the classification of that reach as Class A waters, the Limnology Division carried out a complete limnological survey in the Dubuque area on July 30-31, 1974. Furthermore, following several incidents of public health significance in the area as well as reports of greatly increased disinfection performance at the treatment plant, the Limnology Division returned to the area and with cooperation from Public Health personnel, conducted a thorough bacteriological investigation in the area. The July survey was comprised of fifteen samples for water quality evaluations collected at sites ranging from River Mile (R.M.) 582.7 to R.M. 569.3. Samples were collected from both shore lines, generally about twenty yards from shore, as well as in mid-channel. Additionally, biological investigations were carried out at selected sites by either of two methods. Grab samples of sediment were collected by a Ponar Dredge and passed through a #30 mesh sieve to allow investigation of the benthic invertebrates. Also, hand collections of the attached shoreline community were made from natural substrates. The August survey consisted of collections of samples for fecal coliform bacteria analysis at seventeen selected sites including locations in the Massey Recreation Area. Dissolved oxygen determinations were made at thirteen of these sites and six samples were collected for BOD analysis. River conditions on each sampling date were similar. Data acquired from the Corps of Engineers showed a mean flow at Dubuque of 31,100 cfs on July 30 and 31,000 cfs on July 31. On August 22 the discharge at 0800 hours was 27,600 cfs, but due to rainfall the previous night, the resultant mean discharge for the day was 31,400 cfs.