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Graphic and analytical methods for assessment of streamwater quality : Mississippi River in the Minneapolis-St Paul metropolitan area, Minnesota

Water-Resources Investigations Report 76-94

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Abstract

Historical records were analyzed to determine effects of population, pollution-control strategy, and other factors on water quality of the Mississippi River. Isopleths of DO (dissolved oxygen) concentrations and lines of equal stream temperature indicated periodic data could be used to guide sampling of certain critical conditions in time and space. Long-term records revealed generally mixed changes in quality in the Mississippi River. Several mean-time series were used to show seasonal variation in water quality and effects of initiation of wastewater treatment in 1938. Kendall 's tau statistical test indicated a significant increase in DO in the upper reach of the river during the period of record. If only the post-1938 period is considered, DO conditions remained fairly constant below the metropolitan plant and biochemical oxygen demand increased throughout the main-stem reach. Significant trends in stream temperature were indicated for winter periods using Kendall 's tau procedure. The Mann-Whitney statistical test gave estimates of a 98-percent confidence interval of the magnitudes of change. (Woodard-USGS)

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Graphic and analytical methods for assessment of streamwater quality : Mississippi River in the Minneapolis-St Paul metropolitan area, Minnesota
Series title:
Water-Resources Investigations Report
Series number:
76-94
Edition:
-
Year Published:
1976
Language:
ENGLISH
Publisher:
U.S. Geological Survey, Water Resources Division,
Description:
v, 55 p. :ill., maps ;27 cm.