Oral Session # 97: Restoration Ecology II: Rivers and Forests.
Presiding: J Weishampel
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 203.

Twelve years of water quality trends in Pool 26 of the upper Mississippi River.

Gittinger, Lori1, Soballe, David2, Chick, John1, 1 Illinois Natural History Survey, Brighton, Illinois, USA2 United States Geological Survey, Onalaska, WI, USA

ABSTRACT- The upper Mississippi River is a major resource for multiple uses, including navigation, water supply, habitat for fish and wildlife, and recreation. In order to effectively manage this resource, the Long Term Resource Monitoring Program (LTRMP) was established to enhance understanding of this ecosystem and provide information needed for sound management. The LTRMP has accumulated over 10 years of limnological data, providing a comprehensive and unequalled view of the water quality of the upper Mississippi River. The Great Rivers Field Station, as part of the LTRMP, has performed basic field and laboratory water quality measurements on Pool 26 of the Missisippi River, along with its tributaries and backwater areas. One of the benefits of such a long-term database is the ability to detect trends or change over time. We used time-series analysis on a number of important water quality measurements (e.g. dissolved oxygen, nitrogen, phosphorous, etc.) to determine whether there were any detectable trends, either poolwide or habitat-specific, over the past 12 years. We found a number of distinct trends: total nitrogen, soluble reactive phosphorous and chlorophyll-a showed distinct downward trends poolwide over the past 12 years. Habitat-wise, dissolved oxygen showed a distinct upward trend in backwaters over the past 12 years. Several water quality parameters also showed distinct seasonality, some of which varied among habitats. We believe the ability to detect trends attests to the value of the LTRMP water quality database. Whether these trends will continue can only be determined through continued monitoring of this important resource.

Key words: Mississippi River, nutrients, water quality, time-series analysis