THE TWO FACES OF WATER CHEMISTRY: STRESSOR ON, AND INDICATOR OF, THE ECOLOGICAL 
CONDITION OF THE GREAT RIVERS

Terri M Jicha1, Brian H Hill1, Colleen M Elonen1, Dave W Bolgrien1, Leroy E 
Anderson1, Ted R Angradi1, Sherry L Batterman1, Mary F Moffett1, Mark S 
Pearson1, Debra L Taylor1, Xaoli Yuan2, Paul A Bukaveckas3, Anthony K 
Aufdenkampe4, and John F Sullivan5
1 EPA/ORD/NHEERL/Mid-Continent Ecology Division, Duluth, MN.
2USGS-Upper Midwest Environmental Sciences Center, La Crosse, WI.
3Department of Biology, Center for Environmental Studies, Virginia Commonwealth 
University, Richmond, VA.
4Stroud Water Research Center, Avondale, PA.
5Wisconsin Department of Natural Resources, La Crosse, WI.

A prerequisite of protecting ecosystem health is the ability to quantify extant 
ecosystem condition. The water quality component of the EMAP-GRE research 
includes the development of water chemistry as both an indicator of condition 
and as a stressor to riverine ecosystems.  Water quality indicator development 
includes the traditional use of individual parameters (e.g., total nitrogen, 
total phosphorus, chlorophyll a, etc.), and the development of a water quality 
index (WQI) that incorporates a combination of the single parameters. We compare 
the multimetric WQI, which describes the overall chemical condition of the Great 
River as a single value, to results generated from single water quality 
parameters. EMAP-GRE also explores the use of sediment enzyme activity as an 
integrator of nutrient conditions.  We expect sediment enzyme activity to 
indicate longer-term trends in nutrient exposure, and augment our one time water 
quality sampling. Each water quality parameter and index will be used in 
conjunction with biotic indices to evaluate its relative risk to the biotic 
communities. 
	
Keywords:  Water Quality, Upper Mississippi River basin, nutrient status, 
sediment enzyme activity, indicator, stressor, EMAP-GRE.