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Water Quality of Large Rivers

Importance
Large rivers are an important ecosystem within Great Lakes Network parks, specifically the Mississippi National River and Recreation Area (MISS) and the St. Croix National Scenic Riverway (SACN). Key water quality concerns of these parks include: 1) excess nutrients (particularly nitrogen and phosphorus) from urban and agricultural runoff and wastewater treatment facilities; 2) fluctuations in flow regime caused by climate change, farming drainage, impervious surfaces related to urban growth, or channel engineering; 3) sediment loading from stream-bank and agricultural-field erosion; 4) invasion of exotic species such as common carp (Cyprinus carpio) and zebra mussels (Dreissena polymorpha); and 5) environmental contaminants of emerging concern, such as polybrominated diphenyl ether (PBDE) flame-retardants, mercury, and endocrine disrupters.

Veg Monitoring
St. Croix River

Long-term Monitoring
The Great Lakes Network monitors five sites at MISS on the Mississippi River and 11 sites at SACN on the St. Croix and Namekagon Rivers. Sites at MISS were selected to fill spatial gaps in coverage by other monitoring agencies. At SACN, six sites were randomly selected to represent the entire stretch within park boundaries, and five additional sites were selected to integrate inputs from important tributaries. Sites at each park are sampled monthly during the ice-free season, in alternating years. A multiprobe sonde is used to measure temperature, specific conductance, pH, and dissolved oxygen from the surface to the bottom at 1-m intervals. Clarity is measured with a Secchi disk or transparency tube. Water samples are collected with a 2-m integrating tube or via grab sample for laboratory analysis of alkalinity, dissolved organic carbon, calcium, potassium, sodium, magnesium, chloride, sulfate, total nitrogen, total phosphorus, nitrate+nitrite-nitrogen, ammonium-nitrogen, dissolved silica, total suspended solids, and chlorophyll-a. Data on flow are obtained from U.S. Geological Survey and U.S. Army Corp of Engineers gage stations located near each monitoring site.
This monitoring is integrated with a protocol to monitor diatom remains in surface sediments. Diatoms are a class of algae with silica-based cell walls. When a diatom dies, the remains are preserved in lake sediments. Diatoms make excellent bioindicators because they are generally abundant in aquatic systems and respond rapidly to changes in their environment. Through monitoring water quality and diatoms together, we expect to be able to determine trends in lakes sooner and more accurately than by monitoring water quality alone.
Through sharing our data with other agencies active in monitoring water quality in the two parks, the Great Lakes Network is contributing to a better understanding of water quality trends in these important rivers.

For more detailed information, see the In-depth Information box below.

Network park units with Large River Water Quality monitoring
St. Croix NSR	Mississippi NRRA
NRRA = National River & Recreation Area; NSR = National Scenic Riverway

In-depth Information:

Factsheets:
Executive Summaries:
Annual Reports:
Monitoring Protocols:	GLKN Large River Water Quality monitoring protocol - [4 MB PDF]
Contacts:	Joan Elias, joan_elias@nps.gov
	David Vandermeulen, david_vandermeulen@nps.gov

Additional Water Quality Monitoring Publications

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