Project Overview

Why do we need to study the lower Minnesota River?

All or portions of the lower Minnesota River are listed as impaired due to low oxygen levels and high turbidity on Minnesota's list of impaired waters. These problems have been linked to excessive levels of algae, nutrients, and sediment. The pollutants come from point sources, such as wastewater treatment and industrial facilities, and nonpoint sources, such as agricultural runoff and urban stormwater. A large, predominantly agricultural watershed drains into the lower Minnesota River, joined by urban development and commercial navigation as potential impacts in the Metro Area.

What is a river model?

It's a computer program with a set of equations that attempts to describe all the relevant processes in a river. For example, to understand how algae affect oxygen levels, we need a model that describes the relationship of algae to nutrients, light, temperature, and other growth factors as well as the relationship of algae to oxygen production and consumption.

Can a computer model really mimic a river?

Not perfectly but we can test how well it does. This model will be tested against seven years of data representing a wide range of conditions. We'll test it against the historical years 1988-1991, which included both low and high river flows. Low oxygen levels are most often a problem at low flows, while high sediment and nutrient loads are associated with high flows. We'll also test the model against data collected during 2004-2006 specifically to support the model. In addition, statistical tests will be applied to test how well results from the model match actual measurements from the river.

What data will be collected to support the model?

For many years, the Council has conducted river, stream, and effluent monitoring in the Metro Area. We have five long-term river monitoring stations on the lower Minnesota River near Jordan, Shakopee, Savage, Black Dog, and Fort Snelling. The Council and local groups conduct stream monitoring on a dozen tributaries to the lower Minnesota River, and the Council closely monitors the effluent quality of its wastewater treatment facilities, Blue Lake and Seneca. Other point sources are required to monitor their discharges and submit reports to the State.

The monitoring programs were reviewed and modified as needed to support the model. Special studies were also designed to answer specific questions, such as whether ground-water inputs are significant to the river, and to support key model inputs, such as the rate of oxygen entering the water from the air.

How will the model be used?

The model will be used to set appropriate pollutant limits for discharges from point sources and establish goals for reducing pollutant loads from watersheds. The Council plans to use the model for wastewater facility planning for future growth in the southwestern communities of the Metro Area. The Minnesota Pollution Control Agency plans to use the model to reevaluate allowable pollutant loads to the lower Minnesota River from point and nonpoint sources.

What is the schedule?

2003 Design and initiate the project
2004-2006 Conduct monitoring and special studies
2005-2007 Develop and test the model
2008 Apply the model to different management strategies
2008 Complete final reports

Who are the Project Sponsors?

Metropolitan Council (lead), Lower Minnesota River Watershed District, Metropolitan Airports Commission, Minnesota Pollution Control Agency, US Army Corps of Engineers, and US Geological Survey

Questions/comments? Please contact Cathy Larson at 651/602-1275 or cathy.larson@metc.state.mn.us.