by Kelly McGinnis, Director of the Mississippi River Network

America’s longest river flows for 2300 miles, from Lake Itasca to the Gulf of Mexico. But the Mississippi’s central channel is part of a larger system that includes tributaries like the Illinois River, along with streams, wetlands, oxbow lakes, aquifers, and estuaries. This river system involves surface and subsurface water flows that help meet the varied needs of our society: drinking water, irrigation, navigation, recreation, and wildlife habitat.

In the backwaters on the Upper Mississippi River. The River can be thought of as an interconnected system of many bodies of water. Photo Credit: Michael Anderson

These flows also factor into challenges that our society faces in relation to the river, such as nutrient pollution. After draining from a Midwest farm field – or the Chicago River – a molecule of nitrogen can travel all the way to the Gulf of Mexico. The U.S. Geological Survey has also found that nitrogen can leach into groundwater and continue its way back to the river more slowly as a form of subsurface “legacy pollution.” Both sources help feed the large hypoxic area of low oxygen that forms each year in the Gulf.

Excess nutrient pollution from agriculture and other sources can lead to deadly algal blooms.
Photo Credit: Brenda Culler.

Those are the kinds of connections that America sought to address in the landmark law known as the Clean Water Act. The Mississippi River system includes all of the types of water bodies listed in the Act as jurisdictional “Waters of the United States”: navigable waters, interstate waters, tributaries, wetlands, and territorial seas. The river is a central case study in the Act’s attempt to deal with the issue of downstream impacts from upstream actions.

A 2008 report by the National Research Council examined how the Clean Water Act has substantially reduced pollution to the Mississippi from “point sources” such as industry and wastewater treatment facilities. Pollution from “non-point sources” such as agriculture and urban runoff have been a greater challenge.

“We need to keep the capacity of the Clean Water Act to address the wider connections of water systems”

The NRC Report also pointed to a lack of coordination by states along the Mississippi River, since states focus on their own tributaries and lakes, rather than the main channel. Coordination efforts among river states, such as the Upper Mississippi River Basin Association and the Gulf Hypoxia Task Force, have generally begun with federal action.

Figure 1. An explanatory figure of the 2015 Clean Water Rule from the EPA. This rule employs scientific hydrological principles, like the down-stream effect, to guide water policy.

In 2015, the U.S. Environmental Protection Agency (EPA) addressed the issue of Clean Water Act jurisdiction in a rule that focused on the connections in water systems. To develop the 2015 rule, the EPA drew upon a large body of scientific literature, along with extensive input from stakeholders and the lessons learned from over 40 years of administering the Act.  Those included retaining the long-standing permit exemptions for farming, ranching, and silviculture.

The current EPA is seeking to change the rule for “Waters of the U.S.” with a very different approach that is focused on reducing and reversing the federal role in regulation of these systems. Navigable waters would still be under federal jurisdiction, along with the tributaries, streams and wetlands directly adjacent to them. But regulation of the wider set of connected waterbodies that culminate in navigable waters and drinking water would only be state by state.

Water doesn’t respect jurisdictions, but we have to manage it through law, informed by science.  Removing one piece of the picture, such as a role for science, won’t provide us with lasting solutions.  

We need to keep the capacity of the Clean Water Act to address the wider connections of water systems, because those benefit the diverse needs of society, which are plainly visible in the Mississippi River system.

Kelly McGinnis is the Director of the Mississippi River Network, a nonprofit coalition of organizations working for the health of America’s largest river.

Submit public comments on the proposed rule change here:

For further ways to get involved with the Mississippi River Network, sign up as a River Citizen (free):


U.S. EPA, “Waters of the U.S. (WOTUS) Rulemaking”,

National Research Council, Mississippi River Water Quality and the Clean Water Act: Progress, Challenges, and Opportunities (2008);

Figure 1.