Report Assesses Rivers’ Ecological Status

The Rock Island Engineer District and the U.S. Geological Survey, in partnership with others, released a report on June 22 titled “Ecological Status and Trends of the Upper Mississippi and Illinois Rivers.”

The report is prepared by the Upper Mississippi River Restoration Program, a partnership of federal and state agencies, non-governmental organizations and individuals working together to support Upper Mississippi River System ecosystem rehabilitation, research and monitoring. Although previous status and trends reports were released in 1998 and 2008, the latest one is based on 25 years of data. The picture it offers of the rivers’ ecological health is mixed but encouraging.

The report includes information on long-term changes in water quality, aquatic vegetation and fish from six study areas spread across the Upper Mississippi and Illinois rivers. It summarizes trends in possible drivers of long-term changes in the river, including river discharge and floodplain land cover.

The Water Resources Development Act of 1986 authorized a program to provide fish and wildlife habitat rehabilitation and enhancement in the Upper Mississippi River system. The act implemented long-term resource monitoring and research efforts, including scientific methods to understand changing environmental conditions within the river system. The report describes what was learned from that monitoring.

“Long-term resource monitoring is a primary element of the Upper Mississippi River RestorationProgram and a critical part of helping us better understand and restore our nationally significant river system,” said Marshall Plumley, Corps of Engineers UMRR regional program manager. “Completion of this third status and trends report is a testament of the UMRR partnership and its dedication to building a healthier, more resilient Upper Mississippi River System that can sustain the river’s multiple uses.”

“The report summarizes analyses of more than 25 years of monitoring data to help detect trends, understand change over time and observe complex river patterns,” said Scott Morlock, USGS midcontinent regional director. “Analysis of long-term data provides critical insight to help inform effective management, rehabilitation and resiliency efforts of this important river system. The understanding of river function we learn from the UMRS extends our ability to address large river issues nationally and internationally.”

Key findings from the report include:

• There is more water in the river more of the time with high flows lasting longer and occurring more frequently throughout the system. Water flow is an important factor affecting the quality and quantity of habitat.

• Floodplain forest loss has occurred across most of the system. Healthy floodplain forests provide important habitat for wildlife, and they support outdoor recreation opportunities and access to clean water for millions of people.

• In most of the river system, water in the main channel has become clearer. In parts of the river system, water has become clearer and aquatic plants more abundant, improving habitat for some fish and wildlife. Reduced sediment in the river allows sunlight to reach deeper into the water and promote plant growth. Plants slow the water and anchor sediment, further improving water clarity and triggering additional plant growth.

• Concentrations of nutrients, notably nitrogen and phosphorus, remain high, exceeding U.S. Environmental Protection Agency benchmarks. However, total phosphorus concentrations have declined in many of the studied river areas.

• The river system continues to support diverse and abundant fishes. Popular sport fishes have increased in parts of the river system. However, there have been substantial declines in forage fish that serve as important food for larger fishes and other animals. Invasive carp species (recently renamed “copi”) have substantially affected the river ecosystem where they have become common.

“The Upper Mississippi River flows across five states and tribal lands, multiple agency jurisdictions, the footprint of scores of nonprofit organizations and is central to navigation, agriculture and many essential economic sectors,” said Kirsten Wallace, executive director of the Upper Mississippi River Basin Association, which facilitates interagency consultation among UMRR’s member agencies. “Understanding what is going on in and around the river is needed to inform decisions and guide investments. The status and trends report is just that—a rigorous, scientific assessment of the ecological conditions of the system.”

The full report is available at https://www.usgs.gov/publications/ecological-status-and-trends-upper-mississippi-and-illinois-rivers.