The Tennessee River

The Environmental and Energy Study Institute (EESI) held a briefing about strategies to improve biodiversity and river health along the Tennessee River, which winds through Tennessee, Alabama, Mississippi, and Kentucky. The Tennessee River, one of the most biodiverse rivers in North America, experiences damaging issues ranging from PFAS and plastics to chemical pollution from landfills and manufacturing. These issues threaten both water quality and the health and well-being of the many communities in the river’s watershed.

This briefing highlighted the importance of effective enforcement of local, state, and federal clean water laws and regulations. Panelists discussed the role of federal policy-making in boosting river health, as well as opportunities to support biodiversity.

 

Highlights

KEY TAKEAWAYS

The Clean Water Act, the Clean Air Act, the National Environmental Policy Act, and the Endangered Species Act have all contributed to much cleaner water in the Tennessee River system. Forever chemicals (perfluoroalkyl and polyfluoroalkyl substances (PFAS)) and microplastics (i.e., plastic pieces that are less than 3/16” in diameter) are still found in high concentrations in the Tennessee River.  Runoff during extreme rain events is a main source of contamination carrying both soil from agricultural fields and pollutants from urban areas into the Tennessee River watershed. There are 263 known fish species in the Tennessee River, and 58 of these species are found only in the Tennessee River. Many of these species help keep the water clean and certain species’ health can be an indicator of broader issues with the river. The Southeast receives little federal funding relative to the freshwater biodiversity of the region—it is home to 30% of threatened and endangered fish, but receives less than one percent of state and federal funding for fish conservation.

 

Bernie Kuhajda, Aquatic Conservation Biologist, Tennessee Aquarium

• Humans depend on one one-hundredth of Earth’s water to sustain life, and 25% of all vertebrate specials are found in these same freshwater habitats.
• The greatest freshwater biodiversity in the United States is found in the Southeast.
• A Tennessee Aquarium and University of Georgia study that looked at 290 Southeast watersheds found that three watersheds support a disproportionate amount of this biodiversity: the Tennessee River, the Cumberland River, and the Mobile Basin. This is, in part, because of the unique and diverse geology these rivers flow through.
• There are 263 known fish species in the Tennessee River, and 58 of these species are found only in the Tennessee River. Sixteen fish species in the Tennessee River are federally listed. There are another 125 known species of freshwater mussels.
• Mountain creeks in the Tennessee River watershed are negatively impacted by farming that uses plastic to suppress weeds because that creates impervious surfaces and increases runoff, moving more sediment into the streams.
• Increased sediment, hanging culverts that separate sections of streams, invasive fish, and diseases all threaten native species like the federally-endangered Laurel Dace.
• The Tennessee Aquarium and its partners have a $10 million grant over five years through the U.S. Department of Agriculture’s Natural Resources Conservation Service’s Regional Conservation Partnership Program (RCPP) to work with farmers to keep soil on their fields and out of streams.
• Sustainable management practices for crops include cover crops, vegetated stream buffer zones, and leaving grass between rows to help hold the soil in place. For livestock, the grant is supporting farmers in keeping cows out of streams by providing alternative water sources and fencing. The RCPP is also encouraging rotational grazing to reduce manure and soil runoff into streams.
• The Southeast receives little federal funding relative to the freshwater biodiversity of the region. In an analysis of five years of state and federal funding spent on threatened and endangered fish, for every dollar spent in the Southeast, $46 are spent elsewhere. The Southeast has 30% of threatened and endangered fish, but receives only less than one percent of the funding.

 

Martin Knoll, Professor of Geology and Hydrology, Chair, Department of Earth and Environmental Systems, The University of the South (Sewanee)

• A 2017 study, the “Tenneswim,” found that the Tennessee River is quite clean with a couple major exceptions. There are lots of pharmaceuticals in the water because they do not get broken down by the human body very well and sewage treatment plants also do not do a good job of removing them. There are also herbicides and pesticides.
• The same researchers conducted a similar comprehensive survey and swim on the Rhine River in Europe, which made it possible to compare findings across the two rivers. One major difference between the rivers is that five million people live in the Tennessee River watershed and 50 million people live in the Rhine watershed. The study found lower concentrations of pharmaceuticals, herbicides, and pesticides in the Tennessee River than in the Rhine.
• However, forever chemicals (perfluoroalkyl and polyfluoroalkyl substances (PFAS)) and microplastics were found in much higher concentrations in the Tennessee River than in the Rhine.
• The Tennessee River has some of the highest measurements of microplastics suspended in the water of any river tested on Earth. The majority of these microplastics are polyethylene, which is what single-use plastic bags and light-weight food wrap are made from.
• Thirty-two million particles of plastic are moving into the Ohio River from the Tennessee River every second. This pollution ultimately moves into the Mississippi River and then into the Gulf of Mexico.
• Other toxins in the river stick to the microplastic particles, concentrating the toxins. Then these microplastic particles can get into drinking water and bring all those other toxins along with them.
• Littering is likely a major contributor to the microplastic problem in the Tennessee River. Policies like bottle bills and more robust recycling programs could be used to reduce the amount of plastic that makes its way into U.S. rivers.

 

Bo Baxter, Director, Conservation Fisheries, Inc.

• Conservation Fisheries is a nonprofit hatchery that restores and recovers native freshwater fish that are small, threatened, or endangered. Over the 40-year history of the organization, it has worked with 86 species and has released almost 300,000 animals.
• The Clean Water Act, the Clean Air Act, the National Environmental Policy Act, and the Endangered Species Act have all contributed to much cleaner water in the Tennessee River system. The water is cleaner than it has been in decades, which means that it is possible to put fish back where they once were. Reintroduction is a long-term process taking many years to be successful for most species.
• Certain fish species help indicate that there are bigger issues in a river. For example, some are sensitive to disturbances like increased sediment in the water or to increased toxicity from chlorine, copper, and PFAS forever chemicals.
• Species restoration can only happen once habitat restoration takes place, and that takes partnerships across municipalities, states, federal agencies, and other entities.
• The Tennessee Valley Authority (TVA) operates 48 dams in the Tennessee Valley and there are also over 9,000 other inventoried dams and over 200,000 other barriers in the watershed. This fragments the watersheds and makes it harder for fish to thrive.
• TVA has tried to make improvements to its impact on river biodiversity since the early 1990s. In 2021, TVA established a first-of-its-kind biodiversity policy.

 

Q&A

 

Q: How does the survival of some of the little-known species discussed today relate to the health of more well-known species?

Kuhajda

• Most people have heard of about 20 species in the Tennessee River, and most of those are game species. The vast majority of aquatic animals go unnoticed by the public, but they all work together to clean the water.
• All species are a building block of the ecosystem and when a block is lost, the ecosystem gets weaker. This means people have to pay more for drinking water because it takes more to clean it, recreational opportunities in that body of water may be diminished, and people cannot eat the fish that they catch. Helping the little-known species to survive and thrive ultimately helps humans.

Baxter

• Losing a species is like losing a city service. If the trash pickup services in a city go away, there is a problem on day one in that city. The crawfish serve a similar purpose in a freshwater ecosystem—they shred up dead animals and plant material. When you lose an ecosystem service, it moves up the chain to humans.

 

Q: How does climate change tie into the future of the Tennessee River?

Knoll

• Many areas in the Southeast are receiving more rainfall, which climate models have been predicting. The rain is coming in intense storm events. This means more runoff into rivers, which brings with it more soil and pollutants.

Baxter

• In 2024, the Tennessee River watershed experienced both extreme drought and extreme flooding. Both the Tennessee Aquarium and Conservation Fisheries have had to rescue species from dried up streams.
• Hurricane Helene severely impacted Western North Carolina, and Conservation Fisheries had to stop some of its conservation work because this unprecedented event led to the disappearance of habitats that species relied on.

Kuhajda

• Impervious surfaces and barren agricultural fields make droughts worse because when rain comes, it is not able to sink into the ground and recharge streams. Rather, it runs off.

 

Q: Are there key partnerships that are advancing Tennessee River conservation efforts?

Kuhajda

• Seventeen partners are part of the RCPP, including state and federal agencies, land trusts, and companies.
• Tennessee RiverLine, an effort by the University of Tennessee, is trying to get people in touch with the river by creating “blue ways” to provide river access.

Knoll

• It is easy for all kinds of groups to rally around clean water. The Tenneswim had support from a wide range of entities, including TVA, private foundations, and beer breweries. 

Baxter

• The Tennessee River Basin Network is a group of organizations that includes state and federal partners, land conservancies, and neighborhood associations.
• There are a lot of people starting to look at the river more holistically.

 

Q: What are examples of the relationship between people living and working in the watershed and the biodiversity work discussed today?

Baxter

• Tennessee RiverLine is a great example. It started off with recreation and water quality as it relates to humans. Groups focused on biodiversity are also engaging in order to bring forward a focus on ecosystems.
• Part of the communication to communities and farmers is that best practices are typically not expensive and not hard to apply. Farmers want their soil to remain in the field, too, so everyone is working towards the same goal. 

Kuhajda

• Spring City, Tennessee, has been seeing increased flooding as forests are transitioned to agricultural land. The reservoir there is also home to world-class bass fisheries. Spring City is working with the Tennessee Aquarium to hold a “race to save the Laurel Dace day” in 2025 to highlight what people in the area can do to minimize flooding in communities, protect the bass fishery, and save the Laurel Dace.

Knoll

• There are a lot of recreational cavers in the region and they are very interested in clean water, so they do a lot of cave and sinkhole clean ups.

 

Q: Are ongoing measurements of current microplastic levels available to the public? Are there metrics for the results of different types of litter or microplastic mitigation? Are many mitigation measures working well?

Knoll

• There is no regular monitoring of microplastics in the Tennessee River. The Tenneswim survey provided a snapshot in time.
• It is not easy to collect the samples and it is also challenging to separate the microplastics from the sediment. But there are more researchers in the region focusing on this topic.
• It is an impossible task to remove microplastics that are already in the river.
• It is good to clean up litter in the river. It improves the aesthetic of the river tremendously as well. But to get to the root of the issue, one has to prevent more plastic from getting into the river to begin with. This can be done through more robust recycling programs, instituting bottle bills, and changing the culture around littering.

 

Q: How much publicly available data is there on the biodiversity of the Tennessee River?

Kuhajda

• The Tennessee Aquarium has a Freshwater Information Network that highlights the 400 species in the Tennessee River, the Cumberland River, and the Mobile Basin. People can report photos of fish and the Aquarium verifies them and adds them to the map. There are lists of which species are in each watershed.
• FishNet 2 is oriented more toward scientists, but is publicly available. You can download all museum records on a particular species of fish.

Baxter

• The North American Native Fishes Association maintains a database where you can search by species. NatureServe provides extensive information on biodiversity by region.

 

Q: What is happening in the tributaries of the Tennessee River that is important for the overall health and resilience of the watershed?

Baxter

• The main stem of the Tennessee River is a very altered ecosystem given all the TVA and Army Corps of Engineer dams.
• The natural habitats remain in the tributaries, like the Duck River and Elk River, that have hundreds of miles of relatively unimpacted river. The biodiversity remains on the periphery of the river in its tributaries.

Knoll

• The character of a river is defined by everything that happens in its watershed.
• The tributaries that flow through urban areas provide insights into how pollutants enter the main stem of the Tennessee River.

Kuhajda

• The RCPP program is titled “Ridges to Rivers” because everything that happens on the ridges ends up in the rivers. A new gallery at the Tennessee Aquarium has the same name to emphasize that everything that happens in a watershed ends up in small creeks and ultimately in the Tennessee River.
• Historically, fish could move more freely between tributaries and there would be greater genetic exchange within species. Because these stream fish do not go through reservoirs and are blocked by dams, genetic diversity in the tributaries is reduced, which increases the likelihood of disease outbreaks and leads to less resilience to other impacts.

 

Q: Are there lessons you have learned over the years that apply more broadly to other watersheds in the United States?

Kuhajda

• You need public support to address issues the river is facing. Public education is a must.
• Partnerships are key.

Baxter

• Working with land owners is critical. Conservation Fisheries talks to everyone who is interested in learning about our work.

Knoll

• People are always drawn to rivers and love to be around water.
• When looking at water quality, the same metrics are used everywhere.

 

Q: What are the research needs in the Tennessee River watershed in the coming years?

Kuhajda

• We do not know the life history of most of our species of freshwater animals, like how many eggs they lay and how long they live.
• Models to determine how species or ecosystems will do in the future require this sort of information.
• It is hard to get life history work funded, but it is essential.

Baxter

• Knowing the sensitivities of different species to environmental factors and pollutants is important as well.

Knoll

• Much of the current knowledge on microplastics is anecdotal.
• We are at the frontier of most of what we know about microplastics and PFAS forever chemicals.
• We do not know the impact of microplastics on different aquatic organisms or on humans.

 

Q: If you could encourage a Congressional staff person to spend time today learning more about a specific species, which would it be?

Knoll

• Humans. Water quality affects human health. Reducing microplastics and PFAS forever chemicals in rivers, which ultimately get into drinking water, is essential.

Baxter

• The Snail Darter. The Snail Darter caused the TVA a lot of angst in the 1970s. A lot of people rallied to protect the animal. In 2022, the Snail Darter had recovered to the point where it was removed from the endangered species list. There was direct human intervention in the 1980s, but what really changed the trajectory of the species was implementation of the Clean Water Act, TVA’s changes to its operations, and municipalities cleaning up sewage. The lesson is that if humans allow and enable the environment to recover, species can recover.

Kuhajda

• The Alabama Cave Fish. About 40% of Tennesseans get their drinking water from wells. The more we understand about the cave and spring species, the better we can try to keep pollutants out of groundwater, and the safer that water will be to drink.

 

Compiled by Anna McGinn and edited for clarity and length. This is not a transcript.