A river flows past loose rocks and digging equipment.
Green River Water flows freely after removal of Lock and Dam #6 on the Green River in Kentucky. © The Nature Conservancy

Stories in Kentucky

Freeing the Green

Locks and dams impact how people and wildlife live in and use the watershed.

A group of mussels rest on a sandy riverbank.
Green River Mussels A collection of mussels exposed during the breaching Lock and Dam #6 on the Green River in Kentucky. © Kentucky Department of Fish and Wildlife/Monte McGregor

The natural flow of a river resembles a healthy human heartbeat. Heavy rains send pulses of water downstream in spring, flushing out side channels and signaling fish to spawn. Dry stretches in summer allow seedlings to take root.

Dams and other man-made structures can change these rhythms. In fact, the beat of a heavily dammed river can look almost like a flatline. It causes natural systems to suffer.

In Kentucky, the Spring of 2017 marked a time when the Green River reclaimed its heartbeat. That is when trained workers from the U.S. Fish and Wildlife Service (USFWS) dismantled Lock and Dam 6, an aging steel structure that had not fulfilled its original purpose to control flooding and support navigation since 1951. In addition to involvement by the USFWS, removing Lock 6 resulted from a cooperative effort led by The Nature Conservancy and its partners, including the U.S. Army Corps of Engineers; the Kentucky Department of Fish & Wildlife Resources; the Kentucky Tourism, Arts and Heritage Cabinet; Mammoth Cave National Park; and Kentucky Waterways Alliance.

History of a Heartbeat

People have navigated Kentucky’s Green River for commerce since pioneer days. However, the Green’s natural pulse changed significantly circa 1900 with the advent of locks and dams built on the river and its tributaries—and eventually its headwaters—to aid in commercial navigation.

Eventually, the locks and dams caught the attention of TNC, leading the organization to approach the U.S. Army Corps of Engineers about operating these structures, and especially the Green River Lake Dam, in ways that better mimic the river’s natural flow patterns to support native wildlife while meeting demands for clean water and recreation. The Conservancy’s request came after a scientific analysis revealed that, while water releases from the reservoir resembled natural flows during much of the year, they were up to six times higher and significantly colder than historic flows during the fall—a critical spawning time for many fish and mussels. The introduction of more ecologically compatible flows to the dam helped launch the Sustainable Rivers Program, a collaborative effort to find more sustainable ways to manage river infrastructure to maximize benefits to people and nature. The program focuses on determining unique flow requirements for rivers and then creating operating plans for dams that achieve environmental flows—scientific prescriptions for the timing, quantity and quality of water flow that must occur downstream of dams in order to revive and sustain critical ecological functions and habitat for species. The SRP has been so successful that it has now expanded to 66 federal dams on 16 rivers in 15 states as of 2019. 

The Corps and TNC also began to examine five old locks and dams on the Green River and one on the Barren River. Mike Hensley, TNC's former Green River Project Director, describes the structures as, “old beasts—the oldest constructed in 1836—all showing signs of age and decline.” Hensley notes that removal of these dams is a win for both people and nature. In addition to the positive conservation outcomes, human safety is increased and river recreation improved, adding, “Removing these old, decaying structures, or carefully breaching them, will allow recreation enthusiasts to enjoy miles and miles of these rivers safely without the worry of being swept over a low-head dam.”

Overcoming Obstacles

In March 2017, TNC and its partners transformed planning into action with the permanent removal of Lock and Dam 6. This bold move was made possible by passage of the Water Infrastructure Improvements for the Nation (WIIN) Act of 2016, which included language de-authorizing four locks and dams on the Green River and one on the Barren River.

“The Conservancy played a major role in building support for the legislation among stakeholders, and Senator Mitch McConnell and Representative Brett Guthrie proved instrumental in getting the bill passed,” says David Phemister, TNC’s State Director in Kentucky.

The legislation directs the U.S. Amy Corps of Engineers to transfer ownership of the locks and dams, and associated acreage, to various state and local entities, in several cases for the specific purpose of removing the structures from the river.

Phemister adds, “This is a huge step forward in our efforts to make the Green River healthier, safer and more valuable for a growing outdoor recreation economy.”

In addition to new outdoor recreation opportunities, removing Lock and Dam 6 and other aging structures will yield conservation benefits for the entire Green River system. Allowing for a more fully functional watershed benefits wildlife, including one of the most diverse assemblages of freshwater mussels in the world—species which serve as natural filters for these waters that provide drinking water to the local community.

Hensley says, “Removing this infrastructure from federal ownership presents an enormous opportunity to secure water supply, economic, recreation and conservation wins for the region. I look forward to what lies ahead."

Looking Ahead

TNC and its partners are now preparing to remove Lock and Dam #5, about 14 miles downstream from the site of the former Lock and Dam #6. This  process includes gathering data that will shape and inform a feasibility analysis and, eventually, the removal of the dam.