The Nature Conservancy. Protecting nature. Preserving life.™

A collection of mussel shells from the Green River © Terry Cook/TNC

Winding its way westward through forested valleys, the Green River is at times banked by fern and moss-lined cliffs kept green by natural springs that flow as waterfalls into the river. But it’s the river’s depth that gives it a hue of green, and thus its name. The Green River, though, is much more than just scenic. It gives life to more species of plants and animals than any other tributary of the Ohio River. Perhaps the greatest amount of the Green’s diverse life occurs in an unhindered 100-mile stretch that flows from the Green River Reservoir Dam and through Mammoth Cave National Park—the world’s longest cave system that draws more than 2.5 million visitors each year.

Science-Driven Conservation For more than a decade, the Conservancy has worked along the Green River with landowners, farmers, other non-profit organizations and with local, state and federal agencies to improve water quality and habitat. Guiding the Conservancy’s work are data that show those places along the Green that support the greatest variety of plant and animal species. The Conservancy has teamed with the Kentucky State University to map the Green River corridor, to include “biodiversity hotspots,” as well as the status or use of land along the river. For example, status or use might mean the land is conserved as a park or privately owned and forested, or used as farmland. Such data enable the Conservancy and its partners to focus conservation and restoration efforts on areas where the most significant results can be achieved.

The Flow of the Green—The Heartbeat of Life

Like geese flying south and north with the change of seasons, rivers ebb and flow across the months, sometimes trickling shallow and other times running deep in flood. The Green River is no different. Late summer and fall are the seasons of trickle, while the months of winter and spring bring periodic floods. These seasonal patterns of river flows orchestrate a cycle of life for the plants and animals that make the Green their home, cuing fish to migrate and spawn and floodplain trees to drop their seeds. Even cave-dwelling species such as blind freshwater shrimp depend on the natural pulse of the river.

But in 1969 the U.S. Army Corps of Engineers built a dam in the headwaters of the Green River to control flooding and provide public recreation. While serving these purposes, the dam changed the river’s natural flows and disrupted the life cycles of its species. Then in 1998, the Conservancy began partnering with the Corps to change dam operations in order to sufficiently mimic natural patterns of flow to sustain the river’s natural richness while meeting the needs of people.

The Conservancy’s scientific analysis revealed that water releases from the reservoir reasonably mimicked natural flows during much of the year. However, releases were up to six times higher and significantly colder than natural during the fall, which is a critical spawning time for many fish and mussels. Working together, the Corps and the Conservancy developed a solution that involves releasing water later in the year to avoid the spawning period and to more closely mimic both natural patterns of flow and temperature. Studies are beginning to show enhanced mussel reproduction below the dam. Moreover, local residents are happy as flood protection has not been compromised and recreational access on the reservoir has been extended by more than a month each year.

Based on the initial success at the Green River, the Conservancy and the Corps launched the Sustainable Rivers Project involving similar pilot projects on seven other rivers across the United States. Collectively, these pilots are demonstrating that dams can be operated to sustain the ecological health of river systems while still providing people with more traditional services like flood protection, water supply and hydroelectric power. The Conservancy is now working with the Corps to expand the program agency-wide to affect more than 600 Corps-operated dams on the nation’s rivers.

Green River Conservation Center

The Conservancy, in partnership with the Kentucky Wild Rivers Program, is developing an environmental education site on the Green River in Hart County. A visitors center that is being planned and is slated for construction in 2012 will allow the public, particularly schoolchildren, the chance to learn about and observe the area’s plants, animals and geology. The site encompasses nearly 300 acres owned by Kentucky Wild Rivers and the Conservancy and will also showcase best management practices for agriculture, forestry and native plant restoration.

Healthy Streams Flow through Healthy Forests

In 2001 the Conservancy helped launch the Conservation Reserve Enhancement Program (CREP) along the Green River, focused primarily on working with willing landowners who receive federal and state financial incentives for reforesting cleared lands to improve wildlife habitat. In 2008 the Conservancy helped reach the program cap for the Green River of 100,000 acres. The Conservancy secured permanent conservation easements on 73 of these tracts, which can be used as matching money for the CREP. Such reforestation efforts improve water quality in the Green River and the Mammoth Cave system, benefiting water supply for people and habitat for fish and wildlife.

Green River Snapshot

Size: 1,350 square miles

Location: Central Kentucky; consists of the upper Green River watershed, its tributaries, and the Mammoth Cave National Park

What’s At Stake: The Green River harbors one of the most diverse assemblages of fish and freshwater mussels in the United States. More than 150 fish species and 70 mussel species have been found in the river.

Partners: U.S. Army Corps of Engineers, USDA-Farm Services Agency, USDA-Natural Resources Conservation Service, US Geological Survey, National Park Service, Kentucky Department of Fish & Wildlife Resources, Kentucky Division of Conservation, Kentucky Division of Forestry, Campbellsville University, Eastern Kentucky University, Tennessee Technical University, Western Kentucky University.

Learn More: 

More on the Conservancy’s Partnership with the Corps of Engineers

Sustainable Rivers Project

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