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 Mountain-Prairie Region

Upper Missouri, Yellowstone, and Upper Columbia River Ecosystem Plan
December 2001

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Vision: River and stream systems that function in a natural state and provide for a diversity of flora and fauna.

Resource Description

Mississippi River photoWithin the MOYOCO ecosystem in Montana, the two main river systems are the Missouri River and its tributaries, which flow east to the Mississippi River, and tributaries of the Columbia River, which flow west into the Pacific Ocean.

Trending southward across the western part of Montana, the Continental Divide separates the state's two major watersheds. West of this continental backbone are the Clark Fork and the Kootenai River, important tributaries of the Columbia River. The Clark Fork has as its primary tributaries the Flathead, Blackfoot, and Bitterroot rivers. The Kootenai River rises in Canada and crosses a small area in northwestern Montana.

The Missouri and its major tributary, the Yellowstone River, are the principal rivers in eastern Montana. The Missouri begins at the confluence of the Gallatin, Madison, and Jefferson rivers, near the town of Three Forks. Other tributaries below Three Forks include the Sun, Teton, Marias, Smith, Judith, Musselshell, and Milk rivers. The Yellowstone rises south of Yellowstone National Park in Wyoming, flows north into Montana and diagonally across the southeastern part of the state before joining the Missouri in North Dakota just east of the Montana state line. Main tributaries are the Clarks Fork of the Yellowstone, the Bighorn, the Tongue, and the Powder rivers, all of which also originate in Wyoming.

A tiny area of northwestern Montana is drained by the Belly, Saint Mary, and Waterton Rivers, which, rising in Glacier National Park, flow northeast out of the state and into the Saskatchewan River in Canada. Their waters eventually reach Hudson Bay. Hydrologically, this area lies outside the MOYOCO proper, but for practical reasons is considered a part of the ecosystem.

The area covered by the MOYOCO ecosystem in Wyoming is the source of water for three main drainage systems in the western United States: the Missouri-Mississippi; the Great Basin; and the Columbia. Rivers joining the Missouri include the Yellowstone, Bighorn, Powder, Wind, and Belle Fourche rivers, which flow north. Northwestern Wyoming is drained by the Snake River, a major tributary of the Columbia.

The MOYOCO has numerous lakes and reservoirs. In Montana, most of the natural lakes are in the mountains of the western third of the state. Flathead Lake, with an area of 191 mi2, is Montana's largest lake, and the largest natural freshwater lake in the contiguous states west of the Mississippi River. In Wyoming, the largest natural lake and probably the largest at its altitude (7,733 ft.) anywhere in the United States is Yellowstone Lake, which covers an area of 131 mi2 and has a maximum depth of 320 ft. Just to the south lies the second largest lake in Wyoming, Jackson Lake, with an area of about 40 mi2. Jackson Lake has been enlarged by a dam on the Snake River. Some of Wyoming's reservoirs are of impressive size and include the Pathfinder, Seminoe, Glendo, and Boysen reservoirs.

Rivers Goal 1: Maintain, and re-establish where needed the natural form and function of riverine systems and prevent degradation of riverine habitat.


Work with the partners to achieve water quality standards that are ecologically beneficial.

By 2001, initiate work with local zoning authorities and regulators to develop and implement policies that reduce floodplain development and restore river functions.

Increase functional riverine habitat through restorations, creations, and modification/enhancement where opportunities allow. Attempt 12 projects per year, six in Montana and six in Wyoming, beginning in 2000.

Work with partners to monitor environmental contaminants, identify issues and problem areas, and develop strategies for rehabilitation.

Identify and eliminate fish migration barriers and minimize entrainment losses.

Maintain and restore natural ecological conditions through the prevention and eradication of invasive species.

Rivers Goal 2: Conserve and recover threatened, endangered, proposed, and species of special concern in riverine and impounded reaches.


Implement recovery efforts for threatened, endangered, proposed, and sensitive fish species. Work towards achieving recovery plan objectives within the ecosystem

Develop recovery actions or conservation plans for native and imperiled riverine species.

Establish priority and complete status reviews for species of special concern, initiating one species per year beginning in 2001.

Maintain and improve inventory data with partners for endangered, threatened, proposed, and species of special concern in the ecosystem by 2001 to provide baseline information.

Rivers Goal 3: Fulfill responsibilities for protection, mitigation, and enhancement of fishery and wildlife resources brought about by the construction and operation of dams.


Support conservation efforts for native species through fish culture, management, and conservation within the ecosystem.

Rivers Goal 4: Maintain, restore, and enhance riparian communities.


Inventory and determine the quality of riparian habitats within the ecosystem to provide preliminary baseline information. Support and use FWS National Wetland Inventory riparian mapping system to conduct habitat assessments.

Use existing programs and opportunities to restore and enhance river buffer zones on ten percent of the 100-year flood plain on selected river systems by 2010.

Use existing programs and opportunities to restore and enhance 1,500 acres of oxbow wetlands by 2010 (50% MT, 50% WY).

Support State and Tribal efforts to monitor water quality and biotic communities to promote compliance with Federal water quality standards.

Protect and restore vegetative communities on riverine systems.

Rivers Goal 5: Conserve, restore, and enhance habitat in watersheds to improve the quality and quantity of water in rivers and streams.


Use existing oversight, coordination, and technical assistance to promote sound watershed management. Prioritize watersheds and establish strategies for promoting watershed management.

Use existing programs and opportunities to conserve, enhance, and restore upland, wetland, and riparian habitat in riverine corridors to improve runoff quality and quantity.

Rivers Goal 6: Support educational and recreational activities in riverine systems that are compatible with resource protection and the Service’s trust responsibilities.


Address recreational activities on public lands through the consultation process to ensure compatibility with Service trust responsibilities.

Use education and outreach to raise the public’s awareness of the impacts of certain recreational activities in riverine environments.

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