Official Department Position Papers

The Missouri River in North Dakota (Garrison Reach) - A Report to the Director, 1998

The Missouri River of the 1800s has been inalterably changed as a result of numerous channelization and impoundment projects (six dams were constructed beginning in the 1930s). What was once a turbid, warm, and dynamic river has been transformed and segmented into six large storage reservoirs, more than 700 miles of rock lined channel, and five smaller reaches of unchannelized river with highly regulated flows. Dam construction and channelization have collectively and dramatically modified fish and wildlife habitat throughout the entire Missouri River. Mainstem dams have eliminated migrational movements of fish, modified the hydrocycle, changed the depositional nature of sediment carried by the Missouri River and its tributaries, all but eliminated the periodic inundation of the flood plain, transformed the configuration of the river channel and associated backwaters, and caused colder summer water temperatures.

The Garrison reach of the Missouri River extends from Garrison Dam (river mile 1390) to the headwaters of Lake Oahe approximately 75-150 miles downstream depending on the elevation of Lake Oahe. Though the channel capacity of this reach is 65,000 cubic feet per second (cfs), only once since the closure of Garrison Dam in 1953 has this flow been realized. Similar to the entire Missouri River, striking habitat changes, both within and adjacent to the Garrison reach, have occurred due to dam construction and other activities associated in and along the river.

In order to best meet the needs of the users of this river reach, an objective assessment of management possibilities and formulation of and adherence to a well thought-out plan is an absolute necessity. Public expectations need to be appropriately framed within the context of physical reality. Well-intentioned but unrealistic desires to manage the river for a set of conditions which cannot be economically or ecologically attained must be clarified and avoided. Management actions must consider both upstream and downstream ramifications. Segments need to be managed as part of, not separate from, the whole system. This assessment and plan must be driven by unbiased hydrological and biological data complemented with sound public education. In the end, the goal for the US Army Corps of Engineers (COE) and the state of North Dakota, as well as other states, should focus on sustaining a healthy river environment.

Although significant changes have occurred in and along the Garrison reach of the Missouri River, there have been tremendous recreational benefits associated with the transformed habitat, as well as the operations of the Missouri River System. A world class walleye fishery has been established in Lake Oahe and the Missouri River. The cold, clear waters of some portions of the river are ideal for trout and salmon . Abundant Canada geese use the river for nesting and brood rearing and staging during fall migration. Least terns and piping plovers, two federally listed endangered and threatened species, use sandbars in this reach. Flood control has accommodated development along the Garrison Reach (as of 1992, $488 million in building properties) which has greatly enhanced the quality of life for many people living along this reach.

Conversely, many components of the free-flowing, pre-dam ecosystem are gone and can never be feasibly reestablished. The federally endangered pallid sturgeon and a handful of other native, endemic fishes cannot naturally sustain their populations in the Garrison Reach due to numerous factors including cool to cold water temperatures, low turbidity, and a highly modified hydrograph compared to pre-impoundment. Since some or all of these components in the Garrison Reach will never again provide for the long-term survival of a number of certain indigenous fish species, protection and enhancement of existing habitat for the current aquatic assemblage is the most logical course of action. This includes making the operational changes at Garrison Dam to ensure suitable river flows for the river's natural resources. While a return to a pre-dam condition of warm, shallow, turbid flows favoring native species such as pallid sturgeon and sicklefin chub is not practical, it is possible and most desirable to maintain the existing popular walleye fishery, provide secure nesting habitat for terns and plovers, and improve shallow backwater riverine wetlands and low terrace riparian habitats.

While the Missouri River System has become a segmented ecosystem, every segment from Ft. Peck to St. Louis still impacts the others. Balancing demands requires a holistic approach. For example, maintaining high flows in the Garrison Reach of the river during drought years may deplete cold-water habitat in Lake Sakakawea, thus decimating the major forage base (the rainbow smelt population) in the lake and ultimately, severely impacting this major recreational fishery.

CHARACTERISTICS

The desired and realistic characteristics of the Garrison Reach of the Missouri River necessary to maintain the existing fishery and aesthetic component include:

1. Braided channels in 60 percent of the river.

2. In at least one year out of four, sustained flows >28,000 but <40,000 cfs in April, May, and June sufficient to create and/or scour sandbars for terns and plovers.

3. Flows of 14,000-28,000 cfs from June through August 15 that expose sandbars three years out of four for nesting and brood rearing of shorebirds and waterfowl.

4. Numerous backwater areas, including riverine wetlands, for fish spawning and rearing that maintain their connections to the river at flows of 14,000 cfs or greater.

5. Natural tributary flows that allow for unrestricted fish passage to spawning and rearing areas.

6. A dynamic channel that is allowed to move laterally, through erosion and accretion, rather than vertically which could be a cumulative result of riprapping and channelization.

7. Protection and restoration of flood plain woodlands and wetlands which sustain the river's values.

8. Land management practices which minimize pollution/pesticide inputs.

ISSUES/OBJECTIVES

Issues and corresponding objectives that relate to the management and operations of the Garrison Reach of the Missouri River include the following:

1. Flow Regime

In order to maximize recreational, aesthetic, and fish and wildlife benefits, a planned flow regime should range from a low of 14,000 cfs to a high of 40,000 cfs representing a river stage ranging from 4.5 to 11.5 feet at Bismarck. Predictable seasonal flows, including timely adjustments needed to manage for various authorized purposes, should be a desired goal. Daily minimum and maximum flows necessary to deal with emergency situations should under no circumstance fall below 10,000 cfs or rise above 60,000 cfs and must honestly reflect the severity of the emergency. Unfortunately, to date, the flow regime has often been exclusively driven by downstream needs, such as barge traffic and flood control, usually to the detriment of upstream values.

2. Fish Management

Fish management is dependent upon regulations, access, stocking, water management (i.e., flow regimes), and habitat protection/enhancement. The current Garrison Reach walleye fishery is one of the best in the nation. Northern pike, trout, white bass, smallmouth bass, and channel catfish are also important constituents of the recreational fishery. The flow regime and other parameters must be sensitive to fishery management whenever possible. An example would be the recognition of Lake Oahe's elevation as an important and integral part of the fishery (e,.g. spawning and rearing habitat) in the Garrison Reach. Low flows into Lake Oahe reducing lake pool elevations, allow for establishment of terrestrial vegetation. This should be followed in subsequent years with a rise that inundates approximately three vertical feet of vegetation in Lake Oahe during the spring of the year by April 15. The timing and duration of the rise needs to include backwater areas and provide adequate access for fish passage into and out of the areas. This cycle should be reflected in the COE Annual Operating Plan and occur approximately once every three to four years.

3. Bank Stabilization

Approximately 25 percent of the Garrison Reach has been directly affected by revetments, jetties, riprap, car bodies, tires, sheet/wood pilings, or channelization. The purpose of bank stabilization is to reduce lateral erosion. Although small amounts of stabilization probably cannot be avoided in the future, it must be understood that the cumulative consequence should not degrade the existing habitat. Additionally, the river hydrologically searches out a sediment load. If the river can't recover some of the sediment from the horizontal plane in the form of bank erosion, it will likely take it vertically from the river bottom. According to recent COE estimates, the bed of the river channel has been lowered three to four feet as far as 50 miles downstream of the dam. If river bed degradation continues, sandbar formation may be reduced, braided channels may become fewer, connections to backwater areas will be lost, and diverse habitat types for fish and wildlife would be diminished.

River meandering, including both erosion and accretion, is a natural process that is vital in both the creation and maintenance of a healthy river ecosystem. To prevent this process from occurring risks losing the very characteristics of the river that make people want to live in its proximity. In addition, a $20 million annual water-based recreational industry based primarily on fishing has developed along the Garrison Reach of the Missouri River and upper Lake Oahe. In certain areas of the Garrison Reach, more than two tons of walleye are harvested annually per river mile. If allowed to continue, bank stabilization will likely reduce the remaining spawning and rearing habitat for the river's fishery thus causing the loss of this important state and regional fishing industry.

The economic cost of traditional riverbank protection (riprapping) for agricultural land appears far in excess of the value of the land being lost. According to current COE data, 1,100 acres of shoreline will be lost to erosion in the next 50 years at a present day cost of $274,000. In contrast, bank stabilization of river property would cost approximately $600,000 to $1 million dollars per mile. Sloughing easements, conservation easements adjacent to the river, or acquisition in fee title would appear to be viable alternatives to riprapping, all likely less expensive and much more environmentally friendly, especially for agricultural lands. In the case of residential lots and homes, all government entities (city, county, state, and federal) share responsibility for informing the public that if they build on the flood plain public tax dollars may no longer cover damages which will inevitably occur. While the government cannot prevent homeowners from protecting their personal property using their own resources on their own land, none of us can avoid the public policy dilemma inherent in this issue (i.e., accepting the risks associated with living along the river).

We must accurately determine the cumulative impacts of bank stabilization. Not doing so may cause the Garrison Reach of the Missouri River to become a biologically unproductive, channelized river environment such as that found south of Sioux City, Iowa. Bank stabilization will likely continue to occur at some level, but cumulative impacts must be addressed with the goal of maintaining the integrity of the system. We suggest those with the expertise in hydrology and river morphology address this issue at once! It would be irresponsible to acquiesce to measures which may destroy the very system we use, live next to, and manage in trust for the citizens of North Dakota. Unless an appropriate plan of action based on sound engineering and scientific analysis is formulated, publicly funded stabilization on private lands should not occur.

4. Threatened and Endangered Species

Four federally listed species are present in the Garrison Reach: piping plover, least tern, bald eagle, and pallid sturgeon. Terns and plovers can generally be accommodated by flow regime planning that involves elevated spring flows to create, scour, and maintain sandbars followed by steadily declining and/or lower stable river elevations beginning between June 1 and June 15 through the end of August in four to six years out of ten. Raising river levels after nest initiation should be avoided. Terns and plovers could also be accommodated in years of extremely high flow by habitat development and manipulation including island construction and artificial scouring of existing high elevation islands.

In the Garrison Dam to Oahe Reservoir Reach, the fate of the pallid sturgeon is not very promising. There are fewer reports of pallid sturgeon in the Garrison Reach each year (some years there are none) and it is likely that few of these ancient fish remain. Even reintroduction might prove useless, because essentially no pallid sturgeon habitat, especially for spawning, remains between Garrison and Oahe Dams. Other than for experimental scientific studies, recovery emphasis should be placed in other areas (e.g., Yellowstone River) where efforts will have a higher probability of success.

5. Habitat Enhancement

A tremendous amount of aquatic and flood plain habitat has been lost due to dam construction. Restoration and enhancement of degraded habitat will require involvement and cooperation of several federal and state agencies. The COE, as the lead agency for operation and management of the river, should provide leadership in reversing the trend of habitat deterioration. For example, backwater areas that could be flooded should be identified. These areas can provide spawning and rearing areas for fish, feeding areas for terns and plovers, and habitat for waterfowl and other water birds. In addition, plans should be developed with the COE for island development and habitat manipulation on existing islands to benefit terns and plovers as previously referenced.

Many of the COE's existing bank stabilization structures in this reach were overbuilt and were designed using "river training" engineering standards. A number of existing jetties have been identified by biologists as candidates for notching in order to open up silted side channels. Simple modifications to these and other COE structures could enhance aquatic habitat while maintaining the integrity and original purpose of the structures.

The riparian corridor is in need of protection or enhancement by obtaining conservation easements adjacent to the river or acquisition in fee title. Perhaps some of these areas could have portions of old growth cottonwood forest cleared and wetted (possibly through irrigation) for one year to promote new growth. Another approach could be to allow for climax vegetation consisting of an ash-box elder forest community to develop which would provide significant natural resource values.

6. Development

Commercial and residential development and associated impacts are increasing along the entire Reach, with the highest activity in the Bismarck-Mandan area. This development dramatically increases demand for bank stabilization. Game and Fish estimates based on ground truthing and aerial photographs indicate over 40 percent of the shoreline (wetted perimeter) has been directly stabilized in the Bismarck-Mandan area. Maximum protection of the river ecosystem would call for no further development along the river. This is unrealistic as private land development will continue to occur at a steady or increasing rate. If the river becomes lined with homes and the bank(s) stabilized with riprap, then the very factors which made the area desirable for development may well be destroyed in the process.

The issue of residential development adjacent to the river will remain problematic until a master management plan is completed (not to be confused with the COE's Master Manual for operating mainstem dams) which addresses the cumulative effects of bank stabilization, river access needs, and related impacts created by human demand including restrictions to operational flexibility. At the very least (as stated in #3, page 8), those with the expertise in hydrology and river morphology should address this issue prior to large scale stabilization. The longer we wait, the greater the hazards become.

CONCLUSION

The Garrison Reach of the Missouri River is an important resource for all North Dakotans. It's history, value to adjacent residents, recreational attributes, and natural resources mandate responsible stewardship for today's and future North Dakota citizens. Addressing the issues that may threaten these values in an objective and sensible manner is in the best interest of all those who use and care for the Missouri River, including both government and the public. For us to do otherwise would be irresponsible and a breach of our public trust responsibility.

For more information on this paper, contact:

Greg Power, central fisheries district supervisor, 701-328-6323
Terry Steinwand, fisheries chief, at 701-328-6313
or write the North Dakota Game and Fish Department, 100 N. Bismarck Expressway, Bismarck, ND 58501-5095.

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