HISTORY OF CORPS ACTIVITIES IN DEVILS LAKE
The Corps of Engineers investigated primarily agricultural flooding problems in the Devils Lake area in the 1960's and early 1970's and again in 1980. Also in the early 1980's the Corps began to develop a flood protection plan for the City of Devils Lake. This study culminated in the construction of the levee system in 1986 to protect the City.
A study in the late 1980's focused on broader flooding problems in the Devils Lake region and looked at different solutions, including an outlet to the Sheyenne River. This study highlighted the difficulty of predicting whether the lake will rise or fall. These are the same concerns facing us today.
In 1993 the Corps and the North Dakota State Water Commission began a cost shared feasibility study to develop plans to stabilize Devils Lake. While the feasibility study is continuing in parallel with our emergency activities, many of the feasibility activities related to an outlet to the Sheyenne River are under way now as part of our design efforts that I will speak to in a moment.
However, during this same time period, the region began to experience dramatic rises in the lake levels. Federal, state and local efforts quickly focused on a response to the flooding situation. The Corps provided assistance under the Corps emergency authority. These activities included technical assistance, protection of sewage lagoons and lift stations and emergency equipment and supplies. Preparations were also started to raise the levee protecting the City of Devils Lake. Unfortunately, Federal, state and local response efforts are handicapped by the difficulty in forecasting future lake levels.
We are continuing to provide emergency assistance and are working with the City of Devils Lake and other local interests to raise the levee system in anticipation of additional lake rises. We have been adapting our designs and construction methods to allow for future raises. Even now, we have undertaken an additional two foot raise to help ensure the protection of the City next spring. Our designs are taking in to account the special nature of the Devils Lake area and the likelihood that water will be high for several years. We have adopted an incremental raise approach to be sure that we can continue to provide protection for the City but also to husband the state, local and Federal governments' resources. We want to make sure that we do what we need to do to protect the City.
In the summer of 1995, with the lake levels having risen over thirteen feet in a four year period, at the request of the North Dakota delegation, the Corps developed a Contingency Plan which identified a wide range of possible actions, their likely cost and performance and the responsible agency for implementing them. The measures discussed in the report included: outlets to the Sheyenne River and Stump Lake; upper basin storage; raising the levee protecting the City of Devils Lake; flood insurance; evacuation of the floodplain and relocations; other levees; road raises; and infrastructure protection. This report was released in February 1996 and complemented the efforts of the Interagency Task Force chaired by the Federal Emergency Management Agency. It focused attention not only on the complexity of the problem but most importantly that many different measures would be needed to provide flood relief. Many of these measures, such as providing upper basin storage, relocation of structures, and road raising have already been implemented by other Federal, state and local agencies. The Corps on-going feasibility study, currently scheduled for completion in September 2000, considers these and other measures to develop comprehensive plans that are flexible enough to address the great uncertainty in future conditions.
In 1996 when the lake was forecast to continue to rise, the Corps used information from earlier studies, the on-going feasibility study and judgement, to develop a conceptual emergency outlet plan. This plan provided information on the impacts and performance of an outlet from Devils Lake to the Sheyenne River. Following the release of that report in August 1996, the Corps and the North Dakota State Water Commission held over a dozen public meetings in the Devils Lake basin, with the Spirit Lake Nation, Minnesota officials and others throughout the region to discuss the outlet and its' performance and impacts. The Corps is now undertaking the detailed design of an outlet, as directed in the Emergency Supplemental Appropriations Act of 1997 (P.L. 105-18), and we have issued a Notice of Intent to prepare an Environmental Impact Statement. The Energy and Water Development Appropriations Act, 1998, authorizes and provides $5 Million of funding to initiate construction of an emergency outlet at Devils Lake. These specific funds are available after the Secretary of the Army reports to the Congress that an emergency exists and that the construction is technically sound, economically justified, and environmentally acceptable; and provided that the Secretary of State, after consultation with the International Joint Commission, reports that the project will not violate the requirement& or intent of the 1909 US-Canada Boundary Waters Treaty.
Although an outlet route was tentatively identified during the preparation of the 1996 Outlet Plan, additional route selection efforts were undertaken to address concerns raised by the Spirit Lake Nation. These efforts resulted in a route change that has been agreed upon by the Spirit Lake Nation and the State of North Dakota. As a result of the route change and ongoing design efforts for the pumping station, we would expect some increase in the total discharge from the Devils Lake basin into the Sheyenne River over that identified in 1996 conceptual plan. The changed route and its related design are expected to lessen environmental impacts of the outlet.
As detailed in Mr. Armstrong's statement, the Corps and numerous other Federal agencies have been heavily involved in providing assistance to the state and the local communities during the most recent flooding. I believe these actions reflect the recognition of the serious problem faced by the people of the Devils Lake basin as well as the wide range of measures that are required to deal with this complex problem. The uncertainty that we face in dealing with a closed lake basin requires us to adopt a stance that allows the local, state and Federal governments to make wise use of their resources while continuing to provide assistance.
CORPS PLANS FOR THE FUTURE
My previous remarks illustrate the Corps efforts to adapt to the changing conditions and to continue to provide support and assistance to the region. Now, as we are in the fifth year of record rises, we must turn our attention to the future and the decisions that will be facing us. We don't know Nature's time line that might cause the lakes to spill over into the Sheyenne River and thus it is exceedingly difficult to time the implementation of any flood mitigation measures.
Forecasting the long term lake levels in a closed basin (Figure l) is much more difficult than forecasting the probability of floods in our free flowing rivers and lakes. Flood events on rivers are generally independent events resulting from storms or yearly snowmelt. Devils Lake flooding is dependent upon the previous year's lake level and is related to long term climatological cycles, which makes it much more difficult to forecast. We worked closely with the United States Geological Survey and other agencies in 1994 to improve our ability to forecast lake levels and to attempt to quantify the uncertainty and assess the risk of future lake level increases. To further enhance these efforts, we have finalized an agreement with the University of North Dakota's Energy and Environmental Research Center to work with the Corps to examine the potential of new findings about climate variability in order to improve forecasts for future lake levels. The Corps St. Paul District and Institute for Water Resources will use this information to develop a state of the art decision model. This model will assist decision makers on the critical and exceedingly difficult choices on future actions for dealing with the flooding from Devils Lake. The model will allow us to consider different assumptions about likely future inflows into the lake, test possible solutions to see if they can provide relief, and determine which alternatives work best in such an uncertain situation. This work, conducted in close collaboration with affected groups, will produce decision support tools, forecasts, data and forums that can continue to be used by the Corps, the states of North Dakota and Minnesota, the International Joint Commission, and the people of the Devils Lake region.
We are faced with making further decisions to expend additional amounts of Federal and local funds if the lake continues to rise. More importantly, we are faced with significant impacts to peoples' lives if we don't take the proper actions or if we take the wrong ones. In order to understand the implications of taking various actions, I would like to explain in broad terms the climatic and hydrologic uncertainties that face us.
We do not know what elevations to expect on Devils Lake for next year nor the next several years. We know that it has exhibited great variability over both geologic time (Figure 2) and recorded history (Figure 3). From 1950 to the present, almost a third of the total inflow to Devils Lake has occurred in the last five years. Such a series of large inflows translates to dramatic rises in lake levels. Yearly inflows and corresponding maximum lake elevation and surface area are shown in the table below starting with the 1993 low point of 1422.7 feet, mean sea level (msl).
|YEAR||ESTIMATED ANNUAL INFLOW (acre-feet)||MAXIMUM LAKE ELEVATION (msl)||CHANGE IN LAKE ELEVATION (ft)||LAKE SURFACE AREA (acres)||CHANGE IN LAKE SURFACE AREA (acres)|
|1993||296,000||1427.8 (min 1422.7)||56,600 (47,000)|
|1997||420,000 (thru Sept)||1443||5.2||97,500||17,500|
The lake is currently at 1442.5 feet, msl and is forecast to reach about 1443 feet, msl by winter freeze-up. The volume of Devils Lake at 1443 feet, msl is approximately 1,958,000 acre- feet and covers nearly 100,000 acres. Figure 4 shows a cross-section through the basin and the key elevations linking Devils Lake to the Stump Lakes and then to the Sheyenne River. At the average annual rate of inflow we have seen into the lake over the last five years, it could take about a year to rise to the elevation of the divide between Devils Lake and the Stump Lakes. At this same average inflow, it would take about two years to fill the Stump Lakes to the same elevation as Devils Lake. It would then take about six more years to fill the combined Devils lake and Stump Lakes to elevation 1457 feet, msl, which is where the lake would naturally begin to flow into the Sheyenne River. But we don't know what next year's inflow will be.
There has been concern over the possible environmental impacts of an overflow of the natural divide between the Devils Lake basin and the Sheyenne River. There is a risk of an overflow of the divide which would be several years away even under the continued high inflow conditions I described above. The impacts of such a non-catastrophic overflow would include: erosion and subsequent deposition of sediments in the Sheyenne River; long term inundation of wetlands along the Sheyenne River which could reduce their productivity depending on the duration of their inundation; and higher levels of dissolved solids in the Sheyeune River, that would likely have some effect on the ecosystem but the scope of which is unknown at this time. There is also a danger of contaminating water supplies along the river. Higher treatment costs would occur and alternate sources of water might be necessary for those with special health considerations.
The amount of inflow into Devils Lake is highly variable as shown in Figure 5. We have plans in place to continue to protect the City but the remaining areas adjacent to the lake would continue to be vulnerable. There is some time to consider options before there is a danger of an overflow to the Sheyenne River although damages will continue to occur. The additional information from the work by the University of North Dakota and the Corps offices will be very important in making our future decisions.
Much has been made about an outlet from Devils Lake to the Sheyenne River. A major concern expressed is the salinity (measured as total dissolved solids) of the water in Devils Lake and the Stump Lakes. Current salinity levels vary from about 900 mg/l in the west to nearly 15,000 mg/l in east, as illustrated in Figure 4. By comparison, sea water is usually 35,000 mg/l. These salinities are very dependent upon the level of the lakes and are much higher as the lake levels drop. In 1961, the salinity in East Stump Lake was over 240,000 mg/l or nearly seven times as salty as seawater. Setting aside the environmental, social, and international concerns, let us consider the hydraulic aspects of an outlet. Right now the Corps is working on the design of a pumping system that could move 300 cubic feet per second (cfs). This would amount to almost 200 MGD, which is two thirds more than the average daily use in Washington, D.C. However, based upon the Corps 1996 Outlet Plan simulations, the amount that could be pumped would be much less because of conditions on the Sheyenne and Red Rivers. These limits are both in terms of channel capacity, so that flooding is not induced on those rivers, and the need to meet state water quality standards. An outlet is not a simple solution, nor one guaranteed to work. If very high inflows to the lake continue, a spillway may be a necessary action given the volume of water that may flow naturally to the Sheyenne River.
Along with the North Dakota State Water Commission, we are continuing our feasibility study to develop and evaluate an array of measures to reduce the flood damages in the region in the event the lake continues to rise. From all our earlier studies, it is clear that one component of any comprehensive plan will be an outlet. We are continuing our design efforts for an outlet as directed by the Congress.
In summary, the rising level of Devils Lake has had a serious impact on the region. A great many resources from the Federal, state, and local governments have been committed to address these flooding problems. Future lake levels are unknown but we have studies underway to try to reduce the uncertainty of our forecasts and improve our decision making. We have construction, design, and study efforts underway to address expected problems and insure that we are poised to respond quickly to changes. We are ready to provide needed assistance while being mindful of our responsibilities to the environment and of the impacts to the Federal taxpayers.
Thank you and I will be happy to answer any questions.