Flow Of The Future

The Corps has implemented drought conservation measures while retaining flood control as a priority, said Jody Farhat, chief of the basin’s Water Management Division in Omaha.

“Flood control remains a primary consideration as we move into 2013, despite the concerns about the impacts of the drought on the basin’s resources, due to the potential for flooding caused by localized thunderstorms,” Farhat said.

For now, drought conditions appear to remain the norm for parts of the Great Plains. Southeast South Dakota and northeast Nebraska have experienced exceptional drought, the most severe category.

Dry conditions continue in the upper basin, indicating less-than-normal runoff in 2013. Runoff above Sioux City is forecast to be 20.5 million acre feet, or 81 percent of normal. Runoff for the month of March was 55 percent of normal.

The total volume of water stored in the mainstem reservoir system on April 1 was 48.8 million acre-feet.

“(The Missouri River) system storage is 8 million acre feet below the top of the Carryover Multiple Use Zone in the system,” Farhat said. “That zone is designed to provide service to the eight congressionally authorized purposes, though at reduced levels, through a 12-year drought like that of the 1930s and early 1940s.”

The current falling river levels and the prospects of continued dry conditions has triggered the Corps’ actions, Farhat said.

“Drought conservation measures, such as minimum winter releases and reduced flow support for navigation, are implemented as the volume of water in the reservoir system declines,” she said.

In mid-March, the Corps increased releases out of Gavins Point Dam from 14,000 cubic feet per second (cfs) to 25,000 cfs. The action was taken in support of the navigation season which began April 1 near St. Louis.

The drought has had one measurable impact — a drop in hydropower production. The six mainstem power plants generated 612 million kilowatt hours (kWh) of electricity in March. Typical energy generation for the month of March is 639 million kWh.

The power plants are projected to generate 8.2 billion kWh of electricity this year, compared to the normal of 10 billion kWh.

While much of the Great Plains continues to experience drought, the Corps has not forgotten about the flooding that caused millions of dollars in damage during 2011.

“We will continue to monitor mountain snowpack, rainfall runoff and basin soil conditions to fine tune the regulation of the reservoir system based on the most up-to-date information,” Farhat said.

Mountain snowpack is currently 90 percent of normal in the reach above Fort Peck and 84 percent in the reach between Fort Peck and Garrison. Typically, 97 percent of the peak mountain snowpack accumulation has occurred by April 1.

“The lower-than-normal mountain snowpack indicates we are likely to see below-normal runoff during the months of May, June and July,” Farhat said.

“But it’s still early. As we learned over the last two years, conditions on the ground can change very quickly, so we will continue monitoring basin conditions and make any necessary release adjustments as the spring unfolds.”

Feeling Sedimental

While the Corps deals with changing river levels, two organizations have stepped up their concerns about growing Missouri River sedimentation.

The Missouri Sedimentation Action Coalition (MSAC) will host its annual membership meeting at 5:30 p.m. April 24 at the Riverfront Event Center in downtown Yankton. Tim Cowman, director of the Missouri River Institute (MRI) in Vermillion, will deliver a presentation on the growing sediment problem.

Cowman’s presentation will show the rapidly growing threat of sediment to Lewis and Clark Lake, said MSAC executive director Sandy Stockholm of Springfield.

“It’s hard to imagine the lake 25, 50 or 100 years from now,” she said. “The MRI has developed an illustration and materials to give people a more visual picture of what Lewis and Clark Lake will look like if we don’t address     sediment.”

Currently, the Missouri River reservoirs lose 89,700 acre-feet annually of storage, Stockholm said. That’s the equivalent of 10 square miles of mud, 14 feet deep, she said.

Many people find it difficult to grasp the growing encroachment of sediment, and Cowman’s presentation offers a new dimension, Stockholm said.

“A picture is worth a thousand words. This is a picture of what has happened in Springfield and Niobrara, and the sediment is very visibly progressing to Gavins Point Dam,” she said.

“We expect Lewis and Clark Lake will be 50 percent full of sediment by 2045. Already, it has seen a storage loss of 30 percent. We don’t want it to get worse.”

Additional sediment findings are offered by Mark Sweeney, an associate professor in the Department of Earth Sciences at the University of South Dakota in Vermillion. Sweeney has given presentations and posted his findings online.

“The deposition of sediment has formed a delta in the Niobrara, Neb., and Springfield areas that is encroaching into Lewis and Clark Lake,” he said. “The deposition of this sediment has both negative and positive effects, including rising water tables, localized flooding and increased wetland habitat, among others.

“Ultimately, the reservoir is filled with sediment affecting hydroelectric power generation, recreation and local infrastructure.”

The Corps of Engineers reports that 2,625 acre-feet of sediment is accumulating in the reservoir per year, Sweeney said. This volume of sediment is approximately equivalent to 5.1 million tons, using the Corps’ estimate of 90 pounds per cubic foot, he said.

The sources of sediment entering the lake include the Missouri River, bank erosion at Lewis and Clark Lake, and several tributaries of the Missouri River, Sweeney said. Those tributaries include the Niobrara River, Ponca Creek, Bazile Creek, Choteau Creek and Emanuel Creek, he said.

“The largest of these sources is the Niobrara River, a sandy bed river transporting sediments from the Sand Hills of Nebraska,” he added.

The larger reservoirs will take more time to fill, but the negative impacts are already being experienced, Stockholm said.

“We lose storage of enough water each year to supply more than 800,000 people with 100 gallons per day for an entire year,” she said. “We already have lost enough space to store a flood equivalent to 100 miles long, 10 miles wide, with an average depth of 7 1/2 feet.”

The 2011 flooding showed the importance of water storage capacity, Stockholm said.

“Flooding caused by inflow from tributaries below Gavins Point Dam would have been much worse if the Missouri River dams would not have been able to hold and store runoff water from within and above the system,” she said.

Developing A Plan

MSAC doesn’t see sediment as a totally bad thing, Stockholm said. Sediment is needed downstream of the Missouri River dams for a variety of reasons, including sandbar habitat for threatened and endangered species, she said.

However, MSAC supports reducing the amount of sediment entering the system through sound land management, Stockholm said. Her group also supports managing and removing sediment from the reservoirs in order to sustain the valuable benefits created by the Missouri River reservoir system.

“Sediment isn’t going away. We’re continuing to address and maintain the integrity of the Missouri River in order to maintain the system,” she said.

“If we decrease the sediment coming into the system, it keeps the storage capacity alive in the reservoir. It also keeps out the pollutants with the extra sediment. Wildlife also benefits as part of the living system.”

MSAC considers itself an educational group rather than a political or lobbying organization, Stockholm said. MSAC also seeks to build partnerships for working on public awareness and projects.

“MSAC is a coalition of members up and down the river, so we look at the system as a whole. We don’t focus solely on problems in one area,” she said. “MSAC is concentrating on long-term solutions to sustain the system. We are looking for ideas and specific projects to latch onto.”

However, funding — particularly at the federal level — remains an issue, Stockholm said. That will ring even truer in the face of the federal sequester and future budget cuts.

“We need funding to operate locally and regionally. But there are big sediment projects where it will take federal involvement,” she said.

However, the stakes are too high when it comes to water and can’t be measures in dollars and cents, Stockholm said.

“You get a glimpse of how precious and valuable that water is, when you look at the price of finding and maintaining a clean water supply, especially in the Western states,” she said.

The impact of controlling sediment will be felt far from the Missouri River, Stockholm predicted.

“There are a whole host of communities that aren’t right next to the river but who derive its benefits,” she said. “You look at drinking water, flood control and hydropower. To know the river’s importance, you just need to turn on a faucet or light switch hundreds of miles away.”

You can follow Randy Dockendorf on Twitter at twitter.com/RDockendorf