HUNTLEY—The Yellowstone River will soon have a study worthy of its stature.
A summary of the study, still in draft form, was delivered at a public meeting in Huntley on Wednesday night, and the final report is scheduled to be released during a two-day conference in Billings next March.
The comprehensive study—it comes in at 400 pages, with 1,800 pages of appendices—began in 2004 and aimed to determine exactly how human activity has changed the 670-mile river, and what voluntary practices could best ensure its future health.
“This has not been done before in the history of the world,” said Don Youngbauer, chairman of the Yellowstone River Conservation District Council, which teamed up with the U.S. Army Corps of Engineers to conduct the study.
A handful of experts, addressing an audience of about 35 people at the Yellowstone Valley Electric Cooperative in Huntley on Wednesday, talked about floodplain losses, changing river flows, the effects of riverbank “armoring,” channel migration and more.
Though the Yellowstone’s distinction is that it is the longest free-flowing river in the lower 48 states, “free-flowing” refers only to the absence of dams. There are countless diversion dams, weirs, jetties and dikes that change flow patterns on the river, and an astounding 136 miles of Yellowstone riverbank are armored with riprap.
Riprap, which is placed on banks to prevent erosion and protect farm fields, housing developments, roads, bridges, railroad lines and more, is mostly made of rock, but also of concrete and other materials, including, at various stretches up and down the river, old car bodies.
“The Yellowstone is a wild and wooly river, but not like it used to be,” said Karin Boyd, a geomorphologist who served on the study group’s technical advisory committee.
The study had its origins in the back-to-back flood years of 1996 and 1997. Six environmental groups filed a lawsuit in 1999, contending that the Corps of Engineers had allowed a doubling of bank stabilization permits (for riprapping) on the Yellowstone between 1995 and 1997, as compared to the preceding 12 years.
The lawsuit said the corps issued the permits without understanding the cumulative effects on the river all of those projects. A federal judge ruled against the corps, and Congress subsequently authorized the corps to conduct the Yellowstone River Corridor Comprehensive Study. The study was to determine the cumulative hydrologic, biological and socioeconomic impacts of human activity on the river.
The corps entered into a cost-sharing agreement with the Yellowstone River Conservation District Council in 2004. They also agreed on a scientific project known as the Cumulative Effects Analysis, to provide a basis for any recommended management practices on the river.
The federal government paid for 75 percent of the cost of the study, with the state of Montana and private organizations providing the other 25 percent.
As Boyd explained Wednesday, one of the most significant impacts on the undammed Yellowstone is the influence of the heavily dammed Bighorn River. That river and a major tributary, the Shoshone, are dammed upstream—near Cody and Thermopolis, Wyo.—and in Montana by the Yellowtail Dam near Fort Smith.
The Bighorn River watershed, most of which is in Wyoming, covers almost 23,000 square miles, or one third as much as the entire Yellowstone River watershed. The Bighorn Reservoir behind the Yellowtail Dam has 1.3 million acre-feet of storage.
Because summer flows in the Bighorn are greatly decreased to fill the reservoir, the Yellowstone River has seen substantial reductions of flow downstream of the Bighorn. At Miles City, summer flows have been reduced 48 percent—from an average of 6,200 cfs when the river was undeveloped to 3,200 cfs now.
Another major impact is the withdrawal of water by irrigators, which totaled 3.3 million acre-feet in 2000, or 94 percent of all water withdrawals on the river. However, and this is a big however, only 660,340 acre-feet were actually used by irrigators. All the rest of the withdrawn water eventually made its way back into the river.
Meanwhile, the river has been forced into a narrower channel over the decades, and sizable amounts of floodplain and side channels have been lost to human activity. In the 477 miles between Springdale and the confluence of the Yellowstone with the Missouri River just over the North Dakota state line, 21,000 acres of floodplain are no longer inundated during what is known as a 100-year flood.
This results from decreased flows and the presence of agricultural dikes, levees and railroad berms. Aerial photographs show that most of the city of Forsyth would have been under water in a 100-year flood before protective levees were built. To a greater or lesser degree, Boyd said, the same is true of towns like Livingston, Miles City and Glendive.
As for bank armor, Boyd said, the heaviest concentration of it is between Laurel and Billings, a stretch of river on which fully half the banks are sheathed in riprap.
Another member of the technical committee, Tom Pick, talked about changes to the riparian areas of the river, basically the riverbanks and the wetlands adjoining the river. Pick, a water quality specialist for the federal Natural Resources Conservation Service, said about 20,000 acres of riparian areas were lost because of channel migration between 1950 and 2001.
At the same time, riparian areas on the Yellowstone have become more “simplified,” in terms of loss of diversity and the rise of monoculture. That refers to the spread of invasive species like Russian olive and salt cedar, which crowd out native species like the cottonwood.
Changes to water quality have mainly resulted from increases in nutrients like nitrogen, runoff and discharges from agriculture and industrial uses, pollutant spills (think pipeline breaks) and changes in land use. It may seem odd, Pick said, but the biggest source of phosphorous found in the river is channel erosion, which releases naturally occurring phosphorous.
Turning to fisheries, Pick said the Yellowstone is home to 56 species, more than any other river in Montana. Fish populations are affected by hydrology changes, riprapping, introduced species and other human activity, he said, but it is very difficult to determine changes to the river’s fish population.
Birds are threatened by similar activities, especially those that cause declines in cottonwood stands. All in all, he said, the Yellowstone is still fairly healthy and biologically diverse, but “it’s the rate of change and the dramatic nature of change” that will continue to matter a great deal.
A summary of recommended practices was presented by Warren Kellogg, chairman of the technical committee and a retired watershed specialist for the Natural Resources Conservation Service. Kellogg emphasized that all the recommendations are for voluntary action on the part of landowners and water users.
Recommendations include restoring floodplains, in both agricultural and urban areas, removing side-channel dikes and other blockages where they are no longer needed and producing new floodplain maps to encourage development outside the floodplain.
Another recommendation is to keep any new riprap outside the floodplain, also known as the “channel migration zone,” and to create guidelines for what kind of riprap to use where. Flow deflectors like weirs and jetties, which project out into the river from a bank, but which are frequently ineffective and create a need for further armoring, should be discontinued, according to the recommendations.
Other recommendations call for removing old dumps from the riverbanks, encouraging more efficient irrigation management, and preserving healthy riparian areas by, among other things, improving livestock management and eradicating invasive weeds.
The presentation was followed by a relatively short question-and-answer session. One woman who said she has an agricultural operation on the Yellowstone said she was wary of the study’s emphasis.
“I’m a conservationist, but agriculture comes first,” she said. “For once in our state, let’s make agriculture a priority.”
Youngbauer, a rancher himself, told her that the study is needed to preserve things like agricultural water use.
“If we don’t have good baseline data,” he said, “it’ll be very difficult to defend our water rights.”
Boyd said the study, and the cooperation it encourages, will be very useful when it comes time to seek funding to accomplish some of the goals laid out in the study. She said she, Kellogg and Pick all helped the Musselshell Water Coalition obtain funding for numerous successful projects on the Musselshell River, and funding agencies need to know that there is widespread support for such projects.
“This study gives you credibility in Helena,” she said.
Youngbauer said the best thing about working to promote a healthy Yellowstone River is the amount of pre-existing support.
“When you stand up and say you’re a friend of the Yellowstone River, you don’t have many enemies, worldwide,” he said.
How to weigh in
A final meeting on the draft plan is set for Thursday night in Glendive. The meeting will start at 7 in the community Room of Glendive Alliance Church, 105 Highland Park Road.
The draft report is available for viewing on the Army Corps of Engineers’ website or on the Yellowstone River Conservation District Council’s website. Hard copies are also available at county conservation district offices along the Yellowstone.
Written comments on the plan should be sent to: U.S. Army Corps of Engineers Omaha District ATTN: CENWO-PM-AA, Yellowstone Corridor Study CEA; 1616 Capitol Avenue; Omaha, NE 68102. Comments can also be emailed to: email@example.com. Comments must be postmarked or received no later than Nov. 6.