- Associated Press - Saturday, July 1, 2017

COLEHARBOR, N.D. (AP) - Steve Knorr is absolutely sure he’ll get 24 inches of water on his crops this year.

It’s expensive water, but in an area under extreme drought, he can look out over brilliant fields of green into a cash-flow scenario at the other end.

“Without it, I wouldn’t have a crop,” he told The Bismarck Tribune (https://bit.ly/2sR0VbU ).

Knorr draws that precious water from a pump station on the McClusky Canal into a network of underground pipes and 37 pivot systems that sprinkle fresh water across his nearly 4,000 acres between Coleharbor and Turtle Lake.

The relatively poor ground wouldn’t produce much without the water even in the best of years. Because of it, he can count on twice the yield and income to pay down a $2,000-per-acre investment in addition to water and electric fees.

He has millions invested, each dollar a reason to be concerned about an emerging plan by the U.S. Army Corps of Engineers that could imperil his access to canal water during an extreme drought, just when he needs it most.

What’s afoot is the corps‘ decision to create a first-time plan to protect the dam works’ infrastructure that separates the enormous Lake Sakakawea from its smaller sidekick, Lake Audubon, in a drought scenario.

The two waters are the same, only cleaved by the Snake Creek Embankment that holds the pumping station that sends water from the big lake to the smaller one. The embankment is a critical causeway that carries four lanes of Highway 83 on its surface, the Canadian Pacific rail and mammoth steel towers that bear electric transmission wires across the water.

The problem the corps hopes to forestall is what could happen when Lake Sakakawea drops extremely low in a drought while Lake Audubon remains at its standard operating pool. All that pressure on one side of the embankment unanswered from the other side could lead to embankment failure, said Matt Nelson, an engineer from the corps‘ water control section.

Nelson said this isn’t guesswork.

Back in 2005 - in hindsight a year that doesn’t seem particularly remarkable for being dry - Lake Sakakawea dropped to an elevation of 1,806 feet. Meanwhile, on the other side of the embankment, Lake Audubon clocked in at its usual 1,847-foot elevation, the level that’s maintained every summer, all summer to provide water out its rear door into the 73.6-mile McClusky Canal. That 41-foot difference in elevation from one side to the other was the biggest swing in the lake’s history.

Nelson said the low water did allow the corps to observe the performance of 13 relief wells - installed at the time of construction on the Lake Sakakawea side in the ‘50s precisely to relieve that unequal water pressure. What they observed wasn’t good.

“We could see the relief wells weren’t flowing like they should. Some were blocked with sediment, and others just had very low flow,” Nelson said.

Conversely, pressure gauges inside the embankment had readings of significantly higher hydrostatic pressure than the corps wanted to see.

“That’s what pushed us to move on this,” he said.

A primary concern is that, without the relief wells, a seam of original gravel below and under both lakes could blow out.

In response, the corps proposes to set 43 feet as the largest differential that can be tolerated. At that point, it will start assessing whether to back-flow water out of Lake Audubon into Lake Sakakawea.

“It’s not a set-in-stone number. If the embankment is performing well under that severe loading, we could go to a higher number or it could go the other way,” Nelson said.

A 43-foot difference has never occurred in dam operation history, but that doesn’t mean it never will, Nelson said.

Duane DeKrey directs the Garrison Diversion Unit, the state entity that manages the McClusky Canal complex. It’s his job to worry about what would happen if Lake Audubon were drawn down too far to supply the canal.

He’s frustrated on two levels: First, that the corps is only now realizing 70 years after construction that its original design is flawed; and second, that the failure of the relief wells is coming to light 11 years after the fact.

“Here we are 70 years later, and we’re just learning that the relief wells don’t work. If they did, we probably wouldn’t be here,” DeKrey said.

The way the Lake Audubon feeds into the McClusky Canal works doesn’t leave much room for maneuvering.

Kip Kovar, Garrison Diversion Unit engineer, said the standard summer elevation of 1,847 feet in Lake Audubon is required to maintain flow through the canal headworks and push the water down the canal. Anything lower only compromises the flow until, at 1,837 feet elevation, “There is no water in the canal,” he said.

That means the diversion unit could not honor the dozen irrigation contracts it has with landowners, promising to deliver up to 24 inches of canal water annually to 5,900 acres. Perhaps more worrisome is the effect on the Red River Valley Water Supply Project, which is a partially funded plan to divert treated canal water into the Sheyenne River then into the populated valley out east, DeKrey said.

About $43 million in state funds have been committed to the water supply project and initial work is planned to start this biennium.

“That’s 50 percent of the population of North Dakota,” said DeKrey, emphasizing the impact if the diversion were unable to supply water because of the corps‘ drought management plan.

Nelson said the corps recognizes the potential impact of drawing down Lake Audubon, but its primary responsibility is to ensure the safety of the embankment. It’s also hard to imagine the impact if the highway, the railroad and the power lines were damaged or lost in an embankment failure, not to mention the reality that Lake Audubon wouldn’t be capable of storing water anyway.

There is no going back either and rebuilding the relief wells and probably no point, even if it were possible to drain Lake Sakakawea to do it.

“There’s the performance issue - would they even help?” Nelson asked.

DeKrey said he’s interested in engineered solutions but concedes that would likely cost in the hundreds of millions, if one could be devised, and, at any rate, “it’s not happening under the corps‘ criteria.”

“People shouldn’t be worried, but it definitely can happen and that’s why we want to go through and formalize the plan. This way, water managers can plan. Droughts take a long time to form, two to three seasons, so this wouldn’t come about overnight,” Nelson said.

Back on the farm, Knorr drives along the gravel canal road, where he can watch his pivots deliver the promised water to crops that would otherwise be a total loss this year. He appreciates that the corps‘ is taking an inclusive, methodical approach, and that no one is in a panic mode.

“My concern is that we look at all the plans, the engineering, and decide what is the best path forward and is there anything else we can do. I hope that with all entities working together, we can come up with solutions,” he said. “If they shut off the water, there would be an ‘out of business’ sign on my front window.”


Information from: Bismarck Tribune, https://www.bismarcktribune.com

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