The Fight Between Montana and Wyoming for the Yellowstone River Likely Headed to Supreme Court

The Fight Between Montana and Wyoming for the Yellowstone River Likely Headed to Supreme Court
A dispute regarding a 60-year-old compact that dates to 2007 and before now revolves around irrigation methods in upstream Wyoming.
By Kylee Perez, 2-02-11

  The Tongue River in Montana, a tributary of the Yellowstone, is among the waterways Montana says it gets less of since Wyoming farmers started using sprinkler irrigation. Photo by the U.S. Geological Society.
What Wyoming farmers call more efficient irrigation, Montana farmers call a breach of contract regarding the Yellowstone River.

The two states have been in a legal battle since 2007 over the 1950 Yellowstone River Compact, an agreement that divided available flow from the river and its tributaries among Montana, Wyoming and North Dakota.

Water compacts are typically entered into to avoid litigation, said David Getches, a professor of water law at the University of Colorado at Boulder. The compacts rarely come up in court and when they do, they go straight to the Supreme Court because they involve more than one state.

“They’re an oddity,” he said.

But rather than ward off water disputes, this agreement has led Montana and Wyoming into just that. Although there have been multiple issues with the compact, the current conflict hinges on a claim by Montana that irrigation techniques used by Wyoming farmers are actually using more water from the Powder and Tongue rivers, leaving less for downstream users. Wyoming’s stance is their farmers are simply using a more efficient method to water crops.

Montana alleges the use of sprinkler irrigation can result in an increase in the consumption of water, even if no more acres are actually being irrigated, “because increases in efficiency often result in reduced return flows on which downstream farmers historically relied,” said Montana Assistant Attorney General Jennifer Anders in an e-mail. “We believe that characterizing sprinkler irrigation as an ‘efficiency gain’ to the overall system is a misnomer.”

When the compact was first signed, flood irrigation was the most common method in both states. Basically, farmers would flood their fields and what didn’t go into the ground slowly made its way back to the stream. “When you dump a bunch of water on a field you have to put more water on there than you really want to,” explained Peter Michael, Wyoming Senior Assistant Attorney General.

This excess water is what’s commonly referred to as return flows.

Farmers who’ve abandoned flooding in favor of the sprinkler irrigation systems, although not diverting any additional water to their crops, are, in a way, using more of it. The plants are watered more directly and take in more through their roots, reducing return flows.

This is the basis of Montana’s complaint.

But Wyoming argues the compact only controls how much water can be diverted, not how much water can be consumed.

Interstate compacts intended to put limits on consumption do exist, said Michael, and a version that did that was drafted for the Yellowstone River Compact. That draft was voted down by both Montana and Wyoming before all three states agreed to sign.

A Special Master, an attorney appointed by the Supreme Court to hear the case and make a preliminary decision, sided with Wyoming, saying more efficient irrigation techniques do not violate the agreement.

The Supreme Court is expected to either accept or reject the Special Master’s decision by the end of the term in June, but that’s not likely to end a water dispute that rages on many fronts beyond irrigation techniques.

“That’s years away,” said Michael about a resolution.


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