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Natural Resources & Energy

Wyoming may have to give water from storage reservoirs to fill Tongue River Reservoir in Montana

Tongue River Reservoir
DSCN0876 Wild Earth Guardians
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Flickr Via CC BY 2.0
Tongue River Reservoir near Decker, Mont.

The State of Montana is seeking to fill Tongue River Reservoir through a call as part of their inclusion in the Yellowstone River Compact. This affects several northern Wyoming communities, including Sheridan.

A call is a legal right to obtain a certain amount of water from a river or other waterway for usage, often by a state, region, municipality, or entity that is entitled to it under the provisions of a compact or agreement. Montana instituted a call on April 1 to fill Tongue River Reservoir.

The Tongue River Basin has experienced drought conditions in previous years with below average snowpack and rainfall. These conditions led Montana to implement a call on Tongue River Basin. But Wyoming State Engineer Brandon Gebhart said it’s not a done deal yet. That’s because recent snow and rainfall coupled with possible moisture in the forecast and warming temperatures could provide the necessary water to fill Tongue River Reservoir.

“We’re continuing to allow that storage to accrue [in storage reservoirs in the mountains] but we are monitoring that that if Tongue River doesn’t fill, at some point this summer, we will release those volumes of water from those reservoirs for the purpose of satisfying Tongue River filling,” said Gebhart.

Tongue River Reservoir is located just a few miles over the Montana border near Decker and is approximately 12 miles in length, according to Montana Fish, Wildlife and Parks. If it turns out Wyoming does need to release water to Montana it would have consequences on the storage reservoirs in the Tongue River Valley and specifically in the Big Horn Mountains above Sheridan on tributaries Little Goose and Big Goose Creek. “These are our large irrigation facilities—Park Reservoir, Bighorn [Reservoir], Cross Creek [Reservoir], Sawmill [Reservoir], Dome [Reservoir]. Also, the City of Sheridan storage in Twin Lake,” said David Schroeder, Superintendent of Water Division II for the Wyoming State Engineer's Office.

Schroeder said there isn’t much negative impact currently to irrigators as there isn’t much irrigation as of yet, but conditions could change and that there’s currently about 500 to 600 acre feet of water that is flowing into the Tongue River Reservoir daily.

“What it is impacting right now is Sheridan County for one, water rights for industrial use out of creeks and streams, and they’re starting to ramp up road work near Dayton and Ranchester and Wolf Creek where they really have no other option, so they’re not able to do road work in those areas right now,” Schroeder said.

There are some alternative options for water he said, which they’re working with communities on, but they’re limited.

“There are a couple dozen extra, of less significance, in the tributaries of the Tongue River that we monitored and reported on as well,” he said. “So, if Tongue River Reservoir did not fill, it would impact their ability not necessarily during the time of the call but [during] mid-season irrigation if they didn’t have their reservoir water.”

Created by damming the Tongue River in the late 1930s, the Yellowstone River Compact was ratified by Congress in 1950 and includes the states of Wyoming, Montana, and North Dakota. Montana has state water rights on the Tongue River that date to 1937, which is used in allocating flows between states. In this case, water allocation is primarily centered on pre and post-1950 rights.

Wyoming also holds some senior water rights and what is used for domestic and livestock purposes are excluded from administration, though they could be subject to regulation at a later date if necessary.

“In the future, and of course many other areas are seeing rapid growth, and we’re leaning on these supplies more and more, it could be a concern going into the future,” Schroeder said.

Dayton receives its municipal water from a well while Ranchester does use some water taken from the Tongue River, though those are pre-compact rights, he indicated.

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