DNR sets limit on diverting water from central Minnesota trout stream
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The Department of Natural Resources issued a first-of-its-kind order to protect a central Minnesota trout stream affected by farmers pumping groundwater to irrigate their crops.
The order for Little Rock Creek issued this week sets a sustainable diversion limit — the maximum amount of water that can be removed without causing a negative impact.
It’s the first time the DNR has used the new regulatory tool, which the Legislature authorized in 2023 to help address the impact of increased groundwater use.
The DNR occasionally suspends permits to pump water from rivers and streams during drought years. But the order is the first time the agency has applied the same protection to groundwater, which feeds rivers and streams.
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“It’s the same concept, that we’re trying to protect flows in those systems — for fish and wildlife habitats, for downstream users, for recreation, all those things,” said Jason Moeckel, a section manager in the DNR’s ecological and water resources division.
Farmers with existing permits won’t have to change how much water they use right away. But the DNR won’t issue any new permits until it finds a long-term resolution to the conflict. And it could modify existing permits in the future.
“We’re not going to go in and restrict or reduce what these irrigators are allowed to do in the near term,” Moeckel said. “But what we are saying is that we can’t continue this in perpetuity.”
‘Zone of influence’
Little Rock Creek flows through dry, sandy farmland in Benton and Morrison counties, into Little Rock Lake and eventually, the Mississippi River. The creek’s cold waters support trout and more than a dozen other native fish species.
Between 1969 and 2022, the DNR issued 94 permits for 3.7 billion gallons of groundwater used mainly to irrigate about 12,000 acres near Little Rock Creek, called its “zone of influence.” The actual amount of water farmers use every year depends on rainfall.
The DNR has been studying the impacts of groundwater use on Little Rock Creek for nearly a decade, and believes it is negatively affecting the stream’s ecology.
Water pumped from the ground doesn’t make its way into the creek, Moeckel said.
“So what the stream is experiencing is less flow, particularly during the low-flow times of the year — the driest, hottest parts of the summer,” he said.
Moeckel compared the impacts on fish to squeezing the same number of people into a much smaller room. Studies show that less space affects the long-term survivability of fish and their ability to reproduce, he said.
The DNR order sets a diversion limit of 15 percent of the creek’s median flow in August when the water level is the lowest.
“It’ll still preserve the habitats for that fish community, the stream ecosystem,” Moeckel said. “It’s not saying there’s no impact. It’s just saying that’s what is allowable without an impact.”
Moeckel said the DNR will work with area farmers to explore ways to resolve the water-use conflict, possibly by using groundwater farther away from the stream.
“The concept with Little Rock Creek is to figure out, is there a way to meet the needs of the irrigation systems without having the same impact on stream flow?” he said.
Irrigator concerns
Farmers who live within the Little Rock Creek area question the science behind the decision, and worry about its long-term impacts on their livelihood.
Anna Bregier is vice president of the Irrigators Association of Minnesota. Her family owns Prairie Farm Co. in Rice, which is near Little Rock Creek. They grow potatoes, kidney beans, peas and corn, and have permits to pump groundwater for irrigation.
As a third-generation family farmer with children of her own, Bregier said she thinks a lot about how to irrigate sustainably and keep growing food in the region’s sandy soils.
She questions the modeling the DNR used to set the 15 percent threshold. Bregier said she and other irrigators have decades of experience observing groundwater levels staying the same.
“Our own monitoring wells and the DNR data they’ve been collecting since roughly the 1970s show recharge to these aquifers,” she said. “So we think that they’re healthy.”
For irrigators, who’ve been meeting with the DNR for the past eight years, the order wasn’t unexpected, Bregier said.
But she said it does create uncertainty, and farmers are concerned the DNR could restrict their water use in the future.
“The way the law is written, they have a lot of ability to determine that something is a problem and turn off water,” Bregier said. “So I think we’re still nervous. It just feels like a lot of unknowns.”
Moeckel said although it’s clear that there’s an impact on the stream’s ecosystem, it’s not a crisis situation that requires immediate action.
“This is the situation that has developed over decades,” he said. “There’s not an emergency to step in and stop things right now.”
It’s possible that the DNR will use the same strategy to address groundwater concerns in other parts of the state, Moeckel said.
Other areas where the DNR has been analyzing groundwater use include White Bear Lake in the northeast Twin Cities metro, the Straight River in north-central Minnesota and the Bonanza Valley in west-central Minnesota.