Watching lower Limbo Creek tumble under the hackberries and cottonwoods to the Minnesota River, it's easy to forget the plowed farm fields stretching in all directions.

This is deep in Big Ag country, and little Limbo Creek is caught in an escalating fight over its future between farmers, the county, environmentalists and the state. It's a microcosm of the problems of trying to clean up the polluted Minnesota River, and the outcome could affect the fate of hundreds of other waterways across the state.

Renville County officials last week approved a project to dredge a roughly one-mile section of Limbo Creek's marshy upper reaches to improve drainage from surrounding fields. They did so over objections of the state Department of Natural Resources (DNR) and the Minnesota Center for Environmental Advocacy who say the creek — one of the last largely unaltered waterways in Renville County — needs protection for the greater good.

The county's move comes as the DNR seeks to add the upper stretch of Limbo Creek to the official public waters inventory, making it subject to state environmental review before any changes.

Landowners and Renville County officials say it's merely a ditch regulated by the local drainage authority; the county sued the DNR last week.

The listing, open for public comment until Nov. 30, would be the first in an unusual project to add to the inventory scores of creeks and streams statewide that the DNR says were mistakenly identified as public ditches. The errors affect more than 600 miles of waterways in nearly every county in the state, including some designated trout streams.

Olivia resident Tom Kalahar, a retired technician from the Renville Soil and Water Conservation District, called Limbo Creek a test case.

"If we lose Limbo Creek in Renville County, that's going to empower the agricultural community statewide that this can be fought back," said Kalahar.

Farmers backing the ditch project say that part of the creek has turned into a stinking clogged cattail bog, backing up water onto their fields.

At a recent hearing, Myron Peterson called the affected fields the "economic backbone of our rural community" and said that he's lost scores of acres to the swelling waterway.

"I've seen the devastation," Peterson told county officials. "This is our livelihood."

The DNR and environmentalists say a DNR permit is required for the project, and that the county must conduct the required environmental review.

The ditch dredging project is at odds with goals to control dangerously high loads of sediment and contaminates from farm chemicals, such as nitrogen and phosphorus, washing into the Minnesota River, the state's most polluted river.

Increased precipitation from climate change, heavy tilling of crop fields and engineering of creeks to help drain farmland have dramatically increased the amount of water gushing into the river.

Heavy flows claw at the banks; trees topple in like matchsticks.

"Limbo Creek is one of the last vestiges of what the landscape was," said Elise Larson, a lawyer at the Minnesota Center for Environmental Advocacy.

"If we're not even going to protect the few waterways that remain, how are we ever going to tackle the issues facing the Minnesota River?"

Nature's kidneys

Renville County is a major producer of corn, soybeans and sugar beets.

All the buried concrete, clay and plastic drainage tile beneath the crop fields make it the most heavily tiled county in the state.

Nearly all the local watershed's wetlands have been emptied.

The Limbo Creek project would connect a county ditch to the upper stretch of Limbo Creek, then dig a 5-foot-wide trench through just over one mile of the marshy creek and wetlands, raising a dirt road that runs across it and upsizing the culvert under the road. It will cost about $700,000.

Below that section, Limbo Creek meanders naturally down to the Minnesota River and is already designated a public water.

Jeff Braegelmann, a lawyer for the landowners, said he thinks that even if upper Limbo Creek is designated as a public water, the ditch project would be lawful.

There are exemptions for "repairs," he said, and the drainage system dates to around 1918.

"It is simply cleaning out an old channel that was historically there," Braegelmann said.

Jerry Von Korff, legal counsel for the Renville County Drainage Authority, accused the DNR of overreach.

"We don't believe that the Legislature intended that the DNR, all by itself, could go around the state and change these designations," Von Korff said.

"The entire map is up for grabs. That's really the core of this."

The Minnesota Center for Environmental Advocacy says the county has mischaracterized the project as a "repair" to a lawful drainage system.

The old channel was never approved by the county, said Larson, the lawyer, and they don't have a right to return it to something they didn't have authorization for in the first place.

The group vowed to fight the county's decision.

From an environmental perspective, the cattail bog that farmers consider a problem is very effective at filtering chemicals and other pollutants from farm drainage running into Limbo Creek. Nature's kidneys, Kalahar said, firing up his pickup next to the bog.

"You can't build a better filter," Kalahar said.

Kalahar and others say the ditch project "is an example of what you should not be doing."

He points to nearby Hawk Creek as an example of what can happen. The Korstads' hobby farm teeters on the edge of the harshly eroded banks; a row of walnut trees fell in.

"We move the driveway periodically when it gets too close to the embankment," Donald Korstad said. "I just moved the garage this last summer."

Things are just as bad about 65 miles down the Minnesota River.

The city of Mankato recently spent $2.7 million for emergency work to fix major bank erosion to protect a well that supplies one-third of its water.

It just got an additional $7.2 million in state bonding money for more restoration.

"We don't want any increased velocity in the Minnesota River," said Jeff Johnson, Mankato's director of public works. "We lost over 30 feet of bank over the last five years. It's frustrating for us."

Public waters or ditches?

The DNR said it needs to fix the public waters inventory.

Steven Colvin, director of the DNR's ecological and water resources division, said that section of Limbo Creek should be on the inventory because it meets the statutory definition of a public water.

That means public waters laws apply to protect fish and the waterway ecology, and to control chemicals and sediments.

Limbo Creek is one of hundreds of waterways that years ago were marked on public waters inventory maps as public ditches, when in fact they were not, the DNR said.

The errors were discovered in 2016-17 during surveys of waterways for maps to implement the state's new buffer law. Altogether, the DNR has marked more than 500 sections of waterways to possibly add to the public inventory.

This article has been updated to note that the DNR extended the public comment period until Nov. 30.