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Patrick Springer, Published June 09 2013

Study to look at flooding effect of surface drains

FARGO – The Red River Valley landscape is etched with extensive drainage systems designed to remove water from farm fields to prevent crop losses.

Critics, including Fargo city officials, have complained for years that the drains exacerbate Red River flood crests.

Defenders, including farmers, have argued that drains can reduce floods’ severity and don’t contribute often to river peaks because they are full of snow and ice in the spring.

Now, for the first time, a basin-wide study of surface drainage will try to determine what role, if any, the drains play in flooding.

The ultimate goal of the study when finished, in a little more than a year, is to come up with management recommendations that can guide water boards on both sides of the river.

The goals are to determine how to best manage the existing drain systems to maintain drainage benefits to farmers and to reduce flood flows, said Chuck Fritz, director of the International Water Institute, who is heading the study.

“We live in a highly altered watershed,” Fritz said, noting that field drains are crucial to farmers. “There are very few natural waterways left. The miles of artificial drainage far outweigh the natural waterways, some of which have been altered.”

He added: “Given what’s in place now, how do we manage that?”

The study also aims to guide future drainage modifications or improvements to enhance drainage and reduce peak flows.

A technical advisory committee of 20 experts, all hydrologists or engineers, is steering the study. Members represent various constituencies, including cities, counties, conservation and agriculture.

Drainage, although part of the landscape for decades, has generated controversy and political clashes, especially since the start of the wet pattern 20 years ago.

“The whole goal here was to kind of remove the discussion from the policy makers and the bureaucrats and the advocates,” Fritz said. “I want to focus on the technical aspect here.”

Water management officials in both North Dakota and Minnesota will review the study’s recommendations with an eye toward policy.

“We’re looking for the true science of drainage in the Red River Valley,” said John Finney, chairman of Minnesota’s Red River Watershed Management Board.

His North Dakota counterpart, Jim Lyons, who heads the Red River Joint Water Resource District, agreed.

“Hopefully, it will be helpful to manage the drains,” he said. “We have to know more – is this causing flooding or not?”

The joint water boards in both states came together to form the Red River Retention Authority, which is working to identify upstream retention sites to hold water in order to minimize flooding.

Finney and Lyons, both farmers as well as local water board members, serve as co-chairmen of the retention authority, formed after the epic 2009 flood.

To be most effective, retention and drainage must work together, water managers said.

For instance, drainage is needed to create storage capacity for water retention projects, Lyons said.

“It isn’t the drainage that’s causing the flood,” he added. “It’s the lack of drainage.”

Completing a water management study doesn’t necessarily translate into a quick policy response, however.

Fritz led a study, released more than a year ago, evaluating the effects on flooding of subsurface drainage, often called tile drainage.

The conclusion: Subsurface drainage can exacerbate or mitigate flooding, depending upon how the drains are managed. Managing the drain systems requires installing controls, something not all farmers do.

Both Lyons and Finney said farmers on both sides of the Red River are coming to see the benefits of controlling tile drains.

During times of drought, for instance, farmers could benefit by installing gates on surface drains, or controls on subsurface drains, to hold back water.

Minnesota is working on a policy to manage subsurface drains, Finney said. It’s up to local watershed boards to decide whether to require controls.

In North Dakota, legislation passed in 2011 makes it difficult to regulate subsurface drains, Lyons said. Drainage projects don’t require permits unless they are larger than 79 acres, and water resource districts can’t require controls, he said.

The premise of the law is that subsurface drains help to prevent floods by moving water off fields. That’s not always the case, however, according to the conclusions of the 2012 tile drainage study.

Still, effective management can only happen once the information is in hand to guide policy makers, officials agreed.

The two drainage studies should help lay the foundation, said Lance Yohe, executive director of the Red River Basin Commission, an advisory body with representatives throughout the basin.

“Both of these are good steps forward from our view,” he said of the studies. “We don’t have enough knowledge yet to manage the system.”

As for laws or regulations to require managed drainage, Yohe said, “There’s really no teeth in anybody’s laws to enforce the thing.”

Extensive studies completed or under way in watersheds in both Minnesota and North Dakota to evaluate and identify retention sites.

The Red River Retention Authority hopes to compile a prioritized list of retention projects throughout the valley this fall.

The authority has embraced the goal, first recommended by the Red River Basin Commission, to build enough upstream retention sites to hold

1.5 million acre-feet of water.

That would be enough to reduce peak flows on the Red River by 20 percent in a 1997-magnitude flood, the record in Grand Forks.

Officials say it will take many years – and many millions of dollars – to reach that goal. The same is likely true of managed drainage.

“I don’t think it’s pie in the sky,” Finney said. “I think it’s realistic. It’s going to happen over generations.”

Readers can reach Forum reporter Patrick Springer at (701) 241-5522