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In the aftermath of the August 2007 floods, government and environmental groups, developers and farmers are asking if how our land is used might have contributed to the devastation. And perhaps more importantly, if there is something to be done to prevent another flood of such overwhelming proportion.
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The home of Lynn and Sharon Partington lies in ruin Aug. 23, 2007 along Highway 26 north of Brownsville, Minn. The house was swept from its foundation during a landslide Aug. 19, 2007 caused by heavy rainfall.
(File Photo/La Crosse Tribune)
File photo: Dec. 30, 2007 |
Our bridges
Immediately after the floods, residents raised concerns about whether bridges clogged by debris formed impromptu dams that might have focused the waters toward towns instead of allowing it to dissipate naturally. In Minnesota City and Goodview’s Gunderson subdivision, residents pointed to roadways as a source of problems.
Steve Runkle, a supervisor at the Winona WorkForce Center who lost his Minnesota City house in the flood, said trees and other debris backed up at the railroad in Gunderson.
“It basically formed a dike,” Runkle said. “Once the water got up to that level, it would normally go out into the neighboring corn field, but instead it got backed up by the railroad tracks.”
Bill Huber, a hydrologist for the Minnesota Department of Natural Resources, said the swelling rivers pulled a large amount of trees off banks but wouldn’t go as far as saying that backups at bridges were a contributing factor to flood damage.
“What we can say is that it appears that debris played a big role in the flood damage that occurred in 2007,” Huber said. “Bridges are a likely spot for debris.”
Our farms
How quickly rain flows off land and into rivers, and how much is soaked up by the soil, can be affected by how land is in use by people. Increases in the price per bushel for both corn and soybeans is causing more farmers to plant more crops on more land.
“We’ve definitely seen an increase in land that hadn’t been used before being plowed up,” said Tim Terrill, director of the Winona County Soil and Water Conservation District.
According to a 2005 nutrients and pesticides use study by the Minnesota Department of Agriculture, 64 percent of land in the South Branch watershed of the Whitewater River — an area that encompasses places such as St. Charles and Lewiston — was cropland. Of that cropland, almost 80 percent was used for row crops such as corn and soy beans.
Larry Gates, a retired Department of Natural Resources coordinator for the southeastern Minnesota watershed, said land has become increasingly used for row crops over the past 20 years. Heavy row crop usage creates channels for storm-water runoff, Gates said, causing it to pour quickly into streams and rivers.
He also said that if farmers rotate their crops, instead of repeatedly planting the same thing, more organic matter is returned to the soil, improving the soil structure and increasing infiltration by water during storms. During last year’s floods, Gates said that excessive row crop usage may have quickened the pace of rising waters.
“There were some places right in the area that saw the biggest precipitation that had good land cover, and there really was not much runoff in those areas,” Gates said.
Farmers’ management practices — including techniques to reduce soil loss and mitigate water runoff like using buffer areas of vegetation near waterways and contour farming — may not be enough to counter the increased use of land.
Local governments should think about conservation programs when talking about preventing future floods, said Doug Nopar, of the Land Stewardship Project, an environmental advocacy group.
“Any conversation about building flood control structures needs to include discussions about providing financial and economic incentives to have more land in permanent cover,” Nopar said.
Though increased row crop farming may increase water runoff, how much it actually affected the floods hasn’t been determined. Runkle warned against laying too much blame at the feet of local farmers.
“It’s awful easy to blame farmers,” Runkle said, “I don’t think the blame is well founded.”
Our bluffs
In Houston County, mudslides in places such as Brownsville wiped out houses on the side of bluffs. Ron Meiners of the Houston County Soil and Water Conservation District said developers and residents should think about the wisdom of building on or near those areas. Though he said no hard scientific data has shown development at the foot and along bluffs caused slides, the general consensus is that they contributed to it.
“It seemed to follow a pattern that if there was some kind of disturbance at the toe from a road cut in or a building, or something on top of it, that’s where you saw (slides),” Meiner said.
Huber also said roads may have been a contributing factor in the slides.
“We have to ask the question of road building on the toe of those slopes: Is there something that we can do better to secure those bluffs?” Huber said. “I think (the Minnesota Department of Transportation) does have to look at that.”
Chris Dulian, a MnDOT soils engineer, said the department is always conscious of how road development affects bluffs and water runoff. The problem, she said, is that many of the roads where mudslides occurred were built decades ago, before safety was a prime concern in transportation construction.
“I don’t even know if they had safety manuals back then,” Dulian said. “Now, that’s one of our first and foremost is to protect the traveling public.”
When new roads are built, extensive studying is done to test soil and rock conditions to ensure bluffs are secure, Dulian said. That same scrutiny can’t be expected for roads built over old goat and wagon trails.
“We have to rely on how they were built,” Dulian said. “We have to deal with what we have.”
It’s not just roads. Residential construction on bluffs may have also exacerbated the problem. For about a decade, developers have been restricted from building on slopes with more than a
24-percent elevation grade in Houston County.
Bob Scanlan, planning and zoning administrator for Houston County, said that if bluff development zoning had been less restrictive, much of the damage could have been worse.
“My opinion is that what has been in place over the last couple decades prevented more damage from happening,” he said.
However, there are no current plans to make bluff development more restrictive in Houston County. Even without new zoning rules, Meiner said citizens should take it on themselves to reconsider where they build.
“I know everyone wants to have their dream house, but at what cost?” Meiner asked. “Landowners really need to take a look at where they are going to build and settle.”
It all comes down to personal choice, Terrill said. The best way to avoid a 100-year-flood is to not build in a 100-year-flood plain, he said. Flood plains should be looked at as a geographic location, instead of just an elevation, Terrill said, and too often, just because a house is even just feet above a flood plain level, people assume their house is safe.
“You build a house right next to a stream, you might not be in a flood plain, even though common sense tells you you’re going to get flooded,” Terrill.
