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Wetland Drainage Likely Caused Flood
Wetland drainage likely caused floods
By Tony Dean
For the Argus Leader
Published: March 21, 2007
The flood that hit Browns Valley, Minn., in recent days may have been at least partially man-caused, according to County Engineer Larry Laukos.
The flood occurred when ice jams backed up the Little Minnesota River, something Laukos thinks wetland drainage helped create.
Laukos said he drove through the area and farm fields that should have been wet, weren't wet, noting that some area farmers had drained their land with the runoff going into the river.
This isn't the first time drained wetlands created unexpected runoff. Lake Thompson in central South Dakota, once a large dry slough bed, filled, creating a lake that sprawled over 18,000 acres, and South Dakota officials then attributed the growth of the lake to wetland drainage in the watershed.
Nor should we be surprised at the flooding that seems to occur almost annually at various points along the Red River. Drive into North Dakota on I-29 and soon after crossing the border, you'll see drainage ditches along both sides of the highway, belching water each spring.
Needless to say, that runoff usually ends up in an already swollen Red River because water simply follows the laws of gravity, always flowing downhill.
Wetland drainage also played a key roll in growing North Dakota's Devils Lake from a 39,000 acre lake when I began fishing it back in the early 1970's, to an inland sea now nearly three times that size.
Drainage into Devils Lake no longer goes through a myriad of wetlands, which purified it; instead it now runs down the man-made Starkweather Drain Project, and into Channel A which flows directly into Six Mile bay. Since the water moves much faster though that drainage system, there is little evaporative loss. In addition, the dissolved solids the water flow carries, also pour into the lake.
A study authored by Dr. Gary Pearson of Jamestown, N.D., and Dave Conrad, on behalf of the National Wildlife Federation, noted the amount of water flowing from drained wetlands is about 2 times greater than the recently constructed outlet that is intended to keep Devils Lake at current or below current levels can remove. In addition, many conservationists believe the mere presence of the outlet serves as an incentive for upstream landowners to continue to drain, believing their drainage will make no difference.
When one person drains wetlands, the only benefactor other than himself, is the drainage contractor. Everyone else pays.
And with each drained wetland, we lose another piece of a national treasure - the Prairie Potholes which raise about 50 percent of the ducks that migrate across American skies each spring and fall.
The wetlands most susceptible to drainage are seasonal and temporary wetlands. The seasonal wetlands are usually found in the middle of farm fields and hold water for just 6 to 10 days normally, but of all wetland types, they are the most important to ducks headed north each spring. Because of their shallow nature, they warm quickly, triggering incredible numbers of invertebrates that ducks depend on for food. It is an important protein source hens require to arrive on the breeding grounds in a healthy state.
In addition to their ability to purify runoff water, wetlands also help recharge underground water supplies.
Unknown to most, wetlands also play a key role in sequestering carbon, and landowners can capture carbon credits for storing that water by leaving their wetlands intact. For more information, contact the US Fish & Wildlife Service or the state game agency.
One conservation-minded farmer once told us that he knows drainage is wrong, noting that "runoff should walk off the land, not run."
That drainage plays a role in spring floods in some areas, is no longer debatable. It does and the recent flood at Browns Valley is another example of how drainage designed to benefit one landowner, often harms many others.
Wetland Drainage Likely Caused Flood
