Dennis Anderson
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Supporting the life that supported those species were tens of thousands of potholes, wetlands and shallow lakes — a watery landscape that to a visitor the other day seemed barely imaginable, given the checkerboard-like farm fields that now stretch in every direction.

Among the relative handful of wetlands and shallow lakes that remain in a seven-county region in this part of the state, 153 parcels called federal Waterfowl Production Areas (WPAs) are overseen by Glup and his staff.

Purchased beginning in the late 1950s with proceeds from federal duck stamp sales — the stamps are required to hunt waterfowl in the U.S. — the areas by law must be protected and managed for wildlife, including, in addition to ducks and geese, shorebirds, grassland birds, plants and insects.

It’s a job Glup, a 33-year Fish and Wildlife Service veteran, takes seriously.

“We’re on the front lines of protection,’’ he said. “We want to protect these lands not only for this generation but for future generations.’’

The job is challenging because, in varying degrees, each of the WPAs in his district is a dumping ground for farmland drainage. The result, in many cases, is that silt carried by the drained water piles up sometimes 3 feet deep in the bottom of a wetland. At other times, so much water, some of it laced with farmland chemicals, enters a WPA that its capacity to support nesting waterfowl, or resting waterfowl, is diminished.

One result: fewer ducks — and fewer ducks is one reason a record-low number of waterfowl hunting licenses were sold in the state last fall.

For about 150 years, Minnesota has drained land to grow crops. The earliest beneficiaries were settlers who pushed west of the Mississippi following statehood, along with the railroad and grain barons who bought, stored, transported and traded the wheat, oats, corn, barley, rye, buckwheat and other produce grown by the state’s newest residents.

Litchfield, in fact, was founded in 1869 and is named after the English financier E. Darwin Litchfield, a major stockholder in the old Saint Paul and Pacific Railroad.

E. Darwin probably wouldn’t recognize the region today, so much has changed.

Yet a few constants remain, among them rain, snow and snowmelt. All of which — just as in the late 1800s — must end up somewhere.

But because so many of the region’s many thousands of wetlands and shallow lakes are gone, drained first by horse-drawn trenchers and more recently by subsurface “pattern tiling,’’ much of today’s rain, snow and snowmelt no longer slough into nearby wetlands to infiltrate the ground slowly, en route to aquifers below.

Instead, in many cases the water follows a Byzantine labyrinth of ditches, streams and rivers that surge not only through most WPAs but also through state Wildlife Management Areas before, ultimately, dumping into the Mississippi River flowing south, or the Red River streaming north.

Whatever the negative impacts of drainage, the practice has multiple advantages for modern farmers, foremost of which are higher corn and soybean yields.

Those yields are subsidized in various ways by every Minnesota taxpayer.

The nearly $500 billion federal farm bill, for example, incentivizes (or restricts) drainage through crop subsidies it offers (or doesn’t). Also, farmers can deduct drainage-installation costs from their income taxes, in turn spreading the costs among all taxpayers. And when drainage goes awry, such as during springtime floods, taxpayers pay cleanup costs, sometimes to the tune of millions of dollars.

There are other costs, too.

Glup and his staff must be paid to combat the effects of drainage on wildlife areas. Ditto local Department of Natural Resources wildlife managers and hydrologists. And millions upon millions of dollars have been spent purchasing wildlife lands in Minnesota, some with funds originating with the Clean Water, Land and Legacy Amendment, which fractionally increased the state sales tax everyone pays.

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In 2013, Fish and Wildlife Service researchers conducted an extensive study of a landowner proposal to drain a 60-acre farm field into Eagle Lake WPA, which is in Glup’s management district.

The farmer had installed 9.2 miles of subsurface pattern tiling on the 60 acres in order to drain its existing lowlands. The land lay immediately adjacent to the WPA.

Minnesota state law allows downstream drainage without restriction in many cases. But in some situations, approval must be sought from local watershed management boards or other government units before water can be dumped onto a neighboring property. Such was the case at Eagle Lake.

Glup used the opportunity to commission research of subsurface drainage by Fish and Wildlife Service staff, as well as extensive computer modeling to determine the likely effects on the WPA if the drainage was allowed. (Eagle Lake WPA was already receiving drainage from other sources.)

“Our study was thorough,’’ Glup said. Here’s what it found:

• Subsurface drainage is correlated to increased inputs of nitrates.

• Increased nitrates can significantly alter the trophic state of receiving waters (clear water dominated by emergent/subemergent aquatic vegetation to an algae/turbid state).

• Nitrate concentrations are one to two times higher in subsurface drainage than surface drainage. Wetlands typically can’t remove nitrates efficiently from tile effluent because nitrates bypass the denitrification processes due to high water flows.

• Nutrient inputs and hydrologic alterations rank as two of the top three threats to 135 imperiled freshwater fishes, crayfish, dragonflies and damselflies, mussels and amphibians in the United States.

• Subsurface drainage can alter the hydrology of adjacent and downstream wetlands and riparian areas. Lowered local water tables on agricultural lands also influence water table dynamics in adjacent natural areas and riparian zones that alter the composition of plant communities and their habitat values for wildlife.

In the end, the farmer sold the property to the Fish and Wildlife Service, which plugged the tiling. Blanketed with wetlands and grasses, the area is now part of Eagle Lake WPA.

Glup is well aware that agriculture proponents have studies of their own that say subsurface drainage has more benefits than drawbacks, especially to farmers.

But he’s comfortable with the science that supports the service’s contrary view regarding wildlife areas — included as they are, however unwittingly, in Minnesota’s farm drainage system.

“Our job,’’ he said, “is to protect these areas. It’s the law.’’

danderson@startribune.com