It's an essential truth that too few Minnesotans contemplate as they gaze over the state's rolling fields or across their landscaped back yards. Human development has radically altered the state's landscape.

Native prairie has been plowed under and paved over, wetlands misguidedly filled in. Beneath it all are vast networks of drainage tile to quickly move rainwater off the land.

All of this was done with good intentions.

Minnesota's rich soil has helped feed the world and now, through ethanol, is helping fuel it. The growing communities derided by some as sprawl are home to the citizens who come here or stay here because of the high quality of life.

There is, however, a high price to be paid for this undeniable change in land use, as a newly finalized state plan to clean up a 64-mile stretch of the Mississippi River makes abundantly clear.

The so-called "south-metro" portion of the nation's premiere river, which winds through the Twin Cities down to Lake Pepin, is choking on the sediment swept downstream by the tributaries that drain half the state -- an issue spotlighted last year in the documentary "Troubled Waters."

Minnesotans can no longer duck this truth or their responsibility for the burgeoning environmental disaster. It's time to acknowledge the agricultural industry's role in the shameful health of this part of the Mississippi River.

Dramatic changes in federal farm policy, such as realigning subsidies to reward conservation efforts, as well as voluntary efforts by farmers themselves to slow runoff from their land, are key in achieving the sediment reductions called for in the new plan, which was posted online last week by the Minnesota Pollution Control Agency (MPCA).

Getting that buy-in from one of the nation's most powerful and politically connected industries is a challenge. Farm industry trade organizations already have cranked up the public-relations machine to fight the plan.

News releases and postcards sent to some local watershed officials ludicrously tout the unpublished research of one University of Minnesota scientist -- whose work the industry has helped fund -- as proof that increased sedimentation is natural or the result of climate change. Industry officials also point to urban runoff as the problem.

While cities certainly need to do a better job of controlling runoff, the reality is that these rivers drain mainly from cropland; only 2 percent of the watershed is covered by impervious surfaces. The plan spearheaded by the MPCA is also based on 22 years of data and research by objective scientists.

Their work, much of which has been published in peer-reviewed journals, suggests that vast changes wrought to the landscape have caused water to rush more rapidly over a landscape already geologically disposed to erosion, exacerbating sediment runoff.

Urbanization and precipitation simply cannot account for the tremendous increases in sediment loads documented from 1940 to 1990.

There is an uncomfortable silence that greets questions about how much it will cost to cut in half the sediment clogging this marquis stretch of the Mississippi River. There is no dollar estimate at this time, but it's clear it will be expensive.

However, the nation already spends billions on agricultural subsidies. Congress needs to better align these financial incentives to achieve sediment reduction and other conservation goals.

At the state level, policymakers need to target Legacy Amendment funds for this historic effort. And with record crop prices, are Minnesota farmers able to afford their own conservation investments?

Minnesota officials who spearheaded the project based their recommendations on solid science. Unfortunately, federal law only requires a cleanup plan, not action to carry it out. Policymakers may well decide to ignore the years of research that went into this report.

That would be a mistake.

High sediment loads, mostly from the Minnesota River, prevent aquatic plant growth by blocking sunlight, reducing fish and wild life habitat. The sheer volume of sediment also threatens to turn Lake Pepin into a ditch, with the same process repeating itself further downstream if left unchecked.

The cost of this historic river restoration is high, but the price of ignoring it is unacceptable.

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