Can the disappearing Lake Pepin be saved?

2:55 PM, Oct 29, 2010   |    comments
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LAKE CITY, Minn. -- On a perfect, late October day in the Lake Pepin valley, only the roar of power washers can spoil the sun-splashed fall colors on surrounding bluffs. At the Lake City Marina, crews clean a sailboat they hoisted from the river. Another season of memories and Mississippi River mud drip off.

For boaters, fall always holds the promise of spring. However, here on the shores of Lake Pepin, there are growing fears a final fall is on the way in the not-so-distant future. The mighty muddy is depositing so much sediment into Pepin that experts and river residents say this gigantic section of the Mississippi River is literally choking to death.

Standing on a dock, sailboater John Borman worries, "We're going to lose this jewel. And that's what it is. It's an absolute jewel."

It is a jewel when you consider the shear size of Lake Pepin. Just south of Red Wing, Minnesota, it is the Mississippi River's largest lake. Pepin is 21 miles long and averages nearly two miles across.  Such size makes it hard to believe the lake can just disappear, but boaters are noticing changes.

Mark Warrington says, "You have to be careful where you go."

His son Chris notes, "I think it's just a fact that we've accepted that the lake's slowly filling in."

Lake Pepin changing

But the changes aren't just happening beneath Lake Pepin's surface.

Standing above Wacouta Bay on the lake's very northern end, resident Michael McKay points to a growing island. "So every year that fills in. Then the vegetation starts. You can literally chronicle it," says McKay.

McKay is executive director of the Lake Pepin Legacy Alliance, a group that is trying to save the lake. He puts it bluntly, "The real threat is ultimately, Lake Pepin turns into nothing but a channel."

McKay is not exaggerating.

Lake Pepin gagging on sediment

While sitting at a lakeside table, the Minnesota Pollution Control Agency's Norman Senjem, who is focused on water quality, points to a river map and notes, "Our numbers say that within this century, the upper third, roughly from Frontenac upstream, would fill in with sediment." Simply put, that's just 90 years.

Senjem continues with his agency's stark forecast, "And the rest of the lake would fill in within about 340 years from today."

If the lake's timeline seems staggering, the volume of sediment is as well. Senjem says the amount of sediment arriving in Pepin each year is "almost a million metric tons." To put that in perspective, Senjem says that would fill the same space as a 32-story building on a 330-foot by 330-foot block. The Foshay Tower in downtown Minneapolis is that size.

"So, one of those city blocks is ending up - most of it in upper Lake Pepin - and that's why it's filling in."

Senjem says Pepin's sedimentation rate began accelerating when settlers arrived in the 1830s.

Minnesota River main sediment source

Today, he says a whopping 75 percent of Pepin's sediment flows from the Minnesota River. Half of that comes from two tributaries down by Mankato, the Le Sueur and Blue Earth rivers. Senjem says the
makeup of that sediment allows it to float all the way to Pepin where slower current allows settling.

Senjem notes, "We need to make significant reductions in the area of 60 percent in the Minnesota River, or none of the rest of it's going to really make a difference."

To tackle the sediment issue, Senjem points to the sources. He says a third comes from farm fields. The rest of the sediment comes from stream banks and bluffs, and ravines. Senjem says the water is
just leaving the land too fast.

He adds, "There were good reasons for you know, for focusing on increased agriculture production at the time that it did. These are unintended consequences."

Farmers believe more factors affect Pepin

Not everyone agrees with the MPCA. Farmers believe the causes are far more complex.

"Some will simplify to, well ag has a big footprint, so ag was the major change. I guess I would suggest there are other factors," says Warren Formo of the Minnesota Agricultural Water Resources Coalition.
He estimates 90 percent of Minnesota farmers on erodible land are already practicing soil-conservation methods. He points to other factors.

"From a hydrologic perspective, farm fields are much closer to a natural condition than urban areas or developed areas. So, we need to look at all the impacts that we've done, whether it's draining wetlands, development of roads and fields, cities, even things we've done to the river itself.

As it turns out, The U.S. Army Corps of Engineers is beginning a study to examine natural and human impacts on the Minnesota River.

Possible Pepin fixes

Regardless the cause, it's clear Minnesota faces a huge environmental challenge.

Norman Senjem has seen such challenges before. When he attends Lake Pepin meetings, he carries a walking stick with a carved eagle head on top. "So, if we can bring the eagle back, it's also possible we can bring the Mississippi River back."

To help the river, the MPCA proposes a sediment diet that includes the following: some changes in farming and field drains, compliance with field-stream buffer zones, wetland restoration and new drainage ditch designs. Ultimately, Senjem says Minnesota must "slow down the water."

The MPCA will soon send the Environmental Protection Agency a report diagnosing the problems on the Mississippi River and listing solutions.

Painful Pepin reality

Michael McKay enjoys past environmental victories. Looking over Lake Pepin he says, "It's not unusual to see 20, 30 eagles on the iced edge."

With this latest challenge, he wants action. "I mean shame on us if we take something that was supposed to be around 3,000 years and turn it into 300."

Even if the state can put Pepin on the desired sediment diet, there is a sobering reality: Lake Pepin only has 600 or 700 more years. But, with action, that's double the current estimates.

It is a more distant end for a gigantic natural wonder.

As McKay says, "It truly is the gem. It is a true jewel of Minnesota. It's a standout feature of the whole Minnesota river system.

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