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sem fen 2

Seminary Fen on a fine summer day. Photo: Terry Schwalbe. For a picture of a dramatic fall day at the fen, go to the Star Tribune web story on the fen's dedication.

sterile sedge  beaked spike-rush

Two of the threatened species found on Seminary Fen: sterile sedge, to the far left, and, to the right, beaked spike-rush. Photos: USGS.

valerian   lady-slipper

Two species "of special concern": on the far left, common valerian;
on the nar left, white lady-slipper. Photos: USGS.

sem fen map

Map of Seminary Fen: Minnesota Sierra Club. For more information
on how to help preserve the fen, go to the club's web pages.
41 xing
The Minnesota Department of Transportation's Tier 1 Environmental Impact Statement, Dec. 2008, has recommended putting the new Hwy. 41 river crossing in the C2 corridor, marked in green to left. Though this route skirts downtown Chaska, it "avoids impacts to calcareous fen," in MnDOT's words, as might have occurred with the E2 route, in red, which lies nearest the fen.


A Source of Health among Us and an Invaluable Resource
DNR Dedicates Seminary Fen

After decades of negotiation, aided by the District, the Minnesota Department of Natural Resources (DNR) this spring bought 106 acres of the 600-acre Seminary Fen wetlands complex, in Chaska and Chanhassen, from Emerald Ventures LLS. The agency funded the purchase with about $1.3 million of state bonding passed in 2003.

Seventy-three of these acres it formed into a Scientific and Natural Area (SNA), the heart of a rare calcareous fen with threatened plant species, while allotting the remaining 33 to the adjacent Raguet Wildlife Management Area.

By definition, an SNA is a nature reserve, a protected environment — rich in a natural heritage of plants and animals, fossils, and geologic formations — that scientists can study and citizens too can visit for health and inspiration. A source of wonder and refreshment, an SNA is an invaluable resource. The SNA program itself is dedicated to ensuring “that no single rare feature is lost from any region of the state.” (For details, go to the state DNR site.

In the case of the fen complex, the DNR remains interested in acquiring more property, some of which is fen, the remainder to act as a buffer between the SNA and nearby commercial and residential development. (Besides the fen itself, the complex includes meadow, marsh, and shrub swamp.) As before, the District will facilitate these efforts, as by introducing the DNR to landowners and appraising the property.

What’s a Calcareous Fen and Why Should We Care?
The rarest type of wetland, calcareous fens form on the lower slopes of glacial moraine, like the limestone bluffs along the lower Minnesota. In these stretches, water charged with calcium and magnesium bicarbonates comes to the surface, saturates, and helps maintain thick layers of peat from the decomposition of the plants that grow in this oxygen-poor water seeping up.

In the case of Seminary Fen, the groundwater drains into Assumption Creek. The cold, clear waters of the creek, which form one of the metro’s last surviving trout streams, flow from the fen to the Minnesota River just a mile or so distant.

The saturated soils of calcareous fens are dominated by what the DNR calls “low, tussocky grass-and-sedge … vegetation.” These grasses and sedges bear the humble names of sterile sedge, beaked spike rush, hair-like beak rush, and whorled nutrush, all considered threatened species. The fen also harbors three species of “special concern” —marsh arrow-grass, and two flowering plants, valerian and the small white lady-slipper. [See photos at left, as well as a more extended discussion of these, and similar, wetland species, at the United States Geological Survey's page].

So who cares about such plants? Hannah Texler, DNR ecologist, suggests if we know just a couple of things about these plants we will care. First, she points out, preserving other species preserves us all. “If we protect all the parts, we’re protecting ourselves too. A healthy natural ecosystem like Seminary Fen, which stores groundwater and keeps air clean, keeps us healthy too. This is the simple lesson of biodiversity.”

Second, Texler asserts, the rareness of calcareous fens and the plants that grow in their harsh environment are a sign of our “natural heritage” and, we might add, a sign that we too, at this late date, are still part of nature, not altogether apart from it and hurrying by.

There may be only about 500 calcareous fens in the world, and Minnesota can lay claim to almost 200 of them. They are a rare gift which, with proper care, we can continue to appreciate despite recent — and future — developments.

For more Seminary Fen facts from the DNR, click here.

The Way It Used to Be
When Europeans arrived in numbers in the Minnesota River Valley, in the 1830s, it was full of calcareous fens, stretching from Chaska to the confluence with the Mississippi River. But, then, such fens were part of a vast complex of wetlands, eighty percent of which have now disappeared from the metro area.

We can only imagine such stretches and what they signified to those who visited and witnessed them. They are gone now, for the most part, and yet their imprint lingers in such remnants as Seminary Fen and, in Ft. Snelling State Park, Nicols, Sibley, and Quarry Island fens.

These lingering imprints suggest there was a time when the land existed apart from human uses and utilities. It was simply there, in its own right, a small part of the intricate ecosystem of land and water in this land of sky-filled waters.

American Indians burned the fens to protect and renew the peat and the plants, which, along with the mud, they used for medicinal purposes.

Settlers drained wetlands and developed the land, cleared brush and woods, scoured out fens and meadows, pointed plow into soil.

As farmers probably realized all along, however, fen terrain was not the richest or most fertile. This fact, along with economic opportunity, turned farmers like Clarence Hesse of Chanhassen into developers. In the 1970s Hesse sold off 250 of his family farm’s 330 acres in 5-acre plots and then worked with the city, setting up a plan to preserve the area’s natural features like the bluffs above, the marshes all around, and Seminary Fen just to the southwest of the land.

Such features, as we all know, are valuable both in their own right and their contribution to the human landscape. Families who have settled in Hesse’s development, and surrounding areas, know the natural richness of fen and meadow, creek and bluff.

In the early years of the 20th century, Mudcura Sanitarium was established on the site of the fen, started by two local medical doctors and a businessman. This business, which availed itself of the sulfurous springs in the area, was nationally, even internationally, recognized as a place for restoring health via mud baths, diet, and exercise. In 1951, the building and grounds were sold to the Franciscan order of Catholic priests and became a seminary (thus, the name “Seminary Fen”). This institution operated till 1970; subsequent plans to use the site as a retirement home and, again, a spa fizzled out, and the seminary building was burned down, by vandals, in November 1997. (Our thanks for the historical information in this paragraph to Wendy Biorn, Director of the Carver County Historical Society.)

Where Do We Go from Here?
Despite the care of city, neighbors, and conservation groups, however, the fen is a fragile ecosystem.

It's so fragile, in fact, that it can’t afford to be subjected to extra stresses. In September 2007, Len Kremer, District chairman, wrote to the Minnesota Department of Transportation (MnDOT) urging it not to situate a new Highway 41 bridge over the fen. (The three easternmost routes proposed by the DOT would pass over the fen, while the others, to the west, would avoid the fen but still could affect threatened and endangered species elsewhere, to say nothing of the quality of human life in downtown Chaska, around which traffic could be routed.)

Groundwater flows to the fen, and Assumption Creek must be protected, Kremer pointed out in his DOT letter. If the cold, anaerobic water were to be polluted by runoff or salt, both fen and stream may not recover. The Minnesota Pollution Control Agency, Kremer reminded the DOT, has designated the fen an “Outstanding Natural Resource Value.” In fact, Kremer said the fen “represents a substantial and irreplaceable resource within one of the last, best — and most threatened — stretches of pervious greenspace in the metropolitan Twin Cities area.”

Small Victories Owing to Large Efforts
Just 15 months later, in fact, the DNR, the District, and other interested parties have successfully brought their influence to bear on the DOT, and its Tier 1 Environmental Impact Statement (EIS) recommends routing the new river crossing, which connects highways 212 and 169, via a corridor considerably west of Seminary Fen, marked in green in the map above left.

Such rescues and respites give pause to Dan Ress, a Chaska High School biology instructor, and his young students, whom he has been taking to Assumption Creek and the fen for 10 years now. They go to study the stream's macroinvertebrates. on which the native brook trout feed. Ress calls the place “a special educational resource. It turns kids on and creates the need to know about preservation and wildness.” The fen, he adjudges, “acts like a water freshener for the creek” — and a freshener, too, for young lives and those not too old enough not to care.

Breathing easier, the DNR is developing a stewardship plan for the fen, which should help preserve it in its natural state presuming we can continue to stave off the demands of commerce, transportation, utility, the need to get faster and faster to the further and further places where we live and do business.

According to this plan, prescribed burns will keep native plants healthy; exotic trees (like buckthorn) and brush (honeysuckle from the old seminary grounds) will be removed; ATVs but not softly treading, respectful feet will be kept out; native fen and prairie plants will be re-seeded; and drain tiles that farmers once installed will be removed.

“In wildness,” said Henry Thoreau, “is the salvation of the world.” We find such wildness in Walden Pond, yes, and in Seminary Fen and in other natural habitats close to home that we cut ourselves off from at our peril.

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