The Seminary Fen, one of the rarest ecosystems in the world, goes public today.

After decades of trying to acquire the rare calcareous fen in Carver County, the state Department of Natural Resources (DNR) earlier this year bought about 106 acres of the privately held property for $1.3 million.

At a ceremony today, the DNR will celebrate designating 73 of those acres as a scientific and natural area, which will allow public access and some limited improvements.

"This has been on our radar for a long time," said Harland Hiemstra, a DNR spokesman.

Environmentalists say that only about 500 calcareous fens exist worldwide, with Minnesota home to about 200 of them.

The fens thrive in cold groundwater at the bottom of a slope or bluff enriched with calcium and magnesium.

What makes calcareous fens so unusual is that the low oxygen levels of the waters make plants decompose more slowly, resulting in a spongy layer of moss on the soil. They are the rarest and most protected wetlands in Minnesota.

The Seminary Fen, located within the Minnesota River Valley along Assumption Creek in Carver County, has eight rare or endangered species on the site.

"Fens are extremely unique," said Peggy Booth, the DNR's scientific and natural program supervisor. "They have plants that can grow under no other conditions."

Money trail

Money for the purchase was provided by the state Legislature and Gov. Tim Pawlenty when they approved $1.3 million in state bonding funds in 2003 to preserve the Seminary Fen as a scientific and natural area, the DNR said.

A tentative agreement to purchase the fen and an additional 30 acres, which will be added to an adjacent wildlife preserve, was reached last spring between the property owners and the DNR. The Seminary Fen covers about 160 acres, and the DNR agreed to buy about two-thirds of the acreage.

The negotiations succeeded where other attempts had failed.

In 2004, the DNR, Chanhassen and others tried to purchase the 160 acres for $2.1 million. At the time, the owners thought the property was worth $3 million.

In 2002, a purchase agreement for the fen was signed with a public-private group for $2 million, but then-Gov. Jesse Ventura vetoed the purchase.

The site's designation as a scientific and natural area means that the land will be open to the public but will have minimal improvements or amenities added.

Booth said plans are to build a parking lot, and that's about it.

People will be allowed to wander the area, but the DNR is asking that caution be used so endangered plants are not accidentally damaged.

"This designation is the most light on the land," Booth said. "We don't want people to stomp around out there."

Although environmentalists were happy with the purchase, concern remains about development going on around the area.

There is a possibility that the previous owners could build on their remaining land. Also, the state Department of Transportation is looking to build a new Minnesota River bridge that would run through a portion of the fen.

The Seminary Fen location is one of a half-dozen options MnDOT is considering for the bridge crossing. MnDOT has not said when it will make a decision on its preferred route.

But MnDOT officials have said that the purchase of the Seminary Fen acreage will not have much, if any, effect on the agency's decision on where to place the new river crossing.

In addition to the unique ecology of the area, the acreage has some development on it such as ditches and roads.

The site was once the home of the Assumption Seminary, a college operating in association with St. Catherine and St. Thomas colleges from the 1950s to the early 1970s.

Earlier, it had been the site of the Mudcura sanitarium, which offered mud baths and treatment for rheumatism, arthritis, asthma and skin, kidney and nervous diseases.

Booth said that the land's passage into state hands will allow the DNR to better protect the site from future development and also restore it to its more natural state in coming decades.

"Having it in state control definitely adds more protection to it," Booth said last week. "We would like to restore it to its old state ...

"It's sort of like having a living museum."

Heron Marquez Estrada • 612-673-4280