Compounding the adverse effects of these losses, vast hydrologic changes that have resulted from drainage have degraded many of Minnesota’s remaining wetlands. Some individual and municipal wells also have been contaminated by nitrates from crop fertilizers.
It wasn’t always so. Before white settlement, Minnesota was littered with small “pothole” wetlands that were sometimes wet and sometimes dry, as well as larger wetlands with open-water centers, and shallow lakes. These waters soaked up and filtered rain, snow melt and runoff.
But the loss of about 90 percent of farmland wetlands has rendered many of the state’s remaining wetlands and shallow lakes part of a dramatically contracted “plumbing system” that must accommodate the same amounts of water Minnesota has known for eons.
Even state wildlife management areas and federal waterfowl production areas purchased and curated specifically for wildlife values are part of this rejiggered water-ridding system, serving as they often do as receptacles for drained farmlands and cities’ storm water.
As a result, water levels of many remaining wetlands are too high, or too highly variable, to support plants and insects needed by wildlife.
Which is why so many Minnesota duck hunters — whose ranks once swelled to 170,000, more than twice those who went afield last fall — have hung up their guns, or now pursue birds in the Dakotas or Canada.
But ducks are just a part of a larger Minnesota water-management problem.
Accelerated sub-surface farmland drainage. Topsoil losses. Depleted aquifers. Siltation, or filling in, of the Minnesota and Mississippi rivers and Lake Pepin. The state’s significant contribution to the Gulf of Mexico “dead zone.”
And the aforementioned well-water contaminations.
Each affects Minnesota, and Minnesotans, and will for generations.
But there’s some good news.
One government program designed to replace the continuing loss of Minnesota wetlands is working.
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Several times a year, Jason Kirwin takes a call from someone wanting to build a wetland, not drain one. Kirwin’s company, Environmental Scientific, is located in prime farm country, near Morris, in Stevens County.
Kirwin is a certified wetland delineator, meaning he can determine a wetland’s size and type whether it exists today, or long ago.
People call Kirwin because they want to make money while rebuilding a wetland — in some cases a lot of money. Or they call because they want to enjoy the fruits of a refurbished wetland — such as ducks and other wildlife — and make money.
“But of the calls I get, most of the projects they propose just aren’t feasible for a variety of reasons,’’ Kirwin said. “Either they don’t have a big enough wetland project to make it worthwhile, or they can’t afford, financially, the lengthy process that is required to rebuild a wetland and get ‘credits’ for it that can be deposited in the wetland bank and sold.’’
Minnesota wetlands still can be drained in some instances according to state and federal law, provided they are replaced. The most common replacement method involves the purchase of replacement “credits’’ from the state Wetland Bank.
“The Wetland Bank was established in the early 1990s following passage of the state Wetland Conservation Act by the Legislature in 1991,” said Les Lemm, Board of Water and Soil Resources (BWSR) wetlands section manager.
The Wetland Bank has evolved considerably over the past 25 years. Some restored wetlands that initially were included in the bank were of poor quality, with relatively few wildlife or other benefits.
But beginning in 2009, rules governing the construction, oversite and maintenance of replacement wetlands qualifying for inclusion in the bank were tightened.
“Our performance standards, and those of the federal government, now require a replacement wetland to be restored as much as possible to its natural hydrology, with diverse native vegetation, and protected by a buffer,’’ Lemm said. “Replacement wetlands also must be protected perpetually by conservation easements.”
Property owners who successfully reclaim a qualifying wetland are given one or more “credits” according to the size of the restored wetland. The credits are held in the state’s Wetland Bank, which is administered by BWSR — and in some cases are worth a lot of money.
“In this part of the state, a credit is worth up to about $1.50 a square foot, or in the neighborhood of $60,000 an acre,” Kirwin said. “There are a lot of expenses that go into restoring a wetland, from the planning and engineering to the construction and the monitoring. It can take up to four years, with monitoring occurring for five years after that.
‘‘But for a person who owns a wetland that qualifies for restoration, has enough money and patience to do the work, the financial incentives are there.’’
Prices of credits are market-driven, and vary by region in the state. Credits in farmlands are the most costly, and those up north, the least.
Before drainage can begin, credits must be withdrawn from the bank and paid for, and drained wetlands must be replaced with credits from the same general part of the state. Farmers are allowed to replace drained wetlands on a 1-to-1 basis, but developers and even state agencies such as the DNR are governed by a 2-to-1 replacement ratio.
Currently, about 40,000 acres, or credits, reside in the Wetland Bank, with just over half of those acres in a single northeast Minnesota site that was built by private investors to sell to mining companies.
Withdrawals from the bank have ranged from a low of five when the program began, to 860 in 2005, with almost 10,000 credits withdrawn total.
Yet the question remains: Given that replacement wetlands inevitably will lie within Minnesota’s altered “plumbing’’ system, can they maintain their hydrologic integrity over time?
“That’s a good question,’’ Kirwin said. “I would say they are as good as any out here, and better than most. Twenty years ago, I wouldn’t have said that. But today, the standards for replacement wetlands are high.”