The city of Blaine is working to build up wetlands now in preparation for development later.

At its most recent meeting, the City Council approved $30,000 for a system to "impound" groundwater in a 524-acre parcel near Pheasant Ridge. It also gave staff the go-ahead to seek bids for a half-million-dollar project to remove invasive and exotic plants from that parcel and replace them with native species.

The first phase, which should begin within a couple of weeks, will work to restore water levels in the onetime wetland northwest of 109th and Lexington Avenues. The next phase, which probably wouldn't start until September or October, will involve removing the unwanted species in favor of the natives, which will be introduced by seed and seedling.

The result will be a net gain of 56 or more acres of wetland that can be banked until the city needs to use them to offset the loss of wetlands in future development.

Normally, when the city approves a development project that disturbs a wetland, the developer must replace the lost acreage at a 2-1 ratio, that is, two new acres of wetland for each one lost. The work of finding and restoring or creating wetlands is done by the developer, with aid from the city's Economic Development Authority, under the eye of the state Board of Water and Soil Resources.

If the project discussed by the City Council proceeds as planned, the city will be able to sell or donate credits for the added wetlands to a given future project. Developers still will be able to seek out their own acreage for remediation. The city's estimate of the credits' value is $2.5 million.

Initially, the city planned to proceed only with the groundwater system, which would prevent groundwater from seeping downstream and off the parcel between rainfalls and during dry spells. But along the way, the city learned that by restoring the native vegetation, it could create more wetlands, faster.

"If we [only] put this structure in, we could expect over the next number of years -- maybe a decade or longer -- it would naturally start to come back and be more wetland plants. That's the theory, anyway," said Community Development Director Bryan Schafer. "We're skipping ahead 15 years."

Schafer predicted that the actual cost of remediation will be much lower once the bids come in and contractors can explore alternative methods. It is possible that the Economic Development Authority could fund the entire project, using pooled tax-increment financing money.

The city may be able to start banking some credits within a year or two, depending on how the restored wetland thrives.

"We're telling everybody this is a five-year process," Schafer said. "We may not have the majority of the credits available until five years from now."

Most of the land was deeded to the city in the late 1980s by developers who built the neighborhoods that skirt it, in exchange for required park dedication land. It had been drained long ago, probably for farming, Schafer said. A trail runs through part of it, and another is proposed to link trail heads on Lexington Avenue and 109th, with access points in the surrounding neighborhoods.

One hope is that the work will position the city to get moving on new development across 109th Avenue, on the 160 acres once known as the Trost, Wilson and Carlson properties.

"We didn't go in planning to spend half a million to take out plants," Schafer said. "But it's better to have 50 acres of wetland credit than 15."

Maria Elena Baca • 612-673-4409