NORTH SMITHFIELD — A new economic development plan for Branch Village envisions the existing houses, duplexes and triple-deckers mixed in with small shops and stores, some with apartments on their second floors.

Before they can build that new Branch Village, they have to build a swamp.

The town is seeking a $174,800 grant from the state Department of Environmental Management to construct a man-made wetland what will serve as a biological filter for storm water that runs off Route 146a in the village before ending up in the Branch River.

Branch Village is essentially built on a slope that starts uphill on the northeast side of Route 146a and drops down to the Branch River, which meanders on its way through the area to a rendezvous with the Blackstone River in Woonsocket. That slope means that a lot of the pollutants from the road — bacteria, metals, sediment — are often carried by rainwater straight into the river.

The town wants to create a 12,000-square-foot wetland near the river and channel storm water runoff from the village area to it. Once in the wetland, the water can pool for a time, where the solids will settle, vegetation will eat up fertilizing nutrients and naturally occurring ultraviolet radiation will break down the bacteria all before the water reaches the river.

The wetland would serve an area of about 18 acres, one that includes houses, commercial establishments and an industrial park. John Flaherty of the Branch Village Task Force said the wetland will do more than just naturally treat the storm water before it reaches the Branch River.

“Additional benefits from this project include the creation of both wildlife habitat and a recreational trail through the system, allowing public access to the river as well as raising the neighborhood’s awareness of storm-water runoff,” Flaherty said.

Flaherty said the revitalization task force is developing a more detailed presentation for the Town Council, a presentation it hopes to make on Oct. 6. One of the main sticking points in the plan is whether the redevelopment agency that would oversee land development in the village should have the power of eminent domain — when the government can compel the sale of a piece of property whether the buyer wants to sell or not.

Flaherty said that, if granted, the authority would be used infrequently and is mostly intended to be available in cases where the ownership of a piece of land has to be determined.

Another instance where the agency may come in handy will be in negotiations about land behind the old Providence-Worcester Railroad bed. Flaherty said the railroad still has easements on parcels of land in the area, and eminent-domain power may be helpful should the town have problems in any negotiations about them.

In previous hearings on the plan, some village residents have expressed concerned that such power might be used to move them out of their homes to make room for a new commercial developer. In response to that criticism, Flaherty said the task force may propose exempting any residential property from the agency’s eminent-domain authority and making any use of eminent domain subject to Town Council approval.

“We want to have that tool available,” he said. “That tool can be under any number of locks and keys to prevent abuse.”

jhill@projo.com