A little strip of land leading to Grey Cloud Island Township will get a lot of attention this year as Washington County throws its muscle behind an effort to build a bridge.

The bridge would replace an earthen dam that has served as the main road to the north end of the township since the 1960s, but the project has wider environmental implications. The dam blocks a 2.8-mile Mississippi River channel that, for lack of free-flowing water, is filling with invasive weeds and someday could wind up a swamp.

"Everyone recognizes that it's inevitable if we don't do something," said Township Supervisor Dick Adams, who said the problem has been under study for at least 10 years.

County engineers now will prepare a proposal to commit an estimated $500,000 in county funding to the $1.6 million project, which would include new pavement for County Road 75 and a bridge to restore the channel, known locally as a slough. Under the agreement, the county would turn over the road to the township in 2018.

Grey Cloud Island is actually two islands surrounded by lakes and river channels. The township has a mere 300 residents, but it has the largest limestone quarry in the county on the north island. The south island has a sand-and-gravel operation.

The bridge was the most favored alternative to replacing the dam, County Engineer Wayne Sandberg told the county's five commissioners last week. Several public agencies that examined possible solutions settled on the bridge for reasons such as safety and fish passage, he said, and the higher road would be less prone to flooding.

"Getting all those agencies to agree on anything is a miracle. We have a miracle here because they all agree that a bridge is the best way to go," Sandberg told the commissioners. The presentation came in a workshop, which means no vote was taken.

Whenever the proposal comes up for formal consideration, commissioners will decide whether to pay for the work from the county gravel and wheelage taxes, from the county levy, or from other sources such as federal and state grants.

Also under consideration as a source of money is the county's Land and Water Legacy fund, a voter-approved initiative to save open spaces and improve water quality.

Adams said the Grey Cloud project fits the vision of Land and Water, because fresh water once again would flow through the channel and a bridge would improve the link to parkland on the island.

"That money is not just for land acquisition," he said. "It's for water projects also, and this is exactly what this is."

About half of the funding for construction would come from the South Washington Watershed District, which is leading the project. The balance of the money, about $350,000, would come from sources that haven't yet been determined.

Watershed supervisors weren't fond of installing a less-expensive culvert instead of a bridge, because it would create a fast current especially dangerous to children.

Replacing the earthen dam makes sense from both water quality and transportation points of view, said Commissioner Autumn Lehrke, whose district includes Grey Cloud Island.

In a separate action, the County Board is considering whether to buy property owned by Betty Kartarik to contribute toward an envisioned Grey Cloud Island Regional Park. It would be purchased with Land and Water Legacy money and would be added to other properties the county has acquired for the park.

Kevin Giles • 651-925-5037 Twitter: @stribgiles