Plans for a natural gas pipeline through Dakota County are moving forward, but residents and environmental advocates are asking the company behind it to consider changing its route to avoid Lebanon Hills Regional Park.

"We don't know at this point what the alternate routes could be," said Wendy Heath, a program organizer at Clean Water Action Minnesota who's working with locals to raise concerns about the pipeline. "And so we're asking them to propose a few different ones and then choose the one that's least environmentally impactful."

Northern Natural Gas is planning a nearly 8-mile pipeline that would run from Rosemount to Eagan, then connect to Xcel Energy's Black Dog power plant in Burnsville. The 20-inch pipe would run alongside an existing line that already cuts through Lebanon Hills, and it would affect more than 400 homeowners.

The project's estimated cost is $48 million. Construction would begin in spring 2017.

Locals took some comfort this fall when they learned that Northern Natural Gas planned to drill underground to install most of the pipe, rather than carving out space for it. But they're still worried about possible tree-clearing and soil erosion that could contaminate nearby bodies of water once the pipe is installed.

Northern Natural Gas owns an approximately 60-foot easement for the pipeline that's already there. The new pipeline would mostly follow that existing easement, but residents are still worried that it will disrupt the park.

"Even if they minimize impact in the initial installation, what's going to happen in the future?" said Holly Jenkins, an Eagan resident who lives about a mile from the park and founded the nonprofit group Wilderness in the City.

Pipeline plans are still in the early stages, so little is known about how the park will be affected. Northern Natural Gas is in a "pre-filing" process with the Federal Energy Regulatory Commission (FERC) and will submit a formal application in June, said Northern's external affairs director Mike Loeffler.

Residents have asked if the pipeline could run outside the park, possibly along a road. The Dakota County Parks Department has also asked Northern Natural Gas to present alternatives, said parks Director Steve Sullivan.

The route has already been changed once to avoid a neighborhood, Loeffler said. A resident suggestion for running the line along an existing electrical corridor was considered, he said, but ultimately rejected because it would have had a greater impact on landowners and required closing a major road.

"We can't meet every objection and suggestion that's given to us," he said. "Because every time you make a suggestion, the alternative has its own special impacts."

The Parks Department has talked with Northern Natural Gas about adding more trees and vegetation to the park, Sullivan said.

Still, pipeline opponents want to use this time to communicate their concerns to the FERC. At an informational session Thursday night at the Lebanon Hills visitor center, Jenkins and Heath encouraged a group of about two dozen people to contact the federal agency.

"It's going to be a bit of an uphill battle, but if they don't hear from people, they have no reason to reroute it," Jenkins said.