Sound Transit reports the withdrawal of a petition to pull its permits for aligning light rail and a transit station in the Mercer Slough Nature Park marks the last legal challenge facing East Link.

The Building a Better Bellevue group and Kemper Development Company on April 21 withdrew its petition, which argued Sound Transit’s plans for East Link along Bellevue Way and the west portion of the slough will cause permanent environmental impacts to the nature park.

The withdrawal occurred one day after the city council approved a revised memorandum of understanding with Sound Transit to proceed with light rail construction.

“This was the last of the legal challenges that we had out there,” said Bruce Gray for Sound Transit. “We felt like the shoreline board did a good job granting us the permits and we did quite a bit of work on the EIS.”

Former Bellevue councilmember Don Davidson, who has been speaking for the petitioners, could not be reached for comment by press time.

The state Recreation and Conservation Funding Board also approved on April 9 swapping 6 acres of property in the slough for 1.06 acres of property to be used for light rail adjacent to Bellevue Way Southeast. The RCO had delayed its decision in October to understand the East Link project and alternative alignments that had previously been reviewed.

“We think we have a good path to move on from these kinds of lawsuits and move on with construction,” Gray said.

He said Sound Transit has a healthy mitigation plan to counter impacts from future light rail construction and operation.

That includes replacing about 1,000 trees to be removed along the project with 9,000 trees in the slough, rehabilitating another seven acres of wetlands and adding 7 1/2 acres of storm water treatment adjacent to the slough.

The first phase of East Link construction will be the start of the downtown tunnel in early 2016, Gray said.