MARYSVILLE — Dirt and brambles gave way to mud and mud gave way to water as a habitat restoration project hit a long-awaited milestone Friday.

The Army Corps of Engineers carved a 200-foot-wide gap in a levee built more than 100 years ago between Ebey Slough and 400 acres of farmland. The land hasn’t been farmed in decades and had become a lowland mix of invasive plants and creeks populated by non-native fish.

High tides now will flood the area as they did before levees were built. The brackish mix of salt and fresh water is expected to create a rich environment for native plants and fish, especially wild salmon populations that are in severe decline.

The 400-acre Qwuloolt Estuary project is part of a longterm goal by the Puget Sound Partnership, which fronted $2.6 million for the $20 million project, to restore 7,380 acres of tidelands by 2020. They’ve reached 2,260 acres so far.

The Tulalip Tribes are the lead local agency for the Qwuloolt Estuary work, which has been in progress for two decades with a number of local and national partners including the city of Marysville, Army Corps of Engineers and NOAA.

Tribal Chairman Mel Sheldon Jr. called Friday a “day of celebration” as backhoes dug though dirt and muck to clear a space for water from Ebey Slough to mingle with Allen and Jones creeks, which have been rerouted toward the new opening in the levee.

“To reclaim habitat for a positive environment for salmon means a lot to the Tulalip Tribes, to us personally,” Sheldon said. “Our relationship with the salmon is a deep one and the salmon has been an integral part of Tulalip history.”

Project leaders originally planned the restoration to repair damage from a former landfill site on Ebey Island and to restore the watershed, which should be a lush habitat for the dwindling Puget Sound chinook salmon population. Years of development, including diking and ditching along the slough, have damaged the watershed. The restoration work also is expected to benefit native coho and bull trout.

“The big thing with this is it’s the nursery habitat for the chinook,” said Todd Zackey, marine and program manager for the Tulalip Tribes. “It’s the most important step of their life cycle.”

Zackey is part of a team that plans to monitor the results of the project. They’ve been tracking bird, fish and plant populations along with depth, temperature, salinity and nutrient levels of the water around the project site for about six years. They’ll continue their studies every couple weeks. A camera also has been installed to overlook the estuary and provide a constant view of the project.

“We’re at the halfway point for our work,” Zackey said. “This is an opportunity to learn a lot.”

Before the levee breach on Friday, the tribes and their partners filled drainage ditches, built berms ?throughout the interior of the property and removed invasive reed canary grass that would have died and rotted as saltwater flooded the flats. They also planted salmonberry, willows, nootka rose, Sitka spruce and other native species. The Army Corps of Engineers rerouted Allen Creek to merge with Jones Creek and built a new 4,000-foot-long levee to protect Marysville’s wastewater treatment plant and a neighboring industrial park. It was the most expensive piece of the Qwuloolt project so far.

People in Marysville may see the flooding on the former farmland this weekend and worry, but city officials ask that they don’t call 911 to report it, city spokeswoman Bronlea Mishler said.

“If you see something flooding in this area that hasn’t flooded in a century, it’s OK,” she said. “This was planned.”

The tribes and their partner agencies hope to create interpretive trails around the estuary so people can see the habitat transform. Hopefully visitors also can see wild salmon come back, said Joshua Chamberlin, a fisheries biologist with NOAA. The project already has removed obstacles for salmon by rerouting the creeks and breaching the levee. As time goes by, the habitat will become more rich for them in the estuary.

“It’s good to see this happen,” Chamberlin said. “It’s been a long time coming.”

Kari Bray: 425-339-3439; kbray@heraldnet.com