MARYSVILLE — It’s been two months since the levee at the Qwuloolt Estuary was breached, letting the tides return to the lowlands for the first time in a century.

There are early signs that the action is having its intended effect.

“We’re already seeing marine species like smelt come in,” said Morgan Ruff, the Snohomish Basin Capital Program Coordinator for the Tulalip Tribes.

Biologists monitoring the changes to the landscape have also caught an adult coho salmon in the new estuary.

It’s still early in the process, Ruff said, too early to begin quantifying the results of the project. But the anecdotal signs instill a sense of optimism.

“It’s pretty amazing that as soon as you open up the habitat, the fish start using it immediately,” she said.

Ruff’s update was part of a presentation on Saturday at Sound Living 2015, a one-day conference put on by the Washington State University Snohomish County Extension Beach Watchers program.

The one day event at Mukilteo Presbyterian Church featured half a dozen speakers on various environmental themes, from Salish Sea orcas to beach safety.

Ruff also showed a time-lapse video of the levee breach and subsequent flooding over several days’ time.

Other signs of change in Qwuloolt include a gradual dying off of invasive reed canary grass and its population of rodents.

Much of Ruff’s talk was devoted to the importance of estuary restoration in general, with Qwuloolt providing the most recent example of work to restore salt marshes to the river deltas.

Estuaries provide habitat for juvenile salmon, where they can feed and grow until they head out to sea.

Over the past century, Ruff said, more than 80 percent of historic habitat has been lost to development.

Even after the start of the environmental movement in the 1970s, populations of the nine species of anadromous fish in the basin continued to decline through the early 2000s.

Add to that the continuing effects of environmental change, including more fall floods that harm young fish, and lower summer water flows that keep returns down, and it’s an uphill climb to try to encourage the growth of anything approaching historical returns.

“Our scale is pretty heavily tipped. It’s a challenging place to be if you’re a small fish,” Ruff said.

The ultimate goal outlined in the county’s Snohomish River Basin Salmon Conservation Plan is to bring the population back up to 80 percent of its historic numbers through a combination of habitat protection, restoration, and smart harvesting and hatchery operations.

This is happening at a time when the population of the Puget Sound region is expected to grow to 5 million by 2040, with all the necessary attendant infrastructure, said Erika Harris, a planner with the Puget Sound Regional Council, who was also speaking at Sound Living.

Continued development has led to low stream flows, increased water temperatures, degraded quality of freshwater and sediment — all the things habitat restoration is intended to counteract.

“This paints a pretty gloomy picture when we know the region is going to continue to grow,” Harris said.

The Qwuloolt Estuary is one of three large restoration projects in the Snohomish River basin that are part of the Puget Sound Partnership’s plan to restore 7,380 acres of tidelands by 2020. In addition to the 315 acres of estuary in Qwuloolt, Snohomish County plans to restore 350 acres on Smith Island and the Port of Everett’s Blue Heron Slough project is transforming a similar-size tract on what used to be Biringer Farm next to I-5.

It’s taken the Tulalip Tribes 20 years and $20 million in funds to get the Qwuloolt Estuary to where it is today. Scientists will continue to monitor the new tidal marsh as it continues to return to its natural state.

Chris Winters: 425-374-4165; cwinters@heraldnet.com. Twitter: @Chris_At_Herald.