Thursday, June 27, 2019

Small steps help in the journey to restore salmon habitat

By Tom Pearce

Times change. In the 1800s, there were so many salmon few people gave them a second thought. Where there was marshland, it was easy to dry the land and put it to work.

Now we know preserving and reestablishing salmon habitat is important. That’s part of the reason that where SR 529 and I-5 meet just outside Marysville, we are going to restore a roughly 11-acre site along Steamboat Slough to the way it was in the 1800s – saltwater marshes near where the slough meets Puget Sound.

The restoration is important because beginning before the turn of the 20th-century developers built dikes to keep out water, allowing businesses and farms to use the land. Other projects buried the original marshes with fill material dredged from Steamboat Slough.
The Snohomish River delta used to be a huge estuarine habitat for young salmon. Development 
has reduced that habitat to just 17 percent of what it once was.

And yep, long ago we were among those turning marshes into dry land. Back in the 1950s and ’60s we built dikes and dredged to build up the area where I-5 and the northbound lanes of SR 529 now carry tens of thousands of people each day. The cost was eliminating estuarine habitat, where saltwater and freshwater mix.

Now we realize how important those wetlands are and the effect they have on marine life and the food chain. Tiny marine organisms need calm places to live. Young salmon, which feed on smaller organisms, need a place to grow stronger for their journey to the ocean. Orcas need those salmon to grow and become a food source to help the whales thrive.
Saltwater marshes like this provide an important nursery for young salmon. 

Land development projects have reduced the estuarine habitat in the Snohomish River delta to just 17 percent of what it was more than 100 years ago. Restoring 11 acres may not sound like much, but it’s something, particularly to young Chinook, coho, pink and chum salmon who use this habitat as a nursery before heading out to sea. Sometimes we need to disturb these valuable wetlands. When that happens, we’re as careful as possible. We have a project in a couple of years to build new ramps connecting I-5 with SR 529. To do this, we’ll need to take about 2½ acres of wetland where the highways currently cross.
This project will restore this saltwater marsh by cutting down these trees, lowering the land level and breaching the dikes, allowing tidal flows from Steamboat Slough into the area.

We’re restoring the 11-acre site to replace that 2½ acres and expand the estuarine habitat along Steamboat Slough. In the coming weeks, we will cut down trees that have grown on the site between I-5 and SR 529. We’ll dig out the dredged material to lower the land to its original level, cut channels for water and place the felled trees on the site to add diversity to the habitat. We’ll add native plants that grow well in marshy land. In late summer or early fall, we’ll open the dikes to let the water flow in with the tide. In the end, we’ll add a net gain of about 8½ acres of estuarine habitat. Biologists expect fish to return almost immediately.

A hundred years ago salmon were an afterthought. Now we’re much more conscious of their importance to the ecosystem. It will take a long time for salmon populations to recover. Projects that restore habitat, like this one, will make a difference.