Friday, October 11, 2019

Steamboat Slough now flows in 12½ acres of restored estuary

By Tom Pearce

It was a dark and stormy night. …OK, maybe it wasn’t stormy, but it was dark and there were a couple of really low tides in the early morning hours late last week. That made for perfect conditions for our contractor crews to breach a dike in a couple of places along Steamboat Slough south of Marysville.

As the tide rose, water flowed into 12½ acres of estuary between State Route 529 and Interstate 5 we restored this summer, expanding the “nursery” for young salmon where the Snohomish River meets Puget Sound.

A place for salmon to grow

As recently hatched salmon make their way downstream, estuaries provide a place for them to grow and get stronger for the rigors of life in the ocean. They can grow as they feed on marine life that moves into the estuary and hide from predators among the logs and tree root wads that crews installed on the site during construction as habitat features for salmon and other aquatic critters.

The project is part of our ongoing effort to improve salmon habitat around the state. For many years we’ve been replacing culverts under highways that blocked fish passage, opening up miles of waterways and breeding ground for salmon and other fish. Here in Marysville, this was a case of rehabilitating an area that we covered with fill many decades ago, first to build SR 529 and later for I-5. When we did that, salmon were plentiful and most people didn’t consider the effect on habitat and salmon. Filling in estuaries to create more land for farming or business was common.
The area between the orange barrels is where crews dug out the dike to allow water from
Steamboat Slough into the western part of the estuary.

Now most of us recognize the importance of salmon not just for people, but for other marine life such as orcas that populate the Salish Sea. The rapid decline of salmon populations in our area means less food for orcas in local waters, and has taken its toll on local fishermen as well. Restoring access to more habitat should help with salmon recovery.

More than restoration

Restoring this estuarine environment serves another purpose. It provides advanced mitigation for future transportation projects. In the past it was necessary to fill wetlands for projects, as it was when we built SR 529 and I-5. In those cases, we filled more than was needed. Today, it is necessary to compensate for impacts to wetlands from transportation projects.
As the sun rises so does the tide, coming into the rehabilitated western section of the estuary for the first time.

In 2021 we will need to fill in about 2½ acres of wetland so we can extend an HOV lane on northbound I-5 and add ramps connecting northbound and southbound I-5 with SR 529 near Steamboat Slough, improving access to and from Marysville. The area we rehabilitated to create this 12½-acre estuarine wetland more than mitigates the effect that will be incurred by that project.

It’s all part of a balancing act we frequently deal with – meeting the needs of people while preserving the natural environment, or in this case restoring it. Sites like this provide opportunities for both.

1 comment:

Derek said...

Fantastic project! Well executed! Will look forward to seeing the project site develop into a productive estuary once again over the next several years.

WSDOT comment policy

Post a Comment