New bridges provide improved habitat in two Kitsap County creeks

Contractors are putting the final touches on two new bridges in Kitsap County, both of which are expected to improve the local environment.

One is a 150-foot bridge that crosses the Carpenter Creek Estuary on West Kingston Road near Kingston. The other is a 50-foot bridge that crosses Big Anderson Creek on Seabeck-Holly Road near Holly.

Among local residents, the Carpenter Creek bridge may best be known as the bridge that blocked traffic and forced a detour near Kingston for more than a year — much longer than originally planned. (Recall reporter Nathan Pilling’s story in the Kitsap Sun.) While contract issues remain in dispute, the environmental benefits are clear, according to Joleen Palmer of the nearby Stillwaters Environmental Center.

Replacement of a 5-foot culvert with the bridge over the estuary has obvious benefits for salmon that must fight the current to go upstream to spawn, Joleen told me, but people may not appreciate the importance of the much-expanded salt marsh.

When the roadbed was installed nearly a century ago, it formed a dam, causing water in the stream to back up, which encouraged freshwater vegetation. The saltwater influence was greatly reduced, and critical nutrients coming downstream were deposited before they reached Puget Sound.

The new bridge will allow saltwater to come and go with the tides and for nutrients to flow out more freely. Juvenile salmon coming downstream can pause to grow and acclimate to the saltier conditions they will face.

Salt marshes, which were filled in all too often years ago, are considered highly productive, because dead organic material — detritus — from the stream and estuary feeds bacteria, insects, worms and a multitude of other tiny creatures at the base of the food web.

“Salt marshes are really detritus-based ecosystems,” Joleen said. “You have many invertebrates that eat the detritus and other decomposers. The food sources reach out into the estuary and nearshore habitat to fuel the marine food web. It is not insignificant that the area is now opened up.”

Side channels in the marsh will provide refuge for young fish to grow before they head out to sea. To varying extents, the stream, marsh and estuary are expected to support coho, chinook and chum salmon along with steelhead and cutthroat trout.

Volunteers and students have been monitoring conditions in the watershed to measure the changes taking place. The latest addition to the monitoring effort is an ongoing search for the invasive European green crab. The volunteer program, called the Crab Team, is managed by Washington Sea Grant.

“The estuary is still some distance from known populations of invasive European green crab,” writes Cindi Nevins, a North Kitsap resident who joined the team, “but if the green crabs ever do arrive at Carpenter Creek, they will find exactly the kind of space they love: salt marsh channels, marsh vegetation and quiet lagoon-like waters. Why do we think they’ll love it? Because hairy shore crabs (Hemigrapsus oregonensis) do!”

Throughout Puget Sound, Crab Team members catch and identify hundreds of thousands of crabs in marsh habitat suitable for both the natives and the invaders. The volunteers hope never to catch a green crab, but some green crabs have been found in a few places in Northern Puget Sound and the Strait of Juan de Fuca. By intensifying the trapping effort, the Crab Team hopes to eradicate the invaders, or at least keep them under control.

Cindi’s report, published in the Crab Team’s newsletter, goes on to describe the challenge of catching crabs in the Carpenter Creek marsh, which often drains completely at low tide. Because the traps must be kept submerged to be effective, the volunteers are often forced to set the traps in the evening as the tide comes in and retrieve them early the next morning before the tide goes out.

To celebrate completion of the new bridge, everyone is invited to celebrate “Estuary Restoration Day” on Saturday, June 9, from 11 a.m. to 1 p.m. at Stillwaters Environmental Center, 26059 Barber Cut Off Road, Kingston.

The program will include guided tours to the marsh, live music, food and a native plant sale. Those involved with various aspects of the project will receive special recognition.

For information and videos about the marsh, visit the Stillwaters website.

The bridge over Big Anderson Creek near Holly is more of a highway-safety project than an ecosystem-restoration effort. The wooden bridge, 67 years old, was the last bridge in Kitsap County to be rated structurally deficient because of its overall poor condition. Check out the story in the Kitsap Sun by reporter Ed Friedrich.

Still, the new concrete bridge, which spans 50 feet of stream, is nearly twice as long as the old bridge. That will allow the stream to meander more naturally and at a rate that sandbars can form nearby. At high flows, the stream won’t be squeezed as much through the space under the bridge.

By the way, the official name of the stream is “Anderson Creek,” allowing confusion with two other streams named “Anderson” in Kitsap County alone. I prefer to call it “Big Anderson,” in conformance to tradition by area residents and local institutions. For a further explanation of the issue, read Water Ways, June 22, 2017.

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