Detailed planning and design, followed by thoughtful construction projects, have begun to tame the stormwater menace in Clear Creek, an important salmon stream that runs through Silverdale in Central Kitsap.
Stormwater has been identified as the greatest pollution threat to Puget Sound. In Kitsap County, many folks believed that the dense development pattern in and around Silverdale has doomed Clear Creek to functioning as a large drainage ditch for runoff into Dyes Inlet.
But reducing stormwater pollution is not beyond the reach of human innovation, as I learned this week on a tour of new and planned stormwater facilities in the Clear Creek drainage area. The trick is to filter the stormwater by any means practical, according to Chris May, director of Kitsap County’s Stormwater Division and a key player in the multi-agency Clean Water Kitsap program.
Projects in and around Silverdale range from large regional ponds of several acres to small filtration devices fitted into confined spaces around homes and along roadways.
On the small side, below-grade planter boxes have been installed along Silverdale Way, Bucklin Hill Road and Ridgetop Boulevard to filter runoff flowing into storm drains. One can spot these innovative devices by looking for the protective “cages” that keep people from trampling the young plants.
Rain gardens, another filtering technique, can be installed in people’s yards, along a roadway or anyplace where they can capture a relatively small volume of stormwater. Several housing developments, including Shadow Glen north of Silverdale, have been given the name “green streets” for infiltrating stormwater into the ground rather than passing it into Clear Creek.
On a somewhat larger scale, one strategy widely used in Kitsap County is to reconstruct stormwater ponds in old developments. Old stormwater facilities typically contain a single open pond surrounded by a chain link fence. Such ponds can be enlarged and divided into sections, known as cells. Contaminated sediments settle out in the first cell before the water passes into the second cell, and so on.
The old “stormwater prisons,” as Chris May calls them, may slow down the flow of water, but they have limited abilities to reduce pollutants. New ponds are built more like miniature wetlands, where vegetation helps to settle and absorb the toxic runoff.
Often the edges of an old pond can be sloped more gradually than what was done in the original construction. That reduces the drowning hazard of the old ponds and allows the chain link fencing to be eliminated. Many of the new ponds are now surrounded by a split-rail fence.
Tuesday’s tour, which included public officials and interested citizens, stopped at the Quail Hollow development north of Silverdale, where an old pond was turned into a new wetland with high-tech functions — including a metered discharge and solar-powered aerator. The aerator boosts oxygen levels to keep the water from becoming stagnant during low-flow periods.
A walking trail, which loops around Quail Hollow Regional Pond, will eventually connect to the Clear Creek Trail. As people on the tour walked around the pond, a great blue heron gazed out from the middle of the stormwater wetland.
Amenities like the walking trail and improved wildlife habitat make the new stormwater ponds more appealing to nearby residents, Chris noted.
“I’m told by the birders that this is a nice place to watch birds,” he said.
The next “stormwater park” to be developed will be at Whispering Firs north of Silverdale. It will be another natural pond surrounded by a split-rail fence with a trail eventually connecting to the local trail system.
Another multi-celled stormwater system was constructed on vacant land behind two shopping centers in Silverdale’s commercial area. The project, adjacent to the Clear Creek Trail on the west side of the stream, captures water from the adjacent parking lots and includes a trail connection between T.J. Maxx and Ross Dress for Less.
Chris also showed the group several large culverts, which replaced small ones that had impeded the passage of salmon. One culvert on Sunde Road was replaced with a foot bridge for students going to and from Clear Creek School. Neighbors supported the project, because it eliminated a road that was used as a shortcut by motorists passing through the neighborhood on the way to the school, Chris said.
“A question you should always ask,” he said, “is ‘Do you really need this road?’”
Eliminating the road also created a safe place for people to watch salmon swimming in Clear Creek and a place for students to release salmon as part of the Salmon in the Classroom program.
Tuesday’s tour ended at the Clear Creek floodplain project, which I discussed in Water Ways last September. That $3-million project involved the removal of 30,000 cubic yards of material across 21 acres, including the former Schold Farm on the west side of Silverdale Way and the Markwick property on the east side. The project is designed to slow the flow of water downstream while providing a rich habitat for fish and wildlife.
Rocky Hrachovec, principal engineer for Natural Systems Design, said the key to restoration projects is to understand the history of an area, including the former elevations of the stream at various locations.
“It’s important to understand what was here before and how close we can get to that,” he said. “For salmon, you want some places with shallow, fast water and other places with deeper, slower water.”
During heavy rains, Clear Creek is expected to spill over its banks within the restored floodplain and even shift the location of its streambed over time. Logjams have been carefully located to create hard points to confine the flow within the property, he said. The restored floodplain will essentially store excess stormwater and release it slowly back into Clear Creek.
Andy Nelson, director of Kitsap County Public Works, said the efforts to restore Clear Creek did not come about by accident.
“Everything we have seen here today is the result of a thought process, a vision,” Andy said, commending Chris May for his leadership and the hiring of innovative design teams and construction firms.
Andy also gave credit to other innovators, including those who developed a nursery to produce the wetland plants used in many of the projects and those who organized volunteers to safely capture fish so that they wouldn’t be killed during construction. He also commended many others — from volunteers to construction companies to elected officials.
Clear Creek is not the only watershed in Kitsap County where stormwater is being tamed by removing its powers of pollution and erosion, but it stands as an example of what can be done in heavily urbanized watersheds. While habitat loss along the stream cannot be easily replaced, the various stormwater projects go a long way to restoring the health of Clear Creek.