This is the time of year that road improvements take on a new twist in King County. During the summer months, Road Services Division engineers and biologists combine their environmental and construction skills to work in and near rivers and streams in ways that ensure that fish habitat is protected.

Whenever working around streams and rivers, crews have to get the job done within a certain timeframe known as the “fish window.” This is the period the Washington Department of Fish and Wildlife (WDFW) will allow crews to work in or near fish habitat areas. The fish window usually runs from July 15 to September 15, and it's the time when construction causes minimal impacts to fish migration and spawning cycles.

Working during the fish window can be complicated, but county crews have come up with a variety of techniques to protect fish and habitat while construction is underway. For instance, WDFW requires biologists to complete “fish exclusion” from the work site, which means fish need to be removed from the work area. Biologists will often string block nets up and downstream to temporarily prevent fish passage through the construction site, and then use hand-held nets to remove visible concentrations of fish. To remove fish in hard-to-reach places, such as deep pools and rocky crevasses, fish are stunned just long enough to scoop them into buckets so they can be safely released in another area of the stream. This process also requires biologists to count the number and types of fish found, which helps them and WDFW assess the overall health of the stream.


Biologist Rob Fritz notes species and counts fish before releasing them in safe water downstream.

Fish removal is just one of the environmental requirements the county must comply with when constructing projects within a fish window. Depending on the nature of the project, road crews use a variety of other tools to protect streams near work sites. Natural woody debris such as logs or tree stumps, erosion control matting, silt fences and native vegetation plantings are frequently used to prevent erosion and reduce construction impacts. When bridge crews are working over a stream, the work area is netted underneath to keep debris from falling into the water. And throughout the construction period, crews monitor water quality to ensure impacts are kept to a minimum.

When county engineers assess the need for a project, they look for long-term solutions for a variety of problems. Whatever the construction project – be it bridge replacement, stream bank restoration, or culvert installation – it needs to be built to last well into the future. It has to safely withstand wear-and-tear from traffic, as well as the natural elements. And, now with the efforts to preserve and improve our native fish populations, county crews work to leave the habitat for all the living creatures and vegetation in better shape for future generation.