This highway expansion project in Maple Valley required strict stormwater management due to discharges into Taylor Creek and the Cedar River—both sensitive waterways that support Endangered Species Act-listed salmon populations.

Before Clear Water Services joined the project, previous mishandling of stormwater raised serious environmental concerns. Clear Water was brought in under close oversight from multiple agencies and stakeholders, including the Washington Department of Ecology, WSDOT, King County, environmental consultants, and lead contractors. The site was under constant monitoring, with regular water quality sampling to evaluate system performance.

Within weeks of system deployment, a 100-year storm event pushed the treatment systems to their limits, with turbidity levels exceeding 6,000 NTU in the influent. Operating continuously under emergency conditions, the two treatment systems processed over one million gallons of stormwater and groundwater without a single discharge exceeding water quality limits, successfully protecting the ecologically sensitive receiving waters and restoring confidence in the project’s environmental stewardship.