The Cottonwood Neighborhood Drainage Improvements Project is located near the intersection of Cedar Avenue and Birch Bay Drive. This project replaced failing stormwater facilities and added new stormwater infrastructure to meet project goals. It was identified as a priority capital project in the Birch Bay Comprehensive Stormwater Plan (CT 06) to address flooding and safety problems. Fecal coliform bacteria monitoring data from this drainage show levels about six times higher than similar drainages entering Birch Bay. This amount of bacteria represents a public health risk and makes improving water quality in this drainage a high priority.

Project components include: a new stormwater conveyance system under Cedar Avenue to carry flows from higher elevation land to the beach, a bioswale to clean stormwater runoff from the Seaview Drive and Maple Crest Avenue area and eliminate a hazardous drainage confluence, an improved low-level drainage system on Birch Bay Drive, and removing an old bathhouse foundation on the beach. Separating flows from upland areas from the low-elevation areas around Birch Bay Drive reduces the amount of upland flow flooding lower properties during storm events. A bioswale is a type of low impact development water treatment facility where soil and plants remove pollutants from stormwater (see fact sheet for more information). With the new system in place, the old "black T" outfall structure, which was prone to clogging, was removed.

Project Goals

    • Reduce flooding

    • Improve water quality

    • Address safety and maintenance problems

    • Separate high-level and low-level stormwater systems

Construction Year: 2013

Engineer: Reichhardt & Ebe Engineering and Whatcom County Public Works.

Contractor: Len Honcoop Gravel, Inc.

Construction Contract: $468,000


For More Information: contact the Whatcom County Stormwater division at (360) 778-6230


Newly installed bioswale.

Newly installed bioswale at the corner of Seaview Drive and Maple Crest Avenue.


Project area map