April showers bring May flowers.

At the Port of Tacoma’s administration building, they also help control stormwater pollution while blooming with color.

In time for Earth Day, Port staff spent lunch Friday planting four downspout treatment boxes to keep pollutants from flowing into Commencement Bay.

See photos of the boxes. View a 2-minute video of how they work.

Anita Fichthorn, Port of Tacoma’s water quality project manager, designed the boxes to filter the heavy metals picked up by rainwater coming off the roof.

The boxes were engineered and built by Port facilities development and maintenance staff, using materials readily available at local hardware and building supply stores. The boxes—nicknamed Coho, Steelhead, Chum and King—cost about $600 each to build.

They mimic the natural environment to filter pollutants. Nestled in a bioretention soil mix of sand and compost that controls the flow of water, the plants take up zinc and other pollutants to use during photosynthesis.

“The boxes play a key role in our efforts to control heavy metal releases from our industrial properties,” Fichthorn said. “They also help us comply with the terms of our stormwater permit.”

The boxes were tested last year at Pierce County Terminal and the Port’s maintenance facility. Those pilot boxes removed 99 percent of metals, particularly zinc and copper.

About the Port of Tacoma
The Port of Tacoma is an economic engine for South Puget Sound, with more than 43,000 family-wage jobs in Pierce County and 113,000 jobs across Washington state connected to Port activities. A major gateway to Asia and Alaska, the Port of Tacoma is among the largest container ports in North America. The Port is also a major center for bulk, breakbulk and project/heavy-lift cargoes, as well as automobiles and trucks.