return to Downtown Bellingham map
The grate covering the planter box keeps garbage out and protects the soil media below.

Ellis St. and Ohio St. Bioretention Basin

Where is this located? It is near the corner of Ohio and Ellis Street. Look under the shrub near the corner.

What’s special about this place? Designed to mimic natural processes, bioretention basins like this one are easily adapted to urban areas. The street trees create shade and beauty along the way as well as consume stormwater runoff. With a small footprint, they are a cost-effective way to address stormwater in highly urbanized areas.

About Bioretention Basins

Bioretention basins are shallow depressions that use a special soil mixture and specific plants to collect, absorb, and filter stormwater pollutants flowing off hard surfaces. The soil mixture uses soil, compost, sand, and specific minerals to allow water to soak in rapidly, treat runoff, and support plant growth. Hardy, low-maintenance plants adapted to the local climate and soil moisture conditions are chosen including trees, shrubs, and grasses. These plants can have the added benefit of attracting pollinators, providing habitat for beneficial insects and birds, adding beauty, and improving neighboring property values.

Engineered rain gardens are one type of bioretention basin. Some other bioretention basins include proprietary devices such as the Filterra tree box media filter on Ohio and Ellis Street, and the Filterra BioScape on 8th Street.

Water Quality Benefit: Bioretention basins can capture sediment and bacteria, capture oil, pesticides, fertilizers, and dissolved metals. Plant roots also are host to diverse microbial and fungal populations that filter pollution using biological processes. Bioretention basins that have under-drains usually only filter out large sediment and can allow dissolved pollution to pass through.

Water Quantity Benefit: Bioretention basins reduce flooding by either holding rainwater and releasing it slowly, or by soaking it into the ground. Special soil mixtures are chosen to allow water to soak into the ground. Roots break up the soil so water can soak into the ground more easily. If they are built in an area where the existing soils drains well, then water will soak in and recharge the groundwater below. If the existing soil does not drain well, the bioretention basin will be built with an underdrain that lets water out slowly. In a large storm, if there is too much rainwater to fit in that bioretention basin, it will drain out an overflow pipe or bypass the basin.

Use this button below to open map in Google Maps or skip map

Drains 0.04 acres.

Where does the water come from? The stormwater at this site comes from a short stretch of sidewalk on Ellis Street next to the drain.

Where does the stormwater flow next? Stormwater that does not infiltrate at this site flows through pipes under Ellis Street to the outfall at Whatcom Creek near the intersection of State Street and Ellis Street.