Stormwater infrastructure hidden in plain sight throughout Eugene

Eugene often gets more than 40 inches of rain a year, and all that water has to go somewhere.

Much of the rainfall is absorbed by the ground, but significant amounts land on roofs, parking lots, streets, sidewalks, driveways and other impervious surfaces, becoming runoff.

That's where the City of Eugene's stormwater system comes in.

Runoff flows to street catch basins and then through concrete culverts, pipes and channels, before ending up in the Willamette River or Amazon Creek.

These City of Eugene stormwater structures effectively divert water to prevent flooding, but the runoff often carries pollutants to the two waterways, including sediment, oil, heavy metals, nutrients, pesticides, bacteria and debris. These contaminants degrade water quality, harm ecosystems, threaten aquatic life, and pose health risks for downstream users.

Within the past 10 years or so, Eugene has been building new types of stormwater facilities that are more efficient at slowing, retaining and filtering runoff than older concrete-only structures.

The facilities are built as part of City street projects or by developers to handle runoff in new neighborhoods and in commercial areas.

The newer facilities are not optional. They help Eugene comply with its state-issued permit to discharge stormwater, which requires the City to follow a management program to minimize pollutants, manage runoff and enhance water quality. The facilities also are required for the City to receive federal street construction funds.

Eugene residents may have noticed new types of stormwater facilities appearing along streets in commercial areas and next to streets in newer neighborhoods.

The three most common are rain gardens, stormwater planters and bioswales, all of which use soil, plants and other permeable surfaces to capture and cleanse rainwater and runoff.

"The City of Eugene's green infrastructure, including stormwater planters, rain gardens, bioswales, vegetated medians and street trees, plays a critical role in managing stormwater runoff," said Nick Smith, stormwater and medians maintenance crew lead in the Parks and Open Space division. "These systems help control flooding, reduce harmful pollutants entering our streams and rivers, and improve water quality through natural filtration."

Bioswales are gently sloping depressions with dense vegetation and grass. As runoff flows along the length of the swale, grass and other plants slow and filter the water, allowing it to soak into the soil.

Stormwater planters are typically made of concrete and contain a layer of soil and vegetation. Runoff slowly soaks into the soil, and then makes its way into the ground below or into an underdrain system that flows to local stormwater pipes, or both.

Generally located between sidewalks and streets, stormwater planters were recently installed as part of the reconstruction of Eighth Avenue downtown. They also can be found in recently built neighborhoods, such as on Meadowood Drive, off Gilham Road in north Eugene.

Rain gardens, which use plants and soil to absorb and filter pollutants and allow water to percolate into the ground, are becoming more common in residential areas.

As homes are sold, new owners may not be aware that there is an operation and maintenance document recorded with the deed that requires the property owner to maintain the rain garden and submit a maintenance log annually.

City staff are available to provide assistance and direction if you have questions about a stormwater facility in your neighborhood or new home. Please call 541-682-4881 or email Cristine.A.Inglis@ci.eugene.or.gov

To date, the City has more than 600 environmentally friendly stormwater facilities covering about 13½ acres, Smith said.

Year-round maintenance performed by the City's green infrastructure operations team is vital to ensuring that publicly owned stormwater facilities along streets remain healthy and fully functional. This includes sediment removal, which is important because toxic materials land on streets before they are transported in runoff.

Each year, City crews scrape more than 21 cubic yards of sediment out of the facilities, preventing harmful chemicals from making their way to waterways and natural areas.

By promoting water retention and enhancing groundwater recharge, these facilities "protect our aquatic ecosystems, support biodiversity, and safeguard public health," Smith said. "Additionally, this green infrastructure helps mitigate the urban heat island effect, improve air quality, and create more livable, resilient communities, benefitting both the environment and the people who live here."