What is a Stormwater Filtration Facility?

Stormwater filtration facilities help clean stormwater runoff. There are two main types: green and grey.

Green Stormwater Facilities

Green stormwater facilities mimic nature to filter stormwater runoff. They use layers of soil, rock, and native plants to clean the water. These facilities have an inlet, like a curb cut, that allows stormwater to flow into the facility. The water gets filtered and either soaks into the ground or flows out through an outlet. There are many different types of green stormwater facilities including bioswale, rain garden, stormwater planter, and green roof.

Grey Stormwater Facilities

Grey stormwater facilities use man-made systems, often built underground, to process stormwater. These systems use physical, chemical, or biological methods to treat polluted runoff before sending it to a stream.

Benefits of Stormwater Filtration Facilities

Both green and grey filtration facilities collect and clean stormwater runoff. They filter out pollution, making the water cleaner before it enters local streams.

In Salem, most storm drains send water directly to streams without cleaning it. This water can carry harmful pollution that affects people, fish, and other animals. Hard surfaces like parking lots and sidewalks add pollution to stormwater. When stormwater flows into a filtration facility, harmful sub-stances, like oil from cars, get filtered out.

Green stormwater facilities are becoming more common because they offer additional benefits:

• They provide green spaces in the city.
• They help reduce flooding by soaking up stormwater runoff.
• Their plants provide homes for local animals and pollinators.
• They encourage community engagement and connection.

Is What You See a Green Stormwater Facility?

Some people think green stormwater facilities are just places where weeds grow. However, the plants there, like sedges and rushes, are important for cleaning stormwater runoff and are not weeds. You can tell if it is a stormwater filtration facility by looking for these signs:

• Are there rows of native plants, like sedges and rushes?
• Is there a curb cut or pipe where water flows into the facility?
• Is there a round metal grate, often called a “beehive,” where water flows out?

If you answered yes to at least two of these questions, it is likely a stormwater filtration facility.

Public and Private Stormwater Filtration Facilities

The City of Salem has about 6,000 stormwater facilities. Some are owned and maintained by the City, while others are owned and maintained by private property owners.

Public Facilities - What You Can Do to Help

Public, city-owned stormwater filtration facilities are maintained by the City of Salem. You do not need to help with maintenance, but you can volunteer if you want! Volunteers can help care for green stormwater facilities in their neighborhood by weeding and watering. The City provides guidance and tools, if needed. If you are interested in volunteering, please contact Brian Smith at bcsmith@cityofsalem.net.

If you do not want to volunteer, the best way to help is to let the facilities do their job. You can also report any issues to Public Works Dispatch at 503-588-6311.

Other Ways You Can Help

• Avoid pruning, cutting, or mowing plants.
• Avoid adding pesticides or other chemicals.
• Keep trash and debris out of the facility.
• Avoid throwing cigarette butts into the facility.
• Avoid walking or using heavy equipment in the facility.
• Let the facility do its job of filtering and cleaning water.

Submit a Photo

Please submit a photo of a rain garden or other stormwater filtration facility along with information about where it is located to help us track them over time.

Private Facilities - Inspections

City of Salem staff inspect all stormwater facilities for public and private property owners.

Stormwater staff inspect earthen detention basins every year and stormwater facilities with Public Stormwater Facility Agreements at least once every two years. Other facilities are inspected at least every five years as part of the City’s stormwater National Pollutant Discharge Elimination System permit. If you have a private stormwater facility on your property, you must maintain it. For inspection results or more information, please email stormwateroutreach@cityofsalem.net.