What is Watershed Restoration?
Watershed restoration strives to repair the damage done to our environment and natural systems (like rivers and streams) by poor development choices and human activities. Restoration projects:
- Help manage stormwater to improve water quality in rivers and streams.
- Reconnect and restore floodplains to reduce flooding and protect people and property.
- Support salmon recovery by removing culverts and other barriers for threatened and endangered fish.
- Improve habitat in and around a stream to help reduce water temperatures and create places for plants, fish, and wildlife.
- Build community resiliency, which will make our community better prepared to deal with wetter winters and hotter, drier summers.
One Project, Many Benefits
Each dollar spent on watershed restoration generally results in several improvements to watershed health and benefits for people, fish, and wildlife. Read more about why healthy watersheds are important for our community. For example, when we restore a floodplain and reconnect it with its creek, we help protect people and property downstream from the damage caused by flooding. But that work also can:
- Create habitat for threatened and endangered fish like salmon – giving them a place to find food and rest.
- Provide protection for young fish from a fast-flowing, turbulent stream.
- Replenish groundwater, which flows into the creek during the hot summer months replenishing the creek and helping to keep the water cooler.
- Reduce erosion around and into a stream, which helps protect water quality but also can prevent landslides and property loss.
- Add back into the landscape native plants, which native animals have relied on for food and shelter for centuries.
- Increase the number of trees in the riparian area – the area of land along the edge of the creek – which is essential to keeping streams cool and for adding large wood into a stream later. Read more about this below.
Just like trees, the benefits from these projects build and grow each year. Over time, we see more fish going farther upstream. Native plants and trees spread more seeds to establish more native plants. More trees by the stream provide more shade and cooler water temperatures making it better for fish. Over time (often decades), the benefits from restoration re-establish the natural cycle that had been lost.
Find Restoration Projects
Along with the help of many partners, Environmental Services has completed and is working on many watershed restoration projects around Portland. Learn about current and future Environmental Services projects. Find information about past projects that are now part of our watershed monitoring activities.
What Does Watershed Restoration Look Like?
Stream and Wetland Restoration
We need our natural systems like wetlands, soils, and streams to collect and transport much of our annual rainfall. They work together with our pipe system to protect people and property. But rivers and streams do more than just carry water. They are also home to fish, birds, and wildlife. And, we are required to protect water quality and drinking water supplies for generations to come.
Wetlands are special ecosystems that lie at the intersection of terrestrial (land) and aquatic (water) systems. They are often described as “the kidneys of the landscape” because they filter out pollutants to improve water quality. Wetlands play a critical role in the water cycle. They collect and hold water to prevent flooding. To grow, wetland plants take in elements like nitrogen and phosphorus that could pollute and harm rivers and streams in high amounts.
Stream and wetland restoration aim to restore those functions lost through poor development choices. Projects can include:
- Restructuring a stream channel to remove development – like buildings built next to the stream or in the floodplain – and prior attempts to control its flow. This allows the stream to flow more naturally.
- Removing culverts or other structures that constrict stream flow and cause water temperatures to rise or block fish from swimming through.
- Removing buildings or streets from a floodplain to give a stream space to spread out and reduce downstream flooding.
- Creating backwater channels or ponds to create habitat for fish and wildlife.
- Excavate fill from wetlands. Many wetlands were filled with rock and dirt in order to make it possible to build on them. Removing the fill provides more storage for stormwater, while creating habitat for wildlife, including birds and amphibians.
- Replanting wetlands and stream banks to improve shade, plant diversity, and habitat for wildlife.
Removing Fish Barriers
Structures like culverts under streets or dams in a stream can block salmon and other aquatic species from reaching habitat they need. These structures can also cause erosion, make temperatures in a stream rise, or cause such powerful flows that fish cannot swim through. Removing culverts can open up crucial habitat for salmon and trout that has been blocked for decades.
As Portland made space for streets and buildings, we buried many streams underground in pipes. Buried underground, the stream cannot support fish and wildlife. In pipes, water flows too fast and can cause erosion when the water rushes into the stream.
Daylighting a stream means removing the pipe, returning the stream aboveground, and allowing it to flow naturally. Then, it can again provide critical habitat for fish and wildlife.
Plants provide habitat, soak up rain, cool and clean the air and water, and provide food for fish and wildlife. Restoration almost always involves revegetation: the process of removing nuisance or invasive plants and replanting with native trees, shrubs, and groundcover. Native plants provide food and habitat for our local insects, many of which spend much of their lives in our city’s streams and become food for native fish and wildlife. This cycle helps to keep our streams and rivers healthy.
Adding Large Wood
Logs and other large pieces of wood in a stream provide food and refuge for bugs and fish. Large wood creates pools and prevents erosion. In streams, it collects sediment and stores organic matter like leaves that becomes food for bugs, which become food for fish.
When the Project is Done, Monitoring Begins
Once completed, Environmental Services watches over the restored area. Restoration takes time – years and more often decades. During that time, our monitoring team tracks its progress, checks for restored watershed functions, and makes adjustments when and where needed. Learn more about how we take care of the site after restoration to make sure it’s on the right track.