A year ago, Coffee Lake Creek Natural Area appeared lush and green but was actually an ecological wasteland covered with weeds. This year it will be bare and brown, undergoing preparation to become a wetland again. Next year, thanks to improved water flow and new plantings, it will be on its way to becoming a multicolored, diverse, healthy ecosystem — closer to its historic condition.
Metro has been working toward the restoration of the Coffee Lake Creek Natural Area for years. The site sits at the southern end of a 2.5-mile-long chain of natural areas along Coffee Lake Creek. Other sites have been restored, and now it’s Coffee Lake Creek Natural Area’s turn.
Unlike many restoration projects, you’ll be able to see its transformation, because the once-and-future wetland is circled by roads with sidewalks. Wilsonville’s new Tivoli Park runs along SW Coffee Lake Drive, and the Ice Age Tonquin Trail borders the restoration site. The restoration project aims to increase biodiversity and improve water quality in two main ways.
The first is by changing the way water moves around the site. Since the site was ditched and drained for farming in the 1800s, Coffee LakeCreek has flowed through a straight channel that doesn’t let water spread to the wetlands, where natural processes could cool and clean it. Metro is removing the ditch and changing the site from a flat field to a site with ponded areas, raised hummocks and shallow swales. This will allow water to slowly meander through the site, supporting native plants, insects, fish and wildlife that need a variety of habitats. Water will stay on site longer and filter into groundwater.
Restoring natural water flows to this site will provide water-logged conditions that slow plant decomposition, allowing peat, a special type of soil, to build. Peat is nature’s most effective way of taking carbon out of the air and storing it long-term, but this process only works if peat remains wet. When a peat wetland dries out, like Coffee Lake Creek Natural Area has, the carbon in the peat is released into the atmosphere as carbon dioxide.
By returning the natural area to its past, water-logged self, Metro can reverse that process so the wetland can store carbon once again.
The second restoration approach being used at the site is to remove the reed canarygrass that covers the entire site and replace it with a wide variety of native trees, shrubs, flowers, sedges and rushes, the natural vegetation that was found at this location prior to European American colonization and farming.
Reed canarygrass is an aggressive invasive species that smothered the site in thick thatch mats and grew to over 6 feet in height. Native plants had no space to grow and most wildlife was excluded. The grass also greedily sucked up water, which helped dry out the wetlands. After the project, the dramatic increase in plant variety will increase the food sources and habitats available to fish and wildlife for foraging, breeding, resting, nesting and hiding from predators.
Heritage Pine Natural Area's restored wetland shows what Coffee Lake Creek Natural Area will look like in a few years.
While Metro began some of this work in August, most of the construction will actually take place next summer. Metro will use excavators and other big construction equipment to remove the ditch, contour the ground, create mounds and dig pools. Next comes planting. Over the next two winters Metro will plant more than 120,000 plants and approximately 7,000 pounds of seed. This will include more than 100 species of plants. Restoration crews will keep a close eye on the natural area for the next few years to maintain and establish the young plantings and replant as needed.
After returning Coffee Lake Creek’s water to the floodplain and allowing it to move as it historically did, the wetland will heal. Over time, plants, bugs, frogs, fish, birds and even new peat soil will show up. Plantings will go from tiny seeds and small plants to towering cottonwoods and willows in some areas, and expanses of colorful blooms like camas, wapato and popcornflower in others. The plant communities will support diverse food chains.
Visitors overlooking the site can expect to see wildlife ranging from large animals such as bald eagles down to small insects such as dragonflies and water striders.
You’ll be able to get close to this process thanks to the pathways and pocket parks surrounding the site. Metro’s restoration, in turn, is possible thanks to the people of greater Portland supporting nature.
Funding for the project is provided by the Metro 2019 Parks and Nature bond measure, the U.S. Fish and Wildlife Service North American Wetland Conservation Act, and the Oregon Watershed Enhancement Board.
Future residents
Ducks and other waterfowl
Waterfowl such as American wigeon, mallard and northern pintail travel through the area but have not been able to use the site for breeding or feeding due to its degraded state. After restoration, the site will provide open water, shrub cover for safety, insects and plants such as cattail, bogbean and duckweed for waterfowl to eat.
Songbirds
Birds like willow flycatchers, red-winged blackbirds and barn swallows are expected to use the restored site, feeding on insects produced in the wetlands. These and other songbirds will nest in shrubs like red-twig dogwood or Geyer willow.
Northern red-legged frogs
Frogs are indicators of wetland health. Frogs throughout the world are facing challenges including loss of wetland habitat and disease. The northern red-legged frog is facing similar challenges in Oregon. These frogs require shallow water ponds that stay wet into spring and contain the right types of plants to attach their egg masses. The project will create these ponds. Plantings of native sedges, rushes and grasses such as soft-stem bulrush and rice-cut grass will provide excellent egg mass attachment material.