The City of Portland Bureau of Environmental Services is planning a stormwater management and wetland enhancement project at NE Mason and Airport Way in the Big Four Corners Natural area. The project site encompasses two waterways and a historic wetland that was farmed for some time, then became, in part, a private wetland mitigation site. The site is owned by Environmental Services and Portland Parks & Recreation.
The Mason Flats Wetland Enhancement Project will reduce pollutants in stormwater that drains from more than 600 acres of upland development and roads. This will reduce pollutants that currently enter the Columbia Slough. The wetland will be graded to provide additional water flow, especially the cold spring water from up slope areas to the south. However, the ponds in the eastern portion of the site will not be changed as they already provide healthy amphibian and turtle habitat.
Habitat enhancement will include reducing invasive species like reed canarygrass and increasing the diversity and quantity of native vegetation. This will increase native wetland habitat for sensitive wildlife species, especially red-legged frogs, Western painted turtles, and willow flycatchers and other neo-tropical migratory birds.
What You Will See
You will see heavy construction equipment moving earth and grading the site. Once the grading is finished the city's contractor will install log clusters and snags. The area will be seeded to provide cover and erosion control. Planting will occur during the rainy season to follow.
Construction is tentatively scheduled to begin in spring 2012. Project work in the wetlands and waterways must be completed by October 1 to satisfy regulatory permits and to avoid the complications of working on this wet site.
Traffic Control and Safety
One eastbound lane of Airport Way will be closed during the project. The eastbound bike lane and the other eastbound vehicular lane will remain open at all times. All westbound traffic lanes on Airport Way (two vehicular and one bike) will remain open at all times. Traffic control will include flaggers and speed reductions to ensure safety. Pedestrian access on the sidewalks along NE Airport Way will be maintained and the sidewalks will be kept clear at all times.
Please contact Susan Barthel, Columbia Slough Watershed Program Coordinator at 503-823-7268 or Susan.Barthel@PortlandOregon.gov.