Skip to Main Content View Text-Only

The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

More Contact Info

Subscribe to RSS feed

Most Recent

View Less

Twenty-five Acres of Northeast Portland Wetlands are Sprouting this Spring


Mason Flats Wetland Enhancement stormwater and wetland project is located within the Big Four Corners Natural Area  (NE 170th and Airport Way).  Farmed for many years, the site borders two waterways, cold water springs and historic wetlands. Environmental Services and Portland Parks & Recreation own the site.


New grading reduces stormwater pollutants from more than 600 acres of upland roads and development. Additional water flow and shallow channels connect the site to nearby cold springs and improves water quality. Increased tree canopy in the  summer will also help cool the slough. The project also increases off-channel floodplain and flood storage in the former floodplain of the Columbia River where more than 90% of wetlands have been filled or developed.

BES placed numerous standing logs, root wads, and rocks to increase habitat for sensitive wildlife species, especially redlegged frogs, native fishes, birds and turtles. More shrubs  will especially benefit willow flycatchers and yellow warblers. Several existing ponds and their unique aquatic vegetation remain untouched. Beavers are active on the site and beaver dam construction has been continuous in recent years. The effects of beaver dam building provide additional benefits in this wetland area.

Mason Flats is also providing new nesting habitat for turtles. Two long south-facing slopes and additional mounds of gravelly soil have been designed for turtle nesting. Western Painted turtles use ponds in the eastern portion of the site and the gravel and sun-warmed sites are preferred and necessary for egg incubation.

Mason Flats has been partially planted with grass, willow cuttings and shrubs. It already looks fabulous.  Multiple benefits from projects like these are called for under Portland’s Watershed Management Plan and the City’s Migratory Bird Act responsibilities.


Add a Comment


s. barthel

March 14, 2013 at 2:32 PM

The Mason Flats Wetland area is reserved for wildlife and water treatment. Good viewing of the site is available from the Airport Way sidewalk. We hope you understand that human presence affects birds and wildlife and that water treatment facilities are 'working'. thanks


D, Gold

April 29, 2013 at 1:14 AM

This is a great effort and initiative. If only people would think about the environment before doing the construction then this would never have to be done. I think most of the "civilized" world have destroyed themselves already, and are very out of touch with nature. So I just go to <a href="">ige</a> for wow gold and enjoy a life of blissful ignorance.

Please review our Code of Conduct rules before posting a comment to this site.
Report Abuse (Please include the specific topic and comment for the fastest response/resolution.)

Post a Comment
E-mail (visible to admins only)
 Remember Info Yes   No
Spam Prevention In the Pacific Northwest, what state is Portland in?