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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

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Tryon Creek Report Card

Image of Tryon CreekUPDATED: October 2019

This is a summary of conditions in the Tryon Creek Watershed based on 2019 data from the Watershed Health Index. The scores are a snapshot of conditions across the entire watershed. Conditions can vary in smaller parts of the watershed.

Link to introduction page

Learn more about the Tryon Creek Watershed program and projects

Tryon Creek Hydrology Score: BHard surfaces like roads, rooftops, and parking lots in this watershed create a lot of stormwater runoff when it rains. Stormwater makes stream banks unstable, causes erosion, and deposits sediment in streambeds. Runoff from Interstate 5, SW Barbur Boulevard, and other streets carries pollutants into streams. Stormwater management projects at the Oregon Department of Transportation Baldock Maintenance Yard, the Barbur Boulevard Park and Ride and I-5 at SW 26th that manage runoff from nearly 30 acres, but more work is needed to improve the scores.

About 30 miles of streams flow through the watershed of which about three miles are in pipes. Environmental Services continues to plan projects in this area to restore stream conditions, including bringing some of those piped streams back to the surface.


How to read the scales

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Effective impervious area Effective Impervious Area: 5.3
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Stream connectivity  Stream Connectivity: 6.8

Tryon Creek Water Quality Score: B-

Despite rich stream and habitat resources, substandard water quality limits the overall health of the watershed. E. coli bacteria levels often exceed water quality standards, likely because of sewage leaks and animal waste. Environmental Services is working on projects around the city to replace or repair aging sewer and/or stormwater pipes to protect water quality, public health, and the environment.

Suspended solids and pollutants that bind to solids are a problem that comes from untreated stormwater runoff. Silt and sediment from roads and development accumulate in Tryon Creek. Copper from automobile brake pads is a common pollutant that is harmful to salmon. And in summer, stream temperatures rise above levels needed for salmon rearing.

Ongoing projects to remove invasive plants, restore native vegetation, protect habitat, restore streams, and manage stormwater, like the Multnomah Village green streets, will help prevent further decline in water quality scores.


How to read the scales

What is this? Ammonia-nitrogen Ammonia-Nitrogen: 9.9
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Dissolved copper
Dissolved copper: 5.9
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Dissolved oxygen
Dissolved oxygen: 8.6
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E. coli
E. coli: 2.9
What is this? Temperature Temperature: 4.9
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Total mercury
Total mercury: 1.8
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Total phosphorus
Total phosphorus: 6.3
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Total suspended solids
Total suspended solids: 3.8

Tryon Creek Habitat Score: B+

Habitat conditions vary across the watershed. The best conditions are in the Tryon Creek State Natural Area where the creek is fairly healthy. But more improvements are needed above and below the park.

Protected open spaces like the natural area contribute to good tree canopy and other habitat scores. Active community groups volunteer to remove invasive plants and restore native vegetation.

The low stream accessibility score is because of culverts that block fish access. Environmental Services and partners are planning a project to replace the Boones Ferry Road culvert, which will improve fish passage to the upper portions of Tryon Creek.


How to read the scales


What is this? Bank condition (hardening) Bank condition: 9.8
What is this? Floodplain condition Floodplain condition: 10 10
What is this? Large wood Large wood: 7.4
What is this? Riparian integrity Riparian integrity: 7.2
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Stream accessibility  Stream accessibility: 1.9 1.9
What is this? Substrate composition Substrate composition: 6.0 6.0
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Tree canopy
Tree canopy: 10

Tryon Creek Fish and Wildlife Score: D+

Pacific lamprey, coho salmon, and other native fish use Tryon Creek, but culverts block passage much of the time. Because of good habitat conditions in the Tryon Creek State Natural Area, scores for aquatic insects and birds are fair, although insect species aren’t as diverse as they should be. This means we have more work to do. More than 60 species of birds live in the Tryon Creek watershed for at least part of the year.


How to read the scales

What is this? Birds Birds: 4.1
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Fish: 2.1
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Macroinvertebrates: 5.0

For more information about what we measure and where these scores come from, visit the About Watershed Report Cards page.

See some of what Environmental Services is doing for healthy rivers and streams on the Explore Portland’s Watersheds map.