UPDATED: October 2019

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

Learn more about the Fanno Creek Watershed Program and Projects

Hard surfaces such as streets, rooftops, and parking lots generate stormwater runoff during rainstorms. Runoff has a negative impact on the many small streams in this watershed. It can make stream banks unstable, cause erosion and deposit sediment in streambeds. Projects to improve stormwater management along Beaverton Hillsdale Highway,  SW Capital Highway, and other streets will help improve hydrology, water quality, habitat, and fish and wildlife scores.

Stream connectivity is poor because culverts and piped streams interfere with natural drainage. About 4.7 miles of Fanno Creek and its tributaries in Portland flow through pipes. The City works to bring portions of streams back to the surface when possible.

	Effective impervious area		4.3
	Stream connectivity		5.1

E. coli bacteria levels exceed water quality standards. Sources of E. coli include sewer leaks and animal waste.

Stormwater runoff is a significant cause of water quality problems in this watershed. Silt and sediment from roads, development, and channel erosion contribute to high levels of total suspended solids (TSS). Copper from vehicle brake pads is a common pollutant in stormwater. Stream temperatures increase in summer and exceed water quality standards necessary for salmon rearing. Adding more green street planters and other ways for water to soak into the ground is one solution to reduce stream temperatures.

Projects to remove invasive plants, restore native vegetation, and manage stormwater — like improvements planned along SW Hamilton Street — will help improve water quality scores over time.

	Ammonia-nitrogen		9.8
	Dissolved copper		4.9
	Dissolved oxygen		8.4
	E. coli		2.7
	Temperature		3.0
	Total mercury		1.7
	Total phosphorus		4.1
	Total suspended solids		4.3

Culverts in Fanno Creek limit stream accessibility for migratory fish. Some culverts, such as a section of the long culvert underneath Beaverton-Hillsdale Highway, are outside the Portland city limits. Portland continues to work on projects, like the culvert replacement at SW 45th Avenue, that improve fish passage and stream conditions.

The land along the most of the creek’s banks (riparian area) is narrow and vegetation cover is low. The stream lacks large wood and boulders, and a large amount of sand and silt covers the creek bed. The South Ash Creek Stream Enhancement project  improved in-stream habitat. The project also repaired and protected sewer infrastructure. Tree canopy overall is good and revegetation projects and invasive species management will ensure the scores continue to improve.

	Bank condition (hardening)		7.0
	Floodplain condition		7.0
	Large wood		2.0
	Riparian integrity		4.5
	Stream accessibility		0.0
	Substrate composition		7.2
	Tree canopy		10

Cutthroat trout, at least 100 species of birds, and many other fish and wildlife species live in the Fanno Creek watershed. However, the score for fish is low because only a few fish species are found, and they are not abundant. Culverts and other barriers block access to fish habitat. Aquatic insects are limited by sediment in the stream.

Individual actions like improving backyard habitat, adding rain gardens, and planting trees will help support fish and wildlife across the watershed and complement city infrastructure projects and natural area protection.

	Birds		2.9
	Fish		0.2
	Macroinvertebrates		3.7

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.