Johnson Creek (Willamette River tributary)

Johnson Creek
Johnson Creek near Regner Road in Gresham
Johnson Creek watershed
Location of the mouth of Johnson Creek in Oregon
Etymology	William Johnson, early settler
Location
Country	United States
State	Oregon
County	Clackamas and Multnomah
Physical characteristics
Source	Cascade Range foothills
• location	near Cottrell, Clackamas County, Oregon
• coordinates	45°26′51″N 122°17′18″W / 45.4476206°N 122.2884222°W / 45.4476206; -122.2884222[1]
• elevation	745 ft (227 m)[1] Elevation derived from Google Earth search using GNIS source coordinates
Mouth	Willamette River
• location	Milwaukie, Clackamas County, Oregon
• coordinates	45°26′39″N 122°38′36″W / 45.4442860°N 122.6434273°W / 45.4442860; -122.6434273[1]
• elevation	26 ft (7.9 m)[1]
Length	25 mi (40 km)[2]
Basin size	54 sq mi (140 km2)[2]
Discharge
• location	Milwaukie, 0.7 miles (1.1 km) from mouth[3]
• average	77.5 cu ft/s (2.19 m3/s)[3]
• minimum	9.3 cu ft/s (0.26 m3/s)
• maximum	2,170 cu ft/s (61 m3/s)
Discharge
• location	Gresham[4]
• average	27 cu ft/s (0.76 m3/s)[4]Note: Average discharge rate was calculated by adding average annual discharge rates for the 7 calendar years 1999–2005 and dividing by 7. "USGS Surface-Water Annual Statistics for the Nation: USGS 14211400 Johnson Creek at Regner Road at Gresham, Oregon". United States Geological Survey. 2008. Retrieved March 15, 2008.</ref>

Johnson Creek is a 25-mile (40 km) tributary of the Willamette River in the Portland metropolitan area of the U.S. state of Oregon. Part of the drainage basin of the Columbia River, its catchment consists of 54 square miles (140 km²) of mostly urban land occupied by about 180,000 people as of 2012. Passing through the cities of Gresham, Portland, and Milwaukie, the creek flows generally west from the foothills of the Cascade Range through sediments deposited by glacial floods on a substrate of basalt. Though polluted, it is free-flowing along its main stem and provides habitat for salmon and other migrating fish.

Prior to European settlement, the watershed was heavily forested and was used by Native Americans of the Chinook band for fishing and hunting. In the 19th century, non-Native American settlers cleared much of the land for farming, and the stream is named for one of these newcomers, William Johnson, who in 1846 built a water-powered sawmill along the creek. By the early 20th century, a rail line parallel to the stream encouraged further residential and commercial development. As urban density increased in the floodplain, seasonal floods grew more damaging. In the 1930s the Works Progress Administration of the federal government lined the lower 15 miles (24 km) of Johnson Creek with rock to control the floods. Despite this, the creek flooded 37 times between 1941 and 2006. Since the 1990s, regional planners have tried to reduce flooding by controlling stormwater runoff, creating stream meanders, reducing erosion, replacing impervious surfaces, and protecting riparian buffers.

The Johnson Creek watershed includes the subwatersheds of Badger Creek, Sunshine Creek, Kelley Creek, Mitchell Creek, Veterans Creek, Crystal Springs Creek, and smaller streams. Parks along the creek and its tributaries include natural areas, a wildlife refuge, a rhododendron garden, a botanical garden, and a 21-mile (34 km) bicycle and pedestrian rail trail that follows the creek for much of its length.