page_title: Johnson Creek (Willamette River tributary)
section_title: Macroinvertebrates and fish
hierarchical_section_title: Johnson Creek (Willamette River tributary) / Biology / Macroinvertebrates and fish
caption_attribution_description: A Great Blue Heron wading, in Portland, Oregon, just outside Reed College.
context_page_description: Johnson Creek is a 25-mile 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 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.
context_section_description: A study conducted in 1999 for the City of Portland by researchers from Portland State University found that Johnson Creek had marginal conditions for macroinvertebrates, an important source of food for fish and other aquatic life. The study compared differences in these life forms and in water chemistry from two urban streams, Johnson Creek and Tryon Creek in southwest Portland, with two nearby rural streams and found that benthic communities in the urban streams were degraded compared to the regional reference creeks.
  Most fish species in Johnson Creek tolerate warm water and disturbed conditions. These include red-sided shiners, sculpin, suckers, and speckled dace.
  Large populations of salmon inhabited the creek before urban construction altered the watershed and the stream channel, and in the 21st century, the creek and its tributaries still provide habitat for smaller numbers of chinook and coho salmon, steelhead, and coastal cutthroat trout. Steelhead populations in Johnson Creek are within the Lower Columbia River steelhead distinct population segment and listed as threatened (2011). Chinook and coho salmon are listed as threatened as part of the Lower Columbia River Evolutionary Significant Unit (2011).
caption: A great blue heron wades in Crystal Springs Creek near Reed College.
exif: {"Image Make": "Canon", "Image Model": "Canon PowerShot A620", "Image Orientation": "Horizontal (normal)", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "QuickTime 7.2", "Image DateTime": "2007:07:31 09:18:05", "Image HostComputer": "Mac OS X 10.4.9", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "252", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "628", "Thumbnail JPEGInterchangeFormatLength": "8572", "Thumbnail YCbCrPositioning": "Centered", "EXIF ExposureTime": "1/400", "EXIF FNumber": "41/10", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2007:06:02 06:18:31", "EXIF DateTimeDigitized": "2007:06:02 06:18:31", "EXIF ShutterSpeedValue": "277/32", "EXIF ApertureValue": "65/16", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "65/16", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "146/5", "EXIF ColorSpace": "sRGB", "EXIF SensingMethod": "One-chip color area"}