Fanno Creek is a tributary of the Tualatin River in the U.S. state of Oregon. Part of the drainage basin of the Columbia River, its watershed covers about in Multnomah, Washington, and Clackamas counties, including about or 20,000 acres within the Portland city limits.
From its headwaters in the Tualatin Mountains (West Hills) in southwest Portland, the creek flows generally west and south through the cities of Portland, Beaverton, Tigard and Durham, and unincorporated areas of Washington County. It enters the Tualatin River about above the Tualatin's confluence with the Willamette River at West Linn.
When settlers of European origin arrived, the Kalapuya lived in the area, having displaced the Multnomahs in pre-contact times. In 1847, the first settler of European descent, Augustus Fanno, for whom the creek is named, established an onion farm in what became Beaverton. Fanno Farmhouse, the restored family home, is a Century Farm on the National Register of Historic Places and is one of 16 urban parks in a narrow corridor along the creek.
Although heavily polluted, the creek supports aquatic life, including coastal cutthroat trout (leopard spotted) in its upper reaches. Watershed councils such as the Fans of Fanno Creek and government agencies have worked to limit pollution and to restore native vegetation in riparian zones.
Course Fanno Creek arises at an elevation of above sea level and falls between source and mouth to an elevation of . The main stem begins at about river mile (RM) 15 or river kilometer (RK) 24 in the Hillsdale neighborhood of southwest Portland, in Multnomah County. The creek flows west along the north side of Oregon Route 10 (the Beaverton–Hillsdale Highway), passing Albert Kelly Park and receiving Ivey Creek and Bridlemile Creek on the right before reaching the United States Geological Survey (USGS) stream gauge at Southwest 56th Avenue from the mouth. Shortly thereafter and in quick succession, it enters Washington County and the unincorporated community of Raleigh Hills, crosses under Route 10, and receives Sylvan Creek on the right. Here the stream turns south, passing through Bauman Park, where Vermont Creek enters on the left about from the mouth, and then southwest to flow through the Portland Golf Club and Vista Brook Park, where Woods Creek enters on the left. From here it flows west again for about , passing through Fanno Creek Trail Park and entering Beaverton about from the mouth before turning sharply south and flowing under Oregon Route 217 (Beaverton–Tigard Highway).
Fanno Creek then flows roughly parallel to Route 217 for about through Fanno Creek Park and Greenway Park. Near the southern end of Greenway Park, the creek passes under Oregon Route 210 (Scholls Ferry Road), and enters Tigard about from the mouth. In quick succession, Hiteon Creek enters on the right, Ash Creek on the left, and Summer Creek on the right before the creek reaches Woodard Park, goes under Oregon Route 99W (Southwest Pacific Highway), and flows through Fanno Park and Bonita Park as well as residential neighborhoods. Between the two parks, Red Rock Creek enters on the left about from the mouth. Slightly downstream of Bonita Park, Ball Creek enters on the left. Fanno Creek then enters Durham, passes a USGS gauging station from the mouth, flows through Durham City Park, and empties into the Tualatin River from its confluence with the Willamette River.
Discharge The USGS monitors the flow of Fanno Creek at two stations, one in Durham, from the mouth, and the other in Portland, from the mouth. The average flow of the creek at the Durham station is . This is from a drainage area of , more than 99 percent of the total Fanno Creek watershed. The maximum flow recorded there was on December 3, 2007, and the minimum flow was on September 13, 2001, and September 15, 2009. At the Portland station, the average flow is . This is from a drainage area of or about 7 percent of the total Fanno Creek watershed. The maximum flow recorded there was on February 8, 1996, and the minimum flow was on September 4, 2001.
Watershed Draining , Fanno Creek receives water from Portland's West Hills, Sexton Mountain in Beaverton, and Bull Mountain near Tigard. Nearly all of the watershed is urban. About , roughly 22 percent of the total, lies inside the Portland city limits. The highest elevation in the watershed is at Council Crest in the West Hills. The peak elevation on Sexton Mountain is , while Bull Mountain rises to . About of streams flow through the watershed, including Ash Creek, Summer Creek, and 12 smaller tributaries. A small part of the drainage basin lies in the city of Lake Oswego in Clackamas County, near the headwaters of Ball Creek, a Fanno Creek tributary.
The slopes at the headwaters of Fanno Creek consist mainly of Columbia River Basalt exposed in ravines but otherwise covered by up to of wind-deposited silt. Silts and clays are the most common watershed soils, and significant erosion is common. About of precipitation, almost all of which is rain and about half of which arrives in November, December, and January, falls on the watershed each year. Although significant flooding occurred in 1977, the watershed has not experienced a 100-year flood since the area became urban.
Small watersheds adjacent to the Fanno Creek watershed include those of minor tributaries of the Willamette or Tualatin rivers. Tryon Creek, Balch Creek, and other small streams east of Fanno Creek flow down the eastern flank of the West Hills into the Willamette. To the northwest, Hall Creek, Cedar Mill Creek, and Bronson Creek flow into Beaverton Creek, a tributary of Rock Creek, which empties into the Tualatin River at the larger stream's RM 38.4 (RK 61.8), about upriver from the mouth of Fanno Creek.
Annual report card In 2015, Portland's Bureau of Environmental Services (BES) began issuing annual "report cards" for watersheds or fractions thereof that lie within the city. BES assigns grades for each of four categories: hydrology, water quality, habitat, and fish and wildlife. Hydrology grades depend on the amount of pavement and other impervious surfaces in the watershed and the degree to which its streams flow freely, not dammed or diverted. Water-quality grades are based on measurements of dissolved oxygen, E-coli bacteria, temperature, suspended solids, and substances such as mercury and phosphorus. Habitat ranking depends on the condition of stream banks and floodplains, riparian zones, tree canopies, and other variables. The fish and wildlife assessment includes birds, fish, and macroinvertebrates. In 2015, the BES grades for the Fanno Creek watershed fraction within Portland are hydrology, C; water quality, C+; habitat, B−, and fish and wildlife, D−.
History The previous people of the Fanno Creek watershed were the Atfalati or Tualaty tribe of the Kalapuya, said to have displaced even earlier inhabitants, the Multnomahs, prior to European contact. The valleys of the Willamette River and its major tributaries such as the Tualatin River consisted of open grassland maintained by annual burning, with scattered groves of trees along the rivers and creeks. The Kalapuya moved from place to place in good weather to fish, to hunt small animals, birds, waterfowl, deer, and elk, and to gather nuts, seeds, roots, and berries. Important foods included camas and wapato. In addition to fishing for eels, suckers, and trout, the Atfalati traded for salmon from Chinookan tribes near Willamette Falls. During the winter, the Kalapuya lived in longhouses in settled villages. Their population was greatly reduced after contact in the late 18th century with Europeans, who carried malaria, smallpox, measles, and other diseases. Added pressure came from white settlers who seized and fenced native land, regarded it as private property, and sometimes punished natives for trespassing. Of the original population of 1,000 to 2,000 Atfalati reported in 1780, only 65 remained in 1851. In 1855, the U.S. government sent the survivors to the Grande Ronde reservation further west.
Fanno Creek is named after Augustus Fanno, the first European American settler along the creek. In 1847, he started an onion farm on a donation land claim in what later became part of Beaverton. Other 19th century newcomers along the creek engaged mainly in logging, farming, and dairy farming until the Southern Pacific Railroad and the Oregon Electric Railway lines made the watershed more accessible for urban development around the turn of the 20th century. The Oregon Electric, a system built between 1903 and 1915, ran between downtown Portland and Garden Home in the Fanno Creek watershed, where it split into branches leading to Salem and Forest Grove. The Southern Pacific began running electric passenger trains, known as the Red Electric, in the watershed in 1914. The company that eventually became Portland General Electric installed electric service in the area, and by 1915 the population of the upper Fanno Creek neighborhoods of Multnomah, Maplewood, Hillsdale, and West Portland Park had grown to 2,000.
Passenger service on the Red Electric line ended in 1929, and the Oregon Electric Railway ceased passenger operations in 1933. Private autos largely replaced interurban rail service. Oregon Highway 217 between Durham and Beaverton, and Oregon Highway 10 between Beaverton and Portland, follow the creek. Although passenger rail ceased for nearly 80 years, freight trains continued to use the tracks. In 2009, a new rail passenger service began along a former Oregon Electric line owned by Portland and Western Railroad in Washington County. The Westside Express Service (WES) runs between Beaverton on the north and Wilsonville on the south. The middle stretch of this run lies close to the lower of Fanno Creek between Beaverton and Durham. WES is the first modern commuter rail in Oregon and one of the few suburb-to-suburb commuter rail lines in the United States. At the northern end of the line, WES connects to the MAX Blue Line, an east–west light rail line linking Hillsboro and Gresham via Portland and the MAX Red Line, with connections to Portland International Airport. A proposed MAX line along the Fanno Creek is be the southwest corridor light rail project
The highways and railroads serve a population that increased most dramatically in the second half of the 20th century. When Beaverton was incorporated as a city in 1893, it had a population of 400. By 2010, the number had soared to 94,000, although not all of them lived in the watershed. Tigard, which did not exist as a city until 1961, grew to 49,000 by the year 2013, all in the watershed. Fanno Creek, which had few people living near it until 1850, "is surrounded by the most populous region in Oregon".
Pollution Although the Oregon Department of Environmental Quality (DEQ) rated the average water quality of Fanno Creek as "very poor" between 1986 and 1995, it also noted steady improvement over that span. Historically, Fanno Creek has been polluted by urban and industrial sources, small sewage treatment plants, ineffective septic systems, farming and grazing operations, and illegal dumping. Health and environmental concerns led to the closing of substandard wastewater treatment plants in the 1970s, and urban development reduced the number of farms and farm animals along the creek. A ban in 1991 on phosphate detergents, increased connection to municipal sewers, stormwater management, and greater public awareness helped to reduce urban pollution not coming from point sources, and water quality improved.