Clackamas, Clark, Multnomah, Washington, Polk, Columbia, Tillamook, Marion, Hood River, and Yamhill county boundaries in Oregon and Clark, Cowlitz, Skamania county boundary in Washington. Date of last data update: 2024-12-30 This is official RLIS data. Contact Person: Christine Rutan christine.rutan@oregonmetro.gov 503-797-1669 RLIS Metadata Viewer: https://gis.oregonmetro.gov/rlis-metadata/#/details/1437 RLIS Terms of Use: https://rlisdiscovery.oregonmetro.gov/pages/terms-of-use

Area in which urban services are provided by the City of Portland. This includes some parts of Washington, Clackamas, and unincorporated Multnomah County.-- Additional Information: Category: Boundary Purpose: For mapping and analysis of areas where urban services are provided by the City of Portland. Update Frequency: Quarterly-- Metadata Link: https://www.portlandmaps.com/metadata/index.cfm?&action=DisplayLayer&LayerID=52201

Urban reserves are lands currently outside the urban growth boundary that are suitable for accommodating urban development over the next 50 years. Rural reserves are lands outside the current urban growth boundary that are high value working farms and forests or have important natural features like rivers, wetlands, buttes and floodplains. These areas will be protected from urbanization for the next 50 years.

On 08/19/2011 the Oregon Land Conservation and Development Commission (LCDC) acknowledged (approved) the revised urban and rural reserves map for Washington County. Reserves for Multnomah and Clackamas counties were approved previously. Date of last data update: 2025-10-27 This is official RLIS data. Contact Person: Al Mowbray al.mowbray@oregonmetro.gov 503-797-1843 RLIS Metadata Viewer: https://gis.oregonmetro.gov/rlis-metadata/#/details/2427 RLIS Terms of Use: https://rlisdiscovery.oregonmetro.gov/pages/terms-of-use

The basis for these features is U.S. Geological Survey Scientific Investigation Report 2017-5024 Flood Inundation Mapping Data for Johnson Creek near Sycamore, Oregon. The domain of the HEC-RAS hydraulic model is a 12.9 mile reach of Johnson Creek from just upstream of SE 174th Avenue in Portland, Oregon to its confluence with the Willamette River. Some of the hydraulics used in the model were taken from Federal Emergency Management Agency, 2010, Flood Insurance Study, City of Portland, Oregon, Multnomah, Clackamas and Washington Counties, Volume 1 of 3, November 26, 2010. The Digital Elevation Model (DEM) utilized for the project was developed from LiDAR data flown in 2015 and provided by the Oregon Department of Geology and Mineral Industries. Bridge decks are generally removed from DEMs as standard practice. Therefore, these features may be shown as inundated when they are not. Judgement should be used when estimating the usefulness of a bridge during flood flow. Comparing the bridge to the surrounding ground can be more informative in this respect than simply looking at the bridge itself. Two model plans were used in the creation of the flood layers. The first is a stable model plan using unsteady flow in which the maximum streamflow is held in place for a long period of time (a number of days) in order to replicate a steady model using an unsteady plan. The stable model plan produced the areas of uncertainty contained in the sycor_breach.shp shapefile. The second is an unstable model plan that uses unsteady flow in which the full hydrograph (rising and falling limb) is represented based on the hydrograph shape of the December 2015 peak annual flood. The unstable model plan produced the flood extent polygons contained in the sycor.shp shapefile and the depth rasters and represents the best estimate of flood inundation for the given streamflow at U.S. Geological Survey streamgage 14211500.