This data is maintained by and obtained from Metro GIS. Click the link above to view the Metro GIS metadata for this dataset.

This data is maintained by and obtained from Metro Data Resource Center. Please go to https://gis.oregonmetro.gov/rlis-metadata/#/details/155 for the complete metadata.-- Additional Information: Category: Boundary Purpose: For use as a "base" layer on map products to shade county areas and in analysis to capture areas within each county. Update Frequency: None planned-- Metadata Link: https://www.portlandmaps.com/metadata/index.cfm?&action=DisplayLayer&LayerID=155

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 Linkhttps://www.portlandmaps.com/metadata/index.cfm?&action=DisplayLayer&LayerID=52201

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 ...

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.

This data layer is an element of the Oregon GIS Framework. The Oregon Wetlands Database (2019) is a geodatabase consisting of three feature classes: 1) Local Wetland Inventory (LWI) Wetlands, 2) National Wetland Inventory (NWI) Wetlands, and 3) More Oregon Wetlands (MOW). Each feature class contains polygons representing wetland boundaries. The three feature classes originated from different sources with distinct purposes, methodologies and time frames for generating geospatial wetlands data, and there is overlap among them; however, all are relevant to the conservation and management of wetlands across the state of Oregon. See the metadata of the individual feature classes for more background information and details per dataset.