City of Tacoma GISThis layer generally describes Geologically Hazardous Areas as defined in TMC 13.11.700, including erosion and landslide hazard areas. It is used to review changes to these areas including development proposals, proposals for vegetation modification, and potential violations for compliance with critical area and building codes. This layer was derived from 2018 bare earth lidar. The initial analysis steps include: slope tool to create a % rise surface then using the int tool and reclassify using the 0-15, 15-25, 25-40 and >40 percent slope. Those classifications were converted to polygons. Further refinement was done to reduce the number of polygons. All areas in the >15% classification were deleted, all polygons <200ft in length and all polygons < 100 sq. ft. in area were deleted. Additional simplifying was done to create smoother boundaries of areas and a series of positive and negative buffers was used to remove holes in areas. Additional refinement to this was done including: (Deleted polygons <= 200 sq. ft. for Slope Category 15 - 25%. Deleted polygons <= 100 sq. ft. for Slope Category 25 - 40% & Over 40% ) Data Steward contact: Craig Kuntz, ckuntz@cityoftacoma.org or Lisa Spadoni, Natural Resources Program Manager, lspadoni@cityoftacoma.org.ArcGIS FeatureLayerhttps://hub.arcgis.com/datasets/43139ac9b1c74605bdfcbab523ef19b6_0engTacoma Open DataPublicSteep Slopes (Tacoma) [Washington (State)--Tacoma]Web servicesWashington (State)--TacomaWashington (State)Last Modified: 2026-01-08