3DHP feature density and alignment compared to NHD

Maps showing the improved alignment possible in the 3D Hydrography Program by using hydrography data derived from high-quality elevation data from the 3D Elevation Program (3DEP). The example maps show topography and streams near the border between Skagit and Snohomish Counties in Washington. The map on the left is from U.S. Geological Survey NHD data derived from the 1989 1:24,000-scale topographic map. The map on the right shows more details of streams and a better alignment of streams with topography that result from using hydrography derived from 3DEP data by the Washington State Hydrography Dataset Program in 2023. NHD, National Hydrography Dataset.