The polygon features within this dataset represent the extent of HUC 12 watersheds. Watersheds are defined based on drainage area and confining topography, and are classified according to the existing Hydrologic Unit Codes (HUC). Watersheds were digitized using vectors and rasters derived from LiDAR data acquired for Sonoma Veg Map and NASA in 2013. The projection is California State Plane (CASP) 2, the horizontal datum is NAD83 (2011), the vertical datum is NAVD88 (Geoid 12A), and the units are US Survey Feet.

This dataset is part of a suite of Sonoma County hydrologic data deliverables that were produced in fall 2015 and winter 2016 from the countywide 2013 LiDAR data. The hydrologic products include a set of vector deliverables and a set of raster deliverables. Vector products include stream centerlines, confluence points, hydroenforcement burn locations, and watersheds. Raster products include flow direction, flow accumulation, and a hydroenforced bare earth digital elevation model (DEM). Hydroenforcement of a DEM imparts the true elevations of culverts, pipelines, and other buried passages for water into a Digital Elevation Model, creating a DEM suitable for modeling the flow of surface water. The extent of all deliverables is all of Sonoma County, the Lake Sonoma watershed in Mendocino County, and the Lake Mendocino area.

Appropriate Use: These hydrologic datasets are a mostly-automated first step in the eventual development of a 'localized' or 'LiDAR enhanced' National Hydrography Dataset (NHD). They are suitable for landscape level planning and hydrologic modeling. These data products do not contain a guarantee of accuracy or precision and – without site specific validation and/or refinement – should not be relied upon for engineering level or very fine scale decision making.

The polygon features within this dataset represent the extent of HUC 12 watersheds. Watersheds are defined based on drainage area and confining topography, and are classified according to the existing Hydrologic Unit Codes (HUC). Watersheds were digitized using vectors and rasters derived from LiDAR data acquired for Sonoma Veg Map and NASA in 2013. The projection is California State Plane (CASP) 2, the horizontal datum is NAD83 (2011), the vertical datum is NAVD88 (Geoid 12A), and the units are US Survey Feet.

This dataset is part of a suite of Sonoma County hydrologic data deliverables that were produced in fall 2015 and winter 2016 from the countywide 2013 LiDAR data. The hydrologic products include a set of vector deliverables and a set of raster deliverables. Vector products include stream centerlines, confluence points, hydroenforcement burn locations, and watersheds. Raster products include flow direction, flow accumulation, and a hydroenforced bare earth digital elevation model (DEM). Hydroenforcement of a DEM imparts the true elevations of culverts, pipelines, and other buried passages for water into a Digital Elevation Model, creating a DEM suitable for modeling the flow of surface water. The extent of all deliverables is all of Sonoma County, the Lake Sonoma watershed in Mendocino County, and the Lake Mendocino area.

Appropriate Use: These hydrologic datasets are a mostly-automated first step in the eventual development of a 'localized' or 'LiDAR enhanced' National Hydrography Dataset (NHD). They are suitable for landscape level planning and hydrologic modeling. These data products do not contain a guarantee of accuracy or precision and – without site specific validation and/or refinement – should not be relied upon for engineering level or very fine scale decision making.