News & Information

Old Stream Data Replaced

Replacement Datasets Based on National Hydrography Data (NHD)

SanGIS has provided two new stream datasets on the Regional Data Warehouse. These datasets have replaced the old MAJOR_STREAMS and STREAMS datasets that were on the Regional Data Warehouse previously. These older datasets had been created by SANDAG based on old NHD data some time ago and through an ongoing quality review process were determined to be incomplete and out of date.

Two new layers have been added to the Regional Data Warehouse to replace the older data: FLOWLINES and FLOWLINES_CARTO. Both datasets can be found in the Hydrology category.

The FLOWLINES dataset comprises NHD flowlines covering the two HU6 water basins that cover the County of San Diego. The FLOWLINES_CARTO layer was developed by SanGIS, using the NHD flowlines as a basis, to depict major watercourses within San Diego County and does not include smaller feeder streams and ditches.

The FLOWLINES_CARTO layer was created from NHD Flowline data for streams with GNIS Names assigned. This dataset was projected and these data were then further edited to match San Diego County conditions. Additional stream reaches were added and others removed based on input from SANDAG, County of San Diego and City of San Diego. Flowlines were extended through lakes and to the coastline using aerial imagery as a guide. This layer is for cartographic purposes only and should not be used for flow or other analyses.

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