The 'B118v3NAD27UTM10' shape file shows groundwater basins and subbasins as defined by the California Department of Water Resources. The file is intended for use with GIS software able to import files of suffix '.shp'. Groundwater basins are designated on the basis of geological and hydrological conditions, these usually being the occurrence of alluvial or unconsolidated deposits. When practical, large basins are also subdivided by political boundaries, as in the Central Valley. Basins are named and numbered per the convention of the Department of Water Resources.

PROJECTION PARAMETERS

Datum:    

NAD27

Projection:

CA10 (UTM Zone 10)

Spheroid:

Clarke 1866

Units:  

Meters

Scale Reduction:  

0.9996

Central Meridian:  

-123 00 00 (123 degrees west)

Origin Latitude:   

00 00 00 (0.0 degrees)

False Easting (X Shift): 

500,000

False Northing (Y Shift):

0.00

Source:

Department of Water Resources

ATTRIBUTES

AREA

The area of the polygon in square meters.

PERIMETER

The length of the polygon perimeter of the polygon in meters.

DWR_

DWR Number - includes region number in first position.

SUBBSN_

DWR subbasin number only.

BAS_SBBSN

Combined field of basin and subbasin number.

GWBASIN

Name of groundwater basin.

TYPE

bas    basin

SUBNAME

Subbasin name, where applicable

DWR_DIST

DWR district responsible for individual basin delineation and description ND   Northern District
CD   Central District
SJD  San Joaquin District
SD   Southern District

ACRES

Area of basin or subbasin in acres

Additional Information
The basin boundaries for the revised groundwater basin map were primarily defined using geologic contacts and hydrogeologic divides.  Specifically the identification of the groundwater basins was initially based on the presence and areal extent of unconsolidated alluvial soils identified on 1:250,000 scale geologic maps provided by the California Department of Conservation, Division of Mines and Geology. The identified groundwater basin areas were then further evaluated through review of relevant geologic and hydrogeologic reports, well completion reports, court-determined adjudicated basin boundaries, and contact with local agencies to refine the basin boundaries.