DEPARTMENT OF FISH AND GAME GIS METADATA 

TOMALES BAY EELGRASS (ECOSYSTEM STUDY OF 6/92)

COVERAGE NAME: tb92eel
METADATA FILE: tb92eel.txt
METADATA DATE: March 28, 1997, updated February 20, 1998


COVERAGE DESCRIPTION: 

The coverage shows general eelgrass areas for the Tomales Bay region.
It was derived from files created for the Ecoscan Tomales Bay Ecosystem
Study of 6/92 (essentially a subset coverage of the tb92veg coverage).
Eelgrass data was originally extracted through a process of data
reformatting, table joining with the .acode tables created via the
dxfarc process, and reselecting on the DXF-COLOR field (the only unique
identifier for eelgrass).  Line and polygon topologies were built and
the coverage was projected to Albers, standard Teale parameters.  A
Bed_ID field was added to identify eelgrass polygons by bed number
(this data did not exist with the .dxf files, and may not be entirely
accurate). 


VITAL STATISTICS:

  Datum:                       NAD 27
  Projection:                  Albers
  Units:                       Meters
  1st Std. Parallel:           34 00 00
  2nd Std. Parallel:           40 30 00
  Longitude of Origin:         -120 00 00
  Latitude of Origin:          00 00 00
  False Easting (X shift):     0
  False Northing (Y shift):    -4,000,000
  Sources:                     Ecoscan Tomales Bay Ecosystem Study (6/92)
  Source Media:                Digital Imagery (Color, Color IR) 
                               See Report for further information
  Source Projection:           UTM - Zone 10            
  Source Units:                Meters
  Source Scale:                See Report
  Capture Method:              See Report

  Conversion Software:         ARC/INFO, rev 7.1.1
  Data Structure:              Vector 
  ARC/INFO Coverage Type:      Polygon/Line
  ARC/INFO Precision:          Single
  ARC/INFO Tolerances:         Fuzzy = 1.503 V; Dangle = 0.000 N
  Number of Features:          114 Polygons
  Layer Size:                  .21 MB


DATA DICTIONARY:

(standard ARC/INFO fields AREA, PERIMETER, FNODE#, TNODE#, LPOLY#, RPOLY#,
LENGTH, COVERAGE#, and COVERAGE-ID are not described here)

  Structure of table TB92EEL.PAT
  Number of Records:  114 

  COL  ITEM NAME  WIDTH TYPE N.DEC DESCRIPTION
  
   17  DESCRIP       40 C    -     Feature description.
   57  BED_ID         3 C    -     Eelgrass bed numbers, as listed in
				   the Ecoscan Tomales Bay Ecosystem Study
				   of 6/92 (CDFG bed numbers).  A few beds
				   may be innaccurately numbered, (see DATA
				   QUALITY ASSESSMENT).


DATA QUALITY ASSESSMENT:

The accuracy of this data is adequate for general analyses and medium 
scale overviews of the Tomales Bay region.  It should not be used to 
depict precise locations of eelgrass beds in relation to other geographic
features.  

Some of the data is a bit in question as a few polygon features contained
arcs with differing DXF-COLOR identifiers.  As of 2/98 there are a few
problems with the eelgrass bed identification numbers--there may be single
eelgrass polygons that require more than one bed number (some bed numbers
appear to take up only part of certain beds, i.e. only part of an eelgrass
polygon).  The polygons may need to be split to account for this, or an
ARC/INFO regions data structure might be considered.  As a result, some
beds may be inaccurately coded.


DATA CONTACTS:

Will Patterson, GIS Analyst
916-323-1484; Email: wpatters@hq.dfg.ca.gov