MANUSCRIPT
A set of 1:24,000 USGS paper quad sheets was carefully delineated with approximately 1800 minor or sub- drainage basins. This work was produced over the past 20 years by the USGS-WRD. Generally, the contours on the quads are the primary guide to basin boundaries. Often the 'mouth' of a basin is marked at the site of a stream gauging station, which can be different from the strict geographic location of the mouth.
METHODOLOGY
The major basins were produced from the sub-basins using the Arc/INFO Dissolve command. This removed all lines except boundaries between major basins. This was possible because the Major Basin # is encrypted in the Sub-Basin-ID
The resulting Massachusetts internal major basin boundaries were then Appended to the state outline and shoreline, and processed to result in a statewide polygon datalayer, which is a digital facsimile of the Massachusetts Water Resources Commission official Massachusetts Drainage Basins Map.
All sub-basins on the manuscripts were digitized (refer to SUB-BASINS Datalayer description). Due to good manuscript quality, including the visual edgematching of the 189 sheets, digitizing and edgematching was straightforward. The manuscript author was consulted on the minor errors and ambiguities that were discovered.