Description: The Public Land Survey System (PLSS) is a method used in the United States to locate and identify land, particularly for titles and deeds of farm or rural land. The system is in use in all states except the first 13, Vermont, Texas, and Hawaii. The system has been in general use since the Land Ordinance of 1785. Its basic units of area are the township and section. Sonoma County has Ranchos (Mexican Land Grants), which by treaty are not to be superseded by the Township and Range PLSS. In the Teale Data Center PLSNET coverage upon which this coverage was based, approximately 19% of the State was not gridded into sections. Most of these cases involved Spanish and Mexican land grant areas that were honored by the government of the United States when California became a State, and were subsequently excluded from the section survey process. Other areas were not sectioned because of difficulties in surveying wetlands and mountainous terrain. These unsurveyed areas have been gridded in the DPR PLSNET and can be identified in the PAT by selecting SOURCE = 0 (all labels added at DPR/ISB) and/or in the AAT by selecting EDITED = 1(all arcs that were all or partly added at DPR/ISB). This layer consists of polygons that depict the township and ranges contained in the Public Land Survey System grid for the County of Sonoma. Townships are roughly six miles square, and are numbered north and south from an established baseline. Likewise, ranges are numbered east and west from an established meridian. California uses three baseline/meridians, these being Humboldt, Mt. Diablo, and San Bernardino, abbreviated HB&M, MDB&M, and SBB&M. Township and range values are combined in the redefined item TOWN-RANGE to facilitate dissolve and dropline functions. This layer has been intersected with the State Water Board hydro-basin coverage. The result is that the layer has several fields in the table relating to the hydro-basin coverage, described later in document.