The 2000 Siskiyou County land use survey data set was developed by DWR through its Division of Planning and Local Assistance (DPLA). The data was gathered using aerial photography and extensive field visits, the land use boundaries and attributes were digitized, and the resultant data went through standard quality control procedures before finalizing. The land uses that were gathered were detailed agricultural land uses, and lesser detailed urban and native vegetation land uses. The data was gathered and digitized by staff of DWR’s Northern District. Quality control procedures were performed jointly by staff at DWR’s DPLA headquarters and Northern District. Important Points about Using this Data Set: 1. The land use boundaries were drawn on-screen using the USGS orthophotoquads. They were drawn to depict observable areas of the same land use. They were not drawn to represent legal parcel (ownership) boundaries, or meant to be used as parcel boundaries. 2. This survey was a "snapshot" in time. The indicated land use attributes of each delineated area (polygon) were based upon what the surveyor saw in the field at that time, and, to an extent possible, whatever additional information the aerial photography might provide. For example, the surveyor might have seen a cropped field in the photograph, and the field visit showed a field of corn, so the field was given a corn attribute. In another field, the photograph might have shown a crop that was golden in color (indicating grain prior to harvest), and the field visit showed newly planted corn. This field would be given an attribute showing a double crop, grain followed by corn. The DWR land use attribute structure allows for up to three crops per delineated area (polygon). In the cases where there were crops grown before the survey took place, the surveyor may or may not have been able to detect them from the field or the photographs. For crops planted after the survey date, the surveyor could not account for these crops. Thus, although the data is very accurate for that point in time, it may not be an accurate determination of what was grown in the fields for the whole year. If the area being surveyed does have double or multicropping systems, it is likely that there are more crops grown than could be surveyed with a "snapshot". 3. If the data is to be brought into a GIS for analysis of cropped (or planted) acreage, two things must be understood: a. The acreage of each field delineated is the gross area of the field. The amount of actual planted and irrigated acreage will always be less than the gross acreage, because of ditches, farm roads, other roads, farmsteads, etc. Thus, a delineated corn field may have a GIS calculated acreage of 40 acres but will have a smaller cropped (or net) acreage, maybe 38 acres. b. Double and multicropping must be taken into account. A delineated field of 40 acres might have been cropped first with grain, then with corn, and coded as such. To estimate actual cropped acres, the two crops are added together (38 acres of grain and 38 acres of corn) which results in a total of 76 acres of net crop (or planted) acres. 4. Water source and irrigation method information were collected for this survey, but are not present in this dataset. Contact Tito Cervantes of Northern District for more information about this data. 5. Not all land use codes will be represented in the survey.

This data represents a land use survey of western Madera County conducted by the California Department of Water Resources, South Central Regional Office staff. The field work for this survey was conducted during the summer of 2011 by staff visiting each field and noting what was grown. Land use field boundaries were digitized using 2010 National Agriculture Imagery Program (NAIP) one-meter imagery as the base. Roads and waterways were delineated as a countywide shapefile using the U.S. Census Bureau's TIGER®(Topologically Integrated Geographic Encoding and Referencing) database and then clipped to match the USGS quadrangle boundaries. Field boundaries were digitized after roads and waterways on a quadrangle by quadrangle basis. Digitizing was completed at 1:4000 scale for the entire survey area. They were drawn to depict observable areas of the same land use. They were not drawn to represent legal parcel (ownership) boundaries, or meant to be used as parcel boundaries. Field work for land use surveys occurs primarily during the summer and early fall, so it can be difficult to identify fields where winter crops have been produced during the survey year. To improve the mapping of winter crops, we analyzed Landsat 5 imagery to identify fields with high winter vegetative cover. The identification of these fields was based on an analysis of Landsat 5 scene 4334 from April 4, 2011. Visual inspection of the Landsat scene displayed in false color infrared was used to select fields with high and low vegetative cover. These fields were used to develop spectral signatures using ERDAS Imagine and eCognition Developer software. The Landsat image was classified using a maximum likelihood supervised classification to label each pixel as vegetated or not vegetated, then the zonal attributes of polygons representing agricultural fields were summarized to identify fields vegetated during the winter. Polygons representing these fields were used on laptops taken to the field to highlight the fields which should be checked closely for winter crop residue.Site visits occurred from July through October 2011. Images and land use boundaries were loaded onto laptop computers that, in most cases, were used as the field data collection tools. GPS units connected to the laptops were used to confirm surveyor's location with respect to the fields. Staff took these laptops into the field and virtually all the areas were visited to positively identify the land use. Land use codes were digitized in the field on laptop computers using ESRI ArcMAP software, version 9.3. Some staff took printed aerial photos into the field and wrote directly onto these photo field sheets. The data from the photo field sheets were digitized back in the office.