This map is designated as Final.Land-Use Data Quality ControlEvery published digital survey is designated as either ‘Final’, or ‘Provisional’, depending upon its status in a peer review process. Final surveys are peer reviewed with extensive quality control methods to confirm that field attributes reflect the most detailed and specific land-use classification available, following the standard DWR Land Use Legendspecific to the survey year. Data sets are considered ‘final’ following the reconciliation of peer review comments and confirmation by the originating Regional Office. During final review, individual polygons are evaluated using a combination of aerial photointerpretation, satellite image multi-spectral data and time series analysis, comparison with other sources of land use data, and general knowledge of land use patterns at the local level.Provisional datasets have been reviewed for conformance with DWR’s published data record format, and for general agreement with other sources of land use trends. Comments based on peer review findings may not be reconciled, and no significant edits or changes are made to the original survey data.The 2006 Del Norte County land use survey data set was developed by DWR through its Division of Planning and Local Assistance which, following reorganization in 2009 has been subdivided into the Division of Statewide Integrated Water Management (DSIWM) and the Division of Integrated Regional Water Management (DIRWM). 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 Regional Office. Quality control procedures were performed jointly by staff at DWR’s Statewide Integrated Water Management headquarters and Northern Regional Office, under the supervision of Tito Cervantes, Senior Land and Water Use Scientist. This data was developed to aid DWR’s ongoing efforts to monitor land use for the main purpose of determining current and projected water uses. The associated data are considered DWR enterprise GIS data, which meet all appropriate requirements of the DWR Spatial Data Standards, specifically the DWR Spatial Data Standards version 2.1, dated March 9, 2016. DWR makes no warranties or guarantees - either expressed or implied - as to the completeness, accuracy, or correctness of the data. DWR neither accepts nor assumes liability arising from or for any incorrect, incomplete, or misleading subject data. Comments, problems, improvements, updates, or suggestions should be forwarded to gis@water.ca.gov. This data represents a land use survey of Butte County conducted by DWR, Northern District Office staff, under the leadership of Tito Cervantes, Senior Land and Water Use Supervisor. The field work for this survey was conducted during the summer of 2004. ND staff physically visited each delineated field, noting the crops grown at each location. Field survey boundary data was developed using: 1. The county was surveyed using the 2005 one-meter resolution National Agriculture Imagery Program (NAIP) digital aerial photos as a digital reference for line work and field work. 2. From the 2005 NAIP imagery, digital 7.5’quadrangle sized images were created, with one-meter resolution. These were used in the spring of 2006 to develop the digital land use boundaries that would be used in the survey. The digitizing of these boundaries was done using AutoCAD Map software. 3. The digital images and land use boundaries were copied onto laptop computers that, in most cases, were used as the field data collection tools. The staff took these laptops into the field and virtually all the areas were visited to positively identify the agricultural land use. The site visits occurred between June and August 2006. Land use codes were digitized directly into the laptop computers using AUTOCAD (using a standardized digitizing process). Some staff took the printed aerial photos into the field and wrote land use codes directly onto these photo field sheets. The data from the photo field sheets were digitized back in the office. For both data gathering techniques any land use boundary changes were noted and corrected in the office. Urban and native classes of land use were mapped by both field observation and photo interpretation. 4. The linework and attributes from each quadrangle drawing file were brought into ARCINFO and both quadrangle and survey-wide coverages were created, and underwent quality checks. These coverages were converted to shapefiles using ArcMAP. 5. After quality control/assurance procedures were completed on each file, the data was finalized. The primary focus of this land use survey is mapping agricultural fields. Urban residences and other urban areas were delineated using aerial photo interpretation. Some urban areas may have been missed, especially in forested areas. Before final processing, standard quality control procedures were performed jointly by staff at DWR's Northern District, and at DPLA headquarters under the leadership of Jean Woods, Senior Land and Water Use Supervisor. After quality control procedures were completed, the data was finalized. The positional accuracy of the digital line work, which is based upon the 2005 one-meter resolution National Agriculture Imagery Program (NAIP), is approximately 12.1 meters. The land use attribute accuracy for agricultural fields is high, because almost every delineated field was visited by a surveyor. The accuracy is 95 percent because some errors may have occurred. Possible sources of attribute errors are: a) Human error in the identification of crop types, b) Data entry errors.
