The Lower Colorado Regional Office Geographic Information Systems Group provides geospatial information, applications, analyses, digital and analog maps to manage Reclamation's resources in Arizona, southern California, and southern Nevada in accordance with federal mandates and standards.

The group's projects and products include:

• Soils - Since the early 1900s, Reclamation has used its own soil classification system to determine the suitability of soil for irrigation. Nearly 1.5 million acres of those classified lands have been converted to GIS coverages.
  
  
• Water Contracts - There are approximately 420 water contracts administered by the Lower Colorado Region of the Bureau of Reclamation. The Regional Office GIS group provides a spatial component for data that is stored and administered in a Visual FoxPro database.



• Reclamation Lands - More than 1 million acres of Reclamation-administered lands in Arizona, southern California, and southern Nevada have been digitized and put into a GIS coverage. Each item in the coverage includes the Tract Number and Type. The "Tract Number" is a unique identifier that is used to tie it to the FIRM database, which contains relevant data about the land. The "Type" field describes the acquisition method in terms of Withdrawn, Fee Acquired, and Easement. Some data on State and Private lands is also available.



• Public Lands Survey System - The Bureau of Land Management's web site contains the Public Lands Survey System which follows Geographic Coordinate Data Base (GCDB) standards for accuracy. Validated and non-validated data is available for most of the state of Arizona. (Validated data has been edge matched while non-validated data is not.) A Township map of Arizona has been created using this data and edge matching, with older data rubber sheeted in areas that were not covered. Two coverages for northwest and southwest Arizona have been created down to the section level using this procedure. A small portion of Northeast Arizona is not covered by any data.



• Clipped Digital Raster Graphics (DRG) Images - A library of USGS 7.5 minute quads is available for most of the Lower Colorado Region area. Most graphics have been clipped so they can be mosaicked together, and an image catalog of all DRGs of Reclamation land holdings is also available.



• Reclamation Reform Act - The Reclamation Reform Act of 1982 requires that Reclamation track land irrigated by Central Arizona Project water. Data on soil suitability, grandfather rights, parcel size, etc. along with land ownership for the following water districts is tracked in the GIS system: Central Arizona Irrigation District (ID), Queen Creek Irrigation and Drainage District (IDD), Chandler Heights ID, Roosevelt ID, Hohokam IDD, San Tan ID, Harquahala Valley IDD, Tonopah ID, Maricopa-Stanfield IDD, Unit B IDD, and New Magma IDD.



• Colorado River Cross Sections - Reclamation periodically cross sections the river at strategic locations. The data is used for river modeling to help determine release levels at the dams along the river. These sections are extended beyond the main channel to help determine long term effects of water releases.



• River Miles - One method of finding features along the Colorado River is by the use of River Miles. Since the river is constantly changing, a mile may not always be a mile. However certain anchor points such as Parker Dam are set and never change. Reclamation maintains a coverage of the River Mile system that Reclamation uses. River miles are measured starting at the Southern International Boundary going north. A narrative listing of these points can be found at: www.usbr.gov/lc/region/pao/rvrmiles.pdf.



• Satellite Images - Images along the Colorado River mainstem are available. They have been combined in an image catalog so all the images can be referenced from one theme.



• Natural Resource Mapping - Current and accurate maps of natural vegetation are critical to Reclamation for a variety of natural resource issues. In 1994, riparian vegetation was mapped for the Colorado River above the Mexican border northward to Davis Dam. In 1997, the a contractor again mapped riparian vegetation of the river, but extended the coverage northward to the Lower Grand Canyon, plus portions of the Virgin and Gila Rivers. Riparian vegetation was classified (using a modified Anderson & Ohmart classification system) by interpreting 1997 aerial color photography and using USGS digital orthophotography for georeferencing purposes. Thematic and spatial accuracy of the data were then verified through statistical and field sampling, and an Arc Info polygon coverage of the data was generated.