WATER Soils Data 9/19/97 Detailed soils data are available for Monterey and Santa Cruz County areas only at this time. DATA SOURCES The Santa Cruz County soil data was obtained from the developers of the data layer at CalPoly's Department of Landscape Architecture in January of 1997. It has been certified by the USDA Natural Resource Conservation Service. The Monterey County soil data was obtained from the Natural Resource Conservation Service on February 7, 1997. The data was undergoing final quality control by NRCS at that time, and should therefore be considered "provisional" until final certification takes place. The following quote is from the letter that NRCS sent to accompany the Monterey County soils data: "The files are non-certified State Soil Survey Geographic Database (SSURGO) data. These digital soil maps have not gone through our agency's indepth cartographic digital editing and certification process. As an interim copy, there may be missing or mislabeled polygons and misalignment of soil boundary lines. This dataset should be used with caution and considered as an "Advance Copy, Subject to Change" during the certification period. If you suspect a problem with the data, please contact Essie Johnson, Cartographic Technician at (916) 757-8316. "Enlargement of digital maps to scales greater than 1:24000 causes misunderstanding and misuse of data and infers a level of accuracy that is not reflective of the original source materials. Enlarged maps do not show small areas of contrasting soils that would have been delineated had the original mapping been done at a larger scale. "The depicted soil boundaries and interpretations derived from these maps does not eliminate the need for detailed on-site sampling, testing, and study of specific areas for intensive uses. This information is intended for borad based planning applications. "The maps and attribute data may be modified during the review and certification process. Digital data files are periodically updated. Files are dated and users are responsible for obtaining the latest version of the data. Please feel free to contact [NRCS] to obtain data version status prior to completing final products." INTERPRETATION The key attribute of the soils (as classified by NRCS) is the 'mapunit symbol' or MUSYM field. The characteristics of each type of soil or map unit are found in the Map Unit Interpretation Records (MUIR) data for each county. The MUIR data can be found in separate MS Access 2.0 databases called MoMuir.mdb and SCMuir.mdb in the Soils\MontCo and Soils\SCruzCo directories, respectively. Each County has its own MUIR database. The MUIR data can also be found as a set of text files that can be imported directly into ArcView from the directories Soils\MontCo\MuirMont and Soils\SCruzCo\MuirSCCom. Once imported into your ArcView project, these tables can be linked to the soils attribute tables using the mapunits, thereby allowing you to display graphically such soil features as erodibility, permeability, etc. KEY SOIL CHARACTERISTICS FOUND IN THE PRIMARY ATTRIBUTE TABLES A subset of selected soil characteristics was assembled from the MUIR data and placed in the soil themes' primary attribute tables. These key characteristics are thus immediately available without having to import any additional tables. These fields include: Primefrmld indicates whether the soil represents prime farmland or not. Numcomps tells you how many components are in the soil map unit (there may be more than one component in a map unit, but their spatial distribution within a map unit is not given) Compname Name of the soil components in that map unit. If there are more than one, then a '/' symbol separates them. Comppct Percentage of the map unit which consists of that soil component. Where more than one component name is listed, the percentages are separated by a '/' symbol and correspond to the sequence of component names. Surftex A code for the USDA texture for the surface layer. Surftxdscr Textual description of the surface soil texture. Anflood Annual flooding frequency (i.e., the likelihood that flooding will occur in any give year. Anflodur The duration of flooding in a normal year. Pnddur The duration of surface water ponding in a normal year. Hydgrp The hydrologic group, which relates to infiltration rates. (Where more than one component was included in a map unit and their hydrologic groups are different, the hydrologic group of each component is shown, separated by a '/'). Infnum A numeric code corresponding to Hydgrp, used in creating legends in ArcView. Drainage The drainage class of the soil. (Where more than one component was included in a map unit and their drainage classes are different, the drainage class of each component is shown, separated by a '/'). Drainnum A numeric code corresponding to Drainage, used in creating legends in ArcView. Hydric Y or N to identify hydric soils. (Where hydric characteristics are different for different components within the same map unit, the hydric property is given for all components, separated by a '/'). Kfact Soil erodibility factor of the uppermost soil layer, includes rock fragments. (Where more than one component is included in a map unit, the HIGHEST value is provided.) Kffact Soil erodibility factor of the uppermost soil layer, rock fragment free. This factor is used in the Universal Soil Loss equation to calculate soil loss by water. (Where more than one component is included in a map unit, the HIGHEST value is provided.) Minperm The minimum value for the range in permeability rate for the uppermost soil layer, in inches/hour. (Where more than one component is included in a map unit, the LOWEST value is provided.) Minperm The minimum value for the range in permeability rate for the uppermost soil layer, in inches/hour. (Where more than one component is included in a map unit, the LOWEST value is provided.) Shrinksw The shrink-swell potential of the uppermost soil layer. Wei Wind Erodibility Index assigned to the uppermost soil layer, expressed in tons/acre/year. The MUIR data is more fully described in other documentation found in the Soils\Metadata directory. Reading the MUIR documentation is the key to understanding the wealth of information in the soils data. The fields provided in the primary attribute table are just the beginning... LEGENDS A set of .avl (ArcView legend) files are provided in the Soils/Legends directory. These can be used to display many of the soil characteristics contained in the primary attribute table (i.e., those listed above). To display a map of drainage classes, for example, load the soils theme, then double-click on the theme's name in the Table of Contents area in the left part of the View window. When you get the Legend Editor window, simply Load the legend from the Soils/Legends directory called drainage.avl. Click OK, then Apply, and presto, your soils are classified with pretty colors showing the various drainage classes!