Iowa Depth to Water Table GIS Data
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Author: emlemke
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Depth to water table is the vertical distance from the ground surface to the upper limit of the seasonal saturated zone. Values are interpreted in soil surveys from direct observations at selected sites and from hydromorphic evidence in profiles (redox features, organic accumulations, and horizon patterns). The map summarizes the representative seasonal water table expected under natural conditions; brief, storm-driven saturation is not considered a water table, and modern drainage or grading may shift conditions locally.
Applied Relevance
Shallow depths signal higher risk of waterlogging, rutting, denitrification, and delayed field access; deeper depths indicate better aeration, rooting, and trafficability. These maps help plan tile drainage and outlet placement, schedule operations, screen sites for basements and septic systems, prioritize wetland protection or restoration, and identify areas more vulnerable to contamination or flooding.
GIS Map Folder Download
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GIS Map Details
Source data are USDA-NRCS gSSURGO map units and NASIS attributes where water table depth is stored as low, representative, and high estimates. The statewide raster uses the representative value, generalized to map units and gridded at 10-m resolution to match SSURGO cartography. Color ramps are standardized for county and watershed comparison. Use at regional to county scales; verify site-level decisions in the field because inclusions, drainage alterations, and local grading are not captured.
Metadata – Sources – Limitations
Produced by: Meyer Bohn, Joshua McDanel, and Bradley Miller January (2019)
Created with the gSSURGO mapping toolset for ArcGIS for Desktop 10.6. Available for download at:
https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628
Raster Format: 10-m resolution GeoTIFF, 32-bit floating point
Projection: NAD83 UTM Zone 15N
Extent – West: -96.801571 East: -90.007463 North: 43.644364 South: 40.302683
Soil Survey Staff. 2018. Natural Resources Conservation Service. United States Department of Agriculture. Gridded Soil Survey Geographic (gSSURGO) Database for Iowa. Accessed 27 Oct 2018.
Use limitations: See “Sources of Apparent Error on Existing Soil Maps”. Soil Survey Staff. 2018. Soil Survey Manual – Ch. 4: Soil Mapping Concepts. Natural Resources Conservation Service. United States Department of Agriculture. Available at:
https://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/ref/?cid=nrcs142p2_054254#quality
Scale Range: Not intended for use at scales larger than an order 2 Survey (1:12,000 to 1:31,680).