The County Geologic Atlas and Regional Hydrogeologic Assessment Program

The County Geologic Atlas and Regional Hydrogeologic Assessment Program prepares maps and reports describing the geology and ground-water resources of counties and multi-county regions.  A County Geologic Atlas (CGA) is a systematic study of a county's geologic and ground water resources.  Geologic studies include both near-surface deposits and bedrock.  Ground water studies include flow systems, aquifer capacity, and ground water chemistry.  In some areas sand and gravel deposits, sinkholes, or other features are studied.  Interpretation of sensitivity to pollution is also part of an atlas.  The information is organized, analyzed, and displayed using geographic information system (GIS) technology.  A Regional Hydrogeologic Assessment (RHA) is similar to a County Geologic Atlas in that both geology and ground water are studied.  However, a Regional Hydrogeologic Assessment covers a larger area, typically four to nine counties, in less detail.  The RHA emphasizes near-surface geologic, ground water, and pollution sensitivity mapping. 

Most Geologic Atlas and Regional Hydrogeologic Assessment projects are done in two parts.  The Minnesota Geological Survey (MGS) covers basic geology and creates databases of information such as wells and soil borings in Part A.  The Minnesota Department of Natural Resources (DNR Waters) handles hydrogeology and ground water sensitivity layers in Part B.  Completion of a project's two parts is staggered: Part A is completed about two years before part B, compiling information used to create Part B.  Parts A and B are published and distributed as two separate products, and are available for purchase from the the Minnesota Geological Survey (MGS). 

The following digital data sets are companions to the paper county atlas and hydrogeologic assessment maps and reports available for purchase from the MGS.  Base layer data such as roads, hydrography, and political boundaries, is provided largely from TIGER/Line files.  These GIS data sets (ARC/INFO export format) are available for purchase ($95 each) from the Minnesota Land Management Information Center (LMIC).  Generally, the scale of a County Geologic Atlas is 1:100,000, and the scale of a Regional Hydrogeologic Assessment is 1:200,000.  An exception is the Stearns County Geologic Atlas: Western Stearns County is 1:200,000; Eastern Stearns County is 1:100,000. 

Fillmore County Geologic Atlas
PART A: This data set includes bedrock geology; bedrock topography; surficial geology; watersheds, springs, wells, sinkholes, dye trace paths; sinkhole probability; geologic resources; water wells; and base layers.  PART B: Ground water and sensitivity data set includes hydrology for the Prairie du Chien-Jordan, Franconia-Ironton-Galesville, and Upper Carbonate aquifers; sinkhole probability; springsheds; and base layers. 

Regional Hydrogeologic Assessment - Anoka Sand Plain - Data layers include surficial geology, surficial aquifer water table contours, pollution sensitivity, and base layers.  The area covers Anoka, Chisago, Isanti, and Sherburne counties. 

Regional Hydrogeolgic Assessment - Red River Valley
PART A:  Two areas are represented on the coverages used to generate maps for the Red River Valley Hydrogeologic Assessment.  1) Red River Valley, Minnesota only: contains all of Clay, Norman, and Wilkin counties, and portions of Traverse, Grant, Ottertail, Becker, and Mahnomen counties.  Geologic layers include surficial geology (line and polygon), ice margins, and cross-section lines.  2) Red River Valley extended: contains the above-listed area, plus portions of Polk, Red Lake, and Pennington counties in Minnesota; all of Cass, Traill, and Steele counties in North Dakota; and portions of Richland, Sargent, Ransom, Barnes, Griggs, Grand Forks, and Nelson counties in North Dakota.  Geologic layers include quaternary stratigraphy, ice margins, and cross-section lines. 

Regional Hydrogeologic Assessment - Southwestern Minnesota 
The study area includes all of Pipestone, Murray, Rock, and Nobles counties; and portions of Lincoln, Lyon, Redwood, Cottonwood, and Jackson counties.  PART A: digital files include base layers; surficial geology; sand and gravel pits and quarries; point sampling sites and outcrops; seismic lines; and bedrock topographic contours.  PART B: digital files include base layers, ground water, and sensitivity information. 

Rice County Geologic Atlas
PART A:  Data set includes bedrock geology, surficial geology, bedrock topography, geologic resources, quaternary stratigraphy, database (wells, soil borings, and other drill holes), and base layers. 

Stearns County Geologic Atlas
PART A:  a set of seven coverages includes bedrock geology; surficial geology; quaternary stratigraphy; bedrock topography and drift thickness; mineral resources; database (wells, soil borings, and other drill holes); and base layers.