The STATEMAP program supports detailed geologic mapping of Iowa, with particular emphasis on solving environmental problems. These maps provide a detailed view of the geologic materials that most affect Iowans’ day-to-day activities, and give users a sound base of geologic information from which to make resource decisions.
The National Geologic Mapping Act of 1992 created a mapping program administered by the U.S. Geological Survey (USGS) including a “STATEMAP” component that offers partial financial support for geologic mapping to state geological surveys through a competitive grant process. Projects span one year, and funding is provided as a 50:50 match between federal and state dollars. The State Geologist, in consultation with a State Mapping Advisory Committee (SMAC), sets the priorities for mapping in each state. The SMAC consists of individuals from academics, state and local governments (IDOT, NRCS, planning and zoning), professional societies, private industry (aggregate producers to environmental consultants), and watershed groups. Priorities are based on “State requirements for geologic map information in areas of multiple-issue need or compelling single-issue need and in areas where mapping is required to solve critical Earth science problems.”
The Iowa Geological Survey (IGS) produces both bedrock and surficial maps as either compilation (using existing data) or new (involving field investigations and drilling) mapping projects. The primary project themes promoted by the IGS and its SMAC in recent years are developing areas mapping, impaired watershed mapping, and cooperative mapping with the Natural Resource Conservation Service (NRCS). Maps are made available as PDFs on the IGS publications page and as shapefiles on the Iowa Department of Natural Resources NRGIS library. The STATEMAP fact sheet shows the areas that have been mapped and those in progress.
The IGS began participating when the program started in 1993–94. The first project mapped a segment of the Mississippi River valley covered by the Blanchard Island and Letts 7.5 minute quadrangles in southern Muscatine and northern Louisa counties. Since that time, the IGS has received nearly $3 million in federal funding, with most maps completed at quadrangle (1:24,000) or county (1:100,000) scale. In 2010, the IGS completed a bedrock compilation map of Iowa, a major improvement over the 1969 map. Current projects are focused on the upper Cedar River watershed in northeast Iowa.
Tools unavailable in the earlier years of traditional geologic mapping are applied to STATEMAP projects. The availability of statewide LiDAR data and digital NRCS soil surveys has greatly improved the ability to map beyond conventional methods. All maps are being compiled using geographic information system (GIS) technology. The use of GIS technology facilitates digital access for a large number of users with varied interests and provides flexible use of the geologic mapping for various applied purposes in the future. Other sources of subsurface information used to construct geologic maps include water well records stored in the IGS GeoSam database, engineering borings obtained from public utilities and the Iowa Department of Transportation, USGS monitoring well records, borings made by the IGS, air photos, and satellite imagery.
It is anticipated that the information developed by STATEMAP projects will be used to address a variety of problems related to development and the impact of increasing population density on geological resources. Possible applications include evaluating surface and subsurface drainage problems, vulnerability of groundwater to contamination, suburban expansion into areas of sinkholes (karst), water quality and quantity issues, identification and protection of aggregate resources, and flood management.