Residents in Decorah and throughout Winneshiek County may notice aircraft flying unusually low in the coming weeks as the U.S. Geological Survey begins an aerial mapping project across the Driftless Area. The flights could start as early as November and are designed to improve understanding of the region’s underground geology.
The survey will collect airborne geophysical data across portions of 40 counties in Iowa, Minnesota and Wisconsin. In northeast Iowa, the planned coverage includes Allamakee, Clayton, Fayette, Howard, Mitchell and Winneshiek counties. The southeastern Minnesota portion includes Dodge, Fillmore, Houston, Olmsted, Wabasha and Winona counties.
What residents may see
Survey aircraft will generally follow north-south lines spaced about 1,310 feet apart. Outside populated areas, the planes are expected to operate at approximately 330 feet above ground level. Flights over populated areas will typically be conducted at about 1,000 feet.
The flights will occur only during daylight hours. The USGS said the aircraft carry passive instruments that measure natural variations in Earth’s magnetic field. The equipment produces no emissions expected to affect people, livestock, wildlife or crops, and the project will not collect photography or video imagery.
Why the survey is being conducted
The project is part of the USGS Earth Mapping Resources Initiative, or Earth MRI. The initiative is intended to modernize geological maps and help identify possible mineral, groundwater and energy resources, along with natural hazards.
Scientists say magnetic surveys can help reveal underground rock formations and geological structures. The information may also help identify areas that could contain critical minerals such as nickel, copper, cobalt and platinum-group elements.
“This USGS program offers the Minnesota Geological Survey an opportunity to improve our understanding of geologic resources in the state, including materials needed for cleaner sources of energy and national security,” said Robert Tipping, director of the Minnesota Geological Survey.
In Iowa, Ryan Clark, associate Iowa state geologist for energy and minerals, said the new data will help researchers assess the state’s potential for critical minerals and geologic hydrogen resources.
Winter pause and public data
The aerial survey will pause during the winter months and resume in 2027. Once collected, the project’s data will be made publicly available through the USGS.
Aircraft supporting the work will operate from several regional airports, including Albert Lea, Mason City and Iowa Falls. The project is being reported by LA Communications News, which said the mapping effort is aimed at improving scientists’ understanding of northeast Iowa and southeast Minnesota’s subsurface geology.