DNR has released a new aggregate resource map of Yellow Medicine County (published July 22, 2025)

Geologists in the Minnesota Department of Natural Resources Aggregate Resource Mapping Program have completed a new map showing the potential for sand, gravel and crushed stone resources in Yellow Medicine County. These natural materials, known as construction aggregates, are crucial to the construction of roads, bridges, trails and buildings.

The full dataset, including resource maps and a countywide gravel pit survey, is available on the DNR’s online interactive mapping webpage.

Highway engineers and land use planners in Yellow Medicine County can utilize the science-based aggregate maps to identify local deposits of sand, gravel and crushed stone materials. Sourcing aggregate materials locally can be a good environmental stewardship practice, as it reduces greenhouse gas emissions from transportation and conserves nonrenewable natural resources.

Aggregates are naturally occurring accumulations of glacial meltwater sediment formed during the last Ice Age. The 14,000-year-old deposits of sand, stone and gravel are finite and can only be replenished during another glacial period, so it's important to know where to find these resources and to ensure their long-term availability.

Across Minnesota, about 50% of all aggregate is used in publicly funded infrastructure projects. To put the scale of use in perspective, building just one mile of a four-lane highway can require about 340,000 cubic yards of aggregate.

How geologists map aggregate resources

The resource mapping process begins with identifying landforms likely to contain deposits of sand and gravel using topographic information, aerial imagery and other geospatial data. Since not all materials are suitable for construction, geologists conduct field research to assess the thickness of sand and gravel and evaluate the aggregate's potential for use as a construction material. Once field data is collected, geologists use geographic information systems to create detailed maps that show the locations of the resources.

Statewide mapping efforts

The Minnesota Legislature established the DNR’s Aggregate Resource Mapping Program to provide essential resource maps for communities, planners and industry leaders, enabling them to sustainably utilize limited natural materials and balance infrastructure, economic and environmental considerations. DNR has now completed aggregate maps for 30 of Minnesota’s 87 counties.

The Yellow Medicine County project was funded through a grant from the Minnesota Environment and Natural Resources Trust Fund, as recommended by the Legislative-Citizen Commission on Minnesota Resources. Additional LCCMR funding will allow the DNR to continue mapping in more counties.

To explore the Yellow Medicine County map and learn more, visit the DNR’s online interactive mapping webpage.