Minnesota DNR launches aggregate resource mapping program for counties

The Minnesota Department of Natural Resources (DNR) is mapping natural sand, gravel and crushed‑stone deposits across the state to help counties plan future aggregate extraction. Geologist Chad Crotty explains that each resident uses about 10 tons of aggregate per year for roads, bridges, trails and foundations. The program combines historic maps, lidar‑derived land‑form data, soils and geology maps, and field verification—digging test holes to confirm the presence of usable material.

Itasca and Aitkin counties have already been mapped, and work in Cook County is about half complete, with geology student Brianna Berg and other assistants conducting field checks. Cook County Engineer Robert Kass says the data will enable targeted decisions when opening new gravel pits or locating sand for septic systems, especially in areas with limited developable land.