Half of the groundwater used to grow America’s favorite fruits, nuts, veggies, seeds and greens is drawn from aquifers faster than they can refill, according to a new study. Irrigating 75% of produce and specialty crops with groundwater between 2008 and 2020 helped spare farms from the immediate impacts of droughts, but dependence on draining aquifers could set up producers for future water supply strife.

A new study appearing in Water Resources Research provides the first county-level data on irrigation sources for 65 different specialty crops, including everything from cantaloupes to cabbage. “Up until this point, we’ve kind of been flying blind,” said Jackie Hanley, a civil engineering researcher at the University of Illinois at Urbana-Champaign and the study’s lead author.

Knowing where irrigation water goes and where it comes from—rivers, reservoirs or underground aquifers—is vital for farmers and policymakers deciding how to manage finite water supplies for farms in the face of mounting water scarcity.