Italy’s Po River—its longest river—has fallen to record lows so early in the year that officials and farmers are warning of a potentially severe drought.

In the Po Valley, a farming region that produces much of the agricultural output used for staples such as Parmesan, heat and lack of rain have sharply reduced river flow. One farming area reported that an irrigation canal was shut because seawater would intrude and damage crops. Farmers described fields drying out and soil beginning to crack, with irrigation becoming less reliable as water reserves shrink.

Authorities and water agencies say the Po’s flow has dropped dramatically compared with typical June levels. With the river running too low to push back the sea, saltwater has moved upstream into the lower reaches of the river system, raising fears of salt contamination of farmland and wells near the delta. Barriers meant to stop seawater only work if river flow is strong enough, and engineers said current conditions fall short.

Beyond crop irrigation, the drought is also affecting fisheries. With temperatures high and the river system strained, fishermen have reported difficult working conditions and worsening conditions for shellfish.

Environmental experts and conservation groups say the region is not yet at the point of the worst outcome, but that the pace of water loss is leaving little time for recovery. They point to reduced winter snow and earlier melting—linked to climate change—as making the Po Valley’s water reserves harder to replenish.

Farmers and local officials are considering measures such as water-retention projects and irrigation changes, but many fear these responses may not be sufficient if the drought deepens.