Necva Tastan Sevinc
18 July 2026•Update: 18 July 2026
Prolonged drought and successive heat waves are rapidly drying up waterways and transforming aquatic ecosystems in southern France, with some fish species disappearing while others adapt to warmer conditions, Franceinfo reported Saturday.
Rivers and streams across the Languedoc and Roussillon regions have experienced falling water levels, sharply reduced flows and rising temperatures over the past two months, according to the report.
The French Office for Biodiversity's Onde monitoring network said 16% of rivers nationwide were dry by the end of June, while another 10% had "invisible" flows.
The proportion of dried-up waterways reached a record 22% in the southern Aude department, the report said. Mediterranean departments have been particularly affected, with between 10% and 20% of waterways drying up during summer, compared with a nationwide average of 5% to 10%.
"What is worrying today is the drying up of certain waterways at this time of year, when there are still two months of summer left," Adrien Arazo, director of the Aude Fishing Federation, told Franceinfo.
Critical conditions have been recorded in the Montagne Noire and Corbieres areas, particularly in the upper Aude Valley.
Despite heavy winter rainfall, an unusually dry and hot spring followed by an early, prolonged heat wave caused smaller waterways to lose water more rapidly through increased evaporation, according to the report.
The report said cold-water species, including brown trout and common bullhead, are expected to decline as water temperatures rise.
Meanwhile, chub, barbel, gudgeon and invasive American crayfish could benefit from the changing conditions because they thrive in slow-moving rivers where algae and plankton proliferate.
The French Office for Biodiversity said naturally occurring low water levels were often worsened by human activities, including irrigation and drinking water withdrawals.
Authorities have imposed varying water-use restrictions based on watershed conditions, groundwater levels and weather forecasts.
Arazo warned that rivers already suffering from low flows and reduced oxygen levels faced an increasing risk of drying up, posing "a real risk to the aquatic biodiversity of natural environments."
Ecological Transition Minister Monique Barbut said Wednesday that water restrictions were in effect across all 99 departments of metropolitan France as an "exceptional" and "very worrying" drought gripped the country.
A total of 206 prefectural orders restricting water use have been issued, the highest number recorded since at least 2013.
