Report urges closer Swiss-French cooperation on flood and drought risks

Water risks are testing a border that cuts through one shared region. A report presented on Tuesday urges Swiss and French authorities to coordinate how they manage water around Geneva, Ain and Haute-Savoie, where floods and droughts affect connected river basins and aquifers. Its authors argue that administrative boundaries do not match the way water moves.

The audit was conducted jointly by the Regional Court of Accounts for Auvergne-Rhône-Alpes and the Court of Accounts of the Republic and Canton of Geneva. Barbara Falk, president of the French regional court, described the area as a single metropolitan territory divided by a national border. “Natural phenomena, however, have absolutely no regard for human-drawn borders,” she said.

The report points to droughts in 2023 and 2026 and historic flooding on the Arve River in November 2023 as recent examples of the pressures facing the region. It calls for cooperation to reflect those shared risks.

The region’s waterways form a cross-border network. France and Switzerland share Lake Geneva, described in the report as Western Europe’s largest surface water reserve, along with 2,400 kilometres of waterways, including the Rhône, and several underground aquifers. The audit focuses on watersheds around Geneva, Ain and Haute-Savoie.

The report also highlights how administrative divisions can obscure that physical connection. The Divonne River, for example, takes the name Versoix after it crosses into Switzerland. The change in name reflects a national boundary, while the river itself continues across it.

For the auditors, this means water management should be organised around river basins. The report urges authorities to build a shared “water culture” into their practices, rather than relying only on administrative arrangements. That approach would bring the management of surface water and underground reserves into a common cross-border frame, matching decisions more closely to the connected waterways they govern.

A month’s difference in restrictions can complicate a shared response. The report notes that France and Switzerland have at times put water-use restrictions into effect one month apart. When authorities act on different schedules, residents and water managers on either side of the border face rules that do not line up, even as they draw on connected waters.

The auditors recommend a cross-border water observatory, joint prevention initiatives and closer coordination during crises. Those proposals aim to give authorities a shared view of risks and improve cooperation before and during extreme events.

Falk said the Geneva area is “a rather magical, unique, and extremely complex territory,” with a border running through what functions as one metropolitan area. The report’s recommendations respond to that practical geography: watersheds link places that are administered separately. A basin-wide perspective, the auditors argue, should shape how both countries prepare for drought, flooding and restrictions on water use.

Two agreements signed in 2025 give cooperation a formal foundation. France and Switzerland signed one agreement on regulating the waters of Lake Geneva and another on cooperation over the transboundary waters of the Rhône in September 2025. The report now presses authorities to strengthen day-to-day coordination around Geneva, Ain and Haute-Savoie as climate-related water risks grow.

For residents and communities in the region, the recommendations concern the practical management of rivers, aquifers and water restrictions across a shared territory. A proposed observatory could support a common view of water conditions; joint prevention and crisis coordination could connect the work of authorities across the border.

The audit’s central call is to manage water at the level of river basins and build that perspective into the practices of both countries. The agreements address Lake Geneva and the Rhône, while the report’s recommendations also point to the wider cross-border watersheds around Geneva.