Daily hydrological report – Rhine at Basel-Kleinhüningen, 25 July 2026

On 25 July 2026, the average daily discharge of the Rhine at Basel‑Kleinhüningen was 459 m³/s, a value lower than 1 % of all measured daily averages since records began in 2020. The minimum flow on that day was 359 m³/s and the maximum reached 537 m³/s. All three figures are exceptionally low for the season. The maximum discharge of 537 m³/s ranked 30th over the last 30 days, the second‑lowest among all July days since 2020, and near the very bottom of all daily maxima in the 2020‑present record.

Over the past 30 days, flows briefly recovered but then declined sharply. The highest daily discharge was 1068 m³/s on 2 July, while the lowest was 370 m³/s on 24 July. The long‑term minimum‑flow statistics since 2020, shown in Table 2, confirm the exceptional nature of the current low‑flow period: the daily mean of 459 m³/s on 25 July matches July 2026’s own monthly minimum average, placing this month among the five driest since 2020 and second only to August 2022.

Low water levels on the Rhine have consequences that reach well beyond the river itself. Cargo vessels have to reduce their load to stay clear of the riverbed, so more trips are needed to move the same volume and transport costs rise sharply, with the effect passed on to industries that depend on the waterway for coal, oil products, chemicals and grain. The shallower water also heats up faster in summer. Warmer water encourages bacterial growth, which can produce noticeable odors, and it holds less dissolved oxygen. The combination of higher temperatures, lower oxygen and more concentrated pollutants degrades water quality and can lead to fish kills. Swimming is generally discouraged under these conditions because of the higher bacterial load. Further effects include restrictions on power plants and industrial sites that draw river water for cooling, since they may no longer discharge warmed water without exceeding temperature limits, reduced dilution of treated wastewater, pressure on water supply and irrigation in the surrounding area, and falling groundwater levels along the river that affect riparian vegetation and wells.