On 18 September 2026, the average daily discharge of the Rhine at Basel-Kleinhüningen was lower than 1% of all measured daily discharges since 2020. The daily minimum was 303 m³/s, the maximum was 455 m³/s, and the mean was 407 m³/s. These values are exceptionally low: the maximum discharge ranked 31st over the last 30 days, and it was the lowest maximum flow recorded for any October day since 2020, as well as the lowest maximum flow among all days since 2020.

Over the past 30 days, the highest discharge was 817 m³/s on 22 August 2026, while the lowest was 291 m³/s on 8 September 2026. Table 2 lists the months with the lowest flow conditions since 2020; September 2026, with a minimum average flow of 406.5 m³/s, is the lowest on record, followed by August 2026 at 413.0 m³/s. The current flow is therefore not only below the historical low-flow months but also defines the new minimum for the period since 2020.

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.