On 15 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 mean was 421 m³/s, with a minimum of 348 m³/s and a maximum of 467 m³/s. These values are not notably high; on the contrary, they are exceptionally low for the date. The maximum discharge on 15 September 2026 ranked 31st over the last 30 days, meaning it was the lowest daily maximum in that period. Compared with all September days since 2020, it ranked 1st, also the lowest maximum on record for the month. Compared with all days since 2020, the maximum discharge was also at the very bottom of the distribution.

Over the past 30 days, the highest daily discharge was 817 m³/s on 22 August 2026, while the lowest was 291 m³/s on 8 September 2026. The current flow is therefore close to the lowest level observed in the last month. Table 2 lists the months with the lowest flow conditions since 2020; August 2026 and September 2026 are already included, with minimum average flows of 413 m³/s and 414.5 m³/s respectively. The current daily mean of 421 m³/s is only slightly above these monthly minimum averages, confirming that the Rhine is experiencing one of its most severe low-flow periods in the available record.

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.