Rhine discharge at Basel hits record low since 2020.

September 24, 2026

On 23 September 2026, the Rhine at Basel-Kleinhüningen recorded an extremely low daily discharge of 402 m³/s, placing it among the lowest flows since 2020 and consistent with historic low-flow extremes. Such low water levels raise transport costs, degrade water quality, restrict cooling-water use, and stress water supply, groundwater, and ecosystems along the river.

On 23 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 402 m³/s, with a minimum of 233 m³/s and a maximum of 542 m³/s. These values are not notably high; the maximum discharge ranked 14th over the last 30 days, 18th among all October days since 2020, and was also very low compared with all days since 2020.

Over the past 30 days, the highest discharge was 749 m³/s on 28 August 2026, while the lowest was 188 m³/s on 22 September 2026. Table 2 lists the months with the lowest flow conditions since 2020, and the current low-flow period is consistent with those extremes. September 2026 already appears among the lowest monthly minimum flows, with a minimum average flow of 375 m³/s.


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.



Table 1: Comparison of Rhine River Discharge from 2026-09-23 and historic September statistics
metric '2026-09-23'::date Historic
Average discharge 401.8 862.1
Maximum discharge 541.6 2061.9
Minimum discharge 232.8 187.8


Table 2: The five months since 2020 with the lowest daily flow
Month Min Avg Flow [m3/s]
09.2026 375.0
08.2026 413.0
08.2022 435.9
07.2026 442.1
04.2025 470.4

Figure 1: Rhine River Discharge [m³/s] over the Past 30 Days

Data source: Rhein Wasserstand, Pegel und Abfluss
Additional resources: Data provider: Federal Office for then Environment (FOEN), Hydrological Data and Forcasts

🤖 This text was generated with the assistance of AI. All quantitative statements are derived directly from the dataset listed under Data Source.