Rhine August flow hits historic low, disrupting shipping and ecosystems.

August 3, 2026

On 2 August 2026, the Rhine at Basel recorded an exceptionally low daily discharge of 442 m³/s, marking the lowest maximum flow ever observed on an August day since 2020. Such low water levels have far-reaching consequences, including rising transport costs, degraded water quality, restrictions on industrial cooling, and pressure on water supply and ecosystems.

On 2 August 2026, the average daily discharge of the Rhine at Basel-Kleinhüningen was 442 m³/s, which is lower than 1 % of all daily discharges recorded since 2020. The flow ranged from a minimum of 321 m³/s to a maximum of 517 m³/s. These values are notably low: the maximum discharge ranked 29th out of the last 30 days, and it was the lowest maximum flow ever recorded on an August day since 2020. Over the entire period of record since 2020, it was also the lowest maximum discharge observed on any calendar day.

Over the past 30 days, the highest discharge was 907 m³/s on 3 July 2026, while the lowest was 323 m³/s on 30 July 2026. Table 2 lists the months with the lowest flow conditions since 2020, and August 2026 appears as the second-lowest on record, with a minimum average flow of 442 m³/s, only slightly above the record low of 436 m³/s set in 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.



Table 1: Comparison of Rhine River Discharge from 2026-08-02 and historic August statistics
metric '2026-08-02'::date Historic
Average discharge 441.5 1048.4
Maximum discharge 517.3 2834.5
Minimum discharge 321.1 259.9


Table 2: The five months since 2020 with the lowest daily flow
Month Min Avg Flow [m3/s]
08.2022 435.9
08.2026 441.5
07.2026 442.1
04.2025 470.4
03.2023 471.4

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.