Belgian Spring Stream Dries Up, Rare Fish Species Lost
The Molenbeek-Graadbeek stream in Meldert (Aalst), East Flanders, has completely dried up over a distance of more than 2 kilometers, according to VRT NWS. The spring-fed watercourse, which forms a natural connection between the Kravaalbos forest and the Dender river, has been reduced to a dry bed as Belgium’s ongoing drought intensifies. Environmental experts warn that rare fish species introduced through a seven-year recovery program have been lost.
“It is extremely exceptional that such a spring-fed river completely dries up,” said Pieter Boets of the Provincial Centre for Environmental Research (PCM). “I haven’t experienced this in the past 40 years.”
A Devastating Blow to Species Recovery
The Molenbeek-Graadbeek has been the focus of a dedicated species recovery program run by the PCM together with the Agency for Nature and Forest. Over the past seven years, the program released threatened fish species into the stream—including brown trout, chub, dace, gudgeon, and stone loach—to strengthen or reintroduce their populations.
Boets described the loss in stark terms: “The species recovery program was working well, now everything is lost.” Only at the spring source itself does a small amount of water remain visible, but it is too little to fill the stream bed.
The drying of the stream represents a significant setback for biodiversity conservation in Flanders. The affected species are all threatened in the region, and the stream had been carefully managed as part of the Gestroomlijnd Landschap (Streamlined Landscape) project, which aims to strengthen the natural connection between the Kravaalbos forest complex and the Dender while improving water management.
Drought and Suspected Illegal Water Extraction
The primary cause of the unprecedented drying is the ongoing heat and drought gripping Flanders. On July 16, the Drought Commission declared code orange for the region—the second-highest alert level, signifying “actual and widespread water shortage.” Groundwater levels at approximately 70 percent of monitoring points show low to very low values for this time of year, as VRT NWS reported.
However, Boets suspects that more than natural drought is at play. “We also suspect that the groundwater level is very low due to illegal water extraction,” he said, referring to unauthorized pumping that may be drawing down the water table faster than it can recharge.
The Molenbeek/Graadbeek (OVL-287) has been under a temporary extraction ban in East Flanders since at least 2025, with the ban expanded in July 2026 to cover additional zones as critical thresholds were reached. The ban prohibits pumping water from non-navigable watercourses and public ditches in affected zones, with limited exceptions for livestock watering and emergency services.
Broader Ecological Crisis
The Molenbeek-Graadbeek is not the only waterway suffering. The Grote Nete river in Antwerp province is also experiencing drought-related pressure on protected fish species, with invasive exotic species like Ponto-Caspian gobies displacing native fish that cannot tolerate warmer, lower-oxygen conditions. As researchers at the Research Institute for Nature and Forest (INBO) have warned, the fish population in the Grote Nete threatens to change permanently if extreme summer conditions become more frequent.
August has begun with tropical temperatures of 29 to 33 degrees Celsius and continued drought, according to MeteoVista, with no significant rainfall expected in the near term.
Calls for Better Water Management
Boets emphasized that the situation demands urgent policy attention. “We really need to control this better, especially now that long warm periods threaten to occur more often. The impact can be very large,” he said. “The entire ecosystem around the stream is disrupted. It has consequences for all plants and animals that live around the watercourse.”
He also stressed the importance of improving water infiltration after rainfall. “The water must reach the ground and watercourses as much as possible. It is less good to drain it quickly,” Boets said.
The loss of the Molenbeek-Graadbeek’s fish populations raises critical questions about the future of species recovery efforts in an era of increasingly frequent and severe drought. As climate projections suggest that such extreme dry periods will become more common, conservation programs across Flanders may need to adapt their strategies to account for a changing hydrological reality.
Whether the fish populations can recover once water returns to the stream remains an open question—as does the broader challenge of ensuring that Belgium’s waterways can withstand the pressures of a warming climate.