If it feels like this summer has been unusually hot and dry, that’s because it has been. Summer 2026 has been one of the hottest on record in the UK, according to the Met Office. Combined with very little rainfall, those soaring temperatures have led to drought conditions across much of the country.
Here in the Solent region, dry weather can have a significant impact on our rivers, many of which are chalk streams. These rare and internationally important waterways are fed by underground chalk aquifers that are replenished by winter rainfall. When enough rain falls, groundwater levels rise and water begins to emerge from natural springs in the headwaters, creating the flowing streams we’re familiar with. The upper reaches of these chalk streams are known as “winterbournes” because they only flow during part of the year.
While it is perfectly natural for some of these upper sections to shrink or even dry out during summer, prolonged low river levels in the main channels are becoming more common. Hotter, drier summers linked to climate change, combined with demand on groundwater supplies, are placing increasing pressure on these fragile river systems.
Low river flows are a challenge in themselves, but they can become even more problematic when coupled with nutrient pollution.
Nutrients such as nitrogen and phosphorus enter rivers from a variety of sources, including agricultural runoff and wastewater. In small amounts they occur naturally, but when concentrations become too high they can fuel excessive algae growth, creating what are known as algal blooms.
When river levels are low, there is less water available to dilute these nutrients. This means their impacts can become more concentrated and more severe. Research has shown that drought and nutrient pollution can work together to put additional stress on river ecosystems.
Reduced river flows can also lead to rapid changes in water temperature and oxygen levels. For wildlife, including some of the UK’s most treasured species like the white-clawed crayfish, this can create difficult conditions to survive in. And the effects of drought don’t disappear overnight when the rain finally arrives. It can take many months of sustained rainfall for underground aquifers to recover and for river systems to return to healthier levels.
That’s why reducing nutrient pollution is so important.
The Solent Mitigation Partnership is delivering a range of nutrient mitigation projects across the region, including schemes that help reduce nutrient loading in sensitive chalk stream catchments such as the River Itchen. These projects not only reduce pollution but also enhance habitats, improve biodiversity and help build resilience against future environmental pressures.
By protecting our rivers today, we can help ensure they continue to support wildlife, communities and future generations for years to come.
River Test photo by Stewart Turkington: www.stphotos.co.uk
