Anglers monitoring the River Test and River Itchen have warned of nitrate pollution they describe as “endemic and worsening”.
In the Test and Itchen, average nitrate levels exceeded ecologically safe limits (5 parts per million) in every single month of the third year of monitoring.
The concerns are highlighted in the Angling Trust’s third Annual WQMN report, which represents the largest citizen science water quality dataset ever collected for UK rivers.
The report draws on more than 12,000 samples collected nationally over three years, and points to ongoing environmental harm driven by nutrient pollution.
A high proportion of phosphate tests from both rivers breach the ‘good’ ecological status standards, signalling sustained nutrient pressure.
The Angling Trust claims rivers are being “suffocated” by a cocktail of sewage discharges and agricultural runoff.
The Angling Trust is now calling on ministers, regulators, and Southern Water to treat the Test and Itchen as an emergency priority for clean‑up, tighten phosphate and nitrate limits for chalk streams, and formally use citizen‑science data in enforcement.
Alex Farquhar, freshwater campaigns officer at the Angling Trust, said: “Excess nutrients on the scale revealed translate into algal blooms, fish without enough oxygen to survive, and anglers on the bank wondering where the fish have gone.
“Ecosystems have spent thousands of years finding their balance, but just a few decades of mismanagement and profiteering at the expense of the environment, and the impacts are clear to see.”
Will Millard, adventurer and Angling Trust ambassador, said: “12,000 samples is nothing to be sniffed at, nor is our water.
“With 50 per cent of samples polluted by nitrates and 41 per cent by phosphate, radical solutions are required to fix a broken system.
“The tap is open from sewage, agriculture and road runoff.
“We know the scale of the crisis, and we must work together on solutions.”
The Angling Trust’s citizen science approach uses scientifically validated equipment, rigorous sampling protocols, and repeat observations at fixed sites over extended periods.