What is the state of Dorset's rivers?

According to the Dorset Wildlife Trust, only 15% of Dorset's rivers are in good ecological health, and none are in good overall health.

How are aquatic insects important to Dorset's rivers?

Aquatic insects are described as the "foundation of the river ecosystem" and the "canaries of the river," indicating they are sensitive indicators of water quality.

Home / Environment / Citizen Scientists Sound Alarm on Dorset's Polluted Waterways

Citizen Scientists Sound Alarm on Dorset's Polluted Waterways

Q: What is causing pollution in Dorset's rivers?

Neonicotinoid pesticides from pet flea and tick treatments are being detected in Dorset's rivers and streams at levels exceeding safe limits for wildlife, posing a threat to aquatic ecosystems.

16 Nov

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Summary

Only 15% of Dorset's rivers in good ecological health
Aquatic insects, "canaries of the river", sensitive to pollution
Neonicotinoid pesticides from pet treatments contaminating rivers

Citizen Scientists Sound Alarm on Dorset's Polluted Waterways

As of November 16th, 2025, Dorset's rivers are facing a severe ecological crisis, with only 15% in good health according to the Dorset Wildlife Trust (DWT). The situation is particularly dire for aquatic insects, which volunteers describe as the "canaries of the river" - sensitive indicators of water quality.

Volunteers have been conducting monthly surveys of Dorset's waterways since last year, and their findings paint a troubling picture. The buildup of everyday chemicals, known as "diffuse pollution," is taking a heavy toll on river ecosystems. Of particular concern are neonicotinoid pesticides, which have been detected in Dorset's rivers and streams at levels exceeding safe limits for wildlife.