Citizen Science on the River Mole

We know about the water level on the Mole and at Betchworth Bridge, as highlighted by the flurries of posts on our local WhatsApp Forum group after heavy rain. But what do you know about the water quality at the Mill or in the river as a whole?

 
Over the last three years, innumerable articles and several TV programmes have focused on the poor state of the national sewage infrastructure, and the shocking release of untreated sewage into rivers from storm overflows. Thames Water, our local supplier, was and still is among the worst offenders, managing out-of-date plants at Horley, Dorking and Reigate. An overflow from the former even made it onto BBC’s Have I Got News For You!
 
In 2023 a series of March the Mole protest walks highlighted and publicised the pollution issues, following which the River Mole River Watch action group was formed. Under its auspices volunteers now test the water quality monthly at 32 sites along the river’s 50 mile length, reporting the results on their website and using the data to campaign for effective action. The readings reflect agricultural run-off, as well as sewage discharges. 
 
Local monitoring sites include Gad Brook, Betchworth Brook, Shag Brook above Wonham Mill and Tanners Brook in Brockham. The January 2025 monitoring round revealed phosphate spikes at both the Shag Brook and Gad Brook sites, the latter also producing a ‘poor’ reading for nitrates. Tanners Brook in Brockham earned the worst ‘bad’ level for nitrates. 
 

Brockham was also featured in a shocking New Year’s video shot by our local MP, Chris Coghlan. You can watch it on his Facebook page here.
 

The River Mole aside, there are plenty of opportunities for Citizen Science with both Re-B​ and the 4Bs Biodiversity initiative. If you're interested in helping, please email rebetchworth@gmail.com