Water Quality Monitoring
OVERVIEW
What have we done?
We took samples from the Swale.
Save our Swale citizen science volunteers conducted 22 monthly river sampling sessions since SoS commenced in September 2023. We sampled over 200 times and generated over 1,500 data records from 11 locations along the Swale. These sites ranged from the river source at Wainwath through Richmond town to nearby Brompton upon Swale.
We analysed the samples for pollution.
The results indicate that pollution is present through the river course with increased levels in urban areas but with some spikes of pollution at times even in the higher reaches of the river. Chemical pollution is detectable in levels of ammonia, phosphate and nitrogen arising from sewage release but also in agricultural areas.
We checked the levels of pollution for safety.
These levels did vary between the sites and through the years but frequently exceeded allowable limits for safe bathing. High levels are known to have adverse effects on wildlife and river ecology and were found in many samples. Levels of potentially hazardous bacteria such as E. coli and Enterococci were also measured by volunteers and often exceeded recommended safe levels, particularly when effluent overflows directly into the river. Samples from various tributaries into the Swale also had high levels of pollution so contributing to the levels downstream.
We checked known sources of pollution such as treatment works.
Effluent released from the Richmond treatment works at Easby has particularly high levels of phosphate and of E. coli indicating inadequate treatment. Even when diluted in the river high levels are recorded downstream further reducing water quality in the river beyond.
SAVE OUR SWALE
WATER QUALITY MONITORING REPORT
September 2023 - October 2025
Our volunteers have conducted extensive analysis of over 200 samples of water taken from the River Swale between September 2023 and October 2025. The analysis process, location details and findings are presented in this report collated with the support of microbiologist Keith Thomas. Links to specific report sections can be found below.
Where did we sample?
How did we test our samples?
Conductivity tests show salts in the water, which is data we use to demonstrate natural behaviours of the river and any salt additions (e.g. from roads) to ensure our testing baselines are appropriately calibrated. The full conductivity testing results can be viewed in this section.
Phosphate levels are an indicator of chemical pollution, e.g. from industry, household detergents etc. The full phosphate testing results can be viewed in this section.
Ammonia levels indicate the presence of sewage effluent or agricultural discharge, which is an important indicator of water pollution. The full ammonia testing results can be viewed in this section.
Coliforms levels indicate the presence of potentially pathogenic bacteria, e.g. E.Coli, which could be hazardous to health to river users. The full coliforms testing results can be viewed in this section.
Additional analysis was conducted in various locations and tributaries. We conducted more detailed testing of pollutants and hazardous microorganisms, and the detailed results of this are in this section.
This section presents the conclusions we have drawn from this testing data.