400 analyses every summer!
While swimming is possible almost anywhere in our rivers, we cannot monitor the health quality of the water across all the 1,000 km of water courses in the river basin!
In application of the 2006 bathing directive, the quality of bathing water at the 26 most-visited beaches in the basin is thus analysed very regularly (one to three analyses per week depending on the site).
This means that over 400 analyses are carried out every summer.
Bathing water quality: what do we measure?
We are looking for the presence of two human or animal faecal bacteria: Escherichia Coli and intestinal Enterococci.
If they are present in large enough amounts in the water, they can cause gastrointestinal illnesses in the event of ingestion, ENT infections or skin infections through broken skin.
These bacteria cannot live long outside living organisms and are quickly destroyed by UV radiation.
Invisible to the naked eye, they have to be made to multiply in a laboratory incubator so that they can be counted. This is why it takes at least 24 hours to obtain the results.
If there are any differences between the water quality results displayed at the beach and on the “Ardèche Inf’eau Plage” website, you should trust the most recent information (all the analysis results are dated).
Where do these bacteria come from?
They find their way into rivers through sanitation outflows (water treatment plants, septic tanks, direct discharge etc.), livestock and soil leaching due to rain.
The bacteria we are looking for and analysing have nothing to do with the algae or cyanobacteria naturally present in rivers.
Find out more about cyanobacteria.
Very good overall quality
Of all the analyses carried out every summer, 95% of the results satisfy the bathing regulations (summer 2022 results).
85% of the beaches in the river basin are classified as good to excellent in quality for the 2023 season, and two beaches have the “blue flag” label (the beach on the lake at Villefort en Lozère and the Grain de Sel beach in Saint Martin d’Ardèche).
Everyday beach management
If a problem is detected or a threshold exceeded, the decision can be taken to close a beach temporarily to guarantee bathers’ safety. New analyses will be carried out and the prohibition will be lifted as soon as the water quality meets the requirements again.
At some sites, a sensitivity to storms has been identified. Preventive closures are thus recommended based on the weather forecast.
Beaches closed preventively in the event of storms – what does that mean?
Every summer, despite the frequent heat and dry conditions, southern Ardèche is often subject to storms. While the stormwater is good for nature and water levels, it leaches soils, cavities and amenities and can carry contaminated run-off into the river. This can have a temporary local effect on water quality.
One tip generally applies: avoid bathing immediately after a storm, as the water quality may be lower than usual.
With experience, the few sites that are sensitive to rainfall are being managed increasingly closely: we know how much rain has to fall before the water quality deteriorates. We thus monitor the weather forecast and close the beaches preventively to avoid exposing you to the risk of pollution. The deterioration is very brief, and the quality returns to normal in no more than 24 or 48 hours.
Collective efforts across the river basin
At all these sites, EPTB Ardèche works on behalf of the responsible authorities to monitor water quality and provides its expertise on how to interpret the results and manage the sites throughout the season (preventive closure in the event of storms, investigating cases of pollution etc.).
This represents an investment of over €35,000 including tax per year from the local authorities managing the bathing sites.