Bathing waters in Lazio in 2026: from April to September 1,583 samplings for microbiological parameters and 25 non-compliant results; three emergency phases for the potentially toxic Ostreopsis cf. ovata on the coast and an alert phase for cyanobacteria in Lake Vico
The regional environmental protection agency ARPA Lazio presented the first data from the 2026 bathing season in a notice published on 8 October 2026 on the website of the Italian SNPA system. The season in Lazio ran from 1 May to 30 September; during it and in April, when pre-season samples are taken, 1,583 samplings for microbiological parameters were carried out, 25 of which were non-compliant.
- Algae surveillance: one alert phase for potentially toxic cyanobacteria was recorded in Lake Vico. At sea, for the potentially toxic alga Ostreopsis cf. ovata, three alert phases were declared — two in Civitavecchia and one in Sperlonga — as well as three emergency phases (emergenza): in Civitavecchia, Santa Marinella and Formia.
- From the second half of July the whole coast of Lazio — particularly intensely around Scauri, Latina, Torvaianica and Montalto di Castro — was affected by foam and anomalous colouring of seawater (green, brown, yellow). According to ARPA Lazio, this was mainly caused by a widespread phenomenon of high concentrations of microalgae of various species, with blooms typical of the weather and sea conditions of the period.
- In its season summary, covering April to September, ARPA Lazio notes that no exceedances of microbiological parameters were found during the algal bloom events.
- Since the 2026 season ARPA Lazio, in addition to sending data to the Ministry of Health for publication on the Portale delle Acque, has been publishing the complete sampling results month by month on its own website, together with a short summary: the number of samplings, cases of non-compliance and the status of algae surveillance; a file with all September data is also available.