Bathing water monitoring carried out by Arpa Piemonte in the April-October period. The Agency carries out checks on the bathing water and issues a weekly bulletin with the bathing judgment based on the samples taken on the various beaches. In particular, the data concerns the beaches of the following Piedmontese lakes and streams: Lake Maggiore, Lake Orta, Lake Mergozzo, Lake Viverone, Lake Candia, Lake Sirio, Lake Grande di Avigliana, Cannobbio and Bernardino streams. In addition to the monitoring information on bathing conditions, the dataset includes the link to the monographs of the beaches, the graphs and the values of the sampling carried out and the bulletin issued. Since 2015, the results of the monitoring of cyanobacteria have also been published, carried out routinely in the areas where flowering has historically occurred. The areas suitable for bathing, identified with a Regional Determination at the beginning of each bathing season, are sampled in points whose location , from withdrawal to withdrawal, does not vary. In relation to bathing assessments, the areas fall into two types: 1. bathing areas, ie those for which the outcome of the analyzes on the sample taken is compliant for all the parameters considered by current legislation; 2. areas temporarily unsuitable for bathing, i.e. those for which the outcome of the analyzes on the sample taken is not compliant for at least one of the parameters considered, up to the first favorable analytical outcome following the pollution event, which demonstrates the restoration of quality water. The samples are taken, at least once a month, in the area normally used by bathers, corresponding to a depth of seabed between 80 and 120 cm. The parameters analyzed are chemical, physical and microbiological. Some chemical-physical parameters are detected in the field. If anomalies are visually found, aliquots will be taken to be sent to the laboratory, for the qualification and quantification of any substances present. The microbiological parameters analyzed are: Escherichia coli and intestinal Enterococci. The withdrawal methods and times, as well as the analytical determinations, are defined by Legislative Decree 116/2008 and by annexes A and D of the implementing decree of 30 March 2010.