Sampling operations and measurements of physical and chemical parameters in situ – Collaborative test on a body of water 13th September 2023 As part of its collaboration with the French Biodiversity Office and with the support of the Water Agencies (Agences d’Eau – AE), the national reference laboratory for monitoring aquatic environments, AQUAREF, is organising a collaborative trial on Lake Saint Etienne de Cantalès (Cantal) on 12 and 13 September 2023. This real-world trial, carried out under the guidance of experts from Ineris, involves seven teams from sampling organisations. Each equipped with their own vessel, they will carry out various sampling and measurement operations on site during these two days, in the same zone at the same time. In addition, experts from LNE and AEs from Adour Garonne and Loire-Bretagne will assist Ineris in observing sampling practices to ensure the correct applicability of the Water Plan standards developed by AQUAREF. This trial has multiple objectives: identification and assessment of contamination levels in samples by the sampling operators and/or their equipment, for a list of sensitive and specific micropollutants (such as metals, BTEX, cosmetics, perfluorinated compounds, etc.); evaluation of result variability in relation to sampling operations concerning analytical variability for a list of more conventional substances, such as nutrients and major elements. The results will contribute to strengthening existing standards, raising awareness among sampling organisations regarding the risk of contamination and addressing the initial measurement uncertainties, including sampling operations in water bodies. AQUAREF was born out of the need to strengthen French expertise in the field of monitoring aquatic environments, through the networking of skills and research capacities of the five public institutions directly involved: BRGM, IFREMER, Ineris, Inrae and LNE.