Quality of rivers vis-à-vis ammonium (Percentile 90) on the territory of Breton SAGEs

This map represents the status of Breton water courses at quality monitoring stations vis-à-vis percentile 90 for the ammonium parameter in 2019. The state is represented by a quality class (very good, good, medium, poor, bad), in accordance with the requirements of the WFD (Decree of 27 July 2015 on the assessment of the status of surface fresh water). For each of the stations followed, the winning table contains the data processing history (1995 to 2019): maximum, minimum, mean concentrations, percentile 90 (mg/l) and number of sampling. The treatments were carried out with all available analyses (all collection devices combined). __Origin__ Source of source data: Agence de l'eau Loire-Bretagne (BD OSUR) — OFB (Naiades) — Dreal Bretagne (BD LYXEA), export 2020. Data processing carried out by the observatory of the environment in Brittany in 2020. Coordinate fields are expressed in WGS84. The winning table contains the history of 90* percentiles (expressed in mg/l), maximum, minimum and mean concentrations (expressed in mg/l) and the number of samples since 1995. * For each station tracked, the percentile 90 is calculated, based on the number of available analyses (na), as follows: — Na less than 4: no calculation of Q90; — Na greater or equal to 4: ranking of results in descending order and rank of result to be retained = rounded (0.9 x na + 0.5) Status classes and threshold values (and match in the winning table): Q90 < 0.1 mg/l: Very good condition 0.1 ≤ Q90 < 0.5 mg/l: Good condition 0.5 ≤ Q90 < 2 mg/l: Average State 2 ≤ Q90 < 5 mg/l: Poor State Q90 ≥ 5 mg/l: Bad state No data (0 in the table): Undetermined For more information, you can also consult the data visualisation on the website of l'OEB: https://bretagne-environnement.fr/matieres-azotees-hors-nitrates-cours-eau-bretons-datavisualisation __Partner organisations__ Observatory of l’' environment in Brittany [See this page on geo.data.gouv.fr](https://geo.data.gouv.fr/fr/datasets/85ba0cc683017bb75ea886ab06b01c3c60dce9ce)