Map of aquifer levels in mainland France on 15 April 2026.
© BRGM
Trends observed on piezometers on 15 April 2026.
© BRGM
Trends
On 15 April, the levels in 66% of aquifers were lower, as the depletion observed at the end of March continued, due to the lack of rain during the 2nd half of the month and the beginning of April.
Certain aquifers with slow response times continued to recharge, notably the aquifers in the limestone formations of the Artois, Sundgau and Armagnac regions, in the Rhône-Saône corridor and in the chalk formations of Normandy, as well as the fluvio-glacial alluvial aquifers in the eastern Lyon area. The levels were stable in the fluvio-glacial alluvial aquifers in the Savoie foothills and the limestone aquifers in the Brie region, as well as in the Lutetian limestone aquifers.
As regards responsive aquifers, the overall trend was downwards. Only the Jurassic limestone aquifers in the Brenne-Vienne region and in the Vistrenque basin were still recharging. The levels in the alluvial aquifers in the Roussillon plain and in the limestone aquifers in the Corbières Massif were stable.
Levels in all the other responsive aquifers were down.
Situation observed on piezometers on 15 April 2026.
© BRGM
The groundwater situation
The situation in the less-responsive aquifers was the same as on 1 April. Their levels remained in line with monthly norms, except in the case of the Armagnac limestone aquifer, where levels were moderately high.
The situation in responsive aquifers evolved slightly, with levels dropping due to a lack of rain and many aquifers entering their depletion period.
Levels dropped from "moderately high" to "around average" in the aquifers located in the sedimentary formations of the Cotentin peninsula, in the Britanny and Limousin basement aquifers, the Jurassic limestone aquifers in the Charentes region and in the alluvial aquifers in the northern Alsace plain, the Alpine valleys and the Bas-Rhône-Durance region.
Similarly, the situation deteriorated from "around average" to "moderately low" in the Jurassic limestone aquifers in the Boulonnais, Lorraine and Côte des Bars regions, in the Albian sand aquifers on the edge of the Paris Basin, and in the formations of the Limagne basin.
As regards other aquifers, the levels remained above normal, notably in the alluvial aquifers of the Garonne and lower Rhône, as well as in the Vistrenque basin, where levels remained high to very high.
Forecasts
The forecasts for less responsive aquifers remain uncertain. Since the vegetation has started to grow again, any rain that falls in the coming weeks will only meet the needs of the plants and will not replenish these aquifers, unless the rainfall is particularly abundant. Therefore, the levels in these aquifers will probably remain around normal or moderately low over the coming weeks.
The forecasts are quite positive for responsive aquifers, whose levels are above average overall. Certain aquifers must continue to be monitored closely, notably the Jurassic-arc aquifers on the north-eastern edge of the Paris Basin, the sandstone aquifer in the Vosges and the Triassic limestone aquifers, as well as those in volcanic formations and in the Tertiary basins of the Limagne region. The long-term forecast is much more uncertain. Rain will be needed over the coming weeks in order for levels to remain stable. If there is little rainfall, the growth of vegetation and an increase in abstraction could quickly have a significant impact on aquifers with very quick response times whose levels are already around average, for example the basement aquifers in the Brittany and Limousin regions
Groundwater situation: a new map and more frequent bulletins
The BRGM groundwater status report, which is eagerly awaited by the public every month, is being revamped. It will now be published twice a month, and the map will have a new colour scheme to make it easier to read.
As of 1 July 2025, the comparative map between the current month and the same month of the previous year will also be reissued with the new colour scheme.
Map drawn up by BRGM on 17 April 2026, based on data acquired up to 15 April 2026.
Data source: ADES (ades.eaufrance.fr) / Hydroportail (hydro.eaufrance.fr) / Background map © IGN. Data producers and contributors: APRONA, BRGM, Conseil Départemental de la Vendée, Conseil Départemental des Landes, Conseil Départemental du Lot, EPTB Vistre Vistrenque, Parc Naturel Régional des Grandes Causses, Syndicat Mixte d’Etudes et de Travaux de l’Astien (SMETA), Syndicat Mixte pour la protection et la gestion des nappes souterraines de la plaine du Roussillon (SMNPR).
This map shows the global indicators reflecting the average fluctuations of the aquifers. They are based on point indicators collected at groundwater monitoring points (by means of piezometers).
The "Aquifer levels" indicator compares the current month’s figures with those of the same months in the entire record, i.e. at least 15 years of data and sometimes up to as much as 100 years of data. It is divided into 7 classes, from the lowest level (in red) to the highest (in dark blue).
The grey areas correspond to areas without unconfined aquifers, i.e. with an impermeable or semi-permeable layer above the aquifer, and/or sectors with a very low density of measuring points. This last case primarily concerns mountainous areas with small, heterogeneous aquifers.
The "Evolution of levels" indicator reflects the variation of the water level of the past month compared to the two previous months (stable, increasing or decreasing).
These global indicators reflect general situations and trends and do not take into account possible local disparities.