Hydrogeological situation on 1 June 2025
Depletion was occurring in almost all the aquifers, with levels falling in 75% of cases. However, the groundwater situation remained variable, depending on location: levels were close to or just below normal in the reactive aquifers in the north and above normal in inertial aquifers and in the aquifers in the south of the country and in Corsica. The levels in the aquifers in the Roussillon region and the Corbières Massif remained worryingly low to very low.
The depletion should continue in June, unless there is significant rainfall in areas with reactive aquifers. The current situation in the inertial aquifers in the Paris Basin and the eastern area around Lyon is extremely positive, suggesting that levels should be above-normal over the summer. The forecasts are very pessimistic for the aquifers in the Roussillon plain. The forecasts concerning the other aquifers remain uncertain: somewhat pessimistic for the reactive aquifers in the north and centre of France but more optimistic for those in the south (except in the Pyrénées-Orientales and Aude areas).
Map of aquifer levels in mainland France on 1 June 2025.
© BRGM
Evolution of the trends observed on piezometers from June 2024 to May 2025.
© BRGM
Trends
The depletion period started in February, which is very early, in the reactive aquifers in a large part of the north of the country, and generally started in the inertial aquifers during the spring. It began a little later, between April and May, in the aquifers in the south of France and Corsica.
In May 2025, the depletion was active across the country with 75% of levels falling (61% in April).
In the northern half of the country, there was no change in the trends between April and May. Levels continued to fall, due to the lack of rainfall since February. Even though there were a few storm episodes, the resulting rain did not seep deep into the ground and therefore did not have an effect on the aquifers. The levels in the highly inertial aquifers in the Beauce and Sundgau (southern Alsace) and the Saône corridor were slowly stabilising.
The trends observed in the aquifers in the southern half of France and Corsica depended on local rainfall totals. The levels recorded in many aquifers were decreasing. Indeed, the rain that fell had relatively little effect on the groundwater levels, with storm episodes generating run-off rather than filtering into the soil, and most of the rain that did seep into the ground was consumed by the vegetation. Rising or stable water levels were observed in areas with reactive aquifers that experienced a lot of rainfall, supplemented by snow-melt: the alluvial aquifers of the Adour and Gave de Pau rivers, in the upstream area of the Garonne and its main tributaries, as well as in the valleys of the Alps, the Rhône and Côte d'Azur. Finally, water levels rose in the Roussillon plain.
Comparison between 1 June 2024 and 1 June 2025
Map of France showing the state of the aquifers on 1 June 2024 (left) and 1 June 2025 (right).
© BRGM
Evolution of the situation observed on piezometers from June 2024 to May 2025.
© BRGM
Aquifer situation
The levels in 2024, and notably during the low-water period in October 2024, were particularly high. The changes in aquifer levels varied over the autumn and winter depending on the intensity of the recharges. The situation has gradually deteriorated since February, with the depletion period starting early, particularly over much of northern France.
The groundwater situation was satisfactory overall in May: the levels recorded at 35% of the observation points were below monthly norms, 19% were comparable with monthly norms and 46% were above them (compared with 27%, 23% and 50%, respectively, in April).
The situation was far more satisfactory in May 2024, when 70% of aquifer levels were above monthly averages. The rainfall that occurred in the spring of 2024 significantly boosted the levels of reactive aquifers, and the situation in 2025 is worse than the situation observed a year ago. Only a few reactive aquifers in the south-east had slightly better levels in 2025: the karst limestone aquifers in Provence and the Corbières Massif, the alluvial aquifers in the valleys of the Aude département and in Corsica and the aquifers in the Roussillon plain. The situations in the inertial aquifers were similar to those observed in 2024. Certain levels recorded in 2025 were better than in 2024, notably in the south-west of the Paris Basin (Santerre, Sologne, Beauce and Touraine), in the Sundgau area (southern Alsace) and in the Saône corridor, but others – in the Artois Basin, Champagne, Brie and Tardenois areas and the Savoie foothills – were less satisfactory.
Inertial aquifers
The state of inertial aquifers remained generally satisfactory in May 2025, with indicators mostly above monthly norms.
The situation in the inertial aquifers in the Paris Basin and Artois basin remained stable or deteriorated slightly between April and May. Levels were generally very satisfactory, from moderately high to high. Some monitoring stations continued to observe very high levels in the western part of the Beauce. The situation was less favourable in the chalk aquifer along the Artois coast and in Champagne, with levels either moderately low or comparable to normal levels. These areas have marly chalk formations and so the aquifers are less inertial and react more quickly to dry periods in late winter and spring.
The situation in the Sundgau aquifer (southern Alsace) and the aquifer in the Rhône-Saône corridor changed very little during the 2024-2025 recharge. The levels in the Sundgau (southern Alsace) and Saône corridor have remained, respectively, moderately low or comparable to normal since the summer of 2024, due to their significant inertia. Certain situations varied locally, with levels ranging from low to high. The state of the aquifers in the Rhône corridor was satisfactory, close to normal to moderately high. Locally, levels were satisfactory or moderately high in the eastern Lyon area and less favourable in the Drôme des Collines area (moderately low).
Reactive aquifers
The reactive aquifers in the northern half of the country and in the Massif Central were considerably affected by the lack of rainfall in recent months. The levels, which were moderately high to very high in January, have deteriorated rapidly and were generally unsatisfactory in May, ranging from comparable to monthly norms to low. Levels were particularly poor, from low to very low, in the Jurassic limestone aquifers of Lorraine and the north of the Côte-des-Bars, as well as in the volcanic aquifers in the Massif Central. Low levels were also observed in many wells in the Côtes-d'Armor and Finistère basement aquifers.
As regards the Adour-Garonne basin, the rain that fell in April and May helped to maintain the groundwater levels, with indicators showing levels close to monthly norms to moderately high. The situation changed very little between April and May in the northern part and centre of the basin. It deteriorated in the reactive Jurassic limestone aquifers around the eastern edge of the basin (Causses and Ségala). These aquifers benefited from a very abundant recharge in April but fell back to normal levels in May. Finally, the situation of the aquifers of the Pyrénées valleys was improved by the recharge that occurred in May .
In the south-east and in Corsica, the rains at the end of winter and in spring compensated for the below-average start to the 2024-2025 recharge period. However, the rains in May were not very effective and the situation remained stable or deteriorated slightly compared with April. The aquifer levels remained satisfactory, ranging from close to monthly norms to high. The situation was less favourable in the Aude valley aquifer, which had moderately low levels. Increased pressure on groundwater (irrigation and tourism) was also a factor locally.
Finally, levels remained low to very low in the aquifers in the Corbières Massif and in the Roussillon plain. The rainfall in recent months, particularly in March, significantly improved certain local situations. However, the total rainfall was still far from sufficient to compensate for the overall lack of rain in the area in recent years.
Aquifers with particularly high water levels
Several aquifers had very high levels, when compared with those recorded for May in previous years:
- Levels were high in the inertial aquifers in the south-west of the Paris Basin, which received abundant recharges in 2023-2024 and 2024-2025;
- High levels were recorded in the reactive aquifers in the alluvial formations of the lower Rhône and its main tributaries, which benefited from the rainfall in April and May and the spring snow-melt.
Aquifers with low water levels
The situation was unsatisfactory in several aquifers, where levels were low to very low compared to those recorded for May in previous years:
- The levels in the Jurassic limestone aquifers of the Boulonnais, Lorraine and Jura remained low due to a lack of rainfall over the last four months;
- The aquifers in the volcanic formations of the Massif Central had a low recharge in 2024-2025 and their situations have further deteriorated, with generally low levels;
- Levels were rising or stable in the Roussillon multilayer aquifer and in the karst limestone aquifers of the Corbières Massif, but nevertheless remained low to very low.
Key figures
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75.00%of levels decreased
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46.00%of levels were above monthly averages
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35.00%of levels were below monthly averages
Forecasts
The Météo France seasonal forecasts for June, July and August 2025, higher temperatures are expected across the whole of France. No clear scenario has been established concerning rainfall.
Over the next few months, most of the water that seeps into the soil will be consumed by vegetation and will therefore not filter deep into the ground. The depletion should therefore continue in all the aquifers until autumn, when the vegetation becomes dormant. Only occasional, local recharge episodes are likely to occur during the summer. In order for the state of aquifers to improve and their levels to increase, there will need to be significant rainfall on ground that is already damp. Moreover, this will only improve the situation in reactive aquifers. The demand on water resources through abstraction may also affect the state of the aquifers.
Seasonal forecasts for inertial aquifers
The levels in inertial aquifers (Artois, Paris Basin, Sundgau, Rhône-Saône corridor) will continue to decrease until the vegetation becomes dormant and significant rainfall occurs, i.e. until mid-autumn or early winter. These aquifers are not very sensitive to summer droughts, due to their high degree of inertia. Their situation should remain stable or gradually deteriorate over the coming months. However, this downward trend could be exacerbated by water abstraction, particularly for irrigation, due to high temperatures. This could lead to pressure on local resources.
Most of the aquifers in the Paris Basin and the eastern Lyon area are starting the depletion period in good condition. The levels should remain above monthly norms during the summer. The aquifers in the Artois region (particularly the coastal areas), on the eastern edge of the Paris Basin (Champagne), in the Sundgau (southern Alsace), Bresse-Dombes, Nord-Isère and Bas-Dauphiné were in less favourable situations than in May. The forecasts are more uncertain in these areas and unfavourable situations could arise this summer.
Seasonal forecasts for reactive aquifers
As regards reactive aquifers, the summer forecasts are more uncertain, since they are quickly affected by weather conditions and water abstractions. The situations will depend on local rainfall and on water abstraction over the coming months. However, any heavy storm episodes that occur will probably not help recharge the aquifers, since the water is more likely to run off than filter into the ground, due to the intensity of the rainfall. Moreover, if Météo-France forecasts are confirmed, the higher temperatures will increase the demand for water, mainly for purposes of irrigation and leisure activities.
The summer forecasts look relatively pessimistic for the aquifers in the north and the centre of France, and east of the Massif Central. The dryness of the soil will probably prevent any late spring rain from seeping deep into the ground. Consequently, the situation is unlikely to improve in June. The Lorraine, Côte-des-Bars and Jura limestone aquifers and the basement aquifers in the Armorican Massif were in unsatisfactory condition in May, and they need to be closely monitored.
The forecasts for the coming months seem quite optimistic as regards the aquifers in the south of France and in Corsica, where the levels in May ranged from close to normal to high. The soil remained relatively humid in May and any rainfall in June should filter deep into the soil, in the event of heavy rainfall, if it is well distributed over time and space. However, a prolonged drought could rapidly have an impact on these aquifers, particularly the highly reactive aquifers in basement (Massif Central) and karst limestone formations (western and southern edge of the Massif Central and Provence). Pressure on water resources from irrigation and tourism could also lead to a deterioration in the groundwater situation, in areas where demand is high.
The situation of the Aude alluvial aquifer deteriorated in May and the levels were moderately low. Forecasts are less optimistic for this area and the situation will depend on the effect of rainfall in late spring and summer. Finally, the forecasts for the coming months remain extremely pessimistic for the aquifers in the Roussillon plain and Corbières Massif, regardless of the rainfall and temperature scenario. Levels are expected to remain below normal, and even low to very low for the deep Pliocene-sand aquifer.
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State of groundwater: monitoring by BRGM
Groundwater is a widely used resource: in metropolitan France, it accounts for nearly two-thirds of drinking water consumption and more than one-third of agricultural water consumption. It is also widely used in the industrial sector. Groundwater tables depend on cyclical recharges.
BRGM monitors groundwater levels and quality in mainland France. Discover the actions carried out by the French geological survey and the resources and databases available on groundwater in France.
Aquifer recharge: 3 questions to provide a better understanding of the process
How do aquifers fill up and how do they empty?
Groundwater levels vary throughout the year, from high levels in winter (when vegetation does not absorb rainwater) to low levels in summer (the traditional depletion period).
The fate of rainfall varies greatly depending on the time of year and the condition of the ground surface on which it falls. Usually, the groundwater-recharge period takes place from early autumn (September-October) to early spring (March-April), a six-month period during which vegetation is dormant (with low evapotranspiration) and rainfall is generally more abundant. If the winter is dry, groundwater recharge is very low.
From spring through summer, rising temperatures coupled with the regrowth of vegetation and thus increased evapotranspiration, limit the infiltration of rainfall into aquifers. Between May and October, unless there are exceptional rainfall episodes, aquifer depletion usually continues and levels will keep decreasing until the autumn.
Why do some aquifers recharge faster than others?
Groundwater flows at different rates depending on the porosity (percentage of gaps/cracks in the rock) and permeability (capacity to allow water to circulate, i.e. interconnectivity between these gaps/cracks) of the aquifers. The larger the gaps and the more interconnected they are, the faster the water will flow, for both refilling and depletion.
It takes a given volume of water different periods of time to travel the same distance, depending on the kind of rock formation:
- a few years in a porous formation,
- a few months in a cracked formation,
- and a few days, or even a few hours, in a karst formation.
Inertial and reactive aquifers: what are they?
The impact of the winter recharge varies according to the cyclic nature of the aquifer, i.e., its reactivity to rainfall infiltration.
We refer to aquifers that are:
- reactive (when they are composed of sand, gravel, karst limestone or weathered granite formations). These aquifers are characterised by their rapid reaction times: they can recharge during heavy summer rainfall, but are also highly sensitive to drought. Their levels can therefore vary very quickly over the course of the same season.
- inertial (when composed of chalk, non-karst limestone, sandstone formations). Their reaction times are slow. They can have multi-annual cycles, meaning that they require a long period to recharge or empty.
Cyclicity of aquifers in mainland France.
© BRGM
Map drawn up by BRGM on 6 June 2025, based on data acquired up to 31 May 2025.
Data source: ADES database (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.