Hydrogeological situation on 1 July 2025
In June, the depletion period had set in and levels were decreasing in 87% of the aquifers. The aquifer situation continued to deteriorate but varied according to the region and type of aquifer: generally above monthly norms for the inertial aquifers in the Paris Basin and eastern Lyon area, moderately low to low in the reactive aquifers in the north and close to normal for the aquifers in the south of France and Corsica. Several aquifers in the Roussillon region remained worryingly low to very low.
In July and until the end of the summer, the depletion should continue, unless there is significant rainfall in areas with reactive aquifers. The forecasts are optimistic for the inertial aquifers in the Paris Basin and eastern Lyon area. They are more pessimistic for the reactive aquifers in the northern two-thirds of the country and very pessimistic for the aquifers in the Roussillon plain. The forecasts remain more uncertain for other aquifers and the situations will depend on total rainfall and the demand on water supplies, which is linked to temperatures. The situation will need to be closely monitored in aquifers which currently have levels that are below the monthly norms, as well as in areas where abstraction demand is particularly high.
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 of aquifer levels in mainland France on 1 July 2025.
© BRGM
Evolution of the trends observed on piezometers from July 2024 to June 2025.
© BRGM
Trends
The depletion period began very early this year (as of February) in the reactive aquifers across a large part of the north of the country, and then started in the inertial aquifers in the Artois region and in the Paris Basin during the spring. It began a little later, between April and May, in the aquifers in the south of France and Corsica. From May onwards, the rain that fell was no longer effective in producing recharge episodes.
In June 2025, the depletion was active across the country with 87% of levels falling (75% in April).
This is normal for the period. Rainfall in late spring and summer has little effect on the aquifers; the water that seeps into the ground merely moistens the soil and is immediately consumed by the vegetation. Moreover, the rain that falls during storms (which are often violent, with heavy rain) does not filter down much into the ground. Finally, the high temperatures encouraged evapotranspiration and increased plants' need for water. Water abstractions for irrigation and tourism accelerated the fall in levels.
As a result, in the rare areas that received rain in June, the actual amount of rainfall that filtered deep into the ground was generally non-existent or insufficient to compensate for the volumes discharged via natural outlets or to recharge the aquifers. That being said, in some of the most reactive aquifers, such as the Jurassic limestone aquifer in the Jura, the levels managed to stabilise, due to the rain from the storms.
Stable levels were also observed in the alluvial aquifer of the upstream Garonne, supported by rainfall in the second half of May and by the snowmelt from the Pyrenees.
Comparison between 1 July 2024 and 1 July 2025
Map of France showing the state of the aquifers on 1 July 2024 (left) and 1 July 2025 (right).
© BRGM
Evolution of the situation observed on piezometers from July 2024 to June 2025.
© BRGM
Aquifer situation
The levels during the low-water period in 2024 (October) were particularly high. The levels then varied over the autumn and winter depending on the intensity of the recharges. The overall situation has gradually deteriorated since February, due to a persistent lack of rainfall over a large part of the north of the country, which also affected the south of the country between April and May.
The groundwater situation was variable in June: the levels recorded at 39% of the observation points were below monthly norms, 26% were comparable with monthly norms and 35% were above them (compared with 35%, 19% and 46%, respectively, in May).
The situation was far more satisfactory in June 2024, when 70% of aquifer levels were above monthly averages. The 2023-2024 recharge was abundant and the rainfall in spring 2024 helped maintain the groundwater levels. Only a few reactive aquifers on the Roussillon coast, in Languedoc (Vistrenque, the Hérault, Orb and Aude valleys) and in Corsica were in a slightly better situation this year than at the same time last year. The situation to date in the most inertial aquifers was also better than last year: Beauce, Sundgau (southern Alsace) and the Saône corridor (Dombes-Bresse).
In June 2025, the situation remained stable or deteriorated more or less rapidly depending on how sensitive the aquifers are to drought conditions. The state of the aquifers depended on the amount of rainfall over recent months and the type of aquifer (inertial or reactive):
Inertial aquifers
The state of the inertial aquifers was generally satisfactory in June, with indicators recording moderately-low to moderately-high levels.
In the centre of the country and north-west of the Paris Basin and the Artois Basin, levels were satisfactory, ranging from comparable to monthly norms to moderately high. They were even high in the Beauce region, with some observation points showing very high levels in the western part of the region. The situation remained stable overall compared with May. These areas are home to highly inertial aquifers whose situations change very slowly. On the eastern and southern edges of the Paris Basin and in the coastal part of the Artois Basin, the levels of the less inertial aquifers were close to monthly norms to moderately low. The situation was slightly worse than in May.
The levels in the aquifers in the Sundgau (southern Alsace) and in the Rhône-Saône corridor changed very little during the 2024-2025 recharge period, due to their high degree of inertia. The levels in the Sundgau remained moderately low and those in the Rhône-Saône corridor close to normal, except for the aquifer in the eastern Lyon area, which had a more satisfactory level (moderately high). Certain situations varied locally, with levels ranging from low to high.
Reactive aquifers
The state of the reactive aquifers deteriorated between May and June, due to the lack of effective rainfall. Increased pressure on groundwater (due to irrigation and tourism) was also a factor locally. Only the reactive aquifers in the north-east were boosted by the rainfall in June, and remained in a similar situation to that in May.
The reactive aquifers in the northern half of France have been affected by the lack of rainfall since February. The levels remained unsatisfactory, from moderately low to low. The levels were particularly low in the Jurassic limestone aquifers in the Boulonnais and Lorraine regions and in the basement aquifers from Cotentin to Mayenne.
In the southern half of the country, the state of the aquifers was more satisfactory, often close to monthly norms. The total rainfall in late winter and early spring enabled the aquifers to recharge and then maintain their levels. However, the situations were variable, depending on local rainfall that filtered down during the spring. The aquifers in the karst limestone formations of the Causses du Quercy and the tertiary formations of Provence were moderately low, since these areas received less rainfall during the spring. The moderately high level observed in the alluvial aquifers of the upstream Garonne and its tributaries can be put down to the snowmelt and rainfall in the second half of May.
Finally, levels remained low to very low in the aquifers of the Corbières Massif and 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 several areas between 2022 and 2024.
Aquifers with particularly high water levels
Several aquifers were in positive situations, with moderately-high to high levels in comparison to those recorded during June in previous years:
- The levels observed in the inertial aquifers in the west and south of the Paris Basin and to the east of Lyon, which received abundant recharges in 2023-2024 and 2024-2025, were moderately high, and even high in the Beauce region;
- The reactive aquifers in Jurassic limestone formations from the Bessin region to the Sarthe and from the Brenne to the Vienne rivers continued to have moderately high levels, due to the effects of the abundant recharge in 2024-2025;
- The alluvial aquifers of the upstream Garonne and its main tributaries had moderately high levels.
Aquifers with low water levels
The situation was unfavourable in several aquifers, with low to very low levels compared to those recorded for June in previous years:
- The levels in the Jurassic limestone aquifers in the Boulonnais and Lorraine regions remained low due to a lack of rainfall since February;
- The state of the aquifers in the basement formations from the Cotentin to Mayenne deteriorated and showed low levels;
- The levels in the Roussillon multilayer aquifer and in the aquifers of the karst limestone formations of the Corbières Massif remained low to very low.
Key figures
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87.00%of levels decreased
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35.00%of levels were above monthly averages
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39.00%of levels were below monthly averages
Forecasts
The Météo France seasonal forecasts for July, August and September 2025, higher temperatures are expected across the whole of France. A drier-than-normal scenario is most likely across the country, except in Corsica where no particular scenario has been established.
The lack of rainfall and the high temperatures forecast by Météo-France could accentuate the downward trend. On the one hand, high temperatures could contribute to an increase in the amount of water required by vegetation and an increase in water abstractions (linked to tourist and leisure activities). At the same time, if there is not sufficient rainfall (resulting in dry ground and an increased demand on water supplies, notably for irrigation purposes), the situation may continue to deteriorate.
Over the next few months, most of the rainwater that seeps into the soil will be consumed by vegetation and will therefore not filter deep into the ground. Moreover, 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. Recharge episodes are expected to be occasional, local and of low intensity. In order for the state of aquifers to improve and their levels to increase, there will need to be significant rainfall, which is spread over time and which falls on ground that is already damp. Moreover, this will only improve the short-term situation in reactive 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. This could lead to pressure on local water resources.
The levels observed in the aquifers in the west and south of the Paris Basin and in the east of Lyon should remain above or close to normal levels during the summer. The current situations are less favourable in the aquifers in the Artois coastal areas, on the eastern edge of the Paris Basin, in the Sundgau (southern Alsace), Bresse-Dombes and Bas-Dauphiné regions. 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. In July, the dryness of the soil will probably prevent any rain from seeping deep into the ground and the state of the aquifers is therefore unlikely to improve. In the coming months, the situations will depend on local rainfall totals and abstractions.
The summer forecasts are pessimistic for the aquifers in the northern half of France and in the centre of the Massif Central. The situations in the limestone aquifers in the Boulonnais region and Lorraine and in the basement aquifers of the Armorican Massif were unsatisfactory in June and therefore need to be closely monitored.
As regards the reactive aquifers in the south of France, the forecasts for the coming months are uncertain. A prolonged drought could rapidly have an impact on these aquifers, particularly the highly reactive aquifers in basement (southern Massif Central) and karst limestone formations (western and southern edge of the Massif Central and Provence).
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 scenarios. Levels are expected to remain below normal, and even low to very low for the deep Pliocene-sand aquifer.
Press contact
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 4 July 2025, based on data acquired up to 30 June 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.