Research and analysis

Thames water situation report: June 2024 summary

Updated 12 July 2024

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

1. Summary

Thames area received 18mm of rainfall in June, 34% of the long term average (LTA). All of the areal rainfall units were notably low, except for the Cotswolds West and Cotswolds East units, which were below normal for the time of the year. Soil moisture deficits (SMDs) increased from last month to 76mm across the area and was higher than expected for the time of the year (61mm). Monthly mean river flows at all of our indicator sites decreased in June with all sites recording a normal or higher flows for the time of the year. At the end of the month, groundwater levels at nearly all of our indicator sites continued their seasonal decline, with the majority of the groundwater indicator sites recording higher than normal levels for the time of the year.

2. Rainfall

It was a dry month in June, with Thames Area receiving 18mm of rainfall, 34% of the LTA for the month. This month has been the first month since June 2023 that the rainfall is below 100% of the LTA. All of the areal rainfall units were notably low, except the Cotswolds West and Cotswolds East units, which were below normal for the time of the year. Over the last 3 months, rainfall was normal across Thames Area, with the exception of Cotswolds West (above normal). Rainfall over the past 12 months was exceptionally high across the Area, and this 12 month period to June has been the wettest on record.

3. Soil moisture deficit and recharge

SMDs for in Thames Area increased to 76mm by the end of June. This meant that soils were drier than expected for the time of the year (61mm LTA). As a result of notably low rainfall across majority of the Thames area, the effective rainfall was below average for the time of the year. 

4. River flows

Due to dry conditions in June, all of our indicator sites had decreasing monthly mean flow compared to May. Despite this, all our indicator sites recorded normal or higher flows for the time of the year. This is due to high rainfall over the past 6 months and 12 months leading to aquifer recharge and higher than normal groundwater levels at majority of the sites. Being supported by the strong base flow, the River Kennet at Marlborough was notably high, and the River Wye at Bourne End remained exceptionally high for the time of the year.

5. Groundwater levels   

Groundwater levels at all our indicator sites continued their seasonal decline in June, except for Frith Cottage in the Lower Greensand. Nearly all the groundwater indicator sites recorded higher than normal levels, with the exception of Jackaments Bottom (Inferior Oolite) and Ampney Crucis (Great Oolites) whose groundwater levels were normal. Despite the decline, groundwater levels of the Chalk at Stonor Estate and Gibbet Cottages remained exceptionally high for the time of the year.

6. Reservoir stocks

Reservoir capacity at Farmoor remained at 98% and was above the LTA at the end of the month. Capacity at the Lower Thames reservoirs decreased from 98% in May to 95% at the end of June but remained above the LTA for the time of the year.

7. Environmental impact

There were no flood alerts or warnings issued across Thames Area during June due to the dry conditions. At the end of June 19 abstraction licences were being constrained in Thames Area in order to protect water resources and the environment.

Author: Thames Area Groundwater Resources and Hydrology, enquiriesWT@environment-agency.gov.uk

Contact Details: 020 3025 9659