Wessex water situation: March 2026 summary
Updated 14 April 2026
Applies to England
© Crown copyright 2026
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1. Summary
March 2026 was the first relatively dry month of 2026 with an average of 34mm of rain in Wessex, 54% of the long term average (LTA). The majority of days were dry with the main rainfall event recorded on 12 March. Soil moisture deficit (SMD) rose in March in response to the low rainfall. Monthly mean flows were mostly normal in the north of Wessex but predominantly above normal to notably high in the south because flows were supported by the Chalk aquifer. Groundwater levels in Wessex mainly fell during March. At the end of the month, most groundwater sites, including those on the Chalk, recorded normal or above normal levels. The 2 outliers were Kingston Russell Road (monitoring the Chalk) and Didmarton (monitoring the Inferior Oolite) which both recorded notably and exceptionally high levels respectively. Overall reservoir levels for Wessex Water were approximately 99% capacity at the end of March while for Bristol Water, levels were approximately 97% capacity.
2. Rainfall
An average of 34mm rain fell across Wessex in March (54% of the LTA). Most days in March were dry. Rain fell mostly towards the middle of the month with the largest rainfall event occurring on 12 March. Rain on 12 March accounted for 37% of the month’s total rainfall. Most hydrological areas in Wessex received below normal rainfall with only 3 exceptions. These areas are all in the north and east of Wessex and received normal rainfall in March. The lowest cumulative rainfall was recorded in Poole Harbour and Purbeck which received 26mm (42% LTA). The highest relative rainfall was recorded in the Mendips and River Chew area which received 44mm (65% LTA).
Over the past 3 and 6 months, most hydrological areas in Wessex received exceptionally high rainfall. Despite a drier than average March, the past 3 months were the fourth wettest on record since 1871 with 368mm (163% LTA).
Over the past 12 months, hydrological areas to the north of Wessex received normal to above normal rainfall. In the south of Wessex, hydrological areas received above normal to notably high rainfall.
3. Soil moisture
SMD rose in the latter half of March in response to the low rainfall. At the end of March, all hydrological areas except for the Mendips and River Chew recorded an SMD between 11mm and 40mm. SMD at the end of March was between 6mm and 25mm greater than the LTA across most of Wessex. Three areas to the north west of Wessex, including the Mendips and River Chew recorded an SMD within 5mm of the LTA.
4. River flows
In March, river flows fell in the north of Wessex in response to the drier weather. All flow monitoring sites in the north recorded normal monthly mean flows except for Washford River at Beggearn Huish. Most flows remained higher in the south of Wessex due to supporting baseflow from the Chalk aquifer. Most monitoring sites in the south recorded above normal or notably high monthly mean flows. For most surface water catchments, flows peaked around 13 March following the rain from the day before. In groundwater dominated catchments, flows fell more steadily throughout the month.
5. Groundwater levels
Groundwater levels fell across most of Wessex in March in response to the low rainfall. At the end of the month, most monitoring sites reported normal or above normal levels. In the north, groundwater levels at Allington and Didmarton (monitoring the Greater and Inferior Oolite respectively) peaked during March but began to fall by the end of the month. Groundwater levels in the west and south of Wessex, including in the Chalk aquifer, fell throughout March. Groundwater levels at Kingston Russell Road (monitoring the Chalk) were notably high at the end of the month despite falling throughout March.
6. Reservoir stocks
Both Wessex Water and Bristol Water reservoir levels remained close to capacity throughout March. The combined levels at the end of the month for Wessex Water were approximately 99% capacity while for Bristol Water, combined levels were approximately 97% capacity. These levels are typical for this time of year.
Author: Wessex Hydrology, Hydrology.Wessex@environment-agency.gov.uk
All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.