Research and analysis

Lincolnshire and Northamptonshire water situation: September 2026 summary

Updated 14 October 2026

Applies to England

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

1. Summary

September 2026 averaged 23mm of rain across Lincolnshire and Northamptonshire, 42% of the long term average (LTA) and below normal for the time of year. A low rainfall total meant that there was a 26.2mm increase in the soil moisture deficit (SMD) across the area and river flows and groundwater levels continued to decline. Eight of the 11 key river flow sites recorded below normal flows, or lower, over the course of the month. Two groundwater sites are now below normal for the time of year, while levels at Dunholme Road are notably low. Reservoir stocks reduced by an average of 5% and all 5 sites remain below their normal operating curve as a lack of rain has prevented any recharge.

2. Rainfall

September 2026 was the twenty-sixth driest September on record across Lincolnshire and Northamptonshire (LNA), recording an average of 23mm of rain, 42% of the LTA. Four of the 6 hydrological areas recorded below normal rainfall, while Louth Grimsby and Ancholme and Steeping Great Eau and Long Eau (SGELE) recorded notably low rainfall, with SGELE recording the twelfth driest September since records began in 1871. Rainfall totals were between 33% and 53% of the LTA across the 6 areas.

2026 has been the sixth driest July to September across LNA, since records began in 1871. Exceptionally low rainfall was recorded in 3 hydrological areas, while the other 3 recorded notably low rainfall totals, ranging from 46% to 54% of the LTA. South Forty Foot and Hobhole and Upper Welland and Nene both recorded the third driest July to September on record, while it was the Upper Welland and Nene’s seventh driest. LNA recorded 89mm of rain across this period, just 51% of the LTA.

Over the past 6 months, rainfall across LNA has also been scarce. April to September 2026 was the second driest April to September on record and all six hydrological areas recorded exceptionally low rainfall totals. Fifty-three per cent of the LTA rainfall was recorded across LNA over that period. Louth Grimsby and Ancholme and South Forty Foot and Hobhole recorded their second lowest rainfall totals, while it was the third lowest recorded in the Lower Welland and Nene and SGELE.

Despite the previously dry 6 months observed across LNA, over the past 12 months 645mm of rain has been recorded, on average, 100% of the LTA. All 6 hydrological areas recorded normal rainfall totals for that period, ranging from 96% in South Forty Foot and Hobhole to 105% in Louth Grimsby and Ancholme and Witham to Chapel Hill. The comparison between the second driest April to September and a normal rainfall total over 12 months highlights the 2 extremes experienced over the past year across LNA. An exceptionally wet winter has been followed by one of the direst spring and summers on record.

3. Soil moisture deficit and recharge

SMD significantly increased from the end of August to the end of September 2026, from 100.8mm to 127mm, and is notably high for the time of year. All 6 hydrological areas saw a consistent increase in SMD through the month and all areas have an SMD that notably high for the time of year. Despite a uniform trend across LNA, there is a clear east-west divide in SMD levels. The 3 hydrological areas to the west have an average SMD of 119mm, whereas the 3 hydrological areas to the east have an average SMD of 143mm, a difference of 24mm. All 6 hydrological areas ended September with and SMD 26mm to 50mm greater than their respective LTA.

4. River flows

Despite a small recovery at the end of August from some key river flow sites, the low rainfall totals in September meant flows quickly fell again. Eight of the eleven sites with data ended September with a monthly mean flow below normal or lower, with three of those sites recording notably low flows. Flows ranged from 78% of the LTA at Geldhart’s Mill on the River Nene to just 21% of the LTA at Kate’s Bridge and King Street on the River Glen. Only Louth on the River Lud and Geldhart’s Mill and Upton Mill on the River Nene had normal river flow for the time of year. Due to data quality issues, there is no flow data available for Rase Bishopbridge for September 2026.

5. Groundwater levels   

Groundwater levels across LNA continue to decline as a lack of rainfall continues to restrict recharge. Six of the 9 key groundwater sites have recorded normal levels, or above, for the time of year, with Barton, Horkstow Road remaining above normal. However, limestone sites in the centre of the area are seeing low groundwater levels. Leasingham Exploratory and Grange Farm are both below normal for the time of year, and Dunholme Road is notably low. There was no data available in September at Castlethorpe Bridge.

6. Reservoir stocks

Reservoir stocks across LNA were down 5% on average from the beginning of September as demand remained high and the lack of rain gave little recharge. Stock levels vary from Covenham at 81% full to Hollowell at 53%, down 8% over the month. The 5 reservoirs are 66.4% full, on average. All reservoirs are below their respective target curves for the time of year, however all remain above drought permit trigger levels.

Author: Hydrology Team, hydrology-ean-and-lna@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

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