Research and analysis

Lincolnshire and Northamptonshire water situation: March 2025 summary

Updated 14 April 2025

Applies to England

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

1. Summary

Overall, March was a very dry month, with notably low levels of rainfall falling across most catchments. On average, the Lincolnshire and Northamptonshire area (LNA) received 12mm of rainfall, which was 25% of the long term average (LTA). As a result of the dry weather, soil moisture deficits (SMD) continued to increase in all 6 hydrological areas. By the end of March, the area had an SMD of 16mm, which falls within the normal range for this time of year. Monthly mean river flows ranged from 45% to 102% of the LTA, with classifications ranging from below normal to normal. Following the notably low level of rainfall across LNA in March, the groundwater level trend showed a decline at all indicator sites except Grainsby and Grange de Lings. With the exception of Ravensthorpe and Hollowell, reservoirs in the area ended the month slightly above their normal operating curves.

2. Rainfall

March was a very dry month, with rainfall varying between 21% and 26% of the LTA for the time of year. The average rainfall across the Lincolnshire and Northamptonshire area was 12mm, 25% of the LTA, making it the eighth driest March since the record began in 1871 (classified as notably low). Rainfall was spread evenly across the area with all catchments receiving roughly the same amount of rainfall. Apart from the 2 days (12 and 23 March), which accounted for approximately 62% of the month’s total rainfall, throughout the month, the frontal system did not give catchment rainfall totals higher than 1.3mm during any single event.

Hydrological areas in the east of the area received the lowest rainfall totals.

• South Forty Foot and Hobhole (10mm, 22% of the LTA)
• Steeping Great Eau and Long Eau (11mm, 21% of the LTA)
• Lower Welland and Nene (11mm, 24% of the LTA)

Rainfall was classified as notably low in 5 of the 6 catchments and exceptionally low in the one remaining catchment (Steeping Great Eau and Long Eau). 

Although the 6-month totals map display all 6 hydrological areas classified as normal, a north-south trend pattern is reflected in all the long-term rainfall maps, which unanimously show the slightly higher totals received in the south compared to the north.

3. Soil moisture deficit and recharge

SMD responded in line with the rainfall patterns observed through March. Due to the dry start to March (and a dry end to February), SMD increased sharply across all 6 hydrological areas, but the levels stabilised in the second half of the month when the month’s main rainfall fell.

The lowest levels of SMD were observed in the Ancholme Grimsby Louth (15mm), whilst the highest levels were observed in the Steeping Great Eau and Long Eau (21mm). On average, SMD for the area increased from 2mm at the end February to 16mm by the end of March. This figure is within the normal range for the time of year.

The SMD difference-to-LTA (mm) map in the full report show all hydrological areas are in the 6mm to 25mm category, indicating that they are within the normal or slightly drier than normal for the time of year.

4. River flows

In line with the seasonal trend and in response to the notably low rainfall, river flows for all sites decreased since February, with flows varying between 45% and 102% of the LTA. Flow at 6 sites remained normal, whilst 6 others were considered below normal. The most notable drop in flow has been observed at the Ashley (Welland) which has gone from above normal in February to below normal levels in March. Wansford (Nene) levels show no change in banding since January 2025.

5. Groundwater levels   

Following the notably low level of rainfall across LNA in March, the groundwater level trend showed a decline at all indicator sites except Grainsby and Grange de Lings, ending the month with one site classified as above normal, 7 sites as normal, and one site (Leasingham Exploratory) as below normal.

While Burnham (chalk) banding remained unchanged since November 2024, the Barton Horkstow Road (chalk) and Grainsby (chalk) banding remained unchanged since the previous month. Likewise, Hanthope (limestone) shows no change in banding since the previous month.

6. Reservoir stocks

With the exception of Ravensthorpe and Hollowell, reservoirs in the area ended the month slightly above their normal operating curves. The level at Ravensthorpe and Hollowell was 2.5% below target in March, however levels are not alarmingly low.

7. Environmental impact 

All transfer schemes remained off throughout March. There were 5 flood alerts. There were no flood warnings issued. There were 6 HOFs (Hands Off Flow) active: 4 in the Ancholme River catchment, and 2 in the Nene River Catchment.

8. Forward look

8.1 Probabilistic ensemble projections for river flows at key sites

June 2025: The 2 Nene sites are showing increased probabilities of normal flows. North Brook is showing a reduced probability of extreme flows (both high and low).

September 2025: All sites are showing an increased probability of normal or above normal flows with none of the modelled rainfall scenarios showing exceptionally low levels.

8.2 Probabilistic ensemble projections for groundwater levels in key aquifers

September 2025: All sites are showing an increased probability of below normal levels with none of the modelled rainfall scenarios showing exceptionally low levels.

March 2026: All sites are showing a reduced probability of exceptionally low levels.

Author: Pan 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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