Research and analysis

Lincolnshire and Northamptonshire water situation: April 2025 summary

Updated 14 May 2025

Applies to England

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

1. Summary

April was a dry month with rainfall varying between 33% to 44% of the long term average (LTA) and was classified as notably low to below normal in all the 6 hydrological units, resulting in an increase in soil moisture deficits (SMD). By the end of April, the area had an SMD of 67mm, which falls within the exceptionally high category for the time of year. Monthly mean river flows ranged from 21% to 77% of the LTA, with classifications ranging from notably low to normal levels. Following the below normal levels of rainfall across LNA in April, the groundwater level trend showed a decline at all indicator sites. All reservoirs ended the month around their normal operational curve, with some slightly above and some slightly below target.

2. Rainfall

On average, the Lincolnshire and Northamptonshire area received 18mm of rainfall during April, which was 38% of the LTA. April rainfall totals ranged from 33% to 44% of the LTA (14mm to 22mm) and, as such, were banded as notably low or below normal in all 6 catchments.

Throughout the month frontal system did not give hydrological area rainfall totals higher than 11mm during any single event, with 96% of the month’s rainfall total recorded across 4 days (14, 15, 21, and 22). April rainfall showed a slight east-west divide, with eastern catchments generally receiving more rainfall than those in the west of the area.

Following April’s rainfall, the 3-month total is now showing that the catchments have received exceptionally low to notably low levels of rainfall (a north-south divide). This is a decrease from March’s report, which showed below normal to normal levels of rainfall in all 6 catchments. The last 6-month rainfall totals showed normal levels in almost all of the hydrological areas (except for the Louth Grimsby and Ancholme and Witham Chapel Hill catchments which showed as below normal in the 6-month map). As a result of these low levels of rainfall in April, the last 12 months’ totals displayed normal levels in all of the 6 hydrological areas.

3. Soil moisture deficit and recharge

SMD responded in line with the rainfall patterns observed through April. Due to the dry April (and dry March), SMD increased sharply in all 6 hydrological areas. On average, SMD for the area increased from 16mm at the end of March to 67mm by the end of April. This figure is within the exceptionally high category for the time of year. The SMD difference-to-LTA (mm) map in the full report shows all hydrological areas are in the 26mm to 50mm category, indicating that they are drier than normal for the time of year.

4. River flows

Monthly mean river flows ranged from 21% to 77% of the LTA, and from notably low to normal classification. In most sites, river flow responded in line with the amount of rainfall received in April. Two of the 12 sites were considered to be notably low, 5 at below normal levels, while the remaining 5 sites were classified as normal. Wansford (Nene) levels show no change in banding since January 2025.

5. Groundwater levels

Following the below normal level of rainfall across LNA in April, the groundwater level trend showed a decline at all indicator sites, ending the month with one site classified as above normal, 6 sites as normal, and the remaining one site (Leasingham Exploratory) as below normal. However, at all sites with data, banding remained unchanged since the previous month.

6. Reservoir stocks

With the exception of Rutland, Ravensthorpe and Hollowell, reservoirs in the area ended the month slightly above their normal operating curves. The levels at Ruthland was 3.7% below target curve and Ravensthorpe and Hollowell was 2% below target curve in April, however levels are not alarmingly low.

7. Environmental impact

The Trent-Witham-Ancholme (TWA) transfer scheme has been in use during April. Pumping started first week in April. During April water has been pumped into the Ancholme from the Witham at Short Ferry while transfer from the Trent into Witham at Torksey remained off throughout April. Both the Gwash-Glen and Slea Augmentation schemes remained off in April. There were 5 HOFs Hands Off Flow (HOFs) active during April:

• 2 in the Steeping catchment
• one in the Ancholme catchment
• one in the Witham catchment
• one in the Nene catchment

There were no fluvial flood warnings or flood alerts issued.

8. Forward look

8.1 Probabilistic ensemble projections for river flows at key sites

June 2025: All sites are showing a slightly increased probability of lower than normal flows.

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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