Research and analysis

North West water situation: September 2024 summary

Updated 11 October 2024

Applies to England

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

1. Rainfall

Rainfall for North West England for September was classed as normal with 113% of the long term average (LTA). The Cumbria and Lancashire (CLA) area observed 95% of the LTA also classed as normal. The Greater Manchester Merseyside and Cheshire (GMC) area observed much heavier rainfall with 198% of the LTA classed as exceptionally high.

During September rainfall across North West England was classed between below normal and exceptionally high. The highest rainfall (in terms of the LTA) was recorded in Cheshire Rivers Group hydrological area with 257% of the LTA classed as exceptionally high. This is the wettest September observed since 1871. The lowest was recorded in the Derwent hydrological area with 61% of the LTA classed as below normal. For the rainfall in the 8 remaining hydrological areas across North West England 2 were classed as notably high, 2 were classed as above normal and 4 as normal with the heavier rainfall being seen further south.

Cumulative rainfall over the last 3 months was classed as between notably high and normal. Due to the extreme rainfall in September the heaviest cumulative rainfall (in terms of the LTA) was observed in the Cheshire Rivers Group hydrological area with 155% of the LTA and the lowest in the Ribble hydrological area with 95% of the LTA.

The 6-month cumulative rainfall totals show rainfall classed between exceptionally high and above normal with the Esk (Cumbria) and Derwent hydrological areas both recording their third wettest 6 month period ending in September since 1871. The highest cumulative rainfall (in terms of LTA) was recorded in the Cheshire Rivers group and Derwent hydrological areas with 146% of the LTA, both classed as exceptionally high. The lowest was recorded in the Wyre and Lune hydrological area with 114% of the LTA classed as above normal.

The 12-month cumulative rainfall totals for hydrological areas in North West England are all classed as exceptionally high with the North West England as a whole recording its second highest rainfall since 1871. GMC and CLA observed their highest and second highest rainfall respectively. Individual hydrological areas that recorded notably high 12-month cumulative rainfall were as follows.The wettest since 1871 for:

• Esk (Cumbria)
• Cheshire Rivers Group
• Kent
• Mersey and Irwell
• Douglas

The second wettest since 1871 for:

• Derwent
• Eden
• Wyre and Lune

The third wettest for:

• Ribble

2. Soil moisture deficit and recharge

Heavy rainfall toward the end of September, especially in GMC, resulted in soil moisture deficits (SMD) falling between 0mm and 25mm by the start of October. SMD rose slightly in Cumbria and decreased slightly in Lancashire. Due to the heavy rainfall GMC SMD decreased notably. All areas recorded SMD lower than expected for the time of year.

3. River flows

Monthly mean river flows for North West England were classed as between normal and exceptionally high. Out of the 16 sites in the CLA area 11 sites were classed as normal, 2 sites above normal and 3 sites (Kirkby in Alt, Bullgill in Ellen and Kirkby Stephen in Eden) are missing due to ongoing data issues and the installation of an eel pass. The lowest flow for North West England was recorded at Seaton Mill with 70% of the LTA classed as normal.

Out of the 9 sites in the GMC area 6 sites were classed as normal, 2 sites above normal and one site as exceptionally high. Due to the record-breaking rainfall in the Cheshire Rivers Group hydrological area the highest flow (in terms of the LTA) was recorded at Ashbrook with 416% of the LTA which is the highest monthly average flow ever recorded at Ashbrook for September.

4. Groundwater levels   

Groundwater levels for North West England for the end of September were classed between exceptionally high and normal. The Victoria Road site changed classification from normal to above normal and all other sites remained at the same classification as follows:

• Bruntwood Hall at exceptionally high
• Furness Abbey at exceptionally high
• Priors Heyes at exceptionally high
• Skirwith at exceptionally high
• Richmond Park at exceptionally high
• Brown Bank Lay By as notably high
• Primrose Hill at above normal
• Great Musgrave at normal
• Lea Lane at normal

Levels at Priors Heyes remain high compared to historic levels because the aquifer is recovering from the effects of historically high abstractions.

5. Reservoir stocks

Total reservoir net storage for North West England decreased from 77% at the end of August to 75% at the end of September which is higher than the average of 71% at this time of year but lower than last year when storage was 79%.

At the end of September, reservoir storage (in terms of percentage) was highest at Crummock water which was 100% full and lowest at Longdendale which was 64% full. The combined storage at Haweswater and Thirlmere was 74% which is higher than the average of 61% and the same as last year.

Some of the reservoirs kept low for maintenance work include:

• Audenshaw No.1
• Anglezarke
• High Bullough
• Woodhead
• Torside
• Dingle
• Kitcliffe
• Harlock

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 herein.

Author: Greater Manchester Merseyside and Cheshire Hydrology Team, hydrology.GMMYCH@environment-agency.gov.uk