Research and analysis

North West water situation: August 2024 summary

Updated 13 September 2024

Applies to England

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

1. Rainfall

August was marked by varied weather patterns, both over time and across different areas. Notably, Storm Lilian tracked directly over Cumbria on 22 to 23 August, contributing to an average of 50% of August’s rainfall across indicator sites, and increased river flows.

As a whole, rainfall for north-west England was classed as above normal for August, at 130% of the long term average (LTA). Cumbria observed 195% of the LTA, classed as exceptionally high and Lancashire 98% of the LTA, classed as normal. Greater Manchester, Merseyside and Cheshire (GMC) observed 57% of the LTA, classed as notably low.

Cumbria received the majority of the rainfall that fell in north-west England during August, with any dry periods lasting no more than 3 or 4 days at a time. All coastal hydrological areas in Cumbria and the Esk (Dumfries) were classed as exceptionally high, as they were exposed to the predominantly south-westerly weather systems during August. The Eden hydrological area, which is in the rain shadow of the Cumbrian Fells, was classed as above normal. The highest rainfall (in terms of the LTA) across north-west England was in the Esk (Cumbria) hydrological area at 247%, classed as exceptionally high.

By contrast, Lancashire, and GMC, experienced drier weather. On average, indicator sites in Lancashire observed 13 dry days (a day with less than or equal to 0.2mm rainfall), and indicator sites in GMC observed 16 dry days.

The Ribble, and the Wyre and Lune hydrological areas located in north and central Lancashire were classed as normal. To the south, the Douglas, and the Mersey and Irwell hydrological areas were classed as below normal. The Cheshire Rivers Group hydrological area received the lowest rainfall at 56% of the LTA and was classed as notably low.

August 2024 was also ranked as the wettest August since 1871 (153 years) for:

• Esk (Cumbria) hydrological area, with a rainfall total of 372mm, breaking the previous record of 326mm in 1956
• Derwent hydrological area, at 292mm, breaking the previous record of 288mm in 1891

The 3-month cumulative rainfall period ending in August, which corresponds with the meteorological summer (1 June to 31 August), show a broadly similar trend. With a sharp contrast between coastal hydrological areas in Cumbria and the Esk (Dumfries) hydrological area (classed as above normal to exceptionally high), and the rest of north-west England which were classed as below normal to normal, with hydrological areas in central Lancashire, Merseyside, and Greater Manchester being the driest.

The 6-month cumulative rainfall period, which include both the meteorological spring (1 March to 31 May) and summer, show a clear north-south divide, with hydrological areas north of and including the Wyre and Lune hydrological area being classed as exceptionally high, while southern hydrological areas were classed between above normal and notably high.

This was also the wettest meteorological spring and summer combined since 1871 for:

• Cumbria, with a cumulative rainfall of 898mm, breaking the previous record of 829mm in 2019
• Esk (Cumbria) hydrological area, at 1097mm, breaking the previous record of 986mm in 2012
• Derwent hydrological area, at 949mm, breaking the previous record of 859mm in 2019
• Kent hydrological area, at 1038mm, breaking the previous record of 956mm in 1920

Additionally, this was also the second wettest meteorological spring and summer since 1871 for the Eden hydrological area.

The 12-month cumulative rainfall totals reflect how wet the first half of the past 12-months has been, with all hydrological areas classed as exceptionally high, despite the drier weather in recent months.

The 12-month period ending in August was the wettest since 1871 for nearly all hydrological areas, except for the Ribble, and the Wyre and Lune hydrological areas, which were ranked second and third respectively. Notably for:

• North-west England, at 1675mm, breaking the previous record of 1605mm in 2016
• Cumbria, at 2076mm, breaking the previous record of 1927mm in 2016 by nearly 150mm
• GMC, at 1243mm, breaking the previous record of 1193mm in 2001
• Derwent hydrological area, at 2113mm, breaking the previous record of 1967mm of 2016 by nearly 150mm
• Cheshire Rivers Group hydrological area, at 1106mm, breaking the 147-year-old record of 1069mm in 1877

Additionally, this was the second wettest 12-month period ending in August for Lancashire.

2. Soil moisture deficit and recharge

The spatial difference in rainfall during August is clearly evident in the variability in soil moisture deficits (SMD) across north-west England. There is a clear north-south divide, where some areas in Cumbria and northern Lancashire have become saturated and is wetter than expected for the time of year. Whereas in central Lancashire and in GMC, SMD levels have increased compared to at the end of July, and is drier than expected for this time of year. Overall, SMD levels at the end of August across north-west England ranged from 0mm to 95mm.

3. River flows

Please note that monthly mean river flows recorded at 2 gauging stations; the River Bollin at Bollington Mill the River Alt at Kirkby have not been included in this report due to data quality concerns.

Monthly mean river flows in August showed distinct spatial trends due to the spatial variability in rainfall across north-west England. Compared to July, river flows increased in all catchments across Cumbria, and northern Lancashire. Similarly, river flows increased in most catchments in Central Lancashire, except for the Yarrow catchment at Croston. Meanwhile, river flows decreased at all catchments in Cheshire, Greater Manchester, and in the Yarrow catchment.

Overall, 17 out of 23 sites were classed normal or higher. Notably, all catchments classed as above normal to exceptionally high were situated in Cumbria. The remaining 6 sites, which were classed as below normal to notably low, are all in the Mersey and Irwell hydrological area.

River flows were highest (in terms of percentage of the LTA) in the Ellen catchment at Bulgill (343% of the LTA, classed as exceptionally high), and lowest at the Glaze catchment at Little Woolden Hall (52% of the LTA, classed as notably low).

There were some notable peaks in daily mean flow recorded due to the exceptional rainfall recorded in Cumbria in late August. Daily mean flows above Q1 (this is where mean flow has been exceeded only 1% of the time during the lifespan of the gauging station) were recorded on 23 August at:

• Bulgill gauging station on the River Ellen

Additionally, on 27 August at:

• Cropple How gauging station on the River Esk
• Duddon Hall gauging station on the River Duddon
• Seaton Mill gauging station on the River Derwent

4. Groundwater levels   

Groundwater levels across north-west England at the end of August were classed between normal and exceptionally high. Groundwater levels decreased at Primrose hill from above normal to normal, while Bruntwood Hall increased from notably high to exceptionally high.

All other groundwater indicator sites remained at the same classification:

• Brown Bank Lay-By, classed as notably high
• Furness Abbey, classed as exceptionally high
• Great Musgrave, classed as normal
• Lea Lane, classed as normal
• Priors Heyes, classed as exceptionally high
• Richmond Park, classed as exceptionally high
• Skirwith, classed as exceptionally high
• Victoria road, classed as above normal

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

5. Reservoir storage

Total reservoir storage for north-west England decreased from 79% at the end of July to 77% at the end of August. This is higher than the average of 74% at this time of the year, but marginally lower than this time last year when total reservoir storage was 78%.

At the end of August, reservoir storage (in terms of percentage) was highest at Crummock Water, and Ennerdale Water, which were both at 100% full. This was followed by Lake Vyrnwy which was 90% full. Storage was lowest at Longdendale (63%), due to low rainfall (Woodhead Reservoir rain gauge recorded only 41% of its LTA for August), and ongoing maintenance work within the Longdendale system.

The combined storage at Haweswater and Thirlmere was at 82%. This is higher than the average of 64% at this time of year, and also higher than this time last year when the storage was 68%.

Reservoirs kept low for maintenance works include part of the:

• Longdendale system – Audenshaw No.1, Torside, and Woodhead
• Rivington system – Anglezarke, High Bullough, and Yarrow
• Worthington system – Arley, and Worthington
• Bolton supply system – Dingle
• Poaka Beck system – Harlock
• Piethorne Valley system – Kitcliffe
• Ogden (Barley) system – Ogden Lower, and Ogden Upper
• Barnacre Group system – Barnacre North, and Barnacre South
• Longridge system – Alston No.2, Spade Mill No.1, and Spade Mill No.2
• Dee (Celyn and Brenig) system – Llyn Celyn
• Cowpe system – Cragg
• Ridegate system – Ridegate
• Dubbs system – Dubbs
• Belmont system – Belmont

Author: Cumbria and Lancashire Hydrology Team, hydrology.CMBLNC@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 herein.