South West Lakes management catchment: baseline length of rivers and estuaries polluted by abandoned metal mines
Published 12 March 2025
Applies to England
© Crown copyright 2025
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This publication is available at https://www.gov.uk/government/publications/abandoned-metal-mines-in-england-baseline-length-of-rivers-and-estuaries-polluted-by-harmful-metals/south-west-lakes-management-catchment-baseline-length-of-rivers-and-estuaries-polluted-by-abandoned-metal-mines
This is one of 20 reports, one for each polluted management catchment, on the water quality monitoring undertaken by the Environment Agency to determine the baseline length of rivers and estuaries considered polluted by any of the Environment Act target substances from abandoned metal mines in 2022.
A length of river or estuary is considered polluted where the concentration of one or more of the 6 target substances (arsenic, cadmium, copper, lead, nickel and zinc) exceeds the relevant Environmental Quality Standard (EQS). EQS concentrations are based on ecotoxicology data and set by government at a level that should prevent harmful environmental impacts. When the concentration of a substance in a water sample is higher than the EQS, adverse impacts on the aquatic ecosystem can be expected. The relevant EQS for each target substance are set out in The Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015.
The purpose of calculating this baseline was to enable measurement of the statutory abandoned metal mines target set out in Part 4 of the Environmental Targets (Water) (England) Regulations 2023. This regulation requires that the combined length of English rivers and estuaries polluted by the target substances from abandoned metal mines is, by 31 December 2038, at least 50% lower than the baseline.
In the South West Lakes management catchment, the baseline length of polluted rivers for the abandoned metal mines water target is 12km. We will aim to identify the key sources of metal pollution in this management catchment by carrying out detailed monitoring investigations.
You can find further background and context on the Environment Act abandoned metal mines water target in the national baseline report which should be read together with this report.
The South West Lakes management catchment
The South West Lakes management catchment covers an area of approximately 913km2 and encompasses areas of the Lake District National Park. Go to South West Lakes Management Catchment on the Catchment Data Explorer for an interactive map showing the 3 operational catchments that make up the management catchment. The boundary of the management catchment and all 3 operational catchments are highlighted in Figure 1.
Metal mining in the South West Lakes management catchment
There is some evidence of historical metal mining in the South West Lakes catchment in the area around Bootle and Black Coombe, however, there is little documented information about these mines and further investigation is required. The River Annas was included in this baseline monitoring study due to elevated metal concentrations being detected during routine sampling and the need for further investigation.
Figure 1 shows the locations of mineral veins, known mine water discharges, closed mine waste facilities known to be causing serious environmental harm, and areas of abandoned mine wastes (mining spoil) in the South West Lakes management catchment.
This information has been gathered from various sources including:
- BGS Geological mapping - GeoIndex - British Geological Survey
- Prioritisation of abandoned non-coal mine impacts on the environment
- Inventory of closed mining waste facilities causing serious environmental impacts
- Defra-funded ‘Source apportionment of pollution from non-coal mines’ research project by Newcastle University and Hull University (unpublished)
- Environment Agency water quality data archive
As we can see from Figure 1, most of the historic mining activities in the South West Lakes management catchment were concentrated in the Irt-Mite-Esk-Annas operational catchment and Duddon operational catchment.
Figure 1. Map showing the abandoned metal mines, mineral veins and baseline river monitoring sites in the South West Lakes management catchment
© Environment Agency
The tables below list the catchments (surface water catchments) polluted by abandoned metal mines in the South West Lakes management catchment. These tables highlight where there are known point sources (mine adits or mine drainage levels) and diffuse sources (mine wastes or spoil heaps) within the catchment. The Environment Agency is continuing to investigate point and diffuse sources within the South West Lakes management catchment by undertaking a series of catchment characterisation studies. This will help us identify which sources need to be tackled to achieve the long-term statutory target.
Irt-Mite-Esk-Annas operational catchment: sources of metal pollution
Table 1 summarises which type of pollution sources from abandoned metal mines have been identified within the catchments (surface water bodies) in the Irt-Mite-Esk-Annas operational catchment.
Table 1. Summary of metal pollution sources in the Irt-Mite-Esk-Annas operational catchment
| Catchment (Surface water body) | Point sources of pollution | Diffuse sources of pollution |
|---|---|---|
| Annas | Requires Further Investigation | Requires Further Investigation |
Duddon operational catchment: sources of metal pollution
Table 2 summarises which type of pollution sources from abandoned metal mines have been identified within the catchments (surface water bodies) in the Duddon operational catchment.
Table 2. Summary of metal pollution sources in the Duddon operational catchment
| Catchment (Surface water body) | Point sources of pollution | Diffuse sources of pollution |
|---|---|---|
| Haverigg Pool | Requires Further Investigation | Requires Further Investigation |
Baseline monitoring
The objective of the baseline monitoring was to establish the upstream and downstream extent of surface waters polluted by the target substances from abandoned metal mines. We selected the baseline monitoring sites by first completing a desk study to review previous water quality data, maps and reports. We then made initial site visits to collect samples and to assess the suitability of the site for continued sampling. Generally, at least twelve water quality samples were then collected from each monitoring site.
Within the South West Lakes management catchment, water quality monitoring was undertaken in 2 out of the 3 operational catchments (Irt-Mite-Esk-Annas and Duddon) which are shown in Figure 1. We did not carry out monitoring in operational catchments where there is either no historical metal mining within the catchment or a combination of current and historical monitoring data shows that waterbodies within these catchments are not polluted by abandoned metal mines.
In total, 5 monitoring sites were selected across the South West Lakes management catchment to determine the baseline length of rivers polluted by target substances from abandoned metal mines. The locations of these monitoring sites are shown in Figure 1.
Water quality data collected between 1 January 2022 and 31 March 2024 have been used to determine and validate the baseline length of rivers and estuaries considered polluted in 2022. The length of rivers polluted by abandoned metal mines fluctuates in response to natural variation in rainfall and river flows. However, this length will not materially change unless remediation measures like mine water treatment schemes or diffuse interventions are installed to decrease inputs of metals. Therefore, data collected after 31 December 2022 are considered to be representative of rivers, provided no new remediation measures had been constructed since 2022. No new remediation measures have been constructed in the South West Lakes management catchment since 2022.
Water quality monitoring results
In the South West Lakes management catchment, the target substances measured were cadmium, copper, lead, nickel and zinc. We did not undertake testing for arsenic in this management catchment since historical monitoring data and knowledge of the local geology across the catchment indicated that no rivers are polluted by arsenic in this management catchment.
The baseline water quality data for all monitoring sites are available on the Environment Agency’s public water quality archive.
For a river water quality sample to be considered polluted, concentrations of one or more of the target substances must exceed the relevant EQS set by government when assessed as an “annual average”. The EQS are set out in The Water Framework Directive (Standards and Classification) Directions (England and Wales) 2015.
The EQS are derived using ecotoxicology data and set at a level that should prevent harmful environmental impacts. When the concentration of a substance in a water sample is higher than the EQS, adverse impacts on the aquatic ecosystem can occur, and the sample is considered to be polluted.
To understand the severity of pollution, we calculated a numeric “pollution level” by dividing the measured concentration of the target substances by the EQS. If the pollution level is greater than 1, the monitoring site is considered polluted by that target substance. Therefore, the higher the numeric pollution level, the greater the likelihood of harm to aquatic life.
Baseline polluted river length: South West Lakes management catchment
Our detailed monitoring across a range of flow conditions between January 2022 and March 2024 shows that in the South West Lakes management catchment, the baseline length of polluted rivers for the abandoned metal mines target is 12km.
Figure 2 shows the rivers in the South West Lakes management catchment that are polluted by target substances from abandoned metal mines.
Figure 2. The baseline length of rivers polluted by target substances from abandoned metal mines in the South West Lakes management catchment is 12km
© Environment Agency
Table 3 shows the river length (in km) that are polluted by each of the target substances within the South West Lakes management catchment. In general, the most polluted rivers are impacted by more than one target substance.
Table 3. River length (in km) polluted by each of the target substances within the South West Lakes management catchment
| Target substance | Polluted river length (km) | Pollution level: less than 3 times | Pollution level: 3 to 5 times | Pollution level: more than 5 times |
|---|---|---|---|---|
| Cadmium (Cd) | 12 | 6 | 0 | 6 |
| Lead (Pb) | 3 | 3 | 0 | 0 |
| Nickel (Ni) | 0 | 0 | 0 | 0 |
| Zinc (Zn) | 11 | 8 | 0 | 3 |
| Copper (Cu) | 0 | 0 | 0 | 0 |
Rivers polluted by abandoned metal mines: South West Lakes management catchments
Irt-Mite-Esk-Annas: baseline polluted rivers
The River Annas is polluted by zinc and cadmium. Crookley Beck and Millergill Beck are also polluted by one or more of the target substances. Kinmont Beck is compliant and not polluted.
Figure 3 shows the baseline polluted rivers in this operational catchment.
Figure 3. The baseline length of rivers polluted by target substances from abandoned metal mines in the Irt-Mite-Esk- Annas operational catchment is 10km
© Environment Agency
It should be noted that due to close proximity of some of the sampling points to each other, some of the sampling point markers on this map (blue squares) may overlap.
Duddon: baseline polluted rivers
Whitecombe Beck is polluted by cadmium at the Beck Side Farm monitoring point. There are a number of historical mines located in the headwaters of Whitecombe Beck however, these require further investigation.
Figure 4 shows the baseline polluted rivers in this operational catchment.
Figure 4. The baseline length of rivers polluted by target substances from abandoned metal mines in the Duddon operational catchment is 2km
© Environment Agency
It should be noted that due to close proximity of some of the sampling points to each other, some of the sampling point markers on this map (blue squares) may overlap.