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Water quality

Water Pollution Act

In order for the river quality to be maintained and possibly improved in the face of increased developmental pressures, it is necessary to exercise controls over the discharges to our rivers.

This requirement has been recognised for some time and, as a result, the Water Pollution Act (1993) was enacted under section 5 during early 2005 to enable the issuing of licences for discharges of trade and sewage effluent, the taking of legal proceedings for discharging effluent without or in breach of the conditions of a licence, and the provision for setting regulations for preventing pollution.

River quality

The Government has set targets that 98% of the rivers on the Island should achieve at least 'fair' and above for both biological and chemical water quality.

The latest river quality monitoring report, copy available for download, measured chemical and biological water quality over the period Spring 2015 to Autumn 2016. This report is the sixth detailing long term monitoring on the rivers and streams of the Isle of Man. The first was the “The River Quality Baseline Survey” issued in 1998, which presented results from surveys carried out between 1995 and 1998. The second was “River Quality 2000” issued in 2002. The third was the “River Quality 2005” and two interim monitoring reports in 2009 and 2013 have also been produced. Comparisons have been made between the results from the first three reports to allow comment on long term river quality changes however due to limited data from 2015 and 2016 the data cannot be compared to previous year.

The data used in this report has been treated in a similar manner to that collected by the regulatory bodies in England, Wales and Northern Ireland, whereby a “General Quality Assessment” (GQA) category is calculated from the data for a number of aspects including biological, chemical and nutrient status. This presents a “snapshot” of environmental quality for the major rivers and streams of the island and allows comparison with any future surveys on the Isle of Man and surveys from the United Kingdom.

The chemical water quality across the Isle of Man has improved slightly since 1995 and with more of an improvement between 2000 and 2016. Since 2000 the sampled watercourses achieving ‘Very Good’ or ‘Good’ GQA classification has increased from 91% to 99% in 2016.

For the biological analysis the 2015 and 2016 samples have been analysed using the Biological Monitoring Working Party (BMWP) classification. Full River Invertebrate Prediction Accreditation System (RICT) analysis wasn’t available due to insufficient data. The BMWP is analysed using five categories; very good, good, moderate, poor and very poor. Due to the difference in analysis the 2015 and 2016 samples are not able to be compared to the previous data.  Poor BWMP classification was recorded for parts of Middle River, River Dhoo and the River Neb; good for parts of the River Dhoo, River Glass, Groudle Stream, Crogga River, Mooar Stream and Foxdale Stream.

Throughout 2015 and 2016 not all of the 26 biological monitoring sites were sampled during each season of the year therefore there is limited data and difficult to interpret the results.

Nitrate is derived from land run off containing artificial fertiliser and farm slurry spreading and it is also a constituent of fully treated sewage effluent. In the latest survey, 96% of rivers were in the top three classes for nitrate which is slightly down on the previous two studies at 99%. However there has been an increase in the percentage of sites with ‘Very Low’ concentrations of nitrate to 54% from 47% in the previous study. 

Phosphate originates mainly from sewage effluent and artificial agricultural fertilisers. The concentration of phosphate has decreased with 89% of sites achieving ‘Very Low’ classification. All of the sites in 2015 and 2016 achieved ‘Moderate’ or above GQA classification which is a big improvement from previous results where a couple of areas have higher concentrations of phosphates present.

For further information, please contact +44 1624 685885 or email:

Bathing water monitoring

Sea water sampling following the procedure set out in the 1976 European Directive on Bathing Water (76/160) is carried out at 19 beach locations throughout the island.

The samples are subjected to microbiological analysis for faecal indicator organisms the results from which allow the water to be categorised in to "poor", "good" and "excellent" qualities. These results are updated weekly on 20 occasions between May and September and they are displayed at prominent locations near the beaches in order to inform beach users.

Recent trends have shown improvements in quality at those beaches in the East and South where sewage discharges have been removed and connected to the IRIS scheme for treatment at the new Meary Veg sewage treatment works.

The location of the sampling beaches, proximity of sewage outfalls and levels of treatment given to the sewage can be seen as follows:

Sampling beachNational grid referenceNearest sewage outfallTreatment level
Douglas (Summerhill) SC 3925 7720 Transferred to IRIS Full
Douglas (Central) SC 3884 7685 Transferred to IRIS Full
Douglas (Broadway) SC 3846 7631 Transferred to IRIS Full
Laxey SC 4421 8356 300m North East None
Ramsey SC 4552 9453 1600m North Full
Peel SC 2439 8447 250m North East None
Port Erin SC 1942 6897 Transferred to IRIS Full
Port St Mary SC 2122 6814 Transferred to IRIS Full
Castletown SC 2710 6762 Transferred to IRIS Full
Deryhaven SC 2866 6734 Transferred to IRIS Full
Kirk Michael (Balleira) SC 3131 9144 100m North West Full
Port Soderick SC 3474 7267 None  
Bay-ny-Carrickey SC 2215 6880 Transferred to IRIS Full
Jurby SC 3522 9981 150m North West Full
Fenella (Peel) SC 2414 8444 750m round Island None
Garwick SC 4353 8138 300m South East None

For further information, please contact +44 1624 685885 or email:

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