uses cookies to make the site simpler. Find out more about cookies

River water quality

Until 2010 the Government Laboratory monitored and reported on the quality of inland watercourses on the Isle of Man. This work is now undertaken by the Environmental Protection Unit of the Department of Environment, Food and Agriculture, with chemical analysis performed by the Government Laboratory.

The chemical classification of rivers uses the same scheme as the UK Environment Agency for England and Wales, termed the (Chemical) General Quality Assessment Scheme (GQA). In the UK the Chemical GQA is complemented by a Biological GQA, but due to limited species diversity on the Island a specific Isle of Man Biological Classification Scheme has been formulated based on a similar scheme from Northern Ireland.

The assessment of chemical water quality is based on the levels of organic pollutants and of nutrients in the water, while biological quality is assessed from macroinvertebrate animal life (insect larvae, shrimps, snails, leeches, worms etc). Essentially the chemical data shows the instantaneous condition at the time of sampling, while the biological data shows the overall condition of the river in the longer term. The data are expressed in classification terms such as Good, Very Good or Excellent, allowing ready comparison of rivers both on the Isle of Man and with neighbouring jurisdictions.

Monitoring of river water quality to 2009 was based on samples assessed for chemical quality three times a year and assessed for biological quality twice a year. From 2010 when responsibility passed to the Environmental Protection Unit of DEFA the routine monitoring was streamlined to just continuance of the summer chemistry on the full 86 sites, with 26 of the sites identified as most at risk having continued being tested for chemical parameters three times a year and samples taken twice a year and preserved to enable biological assessments in the event any reason to investigate more deeply.

Baseline survey

Over a 3 year period from 1995 to 1998, the Laboratory undertook a Baseline Survey of river water quality, to classify the Island's rivers according to their chemical and biological quality.

That survey found that 93% of river length monitored for chemical water quality were Good or Very Good, with the main water quality problems related to nutrient enrichment. For biological quality 79% of river length monitored were Fairly Good or better, with 21% Fair or Poor biologically. The main cause of depressed biological quality was sewage effluent discharged from sewage treatment works, with other factors including channel modification (including drainage works), mine drainage, and acidification.

River quality objectives

Based on the baseline survey information, the then Department of Local Government and the Environment proposed River Quality Objectives for all major rivers and streams on the island under the terms of the Water Pollution Act 1993, which after consultation with interested parties were adopted as Government targets. See downloadable documents for a copy of the River Quality Objectives report detailing the rivers’ and streams’ then current quality, target future quality and the timescale over which any improvements were planned.

Key performance indicators

The Department of Local Government and the Environment initially set 2 targets in the form of Key Performance Indicators for river quality: at least 98% of rivers to be of fair chemical quality or better, and at least 98% to be of fair biological quality or better. Subsequently, early in 2009, additional targets for good or better quality were set as a measure of the higher quality end of the spectrum: 88% of rivers for good chemical and 68% for good biological quality. However, following the change in the monitoring regime in 2010 to focus resources more on higher risk rivers, those previous Key Performance Indicators are not directly applicable to the data now being produced.

River pollution incidents

Until 2003 the investigation of River Pollution Incidents was undertaken by the Government Laboratory, however responsibility for this work subsequently passed to the Environment Protection Unit, of the Department of Environment, Food and Agriculture.

River water quality reports

Following the Baseline Survey, full reports were intended to be produced every five years, with interim summary reports in the intervening years. The most recent quinquennial report, from 2005, is available for download from this page (see downloadable documents). Subsequent quinquennial reports have not been produced due to the change in monitoring after 2009, however a number of interim reports have been produced, the most recent from the current monitoring ragime and the last from the previous regime (2009) also being available for download.

In addition, in 2016 a “snapshot” evaluation of the microbiological quality of rivers was undertaken, assessing water quality against bathing water parameters applicable to bathing beaches at or near the river estuaries. The survey was intended to assess whether the rivers might be significant factors in relation to bathing water quality, due primarily to diffuse pollution. The results are not conclusive as the sampling was not keyed to the times of bathing water monitoring, and in any case some beaches are known to be affected by other sources of microbiological contamination (e.g. sewage discharges). However the results do suggest that diffuse pollution could be significant in some cases, and therefore once any direct sources of microbiological contamination have been removed from bathing areas it is likely that a more systematic and thorough assessment of sources of diffuse pollution may be necessary. The snapshot report from 2016 is available for download.

River habitats

As part of its assessment of the physical state of rivers in England and Wales, the UK Environment Agency undertakes surveys of river habitats. The Isle of Man has co-operated with the Agency by facilitating use of the unique isolated area of this Island for pilot studies to develop the methodology, in return for which the Agency has included Isle of Man data in its reports.

The most recent survey was conducted in 2006, with an initial report provided to the Isle of Man by the Environment Agency. Following subsequent survey work across England and Wales the Agency issued a series of reports in 2010 for the regions surveyed, including the Isle of Man. The latter report is complementary to the original report in presenting the data in a different format, and including some data not previously reported, while omitting other data, in line with a common UK-wide format (see downloadable documents).  Additional information can be found on Environment Agency website, in particular an introductory snapshot report and a summary report (see Related Links).

For further information please contact:

Did you find what you were looking for?
Back to top