Avoca River ranks high on country’s polluted list
DESPITE showing some infrequent signs of improvement, the Avoca River is still one of the most seriously polluted rivers the country.
Silver Strand and Brittas Bay beaches meet the strictest of EU standards, while Bray and Greystones can’t quite meet those standards, and the Upper Glendalough Lake and its feeder streams are amongst the most acidsensitive you could find.
These are just some of the results contained in a report released by the EPA detailing the state of the nations environment.
‘Ireland’s Environment 2008’ is the fourth such report carried out and sums up the state of the environment across themes such as climate change, air quality and emissions, waste, chemicals, land and soil.
But perhaps the most revealing statistics can be found in the water quality section, including the water quality of lakes, rivers and estuaries and coastal areas.
Wicklow has the most acid-sensitive lake systems in Ireland, with only the western seaboard any kind of match. This occurs in areas with slowly weathering bedrock formations such as granite, shale, gneiss, sandstone and other associated soils.
It means that surface waters have very low alkanlinity levels and as a result have a poor capacity to neutralise acid inputs. The Upper Glendalough Lake would be one of the largest acid-sensitive lakes in Ireland, which would also affect any feeder streams.
This can result in elevated levels of phosphorus and nitrogen, which can given rise to over enrichment. This is a form of pollution which results in increased phytoplankton growth and intensive algal bloom and a decline in water transparency
Tests carried out between 2004 and 2006 showed the Lugduff River, which flows into the Glendalough Lake Upper, is actually showing signs of improvement. It was regarded as severely impacted each time it was sampled from 1985 to 2003, to moderate on two sampling occasions, to no impact the one time it was sampled during the current period.
However, the forestry surrounding the Lugduff does cause acid inputs and will continue to do so.
Overall a slight improvement is noticeable both at Lugduff and Glendalough.
Initially tests carried out brought about some good news with regards to the Avoca River, but unfortunately it wasn’t to last long.
It had been removed from the list of seriously polluted locations after tests in 2006 noted a marked improvement, but that proved temporary.
Tests in 2007 showed that a 11.5 km stretch of the river was once again classified as seriously polluted. Its proximity to acid mine leachate since the 1850s has always left it very vulnerable.
Only 0.5 per cent of the total river length tested nationally proved seriously polluted.
A number of fish kills were also documented in the Avoca River due to mine wastes. It seems the river recovers from time to time, allowing fish to return. But this recovery is always brief, and toxic conditions reoccur when there is a low flow or high discharge from the old mines, resulting in further fish kills.
The future is also ominous for Brown’s Beck Brook in the Donard area where 0.5 of the river has been caused by agriculture, first noted in 2004.
Annual monitoring of bathing waters was carried out at 131 designated areas throughout the country, including Bray, Greystones, Silver Strand and Brittas Bay beaches. The proportion of seawater bathing areas complying with stringent EU guideline standards fell from 92 per cent in 2005 to 81 per cent in 2007.
But Brittas Bay, both upper and lower sections of the beach, and Silver Strand still meet those strict EU requirements. Bray and Greystones don’t meet the EU Guide Values, but are considered compliant with the less stringent EU Mandatory Values. This means they don’t match the good quality of Brittas Bay or Silver Strand but are still deemed acceptable quality.
Brittas Bay is the only beach in the county deemed of high enough quality to receive Blue Flag recognition. In order to receive such status, a beach must maintain a high standard of water quality, and meet specific environmental and safety services requirements.
While oxygen conditions in the majority of Irish estuaries and coastal waters remain high, by far the lowest levels in the country were recorded in the upper reaches of the Avoca estuary.
Some of the most eutrophic water conditions in the whole country were recorded in the Slaney. This pollution manifests itself in the form of nutrient enrichment.
The scene that greets tourists at the picturesque Glendalough Lake.