Pollution of water supplies is continuing, reports say

The pollution of public water supplies in the west continues apace, according to two scientific reports which expressed serious concern about deteriorating quality. The Western Health Board public analyst's laboratory has called for greater control over the discharge of waste containing phosphate if the "ever-growing" pollution problem is to be tackled.

Some small rural water supplies and group schemes are so contaminated by algal blooms that the water is "unusable", according to the analyst, Dr Des Feeley.

"While algae need about 16 elements for life, it is phosphorous in the form of phosphate that is the principal element controlling growth in most temperate waters," the report states. Phosphate in water derives from domestic/farm waste and from agricultural fertilisers. "In small supplies and group schemes, the treatment available is not able to deal with the large blooms that are increasingly been seen in our waters," the report continues.

Inadequate maintenance or defective chlorination equipment is seen as one of the main contributing factors to the problem in group water schemes. The western reg ion has the majority of group schemes - which serve about 5 per cent of households nationwide. The Western Health Board's laboratory, which monitors for nine local authorities, tested more than 8,000 samples in the past year for compliance with EU regulations.

The report comes only weeks after an Environmental Protection Agency study confirmed a downgrading in the status of Lough Mask, the main water supply source for much of Co Mayo.

It identified over-enrichment by increasing levels of phosphate as the main cause. Formerly classified as oligothrophic (pristine), both Mask and the Corrib are now classified as mesothrophic - even though sewage treatment plants have been upgraded at Tuam, which discharges into the river Clare and Lough Corrib, and at Ballinrobe, which discharges to the river Robe and Lough Mask.

The EPA's 1997 drinking water quality report found the overall quality in the State was "satisfactory", with group water schemes showing improvement. However, it warned against complacency. Since its publication, the Minister for the Environment has announced increased Government spending on rural water supplies.