Drinking water quality hit by farm activities

The quality of drinking water in “high-status” rivers and lakes has dropped dramatically in recent years.

Traditional farm activities such as field drainage, the use of fertilisers and pesticides, and overgrazing are being cited as contributory factors.

Forestry, wind farms, and one-off housing also threaten natural water sources, while septic tank discharges and accidental releases of pollutants are other key factors.

The risks to drinking water supplies are highlighted in a new Environmental Protection Agency report.

Studies show that, in 1987, a reported 30% of rivers were designated “high status”, but that rating slumped to 17% by 2008.

Research funded by the EPA and undertaken by a project team led by Bernadette Ní Chatháin of the RPS Group, has outlined strategies to protect pristine water bodies.

High-status waters such as rivers with healthy populations of freshwater pearl mussel or juvenile salmon require very high standards of protection.

Researcher Fiona Murphy of the RPS Group said that while there has been a reduction in serious pollution, there has been a dramatic loss of pristine waters, which have lost high status.

“We’re having problems in keeping high-status sites and one of the main challenges is to retain that status,” said Ms Murphy.

The pristine sites are seen as fundamental to maintaining spawning grounds for fish and providing a refuge for biodiversity under threat from our developed landscape.

Ms Murphy said the smallest pressure can impact on water bodies that are in top condition.

“The input of a few grammes of phosphorus or a slight increase in silt, for example, will have a much more damaging impact on the ecology of a pristine system than the same addition to an already polluted system,” she said.

The report calls for much tighter planning controls in areas with pristine water catchments. It also urges control mechanisms on the use of pesticides, as well as on forestry and currently unregulated activities such as overgrazing in sensitive areas.

The report draws from recent scientific studies and practices in other EU countries. It also focuses on interaction between water and non-water-related legislation, provides guidance to local authorities and suggests management strategies.

EPA deputy director general Dara Lynott said the report will contribute to the evidence base required to develop actions that will help prevent further loss to our cleanest rivers.