By Bruce Robbins

RIVERS IN the Dundee and Angus areas are in danger of having life-giving oxygen squeezed out of them through agricultural contamination and run-off from sewage plants, the Scottish Environment Protection Agency said yesterday.

The discharge of chemicals such as nitrogen into water courses is encouraging the proliferation of plant life, which eats up oxygen and leads to a condition known as “eutrophication”.

Among those affected are the Dighty, Buddon, Lochty and Monikie burns, the Lunan and Dean waters and the River Esk.

All except the Dighty are already classified as eutrophic, but SEPA says the river that flows through Dundee is in danger of joining the list.

SEPA conducted a review of water quality and found 164 Scottish rivers and 17 lochs at risk from pollution.

A mix of sewage effluent and pollution from agriculture, forestry, fish farming and urban drainage are to blame, the agency said.

Nutrients such as phosphates and nitrates are essential to sustain plant and animal life but, when present in high concentrations, can cause excessive growth of certain plants.

In severe cases oxygen in the water is reduced, causing the death of fish and other aquatic life.

The water may become unsuitable for drinking, industrial use or recreational purposes.

Many Scottish rivers and lochs are naturally low in nutrients and are particularly sensitive to the effects on unwanted enrichment with additional nutrients.

The effects of eutrophy are hard to reverse and SEPA’s head of environmental quality, Tom Leatherland, appealed for farmers and other land users to do their utmost to protect the vulnerable local rivers.

He said, “The situation is bad enough that it’s causing us concern to a point where we want to take management action to ensure that it doesn’t become any worse or gets a little better.

“By designating some rivers and waters as sensitive waters at risk, we can justify the nutrient removal at sewage treatment works which might cost a bit more.

“We’re talking about some very vulnerable and highly regarded ecosystems here and we have to protect these waters.”

It was particularly important, Mr Leatherland said, to protect rivers such as the North and South Esk and the Isla in Angus, renowned for their fishing and contribution to local tourism.

Although Dundee’s sewage is now treated at the Hatton treatment plant, it is still possible for the Dighty to become polluted with diluted sewage during heavy rain.

Rainfall and domestic sewage flows into the same network and there has to be an overflow during heavy storms to prevent sewage backing up into housing.

Controls are already in place to monitor discharges into rivers and lochs and the Angus and Fife areas have the European designation of “nitrogen vulnerable zones”, which limits the amount of the chemical farmers can use in their fertiliser.

SEPA has said it will be working closely with the Executive, Scottish Natural Heritage and other partner organisations to ensure water quality targets are met.