Experts say phosphorus levels in Loch Leven are still too high

Environmental agencies have been working to clean up Loch Leven, near Kinross, after it became infested with blue-green algae in the 1990s.

They said water quality had improved in recent years.

However, the loch was still being polluted by phosphorus from farms and residential septic tanks.

Excessive levels of the element caused poisonous blue-green algal blooms to spread across the surface of the water, threatening plant life and brown trout.

Initial improvements

A recent survey of the loch showed it had started to recover as a result of pollution-reducing measures.

The environmental body Scottish Natural Heritage (SNH) said beds of pondweeds and stoneworts had started to grow back into deeper water since a new sewage treatment facility was built in the area.

Unless septic tanks are regularly emptied there is likely to be significant phosphorus leakage, which will find its way into the loch. Philip Gaskell Scottish Natural Heritage

Strict rules from Perth and Kinross Council on waste water for new housing developments, a reduction in woollen mill discharges and efforts to control soil erosion in fields had also had an impact.

But it said the initial improvements in water quality had stalled and phosphorous levels in the loch were still too high.

Farms and septic tanks are thought to contribute half the phosphorus contaminating the loch.

Philip Gaskell of SNH said: "Unless septic tanks are regularly emptied there is likely to be significant phosphorus leakage, which will find its way into the loch.

"Householders and rural businesses can help by simple measures.

"Buy and use household detergents free from, or low in, phosphorous (check the label) and empty your septic tank regularly - every year or so.