SCOTLAND's state-run water monopoly was fined £10,000 today for a pollution incident in which more than 2000 gallons of sulphuric acid leaked into a top Scottish fishing river.

Alloa Sheriff Court was told that the incident, in July 2011, was caused when a corroded bolt on a tank of sulphuric acid, used as part of the process for purifying drinking water, failed, and allowed up to 2640 gallons (12,000 litres) of the chemical to leak out.

The bolt had not been maintained in accordance with the manufacturer's recommendations.

The court heard that the tank, at Scottish Water's Glendevon Water Treatment Plant near Dollar, Clackmannanshire, is surrounded by a holding "bund" that should have caught the spill.

However the strength of the acid - 96 per cent concentrated - was so high that it burned through the bitumen coating of the bund and the road surface outside and drained into the nearby Castlehill Reservoir.

There it reacted with sludge normally settled and stable on the bottom of the reservoir, and caused a "slug" of pollution to make its way slowly down the River Devon.

The court was told that the combination of the river being turned acidic, and poisonous aluminium being released from the sludge, caused a massive kill of fish, molluscs and shrimps in the river.

Investigators from SEPA, the Scottish Environmental Protection Agency, noted dead trout, perch and sticklebacks littering the river margins.

An estimated 30,000 fish, including 2000 brown trout, were killed in the incident, classified by SEPA was a Category 1 major pollution event.

The Food Standards Agency issued a warning not to eat any fish from the River, and anglers and canoeists were warned to stay away.

The Devon Angling Assocation, which stocks the river, lost thousands of fish, the court was told, and from 4 July 2011 to 19 August 2011 "the amenity of the river for swimming, water sports and fishing was lost to the general public".

Procurator Fiscal Sara Shaw said, "These incidents were, sadly, entirely avoidable.

"Both incidents were brought to the attention of SEPA by members of the public, at which point the environmental damage was already done.

"If proper safeguards, and an effective system for checking and maintaining Scottish Water plant, had been in place, both of these incidents could have been prevented. At the very least, earlier intervention by Scottish Water could have lessened their environmental impact.

"Scottish Water failed to implement appropriate inspection, maintenance and notification systems. That failure, the resultant damage to the environment and the impact on the local communities, is unacceptable." Scottish Water pleaded guilty to discharging concentrated acid into a water course.

It also admitted a second charge relating to a discharge of sewage from St Serfs Sewage Pumping Station, Clackmannan, into the Goudnie Burn, a tributary of the River Black Devon on 1 August 2011.

The discharge, said to have "negatively impacted on life in the water", occurred after the snapping of a "vital cable" that should have triggered pumps and an alarm.

Scottish Water told the court that it had spent "in excess of £4million" not only at the Glendevon plant but throughout Scotland on work to ensure that the sulphuric acid leak could not be repeated.

Sheriff David Mackie said he would have imposed a larger fine, but noted it was a public body with no shareholders, wholly owned by the Scottish Government, and any financial penalty would ultimately fall on the ordinary consumer.