Saving Highland's Loch Flemington 'globally important'
A loch's recovery from severe pollution could help to guide efforts to tackle contaminated water across the world.
Every trout in Loch Flemington, near Nairn, died in a single day in 1995 because of a blue-green algae bloom.
The Centre for Ecology and Hydrology (CEH), near Edinburgh, is now working with the local community to restore the loch's water quality.
Dr Alastair Noble, who has lived near the loch for 40 years, said the project could have global significance.
A treatment called Phoslock was applied to Loch Flemington in 2009.
CEH believed it was the first time it had been used on a natural water feature after previously being applied to man-made ponds and lakes in England.
Phoslock was also applied to Dundee's Clatto Reservoir in 2009, but a lack of good pre-application data has made it hard to assess its success.
Records for Loch Flemington go back 40 years.
Results of tests done in 2010 and this year have shown water quality at the loch has improved significantly since 2009, according CEH.
The loch covers about 35 acres (14 hectares) and sits in the Kildrummie Kames Site of Special Scientific Interest (SSSI).
According to geologists, the SSSI has one of Britain's best and largest examples of a braided esker system formed by debris from the surface of a massive ice sheet being deposited onto the ground in a criss-cross pattern of ridges as the ice melted.
Flemington is also a glacial feature, known as a kettle hole loch. The water lies in a shallow saucer-shaped depression created as the last chunks of the ice sheet disappeared.
Humans have long been attracted to its shores.
The possible remains of an ancient house built on stilts called a crannog have been recorded at one end of the loch by the Highland Historical Environment Record and the Royal Commission on Ancient and Historical Monuments of Scotland's Canmore database.
Centuries later Loch Flemington became to be regarded as one of the best places in Scotland to fish for trout.
A small number of houses, dubbed the Streetie by residents, lie along the north shore.
Concerns in the community about increasing pollution first arose in the 1970s.
Among the sources of contamination was raw sewage flowing into the loch from the nearby village of Croy.
It was one of several communities along the Inner Moray Firth that expanded following the opening of the J Ray McDermott oil and gas fabrication yard near Ardersier.
At its height, more than 3,000 workers were employed at the site before it shut in 2002 after 30 years of activity.
A sewage plant now handles waste water from Croy.
But the damage had already been done to Loch Flemington.
On 30 July 1995 a blue-green algae bloom used up all the oxygen in the water and killed up to 500 trout.
Nearby residents reported seeing 40 to 50 herons gorging on the dead fish.
Retired GP Dr Noble is chairman of the loch's fishing syndicate. The angling group has no fish to catch but continues to exist to support the clean-up effort.
Dr Noble said: "It was very, very sad and scary to see how devastating an effect pollution can have on a loch."
For 10 years straw bales were dropped into the loch because barley straw is an inhibiter to algae.
A leading scientist, the late Pip Barrett, had also taken a keen interest in the fate of the loch.
Dr Noble said: "Unfortunately the straw bales made no difference and we were no further forward.
"Around the year 2000 there was a real depression and a feeling that there was nothing we could do and that it would just remain polluted."
Suggestions of draining and then refilling it, or dredging the loch were rejected amid fears the area would be left with a big, muddy hole.
Three years ago CEH approached the local community about allowing a scientist called Sebastian Meis to carry out research at Loch Flemington for a PhD.
As well as leading detailed monitoring and reporting of the water quality, a one-off application of a modified clay product called Phoslock was made by CEH in 2010.
The treatment, and studies of how effective it is, form part of a £100,000 project running until 2012.
Since the application of Phoslock in 2009, CEH has found the water to be much cleaner with lower phosphorus concentrations.
Algae has been reduced by about two-thirds.
CEH said the longevity of the improvement remained uncertain and was at risk if there was further pollution of the loch.
But Dr Bryan Spears, lead CEH scientist on the project, said: "I am delighted that the local residents and interest groups have mobilised to continue scientific monitoring at Loch Flemington.
"The loch is an internationally important site for aquatic ecology and it is exciting to see the local community take active responsibility for its protection."
CEH is also involved in projects at Loch Leven, Clatto Reservoir, Kinghorn Loch and Coldingham Loch.
Croy Community Council, Scottish Natural Heritage, RSPB Scotland, the British Trust for Conservation Volunteers, Scottish Environment Protection Agency and the Scottish Agricultural College are partners in the Flemington restoration scheme.
Local people involved in the project include retired architect John Pottie.
He has lived by Loch Flemington for 35 years and one of his children can recall swimming in it before it became a health hazard.
Once a month, Mr Pottie paddles out onto the loch to carry out tests to aid Penicuick-based CEH's work.
He records its depth, how far down into the water he can make out a marker and takes water samples from the east and west ends of the loch and from the middle of it. Mr Pottie also notes the weather conditions at the time.
At home, he freezes some of the water samples and carries out tests on others to determine the water's PH and its electrical conductivity.
Other community volunteers cover areas of invasive non-native aquatic plants with black plastic sheeting to kill them off.
Canadian pondweed and New Zealand pigmyweed have been found in the loch and pose an added threat to its wildlife.
Sepa said it was pleased at the progress being made in tackling harmful nutrients.
Senior ecologist Ian Milne said: "This is a long-standing issue and early efforts to improve the loch stalled due to a lack of practical ways of dealing with it.
"It is exciting that this new methodology has become available, and is being applied to Loch Flemington.
"So far the signs that the loch is heading in the direction of ecological recovery are very promising."
Dr Noble agreed the treatment appeared to working.
He said: "But to use my GP experience, we need further work to see if the dose was right and we may need to give further doses to the 'patient' in the future.
"The loch has been much clearer with less algae this summer."
Dr Noble added that the restoration work could have world-wide importance.
He said: "Water is the key to all human life. We cannot do without water, but we take it for granted.
"There is tremendous interest in how we restore water that has either been polluted, or is in the process of being polluted, to make it clean and useable."