Emergency operation to save fish after algal bloom kills hundreds
A section of historic canal has been re-oxygenated after hundreds of fish died when levels of the gas in the water dropped.
About 500 roach and pike died in the Grand Western Canal following a natural algal bloom that grew during the recent heatwave causing a fall in the volume of oxygen.
Water was sprayed onto the surface of the 200-year-old canal near Sampford Peverell in West Devon in an effort to boost levels.
Devon County Council – which used spray bars to carry-out the work – is asking the public to report any further fish deaths.
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A spokesman said: "Several hundred small roach and a number of larger roach and pike died recently when oxygen levels in the canal dramatically declined.
"The problem was caused by a natural algal bloom that grew towards the end of the recent spell of hot and sunny weather.
"When the sunny spell ended and the weather turned cloudy, the algae stopped producing as much oxygen, but continued to deplete oxygen levels at night, leaving fish struggling to survive."
The Environment Agency was informed of the problem and sent a fisheries officer to assess the situation. It then gave the authority the equipment to do the work.
The steel bars are lengths of steel tube with holes, connected to a pump.
Water sprayed from the spray bars lands as mist on the water, helping to increase oxygen levels.
Agency spokesman Paul Gainey said: "We monitored oxygen levels in the canal and made Devon County Council aware of the problem.
"It was caused by dense vegetation growth and particularly the algae bloom during the hot, sunny weather.
"We advised the council to remove a large amount of weed, which they did. There was no indication of pollution."
The project comes several months after an embankment collapsed at nearby Halberton under the weight of water following a torrential rain storm.
More than 16 million litres of water – the equivalent of more than 100,000 bathtubs or 6.5 Olympic swimming pools – flowed through the 23-metre wide breach onto neighbouring farmland in November.
A £3 million restoration is underway to repair the affected area, and provide better protection against future overtopping.
The canal had its origins in various plans, going back to 1796, to link the Bristol Channel and the English Channel by a canal, bypassing Land's End.