The industries under fire from the Scottish Environment Protection Agency (Sepa) said they were working hard to improve their “poor” pollution records.

The Scottish Environmental Services Association (Sesa), which represents the waste industry, stressed that members aimed to exceed minimum requirements and took their environmental responsibilities very seriously.

“The fact that the vast majority of member sites are in the upper compliance bands is a direct reflection of the effort and resources that are continually expended to secure compliance,” said Sesa policy advisor Stephen Freeland.

Scottish Water pointed out that, with 30,000 miles of sewer pipes and 1,800 waste water treatment works, it had more environmental permits than any other organisation in Scotland. “In recent years, we have continued to deliver significantly improved performance across all areas,” said the public company’s chief operating officer, Peter Farrer.

“The vast majority of our sites and networks in this assessment were classed as being either excellent or good. In the last five years, we have reduced the number of pollution incidents by 66 per cent.” A planned £500 million investment over six years would bring further improvements.

The Scottish Salmon Producers' Organisation pointed out that over 85 percent of fish farms were compliant. “Achieving and maintaining such high levels of compliance underpins the industry’s commitment to environmental sustainability,” said the organisation’s chief executive, Scott Landsburgh.

“We continue to work towards achieving compliance with all our sites and have dedicated plans in place to improve the small number of sites that aren’t quite there.”

Rosemary Gallagher, spokeswoman for the Scotch Whisky Association, said: “We are obviously disappointed if, on occasions, the highest possible standards aren’t achieved. The industry works closely with Sepa and other relevant organisations to ensure it goes above and beyond compliance requirements.”

BP said that it had suffered from “some minor non-compliances” at its Sullom Voe terminal in Shetland. “Regarding the Kinneil terminal [at Grangemouth], we are working closely with Sepa to agree a way forward,” said company spokesman, David Nicholas.

The Dounreay nuclear plant pointed out that most of its assessments by Sepa in 2014 had been “good” or “excellent”. It accepted that it had breached gas discharge limits for radioactive tritium, but stressed they were for a limited number of waste stacks, not for the site as a whole.

“To prevent re-occurrences we have undertaken a detailed review of the site’s arrangements for the sampling of authorised discharges,” said Dounreay’s assurance director, Jim Gray. Breaches of the water abstraction limits had not caused any environmental harm, he argued.

The industrial director at Tarmac, Dev Moody, was “extremely disappointed” that the Dunbar cement works had fallen short. “We have made a number of upgrades this year, which have improved our performance and we hope to return to the good environmental rating that we’ve achieved for many years,” he said.

Inverness Airport said it had only recently discovered that there were pollutants entering the waste disposal system from neighbouring areas. “We will continue to work with our neighbours and the regulator to improve this situation and work towards compliance with our licence,” said airport general manager Graeme Bell.

Norbord said that it had reported and rectified a problem with an internal combustion sensor in a boiler. “Sepa has now removed this permit condition and, as a direct result, the Cowie plant is now rated as good,” added company director Steve Roebuck.

The McVities biscuit factory in Glasgow did not respond to a request to comment.