More than 300 industrial sites across Scotland - including a host of well-known names - have been named and shamed by the government’s green watchdog for their “poor” or “very poor” performance on pollution, the Sunday Herald can reveal.

The Scottish Environment Protection Agency (Sepa) has condemned 371 plants for leaks, spills, bad smells, permit breaches and a series of other equipment and management failures. The pollution record of companies in 2014 was significantly worse than in 2013, latest figures show, and Sepa missed its compliance target as a result.

Among those outed by Sepa for failing to control contamination are the oil giant BP at Grangemouth, the Dounreay nuclear plant in Caithness, the Tarmac cement works near Dunbar, and Inverness airport. Repeat offenders included the McVities biscuit factory in Glasgow and the wood plant run by Norbord at Cowie near Stirling.

The largest group of failures were 113 waste and recycling facilities, including landfill sites, metal scrapyards and waste handling stations. Other major industries classed as poor were 50 public sewage works, 42 fish farms, nine food plants, seven whisky distilleries, six golf courses, four crematoria and four coal mines.

Though most of the polluters are identified, suppliers of water and those handling radioactive substances have been kept secret. “Details of their locations and ownership are undisclosed for reasons of national security,” said Sepa.

In its latest “compliance assessment” scores for 2014, Sepa has rated 59 sites as “very poor” and 312 as “poor”. This is two per cent worse than in 2013, it says, and means that it has failed to meet its target of an overall compliance rate of 91 per cent.

Firms have come under fierce attack for their poor record, with critics demanding that Sepa crack down on serial polluters. Operators have, however, defended themselves by highlighting the efforts they are making to improve their performances.

“It's a sad state of affairs that companies in Scotland are getting worse rather than better at tackling pollution,” said Mary Church, head of campaigns at the environmental group, Friends of the Earth Scotland.

“Sepa needs to use the full force of the law to deal with this sorry catalogue of incompetents and chancers and rapidly improve these poor figures.”

It was high time the waste industry stopped getting away with being “rubbish”, she argued. “Perhaps most galling is the long list of food firms, distilleries, breweries, fish farms and golf courses who all trade on Scotland’s reputation for a clean environment but don’t seem to mind trashing their bit of it.”

The Green MSP, Alison Johnstone, demanded that no breaks were given to polluting companies. “The rise in the number of bad polluters shows how little regard some companies still have for their environmental responsibilities, and how urgently we need to implement tougher regulation,” she said.

“We're not talking about harmless hiccups here. Too many operators keep breaching pollution limits year after year with full knowledge of the consequences of their actions.”

Sepa criticised BP’s Kinneil terminal at Grangemouth for “permit breaches concerning the availability of ground flare equipment and maintenance of a drain.” The plant’s rating was improved from “very poor” to “poor” on Friday after an appeal by BP and an inquiry by the Sunday Herald.

The Dounreay nuclear plant on the north coast leaked radioactive tritium gas from waste stacks in breach of authorised limits. It also exceeded its allowance for the amount of water it could extract from radioactive waste vaults six times.

The quarry and cement works run by Tarmac on the East Lothian coast suffered “several breaches of permit conditions,” according to Sepa. These resulted in “dust fallout” and involved blockages, holes in pipes and other equipment faults.

Inverness airport was lambasted as “very poor”. It had failed “to implement an operating and monitoring regime that will allow them to ensure that the licence limits can be complied with,” said Sepa.

The McVities biscuit factory in Glasgow was rated as poor in both 2013 and 2014. “Site is currently not achieving the discharge standards required by the water use licence,” reported Sepa.

The Norbord plant in Cowie has been rated either poor or very poor for four of the last five years. “Continuous monitoring results have breached permit conditions limits,” said Sepa.

One of the whisky distilleries that have broken environmental rules is Ardmore near Huntly on Speyside, which has been rated as poor for the last three years. It is a sponsor of the prestigious ‘Nature of Scotland’ awards run by the Royal Society for the Protection of Birds in Edinburgh later this month.

The Glenlivet distillery at Ballindalloch on Speyside was classed as poor in 2014 due to “multiple failures of effluent discharge standards”. Others were criticised for taking more water than permitted.

Three of the crematoria that failed on pollution breaches were run by local authorities: Daldowie and Linn in Glasgow, and Mortonhall in Edinburgh. A pet crematorium at Larkhall in South Lanarkshire was also labelled as poor.

An angling group anxious about the pollution caused by fish farms criticised Sepa for not doing enough. “The simple question for Sepa is this: where were you when these farms were performing so badly?” said the solicitor for Salmon and Trout Conservation Scotland, Guy Linley-Adams.

“Salmon and Trout Conservation Scotland believes that the Scottish Government is so in thrall to the fish-farming industry that Sepa has effectively had its teeth pulled.”

Sepa’s executive director, Calum MacDonald, admitted that he was “disappointed” at his agency’s failure to meet its compliance target, but defended Sepa’s overall performance. Of the 5,305 sites assessed in 2014, 73 per cent were rated as excellent and 14 per cent as good, he pointed out.

“Compliance is good and getting better, but we are not complacent and are taking a range of actions to improve the situation further. Non-compliance is not an option and several initiatives are currently ongoing which aim to drive up compliance across each sector where ratings have been less than satisfactory.”

He added: “These include revising our compliance assessment scheme so it can provide more timely information, a revised regulatory monitoring strategy which will provide additional compliance evidence, and new enforcement powers recently approved by the Scottish Parliament which include the capability to impose financial penalties.”