To save money and cut red tape, the Scottish Environment Protection Agency (Sepa) is conducting fewer checks on businesses and has cut by more than one-quarter the samples it takes from rivers. The number of enforcement actions has also fallen 22% over the past two years.
Sepa says it is pursuing "better regulation" to more effectively target resources. Critics say it is trying to make the best of a bad job.
"Less regulation almost invariably leads to companies that pollute escaping detection," said Professor Andrew Watterson, head of the occupational and environmental health research group at the University of Stirling.
The mantra of "better regulation" was a euphemism for failing to properly protect the public, Watterson told the Sunday Herald.
According to Sepa, inspections of company sites fell from 9132 in 2010-2011 to 3718 in 2011-2012. The number of samples from rivers fell from 16,710 in 2009 to 12,410 in 2011.
In 2008-2009, Sepa initiated 352 enforcement actions. This compares to 240 in 2009-2010 and 273 in 2010-2011.
A financial report to Sepa's board last month revealed it was facing a budget deficit of £1.6 million next year, rising to £2.8m by 2016-2017.
Friends of the Earth Scotland urged ministers to properly fund Sepa as a matter of urgency.
Chief executive Stan Blackley said: "If they don't, they risk removing the bark and bite from Scotland's environment watchdog and giving serial and persistent polluters a get-out-of-jail-free card.
"Sepa will undoubtedly try to make better use of the limited resources it has, but reductions in the number of inspections made will most likely allow more companies to get away with polluting."
The agency has also come under attack for failing to crack down on the dumping of allegedly contaminated soil from the Edinburgh trams project on a landfill site.
Land remediation company Envirotreat Technologies has warned that Sepa was at risk of creating a "charter for fly-tipping". "Regulation has to be strong and impartial otherwise it is ineffective and open to criticism," said the company's technical director, Neil McLeod. "Unfortunately, the recent impression given by Sepa has been far from convincing. The Edinburgh trams situation is one such example."
Sepa said as investigations were continuing, it was not possible to comment on whether or not enforcement action would be taken.
Chief executive James Curran accepted one reason for cutting inspections and river monitoring was to save money but denied this would lead to poorer regulation.
He pointed out that the number of air sampling sites had increased by 26%, and that Sepa would be doubling assessments under its annual compliance scheme by 2014.
"Better regulation is smarter regulation," Curran said. "We think we are targeting resources much better, and delivering the outcomes that I think everyone in Scotland would want."
Badly performing plants would be inspected more often, while those that performed well would receive fewer visits. Monitoring would increase where risks were high, but be cut where they were low.
The Scottish Government insisted it had protected Sepa's budget as much as possible. A spokeswoman said: "We all need to consider opportunities for delivering outcomes in a better and more efficient way. Sepa's work to refocus some of its monitoring activity is to be commended."