Rogue dumpers are in the firing line after a fuel spillage at an Angus beauty spot.
Dog walkers were warned to steer clear on Thursday following the discovery of diesel in a burn near Kirkton Industrial Estate in Arbroath.
Sepa and Scottish Water were scrambled to investigate after the alarm was raised at the burn which is used by a range of wildlife including otters.
It’s feared the water was deliberately contaminated by dumpers to avoid disposal costs.
The alert comes after litter crusaders warned Angus is being turned into a “giant rubbish tip” as a result of rising levels of fly-tipping and littering.
Recent high-profile dumping incidents include a one-tonne bag of hazardous asbestos that was found at Monikie.
Arbroath East and Lunan SNP Councillor Brenda Durno said the diesel spill was a “deeply concerning incident that could ultimately have a serious negative impact on the environment”.
She said: “I think a key question here is whether this is an accidental spill or leak, or whether the diesel has been deliberately dumped into the drainage system.
“If it is the latter, I will be urging that every effort is made to bring the culprits to justice.
“I know that there is significant concern about the length of time it has taken to get personnel to the scene, and I will be asking for an update on what was done and when by the responsible organisations.”
The watercourse runs alongside a popular dog walking route. There are also fears that contaminated water could poison horses further down-stream.
Ralph Coutts of the St Vigeans Conservation Network said: “There was a visible sheen on the water, accompanied by a strong smell.
“Subsequent visits at 4pm on Wednesday, and mid-morning on Thursday, established that the water remained contaminated.
“We have done so much to improve the area for wildlife, and we know that otters pass very close to the point where the water is contaminated.
“There are also small fish in the water, so it is extremely worrying that this has happened.”
The diesel spill happened in the wake of an investigation by Angus Clean Environments (ACE) which warned the level of dumping and littering could have a negative impact on wildlife and visitors to the region.
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The Angus pressure group was established after Arbroath hosted the first community-led litter summit in Scotland in November 2017.
Sepa and Scottish Water confirmed they were investigating the diesel spill.
A spokesman for Scottish Water said: “Following a report of pollution with an oily appearance affecting a burn close to the Kirkton Industrial Estate in Arbroath, our local sewer response team attended and inspected manholes in the area to look for any sign of oil in the surface water sewers that drain the area.
“No sign of oil pollution was found within the surface water sewers and we have fed this information back to Sepa. We will continue to work with Sepa to investigate this incident and ensure any source of pollution that can be identified is addressed appropriately.”
A Sepa spokesman said: “Sepa officers received a complaint of diesel-like odours and an oily sheen in a tributary of the Hercules Den Burn in Arbroath. An investigation is currently ongoing to identify the source.
“We would like to take this opportunity to thank the members of the public who brought this to our attention, and to encourage anyone who is concerned about potential pollution to contact Sepa as soon as possible.”
The agency’s 24-hour pollution hotline is on 0800 80 70 60. Concerns can also be reported online at www.sepa.org.uk/report.