Visitors to Stanley Reservoir are being urged to take care around the water and look after the environment.
The warning comes from Scottish Water which says anti-social behaviour around the Glenburn site was a major problem last summer.
It has also ordered people to stay out of the water following a number of tragic deaths on Scottish water ways.
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Expecting a high number of visitors this year as more people holiday in Scotland, the national authority says it will not tolerate vandalism or loutish behaviour.
Across its reservoirs in 2020, Scottish Water says it saw damage caused to trees, fires being lit and left unattended, littering, tents discarded, human waste left and vehicles parked inconsiderately.
The Express revealed last August how litter specifically was a major problem at Stanley Park with volunteers collecting over 100 bags of rubbish from the beauty spot.
Team Up to Clean up helpers also retrieved rubbish from the water using kayaks.

Peter Farrer, chief operating officer at Scottish Water, pictured, said: “We anticipate that, because of the easing of lockdown restrictions and the advice about not travelling abroad, many people will be planning to holiday in Scotland and will understandably want to enjoy the outdoors at some of our scenic reservoirs.
“We ask people to act responsibly and respect our reservoirs – enjoy the setting but leave no trace behind.
“They can do this by planning and preparing for their visit. They should consider other people and services including ensuring cars are parked safely and do no obstruct either our working vehicles or the emergency services.”
Also urging people not to enter the water, Mr Farrer warned people of the dangers of open water following the deaths of two teenagers in Scotland in the past two months.
William McNally from Linwood, died last month after getting into difficulty in the River Gryffe while swimming with friends.
Mr Farrer said: “We are also urging people to stay safe.
“There are many hidden dangers in reservoirs which are working assets. Water temperatures can also cause shock and result in someone getting into difficulty.”
Scottish Water is urging people to look at the Scottish Outdoor Access Code before travelling to one of their sites. It offers tips on how to treat the environment and remain safe while in open spaces.
For more information see https://www.outdooraccess-scotland.scot/