Yesterday, Paul Rickett shared pictures on social media which showed several people who had climbed over the edge of the reservoir to sit and relax on the sloped sides, while others had gained access to the top of a water tower - which water sports users are generally advised to stay at least 50 metres away from.
He said that other people had been spotted on inflatables in the reservoir, and some had been verbally abusive when approached.
Mr Rickett’s message on social media said: “Please please please, if this is one your kids or mates or anyone you know who going up there, can you warn them of the dangers of going [into the reservoir].
“That tower houses three huge pumps that come on automatically and you wont swim out of the current. Added to that the water is 13°C colder than the North Sea.
“Mix that with alcohol, and its makes a big difference. The sides are very steep and slippery making it very hard to get out.
“We are only looking out for your safety. The last thing we want up there is an injury or fatality.”
Mr Rickett - who serves as a district councillor for the neighbouring ward of Marshchapel & Somercotes - later told the Leader that the same group of people have been seen visiting the reservoir several times in recent weeks, and some had left behind litter and interfered with private property such as sailing boats.
However, he added that the overriding concern was the safety of those who were choosing to enter the water, or going dangerous close to the edge.
He said: “The surface may seem warm, but the water can be very cold in the early summer. What we don’t want is to have a body in there.”