Piles of litter have been left at an iconic pontoon leading to threats that it could be removed.
Footage of the mess at the Snowdonia, North Wales beauty spot has triggered an outpouring of outrage from those who've soaked in the magnificent view there before.
The heatwave led huge numbers of people to head to Llyn Padarn, near Llanberis to escape the sweltering temperature, the Daily Post reported.
Unfortunately many of them left their rubbish behind, including hundreds of drinks bottles discarded by the water's edge.
Picnic tables were left piled high and the car park was littered with cans and food wrappers.
So many people visited the area that a lake pontoon came close to capsizing under the weight of teenage swimmers, and now police patrols have since been stepped up at the site.
Kim Jones, Gwynedd councillor for Llanberis and Nant Peris, spent the morning with volunteers clearing up the rubbish in the lake's Glyn area.
Afterwards, she said she was “terribly disappointed” and warned that Gwynedd Council might remove the pontoon if litter problems persisted.
Reacting to videos of the rubbish, a Caernarfon woman wrote online: “Absolutely gutted to see this. Very easy to put rubbish in a bag, and put it in a bin.”
A heritage railway worked added: “What the h**l is wrong with people? I’d be ashamed to leave a mess like that.”
Campervan owners joined councillors and locals in clearing the rubbish up on Tuesday.
Some people suggested there were too few bins provided by the local authority and those that are available are not emptied when full.
“We still need more bins,” one person involved in the daily clear-ups said.
“And maybe a warden or someone from the council or a local volunteer to hand out bin bags – and to educate people about looking after these beautiful places.”
Volunteers from Snowdonia Watersports were also involved in the litter picking with Cllr Kim Jones.
Later, she posted photos on Facebook of full bin bags alongside wooden pallets that had also been discarded.
She wrote: “Terribly disappointed to see the area which is so special to us being treated like this.
"I will be discussing this with Gwynedd Council today and emphasizing that they must introduce controls here as a matter of urgency.
“Days like this spoil everything for those who use the Glyn sensibly for canoeing and swimming.
"I’m concerned that if this goes ahead, the council may consider taking the pontoon down completely in future. So please please share the message that it has to be used with respect.”
