Over 2,000 swimmers and would-be bathers were caught risking their lives during reservoir patrols mounted by Bradford-based Yorkshire Water.
Between July 11 and 28, the water company's teams monitored 14 reservoirs and caught 2,300 people taking a swim – or preparing to do so.
Shockingly, that figure included a number of "young, unaccompanied children", Yorkshire Water revealed.
Over 250 of the incidents happened at a reservoir in a rural corner of the Bradford district where a man drowned earlier this summer.
Yorkshire Water says that, during the 18-day period, 265 incidents were recorded at Ponden Reservoir near Stanbury, west of Haworth.
In June, a 27-year-old man from Blackpool – Alan Rasoul – died after getting into difficulties at the reservoir.
And in recent weeks there have been a number of other drowning tragedies at open water sites across the region.
Gaynor Craigie, head of land and property at Yorkshire Water, said: “Tragically we have seen a number of people lose their lives in open water in our region in recent weeks, following on from four fatalities earlier in the year.
“Our sites have seen a dramatic increase in people swimming, particularly during the recent warm weather, with our teams speaking to more than 2,300 people – including young, unaccompanied children – at just a handful of our sites between 11 and 28 July. We know the true number of people entering reservoirs across the region will be much greater and we would urge people not to take risks by getting into reservoirs for any reason.
“There are several dangers associated with open water at reservoirs, which are often underestimated. These include cold water shock, unseen objects, the hazards of operational machinery and underwater currents.”
The patrols have been extended to a 15th reservoir, although Ponden remains the only one being monitored in the Bradford district. Yorkshire Water is holding discussions with a range of organisations responsible for watercourses, as well as the emergency services and open water swimming groups, to work together to further warn of the dangers. And awareness-raising sessions have been held with schools.
Councillor Rebecca Poulsen, whose Worth Valley ward includes Ponden, echoed the call for people to stay out of the water.
“Places like the reservoir in beautiful locations look enticing on warm sunny days but people can’t see the hidden dangers,” she says.
“The water can be extremely cold – even on very hot days – and there are dangerous currents.
“Signage warning people not to swim has been improved at the site and Yorkshire Water is working with other organisations and schools to try to get the message across.”
An inquest opened in late June hear that Mr Rasoul, born in Kurdistan. was on his way home with a companion when he stopped off for a dip in Ponden Reservoir. The coroner outlined that Mr Rasoul was pronounced dead at 10.18pm on June 15 at Ponden Reservoir. The coroner's court heard that a post-mortem by a Dr Knight confirmed that Mr Rasoul died by drowning.