Police are urging people not to risk swimming in local rivers after youths were reportedly swimming in River Witham in the Boultham area on August 13.
PCSO Matt Flack said: “These people were swimming very close to the sluice gates (pictured), and if these gates had been open, or opening whilst they were in the water, they could easily have been sucked in.”
He added: “If people have been inspired to take to the water by the Olympics, or just need to cool off during a hot spell, then use one of the many public pool facilities in the county.
“Swimming in rivers could result in injury or death and is just not worth the risk.”
Police have received a number of reports from concerned residents who have spotted people swimming in Lincoln’s rivers during the summer.
Officers said public rivers are not safe places to swim, as it’s easy to misjudge the depth and flow of the water, and there can be unseen hazards under the water too.