South Yorkshire Police and various emergency services were at Ulley Reservoir near Rotherham on Friday afternoon after concerns for his safety.
The boy, whose name and age has not been disclosed, had got into difficulty in the water at the reservoir.
A brief statement from the force this afternoon said: "Emergency services currently have multiple resources on scene at Ulley Reservoir, Rotherham.
"At 3pm, police were called to concerns that a teenage boy had got into difficulty in the water.
"Numerous agencies have responded, and specialist search teams are doing everything they can to find him.
"The boy’s parents have been informed and are being supported by our officers. Please avoid the area while the teams carry out their work."
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