Shropshire Council issued the warning this afternoon as river levels remained high throughout the county with more than a dozen flood alerts in place.
On Saturday afternoon the authority tweeted: "We've had reports of some young people going into flood waters.
"Flood waters can be dangerous, fast flowing, conceal dangerous debris and may be contaminated with waste.
"If you see anyone entering flood water please report this to 101. If there's threat to life call 999."
The message comes after youths were accused of tampering with a flood defence pump set up to protect homes in Shrewsbury.
A Shropshire Fire and Rescue Service spokesperson said the pump in Coleham Head began leaking as a result.
Firefighters were called at around 10pm on Thursday but were unable to fix the issue, so Severn Trent Water engineers had to attend.