FRESNO COUNTY, Calif. (KSEE/KGPE) – While the Central Valley deals with extreme heat this week, local officials warn residents about the dangers of swimming in unsupervised areas.

“I mean, just don’t. That’s the bottom line. You can’t get into that water and just get out of there,” said Shane Brown from the Fresno Fire Department.

Brown has spent the last few days training firefighters for water rescue missions. He says during the training, they were called to multiple water rescues, as more people try to find relief from the summer heat – often underestimating the power of the water.

“They had the drowning at the Avocado Lake, the ponding basin, two from the canal… If you jump in the rivers around here, within one hour, you can expect to be approaching death. The hypothermic reaction happens instantaneously,” he said.

On Monday, the Fresno County Sheriff’s Office dive team recovered the body of 34-year-old Jose Carrillo, who drowned in a ponding basin at Conejo and West avenues.

Officials say he became tired and unable to swim any further. Sheriff’s Office spokesperson Tony Botti reminded people of the dangers of swimming in undesignated areas.

“This is not a place to go swimming. You only swim in designated areas. Canals and ponding basins are not those places,” he said.

Brown said while ponds don’t have fast-moving water like rivers and canals, the water temperature is much colder than most people expect, and people’s feet can get stuck on the bottom

“The ground below it is so soft – it’s that mud that feels like quicksand – and then people start to struggle, and the more you struggle the more you get tired in the water, then you start really cold, hypothermia sets in,” he said.

Brown reminds people to always wear a lifejacket even if you believe you are a good swimmer, always tell someone where you are going, and know your limits in the water.