A group of people jump into the Clackamas River at High Rocks Park to stay cool in Gladstone, Ore., July 15, 2025.
Morgan Barnaby / OPB
During extreme heat, many Oregonians will seek relief in local swimming holes. But officials are warning that while the air may be hot, the water often isn’t — and dangerously cold water can still pose serious risks even in the middle of summer.
High air temperatures don’t necessarily translate to warm water, especially in natural bodies like rivers and streams which are typically fed by melting snowpacks.
According to the National Weather Service, unsuspecting swimmers can be caught off guard by cold water temperatures and experience “cold shock” — an involuntary reaction to sudden immersion in cold water that causes the body to gasp for air and accidentally inhale water.
Cold water can drain body temperature 25 times faster than cold air putting even strong and experienced swimmers at risk for cold shock and hypothermia.
Swimmers can stay safe and cool this summer by:
- Wearing a properly fitted lifejacket.
- Swimming sober.
- Being aware of submerged hazards like rocks, debris and branches.
- Swimming during daylight hours — never in the dark.
- Avoiding cold shock by gradually entering cold water rather than jumping or diving right in.
It is also vital for people to stay hydrated while they are swimming, said American Medical Response Lifeguard Andrew Evans — who patrols the High Rocks swimming site along the Clackamas River in Gladstone.
“I would say if you are going to go outside recreating in the hot temperatures make sure you’re properly hydrated, you can’t have too much water,” said Evans. “Maybe bring some electrolytes if you’re going to be out working hard all day, bring an umbrella, bring a sun hat [and] wear sunscreen.”
Related: Check out OPB's extreme heat resource center
Other safety tips to follow include never swimming alone.
Rick Graves, a spokesperson with Portland Fire & Rescue, encourages people to always swim with a partner and to take extra precautions with kids in the water.
“Never take your eyes off the water,” Graves said. “ Put your phone away.”
Water Safety Public Service Announcement☀ The summer heat and swim season are here! While many of us can't wait to get in the water to cool off in beautiful natural waterways and streams, a reminder that even calm waters can hide dangers. As Multnomah County Health Department Richard Bruno and Portland Fire & Rescue Rick Graves remind us, always wear a life jacket and watch children around water to ensure their safety. Children should only go into the water with: ➡️ Adult permission ➡️ With a properly fitted children’s life jacket. Remember: Water wings (and floaties) are not life jackets! You can find a map of beaches with loaner jackets and tips on how to select the right life jacket at: multco.us/info/swim-and-splash-safely or multco.us/hot. w - City of Portland, OR, Multnomah County Health Department, Portland Bureau of Emergency Management, Multnomah County Department of County Human Services SPANISH ¡Llegó el calor del verano y la temporada de nadar! Muchos de nosotros estamos ansiosos por meternos en el agua para refrescarnos en hermosos ríos y arroyos naturales. Esto es un recordatorio que incluso las aguas tranquilas pueden esconder peligros. Como nos recuerda el Dr. Richard Bruno, oficial de salud del condado de Multnomah, y el ex salvavidas/bombero de Portland, Rick Graves, siempre use un chaleco salvavidas y vigile a los niños cerca del agua para garantizar su seguridad. Los niños solo deben entrar al agua con: ➡️ Permiso de un adulto ➡️ Con un chaleco salvavidas infantil bien ajustado. Recuerda: ¡Los flotadores no son chalecos salvavidas! Puede encontrar un mapa de playas con chalecos salvavidas de préstamo y consejos sobre cómo seleccionar el chaleco salvavidas adecuado en: bit.ly/4lMMRYe
Posted by Multnomah County, Oregon on Friday, July 11, 2025
If someone is experiencing a health emergency related to cold water exposure, officials recommend moving them to a warm area, immediately contacting 911 and removing wet clothing.
Swimmers should also be on the look out for toxic algal blooms, which pose health risks to both humans and pets.
Warnings signs include:
- Changing colors including red, dark green, blue and brown.
- Density such as thick or chunky water.
- Clarity such as cloudy or hazy water.
- Unpleasant smells.
If the water looks or smells suspicious, stay away.
