ANNAPOLIS, Md. — As spring temperatures rise and Marylanders flock to the Chesapeake Bay, Atlantic Ocean, and the state’s rivers and lakes, the Maryland Department of Natural Resources (DNR) is issuing a critical reminder about the dangers of cold water.
Despite warming air, water temperatures in most Maryland waterways remain below 70 degrees—classified as cold by the National Weather Service (NWS)—posing significant risks of cold shock, physical incapacitation, and hypothermia for anglers, boaters, and paddlers.
Cold Water Dangers and Survival Strategies
Cold water, defined as 70 degrees or lower, can trigger life-threatening conditions even in spring. The Chesapeake Bay, for instance, averages 55 degrees in March, per NOAA data, while the Potomac River near Charles County hovers around 50 degrees. Warm air creates a false sense of security, but immersion in cold water can lead to cold shock within 1-3 minutes, causing involuntary gasping, rapid breathing, or hyperventilation, which may result in drowning if water is inhaled. One in five cold water deaths occurs within the first minute, with cold shock possible in water as warm as 77 degrees, according to the NWS.
After 10-30 minutes, physical incapacitation sets in, impairing muscle control and making it difficult to tread water or move extremities, even for strong swimmers. Without a life jacket, this can be fatal. Prolonged exposure leads to hypothermia, with core body temperatures dropping below 95 degrees, causing cognitive decline and unconsciousness. Even after rescue, core temperatures may continue to fall until the victim is in a warm, dry environment.
The 1-10-1 rule outlines survival stages: one minute to control breathing, 10 minutes of viable muscle control for self-rescue, and one hour before hypothermia-induced unconsciousness. Survival hinges on preparedness, such as wearing life jackets, wetsuits, dry suits, or survival suits.
Maryland law requires children under 13 to wear life jackets on boats under 21 feet while underway, and all recreational vessels—including kayaks and paddleboards—must have one personal flotation device (PFD) per person. Techniques like the Heat Escape Lessening Posture (H.E.L.P.), where individuals draw knees to chest and cross arms, and the huddle position for groups, help preserve body heat.
