River Safety: Currents, Cold Water and Hidden Hazards

River swimming is riskier than it looks because the water is always moving. A current can knock you off your feet in shallow water, push you into fallen trees and rocks, and carry you far from where you got in, so wear a life jacket, never try to stand up in fast water, and stay out when the river is high after rain.

Rivers also hide their dangers. The surface can look smooth while the water underneath moves fast. This guide explains what to look for, what to do if the current takes you, and when to stay on the bank.

6 inches

Why moving water is different

In a lake or pool, you can stop and rest. In a river, the water keeps pushing, even when you're tired. The American Red Cross warns about fast-moving currents, waves and rapids, even in shallow water (opens in a new tab), and says to be careful when standing so the current doesn't knock you over (opens in a new tab).

A few facts from the National Park Service (NPS) help you read a river:

• The current is faster on the outside of a bend. NPS notes that river current is usually faster on the outside of a bend, and spirals down toward the bottom (opens in a new tab).
• Where streams meet, the water gets messy. NPS warns that where other streams join, there can be strong cross-currents, sandbars and debris (opens in a new tab).
• Rivers are cold. NPS lists cold water and hypothermia risk, even on warmer days (opens in a new tab), among river hazards. Cold water can make you gasp the moment you fall in. See cold water shock.

Because the water never stops, life jackets matter even more here. NPS advises: if you go swimming in a river, always wear your PFD (life jacket), even in calm water (opens in a new tab). CDC says children should wear life jackets for all activities in and around natural water (opens in a new tab).

Strainers, undercuts and debris

Some of the deadliest river hazards are ones you can barely see.

• Strainers. A strainer is anything that lets water flow through but stops a person: a fallen tree, a pile of branches, a fence or debris. The current can push you against it and hold you there. NPS warns: avoid strainers. Even in slow water, these can trap you and be the cause of a fatality (opens in a new tab).
• Undercut rocks and sieves. NPS lists undercut rocks, sieves and strainers (opens in a new tab) as river hazards. Water can flow under or between rocks where a body cannot.
• Hydraulics. Where water pours over a ledge or a dam, it can circle back on itself. NPS warns that recirculating currents can hold a person underwater (opens in a new tab). Low dams are a special danger: see low-head dams.
• Rocks under the surface. NPS explains that upstream V shapes on the surface point to rocks, and downstream V shapes with standing waves point to gaps between rocks (opens in a new tab).

The rule is simple: if you see a fallen tree or a pile of debris in the water, stay well upstream of it and away from the current that flows into it.

High water after rain

A river can change in hours. NPS says area streams rise rapidly to unsafe levels after moderate to heavy rains (opens in a new tab), and that water levels, streamflow and conditions can change quickly with weather and rainfall (opens in a new tab). CDC adds that local weather can change quickly and cause dangerous flash floods (opens in a new tab).

Before you go:

• Check the weather forecast for the whole day, not only the morning.
• Check river levels and flood warnings on NOAA's National Water Prediction Service (opens in a new tab) or the USGS National Water Dashboard (opens in a new tab). NPS notes that rivers are safer for beginners at or below average levels (opens in a new tab).
• Plan a way out. NPS advises always having a second escape route (opens in a new tab) from the river.

Never cross flooded ground on foot or by car. The National Weather Service says just 6 inches of fast-moving flood water can knock over an adult (opens in a new tab), 12 inches of rushing water can carry away most cars (opens in a new tab), and it is never safe to drive or walk into flood waters (opens in a new tab). For floods near home, see flash flood safety at home.

If you are swept away

Panic makes people stand up or swim straight against the current. Both can make things worse. Use the NPS method instead:

1. Roll onto your back. NPS teaches "bottoms down": float on your back with your bottom down and feet up, facing downstream (opens in a new tab).
2. Keep your feet up and together. NPS advises: keep your toes up and your feet together, pointed downstream. Never try to stand up in fast water unless it is too shallow for swimming (opens in a new tab). Your feet, not your head, will meet any rocks.
3. Look downstream. Watch for strainers and steer away from them.
4. Head for shore. When the water slows, or you're past the hazard, swim to the nearest bank.
5. Let the gear go. NPS says don't take chances saving equipment (opens in a new tab). A cooler or a tube can be replaced.

Practice this position in calm water with a life jacket on, so your body knows it before you need it.

Wading, tubing and crossing

Most river trips don't start as swims. People wade to cool off, cross to the other bank or float down on a tube. These tips cover the common cases.

Wading. Wear a life jacket in moving water. NPS advises wearing a personal flotation device if you're in moving water (opens in a new tab) and closed-toe footwear, stepping carefully into and out of the water (opens in a new tab). Go in feet first: the Red Cross says to always enter unknown or shallow water feet first (opens in a new tab).

Crossing. Fast water doesn't need to be deep to knock you over. Remember the warning about 6 inches of fast-moving flood water above. If the current is strong, don't try to cross on foot. Look for a bridge or turn back, and never cross a flooded road or trail.

Tubing and floating. Wear your life jacket, buckled, the whole time you're on the water. Before you start, NPS suggests you file a float plan with a friend or loved one (opens in a new tab) and know your put-in and take-out points (opens in a new tab). Stay sober: CDC says to avoid drinking alcohol before or during swimming, boating or other water activities (opens in a new tab).

Kids at the river. Keep young children within arm's reach and in life jackets, even at the edge. A child who slips on a rock can be in the current in a second. For paddling trips, see kayak and canoe safety.

If someone else is in trouble

Moving water is dangerous for rescuers too. Virginia's wildlife agency says that near hydraulics, rescuing trapped individuals is dangerous and often unsuccessful (opens in a new tab), and that a rescuer should throw a line from shore (opens in a new tab). Learn the basics in reach or throw, don't go.

What you can do today

• Bookmark a river-level site, such as NOAA's National Water Prediction Service (opens in a new tab), and check it before your next trip.
• Make sure every child, and every adult who isn't a strong swimmer, has a life jacket that fits.
• Teach your family the "feet up, facing downstream" position and practice it in calm water.
• Agree on a family rule: no wading or swimming after heavy rain, and never in flood water.
• Print the open-water checklist for your river bag.

For calmer water, see lake swimming safety, and for creeks on a hike, see swimming holes, creeks and waterfalls.