Low-head dams have gained various nicknames over the years, including "the killer in our river" and "drowning machine", which isn't exactly encouraging. Generally, it's best to avoid them altogether. But what if that isn't possible when paddling on a river? This post takes you through different methods when approaching a low head dam in a kayak or canoe.

What is the purpose of a low-head dam?

A low head dam is a man-made structure, comprising of a perfectly uniform drop in a river. Filling the width of a river, they are designed to raise water levels, improve the quality of water supplies, and water irrigation.

However, they are also very dangerous to people on or in the water. It isn't just kayakers and canoeists who can find them deadly; swimmers are also in great danger if they find themselves approaching a low-head dam.

These dangers are made worse by the lack of visibility. It is difficult to spot a dam in a kayak, small boat, or by swimmers. Imagine an infinity swimming pool which appears to carry on - the same happens with a low-head dam.

Swimmers, kayakers and canoeists can find it very difficult to spot a low head dam

While the surface of the water appears to be calm, the physical part of a low head dam is several metres underwater. This means that they are often silent, so there's also no noise to give them away. Coupled with their silence, the refraction of light can make them appear shallower than they are, hence why they are so dangerous.

Most low head dams are manufactured, but some are natural - either way, they're deadly.

Even at low speeds, water flowing over the dam is enough to put kayaks and canoes into turbulent waters.

Why should you stay away from low head dams with paddle vessels?

If the low head dam description wasn't enough to explain the dangers of low head dams for paddlers, let's dig a little deeper to explain why you should avoid them.

1. They can be impossible to spot

When approaching a low head dam, they can be almost impossible to spot, because they are fully submerged.

When you're in a canoe or kayak, you don't have the elevation to see the disturbed water in the dam's wake that indicates its presence.

If you're in a canoe or kayak, you likely won't spot a low head dam until you're on top of it. Canoe seats have a slight advantage due to their higher elevation, and therefore better view. With kayakers sitting lower on the water, the situation is even worse.

2. They are often unmarked

Making the visibility situation worse, you also can't rely on low head dams to have warning signs.

They often don't have signage to indicate that one is coming up, and they're not always on maps either. This can also make your planning difficult.

The surface of the water doesn't provide many clues for kayakers.

3. The "boil"

The currents around low head dams can be easy to underestimate. If you also overestimate your own physical ability to overcome them, then you're putting yourself in a dangerous situation.

It's important to note that it isn't the low head dam's size that's the problem, but the destructive power of the currents. The forces caused by the water flow are so powerful that they suck in everything. That includes debris, people and boats. They get sucked over the dam and into the circulating current below - known as "the boil" - where you encounter high hydraulic forces and low buoyancy.

The forces caused by the water flow are so powerful that they suck in everything

This is a pretty scary combination of forces that could prove fatal to anyone unlucky enough to be trapped by the pressure of a low head dam.

4. Rescue is difficult (or impossible)

Due to the current, even if you do find your way to the surface, the force of the continuous water flow draws you back underwater and makes it nearly impossible to escape.

Whilst wearing a PFD is always recommended on your kayak or canoe, the turbulent water of a low head dam can generate enough water pressure to render your PFD ineffective.

If you do end up trapped in a low head dam, rescue is also extremely difficult if not impossible. Many rescue teams have ended up becoming victims themselves.

5. Floating debris

With higher rainfall, often comes debris in low head dams, including tree branches and other solid materials floating in the water.

As if it couldn't get much worse, you could find yourself being trapped and severely injured while trying to fight the currents at the same time.

How to avoid a low head dam

Given the above, we think you'll agree that the best course of action is to avoid low head dams altogether! But, if they're invisible and poorly marked, how are you meant to do that?

1. Check local waterways

While a low head dam won't always be marked on maps, planning your route is still your best line of defence to avoiding them.

Consider the following precautionary measures when paddling a new river:

• Take the time to plan your paddling journey and get to know the river.
• Get familiar with the area so you can gather information about the waterways.
• Speak with locals or the nearest paddling club. Local paddlers are often the best source of information about the river and might have life-saving tips.
• Do your own research with detailed waterway maps and guides as well, paying special attention for a low head dam on your route.
• If you become aware of a low head dam, avoid it. Adapt your route and, if that's not possible, traverse that area on foot instead.
• Make sure you don't rely just on warning signs, as they are not always marked. Keep an eye out for signs and potential indicators that there may be a low head dam ahead.

2. Keep your distance

If you still come across a low head dam in a canoe or kayak, despite your research, keep your distance.

Keep an eye out for the warning signs - the sooner you spot it, the more time you'll have to react while the waters are still relatively calm.

As long as you maintain a good space from the dam, you should be able to reach the nearest bank.

The safest course of action for any kayaker or canoeist is to reach the bank - the closer you get to a low head dam, the more difficult it becomes to steer yourself away. The currents will take over completely and draw you in.

Taking early action will mean you can be paddling back upstream away from the danger. Use your energy to paddle back upstream and reach the shore, rather than getting any closer.

3. Walk your kayak around the dam

If you need to, or want to, carry on kayaking along the same route, the only safe way to pass the dam is to portage around it, and avoid the situation altogether.

Paddle to the shore and portage your kayaks (walk around the dam) until you reach safe waters. Be extra careful though about having a big enough clearance from the dam. You may have to carry your kayak up to 30 metres to be extra safe.

This is because the "boil" can affect large areas around the dam - even at significant distances, the currents can be dangerous and it's best to avoid them entirely. Only put your kayak back in the water when you're sure that the danger has passed.

It might be annoying - carrying your boat - but it's better than being caught in the currents from the dam.

Summary

So, in summary, what should you do when approaching a low-head dam in a canoe or kayak?

Remember, there is no way to stay safe in a "drowning machine" when kayaking, so you must avoid the dangerous situation by paddling away to the shore.

Never underestimate the force of the current, and how it can pull you and your boat underwater. Don't go near it, as the hydraulic power of the current can pull your kayaks into the dam even at a distance.

Related information

• Are you looking for more information on kayaking safety? Read our guide to canoeing and kayaking safety
• Wanting to safely take your kids kayaking with you? Learn about kayaking with kids
• Trying to decide between a kayak and a canoe? Read about the difference