Lightning in the Boundary Waters

     Friends and I were out picking blueberries in the afternoon sun one day. We had our hearts set on taking a swim when we were finished but a dark cloud was moving in on us quickly. Soon it started to rain yet we still longed for a quick dip in the river.  Floating in the water we saw a flash of lightning in the sky. We all knew the water probably wasn’t the safest place to be during a lightning storm so we didn’t swim long. Of course the conversation of just how dangerous it is to swim during a lightning storm came up so I had to look into it.  As I thought you’re safer swimming than in a boat or a canoe and you never want to be the highest point anywhere.

From the web…

The chances you’ll actually be struck by lightning while swimming are in fact fairly trivial compared to your chances of meeting dozens of other fates. Over the course of a lifetime, you’re much likelier to be killed (for instance) in a fall.

That said, you can see why most people tend to err on the cautious side in this area. A lightning strike certainly can cause a lot of electric current to pass through water – not for miles and miles, but shorter distances, sure. Responding to a question sent to USA Today about whether it’s safer to swim in salt or fresh water during a lightning storm, Greg Forbes of the Weather Channel chose the correct answer (none of the above), then cautioned, "The lightning current may spread out in all directions and dissipate within 20 feet or so, but don’t bet your life on how close the strike will be."

And swimmers do, in fact, sometimes get struck by lightning. In 2005, for instance, three people were struck while swimming in the ocean near Tampa, and four more were hit (two of them seriously injured) in waters off Chiba Prefecture, Japan. Swimming pools aren’t necessarily safer. In July 2006 a 50-year-old Briton was dangling his feet in the pool at a rented villa in Italy when lightning struck the water, killing him and injuring a friend. In fact, experts recommend staying out of indoor pools during an electrical storm, as well as showers and tubs, as current from lightning has been known to travel through plumbing.

As you guessed, a big part of the risk here has to do with lightning’s tendency to strike the highest point around – i.e., you don’t want this to be your head. Being on an open boat in a lightning storm is probably even more dangerous than swimming, suggests Mary Ann Cooper of the University of Illinois Lightning Injury Research Program, as "increasing your height by any amount increases your chances of being hit by a calculable amount. … Avoid being the highest object anywhere, be it a beach, small open boat, pier, meadow, or ridge." According to the National Weather Service,

The vast majority of lightning injuries and deaths on boats occur on small boats with NO cabin. It is crucial to listen to the weather on a small aquatic vessel without a cabin. If thunderstorms are forecast, don’t go out. If you are out on the water and skies are threatening, get back to land and find a safe building or vehicle.

The NWS goes on to say that boats with cabins are safer, particularly if they’ve been fitted with lightning protection, but one should avoid using the radio in a storm unless there’s an emergency.

Looking at government data (.pdf) collected between 1959 and 2005, we see that incidents involving boats and water account for 13 percent of all lightning fatalities nationwide (among cases where circumstances are known), coming in behind instances where victims were out in the open (28 percent) or under a tree (17 percent). In Florida, which ranks first among the states in lightning casualties, boating and other water-related incidents make up 25 percent of lightning deaths.

Why don’t fish get killed by lightning strikes? Well, actually, they do. I’d suggest you check out a 1941 article in Copeia (a scientific journal about fishes, amphibians, and reptiles) called "Mortality at Fish Hatchery Caused by Lightning," but really the title pretty much says it all. A 2005 episode of NOVA documents an instance of fish in a koi pond being injured by lightning; my guess would be that fish electrocution by lightning is a pretty underreported phenomenon. But fish typically don’t get killed in large quantities by lightning because, as you guessed once again, they tend to swim deeper than humans do, while according to Florida physics professor Joseph Dwyer "most of the current from the lightning flows over the surface of the water."

Canoeists send out distress signal after lightning strike in Manitoba

BLOODVEIN, Man. – An Ontario woman is recovering from injuries after she was struck by lightning while canoeing with six other people in Manitoba’s wilderness.

RCMP say a group of women and girls were on an organized camp trip and were paddling along the Bloodvein River near Lake Winnipeg on Sunday when a sudden storm approached. They were going to shore when the 23-year-old woman was hit by lightning.

A 15-year-old girl, who was helping the woman pull their canoe to shore, also felt a jolt, said RCMP spokeswoman Sgt. Line Karpish. She "got a pretty good shock" but wasn’t injured.

Karpish said the group was well-equipped and managed to send out a GPS distress signal from a safety device. An emergency response co-ordination centre in Houston, Texas, then contacted the RCMP.

Mounties initially asked for help from the military’s rescue centre in Trenton, Ont. But officers quickly tracked down an available Manitoba government helicopter. Its pilot was eager to help.

Two officers jumped on board and the search chopper quickly found the canoeists, just before nightfall.

The group was waving frantically at the helicopter when it arrived, about two hours after the SOS went out.

The pilot was able to land in a nearby clearing and the woman was taken to a nearby nursing station. Karpish said she was then air-lifted to a Winnipeg hospital as a precaution.

"She’s lucky, very lucky."

The girl remained with the group.

"She felt she was not hurt and wanted to carry on with the trip. By all appearances, she seemed just fine."

Karpish said such remote rescues don’t always have happy endings. Several factors, including the group’s GPS device and the available helicopter, fortunately came together.

"This was bang-on the best case scenario we could ever ask for. Sometimes everything goes wrong but sometimes everything goes right."

It is the first public report of any injuries due to the thunderstorms that swept through Manitoba on Sunday.