Drowning Series Part 2: The Science of Lake Currents
Powerful currents on the Great Lakes have caused more than 150 drownings since 2002, according to researchers. Those currents can appear suddenly, says Mark Breederland, an educator with Michigan Sea Grant.
“The wind is key. It can start up pretty calm. Pretty soon it picks up – you’re out there, just enjoying the beach and you’re not really thinking about it,” Breederland says. Michigan Sea Grant is a university program focused on preserving Great Lakes resources through education and research. “All of the sudden, the waves have come way up from what they were when you first started.”
When a drowning occurs, people often attribute it to an undertow. Scientists say it’s much more complicated than that.
There are three main types of deadly currents in the Great Lakes. First, there are structural currents which run along piers or break walls.
“Depending on the angle coming in and what direction the waves are pushing you, that could be a very dangerous area,” Breederland says.
Those currents develop because a lot of structures throughout the Great Lakes are solid all the way to the lake bottom. In the ocean, many piers are supported by big stilts, allowing water to move underneath.
Powerful currents can also develop in open water.
“The waves can actually come along the shore and form longshore currents that go up and down the lakeshore,” Breederland explains. “They can break through a sandbar, and actually come back with a wave return – in a sense, being a rip. It could actually knock you off your feet.”
That’s not all there is to worry about. A seiche is the Great Lakes version of a tidal wave. Imagine a lake as a giant bathtub, with strong winds pushing water back and forth, gathering strength.
In 1844, a 14-foot seiche on Lake Erie resulted in the deaths of 78 people. And in 2003, a seiche in Lake Michigan resulted in a deadly 4th of July, according to National Weather Service meteorologist Megan Dodson.
“People thought it was safe to go back into the water because the waves weren’t that high. They were only two to three feet,” Dodson says. “Since we had that additional factor of the water fluctuating, they went into the water and there were rip currents and they were really strong, and we lost seven people in a five-hour period.”
Dodson maintains a life-and-death count of the currents’ impact. It’s called the Great Lakes Dangerous Currents database.
Since 2002, there have been some 480 recorded incidents – fatalities or rescues – caused by a current. The database helps Dodson find patterns and better predict when currents are likely. Based on those conditions, the National Weather Service sets beach forecasts for all five of the Great Lakes.
But there are limitations, beginning with how Dodson gets her information.
“We’ll look through the media articles and say ‘Okay – was it a rescue or fatality? If so, is it related to currents?’” she says.
Dodson relies on news reports because there isn’t an official government reporting system in place to track these incidents. She acknowledges the database may undercount the number of drownings.
The database started in 1998 after 12-year old Travis Brown died. He got caught in a rip current on Lake Michigan.
“Prior to that incident, people didn’t really think that rip currents could really happen on the Great Lakes,” Dodson says.
According to the database, there have been fewer current-related drownings in recent years. That may be due to better education about dangerous waves – or simply to colder summers. Dodson notes that because of the warm summer this year, it may be difficult to sustain the trend.
For more information, visit Michigan Sea Grant and NOAA's website on Dangerous Currents .