There’s something strange happening in one of the Great Lakes. The waters are changing color, turning from their usual blue to a strange, ethereal green. Sure, it might look beautiful, but the cause of the new hue is actually something to be really concerned about. And it may well be getting worse.
When it comes to surface area, Lake Erie is the fourth biggest of the five Great Lakes. In global terms, it’s the 11th biggest lake in the world, covering an area of nearly 10,000 square miles. At its longest point the lake stretches way over 200 miles, and at its widest it’s nearly 60 miles from shore to shore.
And while it might not have the depth or volume of the other Great Lakes, it’s still an enormous stretch of water. But the lake has had something of a troubled history. And this most recent episode in its turbulent life has scientists understandably worried. However, it’s not just the researchers who are fretting about the impact of the change in colour of the water.
A report in Time from the 1970s claimed that Lake Erie was so polluted that it was “in danger of dying by suffocation.” This prompted a response from both the communities that surround and survive on the lake, and from concerned political bodies. The pollution in the lake was curtailed. But in recent years, it looks like the problems have begun to surface again.
Since the clean-up, scientists from Heidelberg University’s National Center for Water Quality Research have been monitoring the lake and its tributaries. And their findings have shown that the change of water color is down to a combination of factors.
The first part of the problem is the algae that live in the lake. It’s these organisms that create that distinctive green coloring in the water. But the massive blooms that have been seen in recent years only began to sprout again in the 1990s. Which means there must be something else that’s contributing to the change in the lake.
And now researchers have realised that the second cause is phosphorous. This chemical interacts with the algae in the lake, causing the blooms to be even bigger than usual. And that can lead to some pretty catastrophic consequences for the human and animal residents of Lake Erie.
There are a number of places where this phosphorous comes from. Some of them can be identified – a large water treatment plant in the Detroit area is partly to blame, for example. But it turns out much of the chemical is emanating from areas that are much harder to pin down. And it’s these sources that account for a large percentage of the phosphorous that makes its way into Lake Erie.
The Maumee River runs from Indiana into Lake Erie. It’s 137 miles long and passes through large swathes of farmland en route to the lake. Scientists estimate that 85% of the phosphorous that enters Lake Erie from the river stems from these agricultural fields. Or, to be more precise, from the fertilizers that farmers use on them.
When the phosphorous enters the lake, it sends the algae’s feeding patterns into overdrive. This process, which scientists call eutrophication, essentially involves a large amount of nutrients entering an ecosystem. The algae devour the nutrients and begin to multiply. And the end result can be incredibly harmful.
That’s because the algae in Lake Erie contain a cyanobacteria known as microcystis. And under the right conditions these tiny blue-green creatures can create a toxin – microcystin – that’s harmful to both humans and animals. Sadly, that’s not the only threat that the algae pose, either.
When a large algae bloom dies, it can leave behind what’s known as a dead zone. As the organisms start to rot away, they use up all the oxygen in an area, meaning that other forms of life simply can’t survive there. Furthermore, even before the bloom starts to die, there are other problems that can occur.
The blooms can also block out the sunlight from reaching underwater creatures, leaving them without the light they need. If that wasn’t bad enough, the algae can also clog up fish gills, rendering them unable to breathe. And that’s before we move on to how they can affect humans.
Back in August 2014 another large algae bloom forced the water supply in parts of Ohio to be switched off. Mindful that microcystin can cause liver damage in humans, authorities had cut the supply to try to avoid a catastrophe. Some 500,000 residents around Michigan and Toledo were left without water for three days. But that’s just the tip of a potential disaster iceberg.
That’s because nearly three million people get their drinking water from parts of Lake Erie. You can imagine the scale of the problem should a more severe algae bloom occur. Thankfully, while toxin levels from the current bloom are being tested at intake pipes in the area, currently they’re at a level not harmful to humans.
One of the reasons that algae blooms in Lake Erie have become so problematic in recent years could be down to global warming. Changes in the rainfall of the region have meant that there’s more runoff from farmland. And more runoff means that there’s more phosphorous making its way into the ecosystem of the lake.
Plans are in place to try to prevent the phosphorous from entering the water in the first place, but some argue that these won’t be enough. Nevertheless, a number of the states around the Great Lakes are hoping to cut the levels of phosphorous entering Lake Erie by 40% by 2025.
Officials believe this can be achieved by changes in the way wastewater is dealt with, as well as by altering some current farming practices. But since the changes to farming are set to be voluntary rather than mandatory, skeptics claim this will have little impact on the problem.
Things have gotten so bad in the area that in September 2017 the mayor of Toledo wrote to President Trump asking for help in combating the algae blooms. Paula Hicks-Hudson wrote in her letter that Lake Erie needs to be declared impaired by the U.S. Environmental Protection Agency to give it a chance to be saved.
This step would allow the Clean Water Act to regulate the nutrients flowing into Lake Erie, thus starving any future algae blooms of nourishment. In her letter, Hicks-Hudson wrote, “As I look out my office at a green river, I can tell you one thing: The status quo is not working.” And if scientists are right, it’s only going to get worse.