A potentially harmful algae bloom covered more than 700 square miles in the western basin of Lake Erie last week, turning the lake bright green and alarming residents and local officials.
Scientists say that algae blooms have been a growing problem for Lake Erie since the 2000s, mostly because of the extensive use of fertilizer on the region’s farmland.
The algae blooms contain cyanobacteria, which, under certain conditions, can produce toxins that contaminate drinking water and cause harm to the local ecosystem.
During last week’s bloom, the amount of toxins in the algae remained low at the intake points where towns draw water from the lake, according to officials.
Lake Erie’s algae blooms are driven by
a landscape dominated by agriculture.
Rain causes nutrients from fertilizers on farmland to run off into rivers.
The nutrients travel along rivers, eventually reaching Lake Erie.
In the Maumee River, the largest tributary to any of the Great Lakes, green algae was visible last week in an aerial photograph.
According to experts, excess nutrients that are transported by the Maumee River can be a good indicator of how severe an algae bloom in the lake will be.
Millions of people get drinking
water from Lake Erie. Previous
blooms have been toxic.
While not all algae blooms are toxic, they can produce a type of toxin called microcystin that can cause serious liver damage under certain conditions. Dangerous levels of the toxin caused Toledo, Ohio, to shut down the drinking water supply of a half-million residents for three days in 2014.
In total, almost 3 million people get drinking water from the central basin of Lake Erie. Officials have been testing the intake pipes in the lake where towns draw water and report that the current toxin levels are low.
Note: Only intake points for towns and cities in Ohio are shown.
The blooms are hurting
the region’s economy.
Lake Erie attracts millions of visitors for beaches and recreation like fishing, and many businesses stand to lose money during large algae blooms.
David Spangler, vice president of the Lake Erie Charter Boat Association, describes the algae as a musty-smelling, lime-green skin on the lake’s surface that’s so thick you could write your name in it.
“An awful lot of money may go someplace else other than Ohio if we continue having these issues in the lake,” Mr. Spangler said. He noted that in 2015, an algae bloom kept boats out of the lake for six to seven weeks.
The algae blooms are getting larger.
Since the 2000s, algae blooms in Lake Erie have become much more extensive.
According to one study by the Carnegie Institute for Science and Stanford University , most of the increase in the size of the blooms can be attributed to a rise in the amount of dissolved phosphorus flowing into the lake.
In the 1980s, researchers started tracking algae blooms in Lake Erie. They were mostly small, but changes in farming practices caused them to spike.
The blooms are expected to grow more harmful as global warming changes rainfall patterns.
According to local experts, storms have become more intense in the region, carrying more nutrients from the farmland into the lake.
Another study from the Carnegie Institution for Science shows that extensive algae blooms will continue to grow throughout the continental United States and around the globe, especially in Southeast Asia.
The mayor of Toledo, Paula Hicks-Hudson, wrote a letter to President Trump on Sept. 26, calling on the federal government to declare Lake Erie impaired, which would allow for the lake’s nutrient loads to be regulated under the Clean Water Act.
“There is something very wrong with our country when our rivers and lakes turn green,” Ms. Hicks-Hudson wrote in her letter. “As I look out my office at a green river, I can tell you one thing: The status quo is not working.”
Original Article (with full labels on images and diagrams)