Another summer, another run of toxic algal blooms

Last year—largely due to farm runoff—the number of algal blooms in U.S. lakes tripled.

In Mississippi, a bluish-green algal bloom has closed all the beaches. 

The timing couldn’t be much worse. It was a holiday weekend, and local business owners on the Gulf of Mexico were counting on revenue from tourists. Instead, the algae arrived. It killed the oysters in at least one harvesting region. Then it shut down one beach after another, as it can cause rashes, stomach cramps, nausea, and diarrhea for swimmers. 

This particular outbreak can be traced back at least in part to the flooding that inundated the Midwest earlier this year, The New York Times explains. Floodwaters flushed into the Mississippi River, which rose high enough that the Army Corps of Engineers opened a spillway that empties into Lake Pontchartrain, which is connected to the Gulf of Mexico. The resulting flow of water and nutrients feeds the algae, which in turn sucks oxygen out of the water and stresses fish and crabs. 

When it all winds up in the gulf it culminates in a “dead zone,” a low-oxygen swath of water where fish can’t survive.
As National Oceanic and Atmospheric Administration oceanographer Richard Stumpf told NBC News, algal blooms are primarily caused by runoff from manure and synthetic fertilizers used on farmland. The decreased salinity in the water and changes in temperature may also have contributed to this one. A breathtaking graphic feature from the Wall Street Journal earlier this month illustrated that process: Nutrients run off into the Mississippi River, starting near its mouth in northern Minnesota, and accumulate all along its path. Farms in Iowa alone sent more than half a million tons of nitrates into the river in 2016. The water gets another flush of unhelpful nutrients via chicken farm runoff from Arkansas and Mississippi before it flows into the Gulf of Mexico.

The farm runoff creates all sorts of problems along the river: It can taint well water, which in turn may cause dangerous blood conditions in babies and cancer. When it all winds up in the gulf it culminates in a “dead zone,” a low-oxygen swath of water where fish can’t survive. The dead zone is forecasted to reach the size of Massachusetts this year. And this weekend the algae began impacting tourism as well. 

The Mississippi isn’t the only body of water affected by farm-related, toxic algal blooms. Last year, we reported that the number of blooms had tripled from the year prior, growing so severe in Ohio that Governor John Kasich declared Lake Erie “impaired.” The Environmental Working Group is tracking this year’s blooms in a database updated weekly. 

At the federal level, regulations affecting farm runoff are notoriously lax.
After Lake Erie became so polluted that Toledo residents had to avoid their own taps in 2014, Ohio advocates stepped up organizing efforts around the lake. Earlier this year, voters approved a Bill of Rights for the lake. Citizens can now sue on behalf of the lake when it’s in danger of being harmed. 

It remains to be seen whether or not this will be an effective approach for preventing runoff into the lake. At the federal level, regulations affecting farm runoff are notoriously lax: As Civil Eats reported last year, these rules are often based on incentivizing conservation measures, and critics say state-level enforcement of maximum daily runoff limits has been limited. 

In the meantime, there’ll be no swimming in Mississippi. Maybe that means the Gulf of Mexico will one day get a Bill of Rights of its own. 

H. Claire Brown is a senior staff writer for The Counter. Her work has also appeared in The Atlantic, The Guardian, and The Intercept and has won awards from the Society for Advancing Business Editing and Writing, the New York Press Club, the Newswomen's Club of New York, and others. A North Carolina native, she now lives in Brooklyn.