The Conversation (0)
The NY Times reported that the Ohio River, transformed by mining and industrial waste and sewage overflows into the nation’s most polluted major waterway, has a new and unexpected tormentor this fall: carpets of poisonous algae.
The NY Times reported that the Ohio River, transformed by mining and industrial waste and sewage overflows into the nation’s most polluted major waterway, has a new and unexpected tormentor this fall: carpets of poisonous algae.
As quoted in the article:
Pads of toxic blue-green algae have speckled nearly two-thirds of the 981-mile river in the last five weeks, experts say, in an outbreak that has curbed boating, put water utilities on alert and driven the river’s few hardy swimmers back to shore.
The only other recorded toxic algae bloom, in 2008, covered perhaps 40 miles of the river. In contrast, the latest bloom stretches 636 miles from Wheeling, W.Va., to Cannelton, Ind., and traces of algae have appeared as far west as Illinois.
What causes the blooms is clear: Tides of phosphates and nitrates, flushed into the river from fertilized fields, cattle feedlots and leaky sewers, provide food for the algae, which are actually bacteria. Hard rains in parts of the Ohio Valley basin this summer appear to have washed more than the usual amount of the chemicals into the river and into Lake Erie.
The algae need hot weather, sun and still water to flourish. All were abundant in August and September, when a dry spell reduced the Ohio’s flow and cleared its usually muddy waters.
But if this year’s algae epidemic can be explained, why it has not appeared before is a murkier question.
The river absorbs a colossal amount of phosphorus — nearly 42,000 tons in an average year — but “while we have seen a very slight increase in phosphorus over the years, it’s not something that stands out,” Richard Harrison, the executive director of the Ohio River Valley Water Sanitation Commission, said in an interview. “It’s still something we’re investigating.”
Some scientists, however, suspect changing weather patterns in the region. Since the 1970s, average temperatures and rainfall have been slowly increasing in the Ohio River basin. So has the frequency of heavy rains — the steady downpours that wash fertilizer off farmlands and overwhelm sewage systems in big cities along the river’s course.
Richard Stumpf, an oceanographer at the National Oceanic and Atmospheric Administration, is leading an effort to forecast algae blooms. “These climate phenomena are consistent with our understanding of how these things work,” he said of the blooms. “We do expect them to be more common when you have wet springs followed by long, warm summers.”
Some states in the river basin are trying to rein in phosphorus discharge; Ohio and Indiana, for example, recently banned phosphates in lawn fertilizers. Federal and state officials are working, so far with limited success, to reduce fertilizer use and runoff on farms.
