Farm fertilizer runoff creating a worsening algae bloom problem in U.S., global waters

Fertilizer runoff created the largest-ever 'dead zone' in the Gulf of Mexico this summer, caused by algae bloom using up most of the oxygen in the water. (National Oceanic and Atmospheric Administration graphic)

"Harmful algae blooms have become a top water polluter, fueled by fertilizers washing into lakes, streams and oceans. Federal and state programs have spent billions of dollars on cost-sharing payments to farmers to help prevent nutrient runoff, yet the problem is worsening in many places," John Flesher reports for The Chicago Tribune.

Several factors contributing to larger algae blooms include warm water temperatures, slower water circulation and too many nutrients, like the nitrogren and phosphorus present in fertilizers. Nutrients can come from fertilizers from farms and urban lawns as well as industrial wastes and sewage.

Some of the algae blooms can be toxic to humans and animals; one such toxin, microsystin, was found to be present in almost 40 percent of lakes sampled around the nation (though at low levels that wouldn't likely hurt anyone). Even blooms that aren't toxic to humans can stink, discolor the water, and kill fish.

The U.S. isn't the only one experiencing increased algae blooms, according to the National Oceanic and Atmospheric Administration. "China's largest blooms on record washed onto beaches in 2013 from the Yellow Sea, as bulldozers scraped up rotting mats by the ton. A bloom the size of Mexico spreads across the Arabian Sea twice a year," Flesher reports. And blooms in Greece, Italy and Spain cost the economies of those countries a total of $355 million annually.

The problem may get worse. Since warm water encourages algae blooms and the global temperature is warming, more algae blooms could happen. If greenhouse gas emissions continue increasing, nitrogen runoff could increase 19 percent by the end of the century, according to a study in Science.

The U.S. government has had laws in place since 1998 to deal with harmful algae, but only began focusing on inland waters in 2014--without additional funding. The U.S. Department of Agriculture has spent $1.8 billion since 2009 on preventing fertilizer runoff, the majority of which was pledged to farmers in Texas, Kansas, Oklahoma, Indiana and Nebraska.