Phosphorus Pollution and Algae Blooms in the Geist Reservoir
Phosphorus Pollution and Algae Blooms in the Geist Reservoir
IN Our Water - Indianapolis, Indiana


Scott Rodgers enjoys his job as an executive recruiter for technology firms, his home on central Indiana’s Geist Reservoir and his 27-foot Fountain performance boat, which he takes out regularly on the 1700-acre lake. What Rodgers, who directs the Geist/Fall Creek Watershed Alliance, doesn’t enjoy are the blue-green algae blooms that foul Geist Reservoir most summers.

These blue-green algae blooms are not flowers or tiny plants as the name suggests but are actually floating bacteria called cyanobacteria. The name is confusing, but the damage they do is very clear. Harmful algae blooms cause taste and odor problems in drinking water, pollute beaches with green pond scum, starve fish and other animals of oxygen, and, worst of all, produce toxins that can damage the skin, nerves and liver.

Geist Reservoir is one of three reservoirs that supply Indianapolis’ drinking water, so it was even more disturbing when monitoring in August by the Center for Earth and Environmental Sciences at Indiana University-Purdue University, Indianapolis, showed cyanobacteria counts exceeding 100,000 cells per milliliter and toxin levels above 6 parts per billion. That’s high enough to make swimming and ingesting the water dangerous. The same is true statewide; this summer the state’s health department warned Hoosiers that exposure to water in many Indiana lakes could lead to rashes, stomach aches and tingling fingers and toes. People need to wash with warm soapy water after exposure. The risks are real: Last year in Grand Lake in St. Mary’s Ohio, severe blue-green algae blooms sickened 11 people and killed three dogs.

Controlling phosphate pollution could prevent these algae blooms, says Lenore Tedesco, a freshwater algae expert who directs the Center for Earth and Environmental Science at Indiana University-Purdue University, Indianapolis. In healthy Midwestern rivers and lakes, larger plants, diatoms and green algae dominate. But most rivers and lakes in Indiana have an overabundance of phosphorus caused by fertilizer from farms and suburban lawns, sediment from farms, pet waste and pollution from leaking septic systems. The phosphorus pollution is enough to throw the lake out of its natural balance. Then when it gets hot and dry in July, the cyanobacteria take off, causing the green (or sometimes black) slicks that coat Indiana lakes.

Individuals can help by using phosphate-free fertilizer, properly disposing of pet waste and other simple steps. But to solve the state's algae problem, Indiana needs to set statewide standards for nutrient pollution. Indiana is “about ten years late” in responding to a U.S. EPA mandate that it delineate phosphate levels that it permits in lakes and streams, Tedesco says. But the Indiana Department of Environmental Management has finally begun to develop draft phosphate standards for lakes.

ELPC helped develop strong statewide nutrient standards for Wisconsin in 2011. Wisconsin’s standards encourage industries and water treatment plants to work with farmers and landowners to find affordable ways to reduce overall phosphorus pollution. ELPC will work with IDEM to develop standards that address Indiana’s phosphorus pollution problem.

Without measures to control phosphate and other kinds of pollution, Rodgers worries that Geist Reservoir could one day resemble lakes in northern Indiana and Wisconsin which have become “big green muck pits,” he says. But he’s hopeful that by working with people upstream and downstream, Geist Reservoir will one day be a place where his family and neighbors can safely boat and swim. 

How you can help: Click here to write the Indiana Department of Environmental Management and ask them to protect Indiana waterways from dangerous algae blooms.





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