How to Reduce Disease Bacteria in Lakes and Ponds

Even lake and pond water that looks clear and clean may harbor disease-carrying bacteria. There are millions of types of bacteria but only a few of these are harmful to humans. Harmful bacteria from animal feces or human sewage can wash into watersheds after rainfall and can quickly contaminate a lake or pond. Other contaminant sources include infected swimmers, sewage discharge from boats, and malfunctioning septic systems.



Bacteria can infect people if they are swallowed, inhaled, or come in contact with an open wound. Infections from pond or lake bacteria can affect ears, eyes, brains, skin, bowels, throats and lungs. One way to evaluate water quality is to measure "indicator" organisms and then estimate the amount of fecal contamination in the water. Fecal coliforms such as E. coli and enterococci are indicator organisms that can measure the amount of fecal bacteria contamination. Other dangerous bacteria like Vibrio cholerae that is responsible for cholera outbreaks can also be present in pond and lake water.



Even deadlier bacteria such as Naegleria fowleri, a brain-eating amoeba incubates in the nutrients found in the mucky organic sediment at the bottoms of ponds and lakes. When the muck is stirred up, the Naegleria fowleri float in the lake water. If it swims up a swimmers nose, it then burrows into the brain and eats it within a week.



One way to reduce disease bacteria in lakes and ponds is to remove the sediment and muck at the bottom where bacteria thrive. One way to do this is to dredge the pond or lake, but this doesn't prevent the muck from returning, and it also can be very costly. Another way is to add microbes that eat bacteria to the pond or lake. Microbial bioaugmentation is perhaps the fastest way of addressing high levels of fecal bacteria in lakes and ponds. But again, it does not provide a permanent solution.



The only sustainable solution to reducing disease bacteria in ponds and lakes is to mimic and accelerate the natural process of oxygenating the bottom to rid the bottom of toxic gases and eventually the bottom sediment. By adding an aeration system to the pond or lake, beneficial bacteria can live and feed on the bottom muck. During the oxygenation process, muck is biodegraded into carbon dioxide, water and a very small amount of inert "ash". The muck and organic sediment at the bottom begins to disappear, and disease bacteria have no place to incubate. Adding beneficial muck-eating bacteria at the same time as the aeration system is installed can accelerate this process.



With the organic sediment gone from the bottom, anaerobic disease bacteria cannot thrive and the pond or lake becomes safe again for swimming.