GREENSBURG – Many Decatur County residents near Lake McCoy have noticed a foul stench in the air and those that get close to the shore are met with a disturbing sight- hundreds of dead fish at the water’s edge.
As one approaches the shore, the stench of the lake grows stronger. When the actual shore comes into view, the grisly line of fish carcasses can be seen all along the edge of the water, complete with swarms of opportunistic insects. Mysterious and perhaps ominous bands of lighter-colored water and serpentine ribbons near the shore are visible. The water around the dead fish has an oily, iridescent sheen.
One might develop several theories for the cause of the massive fish kill- pollution, geological activity, or even global warming. However, the actual cause is completely natural. Both the Department of Natural Resources (DNR) and the Indiana Department of Environmental Management (IDEM) investigated reports of the fish kill.
According to Indiana Conservation Officer Corey Norrod, both the DNR and IDEM conducted a number of water tests to rule out pollution as the cause of the changes at Lake McCoy. IDEM officials discovered negligible levels of ammonia and tolerable levels of dissolved oxygen, proving that an unknown contaminant did not kill the fish.
DNR conservation officers investigating the report concluded that the light bands seen across the lake were actually ordinary pond scum, which is very common in stagnant water and forms a greenish film near or on the surface. The algae that comprises the pond scum is the base of the food web in the lake’s habitat. Conservation Officer Norrod also reported that Lake McCoy appears to have a longstanding problem with excessive nutrient and sediment runoff. The excess nutrients in the water can hamper plant life, which supplies some of the oxygen in the water.