The pathogens is known to proliferate in waters experiencing temperatures higher than normal. The microcysts of the pathogen can remain viable for several years after encysting. And, are usually formed during winter months where they await a temperature shift to above 54F. If these warmer conditions existed in the reservoirs that provide municipal waters to the public, the pathogens can be introduced into a healthy aquarium system. Population concentrations may also be increased if hatcheries, which usually experience overpopulation of their stock, share the same waste-water treatment plant as the municipal water district. Chlorinating the water kills most of the pathogens. But, not all. Especially if the chlorination full dose was miscalculated or the contact time was reduced due to demands on the system.