A malfunctioning or poorly maintained septic system on Otisco Lake can significantly degrade lake water quality by releasing untreated or partially treated wastewater into the surrounding soil and groundwater, which ultimately flows into the lake; this wastewater carries nutrients—especially nitrogen and phosphorus—that fuel harmful algal blooms and invasive aquatic plant growth, as well as pathogens and organic matter that reduce dissolved oxygen and harm fish and other aquatic life.

Properly sited, regularly inspected, pumped, and maintained septic systems with intact drainfields minimize these risks, while older or undersized systems, systems on poorly draining soils, or systems for seasonal homes left unused for long periods are more likely to leak and contribute to nutrient loading, clarity loss, and public health concerns. Regular maintenance, timely repairs, and upgraded systems where needed are among the most effective actions homeowners can take to protect Otisco Lake’s ecological balance and recreational value.