Letter from Chip Northrup Cape Cod Water: a Cautionary Tale Most septic systems are designed to remove solids and bacteria, not nitrogen and phosphorus. The harmful algae blooms, or HABs, in Otsego Lake are driven by two key nutrients: nitrogen and phosphorus. Septic systems in the Otsego Lake watershed—including ones that are adjacent to the lake—may be leaking nitrogen and phosphorus into the soil, which may subsequently enter the lake, feeding a toxic bloom. Old-fashioned septic tanks are the culprits…