The fragile shared landscape of Stinson Beach and Bolinas—the lagoon and dunes, eroding bluffs and meandering creeks—leaves scant room for error in disposing of human waste. 

Stinson relies entirely on private septic systems, many built over shallow groundwater and vulnerable to flooding. In Bolinas, about a quarter of the town is connected to an aging sewer system and about half of the town’s roughly 470 septic systems are unpermitted or lack documentation.

Climate change…