Few other estuaries worldwide receive higher nutrient loads, measured on an area basis, compared to San Francisco Bay. The region's forty-two Publicly Owned Treatment Works (POTWs) account for >60% of dissolved inorganic nitrogen and dissolved inorganic phosphate inputs to the system, with higher levels in portions of the Bay. Nutrient loading from municipal sources has increased over the last two decades, with levels plateauing over the previous several years, corresponding with population trends.
