Scientists are reviewing two recent San Francisco State University studies that note the deleterious effect high ammonia levels have on the delta's food chain.
While ammonia does not make fish unsafe to eat, the studies indicate it interrupts the natural food production of the tiny aquatic animals that salmon, smelt and bass feed on. Populations of all three species are in decline.
If the findings hold up under peer review, the costs of cleaning ammonia from the water could be as high as $1 billion, which could triple the region's monthly sewage bills, says the Sacramento Regional County Sanitation District .
