Pollution from inland sources of fertilizer and manure is threatening bays and estuaries in the U.S., according to a report released this week by the Pew Oceans Commission. The study stated that nitrogen and ammonia from these sources are producing toxic algae blooms, depleting oxygen levels, and destroying sea grasses and coral reefs. Leon Panetta, the commission’s chair and a chief of staff under former President Clinton, warned that “dead zones” like the one in the Gulf of Mexico are likely to proliferate as heavy coastal development continues. In other manure news, environmental groups filed a racketeering lawsuit yesterday accusing the nation’s biggest hog processor, Smithfield Foods, of deliberately fouling water, air, and soil.