Baltimore's harbor, the lower Patapsco River and the streams that feed into it earned water-quality scores last year ranging from 51 percent to 57 percent, up from 41 percent in 2012. The water remains murky, though, and polluted with trash, sewage and other wastes, which under certain conditions can feed algae blooms and cause fish kills. The Inner Harbor and Middle Branch also have unsafe levels of bacteria much of the time.