When looking for culprits to blame for the Chesapeake Bay's foul shape, it's tempting to point fingers at smelly sewage treatment plants, or at farmers whose flocks or herds of animals produce highly visible, not to mention odoriferous, mounds of manure.

But before pointing fingers, maybe we should look a little closer to home. Household pets, particularly the legions of dogs taken for walks every day, collectively are a significant source of water pollution, experts say, and even a threat to human health.

The Chesapeake Bay Foundation issued a report today highlighting the ways in which pollution and bacteria put humans at risk when they swim in the bay or its tributaries, when they eat locally caught fish or when they drink water from wells.  I wrote a story about it for The Baltimore Sun.

The report cites the usual suspects for much of the pollution that is linked to disease-causing bacteria, harmful algal blooms and toxic substances in the water.  It points to farm animal waste, for instance, as a likely source of nitrates getting into ground water and people's wells on the Eastern Shore and in southeastern Pennsylvania.

But it's another story in urban and suburban areas.  According to a state study, pet waste is the leading source of bacteria found in a stretch of the Severn River where a few years earlier a Crownsville man acquired a life-threatening bacterial infection after swimming with a mild scrape on his leg. 

The 2008 state study estimated that 69 percent of the bacteria found in the water came from pets, with wildlife contributing about 24 percent, livestock and humans just three percent each.  And the report noted that about 41 percent of the dog owners in the area admitted they do not pick up after their pets most of the time.

So, fellow dog owners, ask yourselves, how diligently do you clean up after your four-footed companions?  Do you scoop the poop?  Put it in the trash, bury it or even flush it down your own toilet?  That's what expert say you ought to be dong with it.