Courant.com

Dogs are great companions. But don't be fooled by that look of soulful innocence; dogs are prime culprits in the pollution of Connecticut's ponds, rivers and harbors.

Amazing fact: Using DNA technology, researchers identified doggie poo as the source of nearly 20 percent of the bacterial pollution in a Seattle-area watershed. Officials for the Connecticut Department of Environmental Protection say that finding is in line with studies identifying non-human waste as a significant cause of water pollution.

The bacteria and parasites threaten public health, shut down beaches and contaminate commercial shellfish beds. Nitrogen and other nutrients boost blooms of weeds and algae, which rob the water of oxygen.

Dogs and other critters only do what comes naturally. The problem is they're doing it in places that are densely populated and paved.

Lacking natural buffers (trees and shrubs) to catch and absorb polluted rainwater, the untreated water gets channeled into storm drains and injected into the nearest lake, stream or river.

Owners who don't pick up after their pooches are also to blame.

Last year, a pet-poo-pickup campaign targeted five parks and beaches. Visitors who brought along four-legged companions got baggies, hand sanitizers and sermons on the virtues of cleanliness.

The program worked. The prior year, the parks had nine instances of high bacteria levels and four days in which beaches were closed. The year of the program there were no reports of high bacteria or beach closures — despite an increase in visitors.

So pick up after your pet. It's a small courtesy, but it has big benefits.