Environmentally friendly shoppers face a dilemma when the grocery store clerk asks, “Paper or plastic?” Choose paper, and they’re cutting down trees. Choose plastic, and they’re clogging the landfills.

But Washington, D.C., has found a way to put those disposable bags to use in saving the Anacostia River, a tributary of the Chesapeake Bay.

Considering the city’s Department of the Environment found in a study that plastic bags make up 21 percent of trash in Anacostia – and 47 percent in its tributaries – that claim may seem impossible. How could the pesky pollutants ever help the river?

On Jan. 1, the District started charging a 5-cent bag tax on paper and plastic bags at stores that sell food or alcohol. The goal was not only to encourage the use of reusable bags but to protect and provide for the heavily polluted river that flows past Southeast Washington.

As a part of the D.C. Council’s Anacostia River Clean Up and Protection Act of 2009, the majority of the proceeds go to fund cleanup efforts. For each bag, 1-2 cents goes back to the businesses, while the rest is sent to the Anacostia River Clean Up and Protection Fund, according to the Washington Post. The D.C. Department of the Environment will use the fund, which also receives money from other sources such as a new commemorative license plate, to clean the river and its tributaries as well as to provide citizens with reusable bags.

In the month of January alone, the tax already made almost $150,000, the Washington Post reported this week. And it also has resulted in a significant drop in disposable bag use, benefiting the river from two directions.

Washington has found a creative way to turn a negative but largely unchallenged part of life into a positive force for the city, the Anacostia and the Chesapeake. And shoppers still debating “paper or plastic” can breathe a little easier knowing they can still help save the bay.