After decades of discouraging news, the people most directly responsible for cleaning up the polluted Chesapeake Bay estuary are beginning to smile.

    Progress is being made, they say.

    Nick DiPasquale, director of the Chesapeake Bay Program, said last week that the progress being seen has come from a variety of initiatives, but most significantly from upgrades to wastewater treatment plants throughout the Bay region.

    Improving wastewater treatment has long been seen as the most direct way of making significant progress toward a cleaner Chesapeake, and DiPasquale says that has certainly been true during the past several years.

    In 2010, and Environmental Protection Agency, which is a participant in the Bay Program, issued something called the Bay’s TMDL (Total Maximum Daily Load). Informally known as the “pollution diet” of the Bay, the TMDL sets the amount of nitrogen, phosphorus and sediment that can flow into a waterway while maintaining a level of water quality that allows for improvement.

    With those numbers in place, Virginia, Maryland, Pennsylvania, New York, West Virginia and the District of Columbia went to work on improving wastewater discharge quality — and with considerable success. In 2014 and 2015, fully 41 percent of the bay-wide nitrogen reductions and 38 percent of phosphorus reductions were attributable to sewage plant improvements.

    Sewage treatment facilities have actually exceeded what was thought to be the technological limits of improvement in some instances, DiPasquale said.

    For the Bay, though, the improvements are a beginning, not an end. In Pennsylvania, for example, significant reductions in agricultural runoff have been difficult to achieve, and that will be needed for progress to continue.

    Likewise, stormwater runoff, which carries a lot of sediment as well as nutrients into the Bay’s tributaries, defies quick improvement. And retention ponds and other stormwater filtration devices have to be maintained, essentially forever, if they are going to filter stormwater for generations to come.

Nevertheless, the progress that has been made thus far is real and worth celebrating.