Water quality in a little more than 39 percent of the Chesapeake was good enough during the last three years to support Bay creatures, from worms to crabs to fish, figures released Thursday show.
That was the second-best extent of good water quality seen in any three-year period since coordinated Chesapeake monitoring efforts began in 1985, according to the state-federal Bay Program partnership.
From 2014 through last year, 39.2 percent of the Bay attained clean water standards for clarity, algae concentrations and dissolved oxygen. That was just below the record-best extent in 2008–2010, when 39.5 percent of the Chesapeake met cleanup goals.
Officials said the numbers show that decades-long cleanup efforts have improved conditions in recent years, including a record-high abundance of underwater grasses, a key indicator of the estuary’s health. Still, Bay Program officials and environmental advocates alike noted that the latest figures show that 60 percent of the Bay falls short of water quality objectives.
“While these improving trends are encouraging, we must ramp up our efforts to implement pollution control measures to ensure progress toward 100 percent of the water-quality standards is achieved throughout the Bay and its tidal waters,” said Nick DiPasquale, director of the U.S. Environmental Protection Agency’s Bay Program Office.
The water-quality standards are designed to ensure that Bay-dwelling creatures — from bottom-dwelling worms to striped bass swimming along the surface — have enough oxygen to survive. They’re also intended to bring back clear water that would allow the recovery of the Bay’s once-vast underwater grass meadows, which provide habitat for juvenile fish and crabs and food for waterfowl. Meeting the standards would also curb the growth of algae blooms that often plague the Bay, some of them harmful, even toxic, to fish and animals.
To meet those water-quality goals, the EPA in 2010 established the Chesapeake Bay Total Maximum Daily Load, or pollution diet, which imposes limits on the amount of water-fouling nutrients and sediment that could come from each state and river.
The numbers set in the TMDL are in the process of being re-evaluated, but preliminary estimates from computer models suggest the region as a whole is not on pace to take all needed cleanup actions by 2025, as required by the EPA.
That lag seems to be confirmed by separate water-quality data released this week by the U.S. Geological Survey, which showed that among the Bay’s nine largest tributaries, four had improving nitrogen levels, four were getting worse, and one had no trend over the last decade.
For phosphorus, the other key nutrient, only one tributary — the Patuxent River in Maryland — showed improvement, while five got worse and three had no trend.
“Our water is getting cleaner, leading to smaller dead zones and more Bay grasses and oysters,” said Beth McGee, Chesapeake Bay Foundation director of science and agricultural policy. “But water quality still has to improve in 60 percent of the Bay, meaning that we can’t take our foot off the gas pedal. We need increased efforts from both the states and federal government.”
Officials evaluate water quality by examining measurements over three years, to reduce the impact of a single year’s weather on the Baywide assessment. Heavy rain can drive more water-fouling nutrients off the land and into the Bay, while high summertime winds can stir up the water, reducing the oxygen-starved dead zone.
The data suggest there has been a significant overall improvement in Bay water quality since monitoring efforts began in 1985. In the first three-year assessment from 1985–87, just 26.5 percent of the Chesapeake attained water-quality standards.
“Robust funding, science, and stewardship are paying off and cleaning up the Bay, but we still have a long way to go,” said Ben Grumbles, secretary of the Maryland Department of the Environment.