For several years, some indicators have suggested that the Chesapeake Bay ecosystem is at its healthiest in generations. But scientists have been hesitant to call it a trend — until now.
They say they are sure: The estuary is on a "significant" upswing.
“We’ve been waiting for this moment where we could say the bay as a whole is getting better,” said Bill Dennison, vice president for science applications at the University of Maryland Center for Environmental Science. “Now we can say it.”
Scientists from Maryland and Virginia gave the Chesapeake a C grade for the third consecutive year in the annual report card released by the center Friday. While that indicates more progress is needed to restore long-degraded waterways, researchers say it’s clear evidence that cleanup strategies are working.
“We finally have a positive trajectory that’s significant,” Dennison said. “We went from not significant to very significant in terms of the statistics this year.”
But as they celebrate the progress, some leaders say they worry the effort is under threat.
Recently released Chesapeake Bay Program data suggest Pennsylvania is lagging in its efforts to reduce pollution, and to a lesser extent, so are Maryland and Virginia. And the Trump administration has repeatedly proposed major cuts to the federal program. Congress has not approved them.
Gov. Larry Hogan recently sent a letter to EPA Administrator Scott Pruitt and leaders of other bay watershed states and the District of Columbia demanding that each jurisdiction “does its fair share” in the cleanup, and that the EPA continue to serve as a referee.
“Now is not the time to lose momentum,” Ben Grumbles, Maryland environment secretary, said Thursday. “Our federal partners need to continue to provide funding and science and ensure that the regulatory backstops remain in place and that we ensure accountability.”
The report card takes into account levels of pollutants such as nitrogen, phosphorus and sediment, and other measures of ecological health, including water clarity, oxygen content and abundance of underwater grasses, shellfish and microorganisms. The authors this year cited significant increases in dissolved oxygen levels and grass growth, and declines in phosphorus, nitrogen and chlorophyll, an indication that those nutrients are fertilizing fewer and smaller blooms of algae.
Algae blooms fueled by farm runoff and sewage pollution have plagued the bay for decades, clouding waters, blocking sunlight, and stripping waters of oxygen when they die and decompose.
Bay health fell to its nadir in 2003, according to data collected by UMCES going back to 1985. As recently as 2011, conditions were worsening. The center gave the bay a D+ for overall health that year. But since then, scores have improved in five of the past six report cards.
“These improvements are encouraging for water quality, and have positive impacts on the ecosystem,” the scientists reported.
One positive impact has been the spread of underwater grasses, which increase oxygen content in the water and provide habitat for young fish, crabs and other aquatic creatures. An annual survey found record abundance of grasses — for the first time, more than 100,000 acres are visible across the bay.
“As water quality improves, they colonize these areas and grow very rapidly,” said Robert Orth, a professor at the Virginia Institute of Marine Science. “The recovery we’ve seen in some of these places has been quite impressive.”
While bay recovery has appeared strong in recent years, there have been questions about how much of the improvement could be linked to favorable weather or other matters of chance, not the effort that began in 2010 to set a pollution “diet” for the Chesapeake.
Dennison said this year’s report card results are the first with statistical significance — indicating that scores have improved so much the progress could not be simply due to chance. The scientists credit the pollution diet.
To bay advocates, that’s a valuable endorsement of state and federal programs and funding they are working to defend.
“Scientists are the most skeptical people you’re going to run into,” said Beth McGee, director of science and agricultural policy for the Chesapeake Bay Foundation. “They’re never going to want to stick their neck out unless they’re sure of what they’re seeing.”
Though many of the indicators are improving, some scores remain poor. Dissolved oxygen levels scored an A, but nitrogen levels earned a C+. Chlorophyll levels got a D+ and water clarity an F.
The scientists said the improvements mean bay ecosystems should be more resilient in the years to come, but they expect fluctuation. Heavy rain so far this year could mean worse scores on next year’s report card, because increased runoff means more pollutants get washed into waterways.
Also, this year’s report card includes blue crab population data from a survey conducted during the winter of 2016-17, which showed that spawning-age female crabs were at their most plentiful since at least 1990.
The data collected last winter was less rosy — cold weather killed off a third of adult crabs, and the overall population fell by 18 percent compared to the previous season.
It’s only one factor, scientists said, but it could drag down next year’s grades.