BALTIMORE -- The overall health of America's largest estuary declined last year due to the effects of record-breaking precipitation washing more pollutants into the water, but scientists described the difficult year as a dip for the Chesapeake Bay and not a disaster.
For an annual report card evaluating the 200-mile-long (322-kilometer-long) bay, researchers at the University of Maryland Center for Environmental Science on Tuesday gave the Chesapeake a grade of 46% for 2018, down from 54% in 2017. All of the indicators factored into the bay's health index declined or stayed flat last year. Its letter grade of "C'' is unchanged.
A punishing cycle of heavy downpours in the mid-Atlantic region increased sediments and runoff pollutants into the Chesapeake Bay last year, ending four successive years of largely positive health indicators. Maryland's Baltimore area, for example, was deluged with 72 inches (183 centimeters) of rain in 2018, 175% above normal rates.
A preliminary analysis shows nitrogen pollution saw its worst scores in densely populated areas, while phosphorous scores were particularly bad upstream along the Susquehanna River in southeastern Pennsylvania. These "nutrient" pollutants provide a buffet for algae and lead to low-oxygen conditions that can suffocate underwater life and shrink habitat in the bay, which is fed by numerous rivers and streams.
The Chesapeake's water clarity continued to get a failing grade, seeing a reduction of 10 percentage points. Total nitrogen notched a C-, losing 15 percentage points from the previous year. Aquatic grasses — a key habitat providing a home for important species including blue crabs and striped bass — scored a D-, losing 13 percentage points. Fish populations declined in 2018.
But despite the decreases, scientists say overall bay health is still significantly improving over time, with total phosphorus, nitrogen, dissolved oxygen, and aquatic grasses showing improving trends over years. And while the Chesapeake will never be restored to the condition it was in when Capt. John Smith wrote about its pristine waters and abundant fish in 1608, scientists say its recent health trajectory remains positive.
For Bill Dennison, a marine science professor and official at the University of Maryland Center for Environmental Science, the fact that the Chesapeake wasn't more negatively impacted by 2018's intense rainfall is a positive sign that decades of restoration and resiliency efforts are indeed working.
"The bay is showing some resilience," Dennison said at a gathering in Baltimore that drew a small crowd of state and federal officials.
But as climate change effects accelerate, bringing more volatile weather and more intense downpours to the region, officials said much more needed to be accomplished to effectively reduce nutrient and sediment pollution.
Ben Grumbles, secretary of Maryland's Department of the Environment, said the latest UMCES report card sends a "strong, strong signal" that all the bay states need to keep doing more to prevent runoff and build up climate resiliency practices "to deal with an increasingly wetter and wilder mid-Atlantic region."
Kate Fritz, director of the nonprofit Alliance for the Chesapeake Bay, agreed. "We can't take our foot off the pedal now, not with threats of climate change knocking on our door every day," she said Tuesday.
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