BALTIMORE (AP) — 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.
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