Buoyed by a resurgence in aquatic grasses and water-quality upticks in several rivers, the Chesapeake Bay remained moderately healthy in 2017, according to the latest ecological report card from the University of Maryland Center for Environmental Science.The Chesapeake Bay has earned a 'C' grade for the sixth year in a row in the annual report card issued by the University of Maryland Center for Environmental Science.  (Dave Harp)

The Bay’s overall condition garnered a ‘C’ letter grade for the sixth straight year, and its health score remained unchanged from 2016, at 54 percent. Scientists see positive signs in that stability, though. They note that the Chesapeake’s health scores have gone up and down since UMCES began issuing annual report cards 11 years ago. But for three years now, the estuary’s overall health score has held relatively steady.

Scientists detailed the report card results Friday morning by the Potomac River in the District of Columbia, where they were joined by state and local officials.

“It is the first time that the Chesapeake Bay report card scores are significantly trending in the right direction,” Bill Dennison, UMCES vice president for science application, said in a press release announcing the results. “We have seen individual regions improving before, but not the entire Chesapeake Bay. It seems that the restoration efforts are beginning to take hold.”

In 2017, aquatic grasses earned their best score ever, for the first time in decades covering more than 100,000 acres of the bottom of the Bay and its tributaries. Still, submerged aquatic vegetation, as the grasses are also called, scored a moderate 44 percent because the overall grass recovery goal is to reach 185,000 acres by 2025. The 2017 score is a 5 percent improvement over the prior year, and a 32 percent increase since 1986, when the score was only 12 percent, based on a review of data collected then.

The 2017 assessment also gave a record-high combined score for the health of striped bass, Bay anchovies and blue crabs, three ecologically and economically important fish species. Striped bass registered continued optimal health, while crabs and Bay anchovies both received slightly higher grades than the previous year. Survey results released in May reported a drop in the Bay’s adult crab abundance, particularly for female broodstock, but there was a big increase in juveniles, so state fisheries officials declared the overall crab population healthy and sustainable.

Five of the seven indicators of Bay water-quality tracked in the report card either improved or held steady in 2017. Dissolved oxygen levels earned the highest score, 89 percent, trailed by progress in reducing the nutrients phosphorus (76 percent) and nitrogen (59 percent).  However, water clarity and an indicator measuring algae growth in the Bay both have been showing significantly declining trends, the assessment noted. The abundance of bottom-dwelling worms, clams and other tiny organisms also showed no improvement over time.

While the Bay’s overall health remained unchanged, seven of its 15 regions registered improvements in 2017 and none declined, according to the report card. Virginia’s Elizabeth and James rivers saw significant improvements last year, as did the Upper Western Shore in Maryland. The Elizabeth, in particular, once deemed one of the most degraded Bay tributaries, raised its letter grade from a ‘D’ to a ‘C.’ The James improved to a ‘B-minus.’ 

Eight regions, however, showed no improvements, with the York River in Virginia and the Patuxent River and Lower Western Shore in Maryland earning ‘D’ grades for relatively poor ecological health.  The Patapsco and Back rivers around Baltimore garnered the lowest grade, ‘D-minus,’ but those rivers, which once earned failing ‘F’ grades, showed significant improvement in 2017, according to the report card.

Beth McGee, the Chesapeake Bay Foundation's director of science and agricultural policy, said the report card shows that the Bay cleanup plan, often referred to as a "pollution diet," is working. 

“And there is more good news," McGee added. "New research indicates that as pollution is reduced and the dead zone gets smaller, one of the negative feed-back loops that feed late summer algae blooms is uncoupled.   This change in the Bay’s natural processes, while still in its early stages, bodes well for the Bay’s recovery.”

(As originally posted, this story misstated how long Bay health report cards have been issued. The first one was in 2007.  The Bay Journal regrets the error.)