A cargo ship passes the Sandy Point Shoal Lighthouse on the Chesapeake Bay. The lighthouse is just north of the Bay Bridge. (Mark Wilson/Getty Images)

Scientists rated the health of the Chesapeake Bay a D-plus in a report released Monday, the first time in a decade that the health of the bay has decreased.

Officials at the Chesapeake Bay Foundation, which issues a report card every two years, cited record regional rainfall as the cause of increased pollution and poor ­water clarity in the bay, which had seen substantial improvements to its health in recent years.

“Simply put, the bay suffered a massive assault in 2018,” William Baker, president of the Chesapeake Bay Foundation, said in a news conference Monday. “The bay’s sustained improvement was reversed in 2018, exposing just how fragile recovery is.”

Baker said the “grim reality” is that the bay faces challenges on multiple fronts, including at the federal and state levels.

He said President Trump’s efforts to roll back environmental regulations threatens progress that has been made in the bay, which had been due in large part to a 15-year, $19 billion cleanup plan that is administered by the Environmental Protection Agency and holds the six states in the Chesapeake watershed to specific pollution limits.

Trump has tried to dramatically reduce the plan’s funding, but congressional support for the restoration effort remains strong. Studies show that cutting pollution — including nitrogen and phosphorous from human activities — has reduced the size and number of “dead zones” where fish, oysters and other creatures die in oxygen-depleted water.

Marks for nitrogen and phosphorous pollution declined in this year’s report, compared with 2016, when the last report was released. The bay received a ­C-minus rating then.

Baker said severe pollution in Pennsylvania’s portion of the Susquehanna River, which supplies 50 percent of the bay’s fresh water, contributed to its declining health. He said there are 19,000 miles of streams and rivers in Pennsylvania that are polluted and suggested that the state must find the “political will” to fully fund efforts to bring them back to health.

Debora Klenotic, a spokeswoman for Pennsylvania’s Department of Environmental Protection, said the state “has been working diligently to be a good partner on bay cleanup efforts.” She cited more than $2 million in state support to help farmers create sediment management plans and more than 100 water-quality projects.

The Conowingo Dam, on the Susquehanna near Maryland’s border with Pennsylvania, is no longer trapping pollution attached to sediment. Officials counted on the hydroelectric dam to block large amounts of sediment in the Susquehanna from reaching the bay and smothering aquatic grasses and affecting other wildlife. But the reservoir behind the dam filled with sediment far sooner than expected.

Virginia and Maryland were closer than Pennsylvania to reaching their pollution reduction targets in 2017 but still need to accelerate pollution reduction from agriculture and urban and suburban runoff, according to the report.

The Chesapeake Bay Foundation, which has been reporting on the health of the bay since 1998, examines data for 13 indicators in three categories: pollution, habitat and fisheries.

Scores for oysters, crabs and rockfish remained the same in the new report, and the score for shad declined.

Two of the 13 indicators — dissolved oxygen and bay grasses — improved in this report, compared with 2016. Baker said those improved indicators could mean the bay is “developing a resilience” that could help it overcome damage caused by the record storms and rainfall, which dumped polluted runoff into the bay.

Washington and Baltimore, along with dozens of other locations in the Mid-Atlantic, experienced their wettest years on record in 2018, the result of a string of storms in the region that began in May.

Asked about the effect that climate change will have on the Chesapeake, Baker said that “more storms and more intense storms” will mean “more runoff, sediment and pollution coming into the bay, and more disruption to the system.”

He said rising water temperature, which means decreasing oxygen levels, will present problems for species living in the estuary.

The goal is for the Chesapeake to earn a score of 40 by 2025. The ultimate goal is a score of 70, which foundation officials say would mean the bay had been “saved.” This year, its rating was 33 — down from 34 in 2016.

To reach a score of 40, all jurisdictions will have to meet their goals laid out in the Clean Water Blueprint put in place in 2010, Trump will have to stop rolling back regulations, and serious and immediate efforts will need to be made to address climate change, Baker said.

The report was released the week both the Virginia and Maryland legislatures are scheduled to convene.

Virginia Gov. Ralph Northam (D) has proposed “historic” investments in a cleaner Chesapeake Bay, proposing a five-year plan that he said would represent the largest investment ever in Virginia’s water quality.

Maryland Gov. Larry Hogan (R) chairs the Chesapeake Executive Council of the Chesapeake Bay Program, which is made up of the governors of the six watershed states, the D.C. mayor, the chair of the Chesapeake Bay Commission and the head of the EPA. The Hogan administration said it has invested a record $4 billion in cleanup and conservation efforts. The governor has been critical of Pennsylvania’s and New York’s efforts, saying that Maryland’s neighbors to the north could do more to help restore the bay.