Underwater grasses that provide vital places for fish and crabs to live and hide from predators covered more than 100,000 acres of the Chesapeake Bay in 2017 — the most ever recorded in a 34-year aerial survey, scientists said Tuesday.

The Virginia Institute of Marine Science found 104,843 acres of grasses across the estuary, the first time since it began its survey in 1984 that vegetative coverage surpassed the 100,000-acre threshold.

It was a third straight year that grass acreage grew, gaining by 5 percent from 2016 to 2017.

The Patapsco River was among the areas with the strongest grass growth. Acreage jumped more than three times, from 3 acres in 2016 to 14 acres in 2017.

Officials with the Chesapeake Bay Program, the federal office that released the data, said the survey results show that its work with bay watershed states to limit pollution is working. The federal-state partnership adopted a “blueprint” in 2010 to reverse decades of environmental degradation and restore the bay’s health by 2025.

The Annapolis-based bay program has faced proposals of cuts from President Donald J. Trump’s administration, but Congress has spared its $73 million budget.

“This achievement is a true example of the power a partnership can have and I call upon all of our partners to continue their efforts toward this remarkable recovery,” said Jim Edward, the program’s acting director.

The vegetative growth is a result of programs to reduce pollution and runoff from farms and urban pavement, scientists said. The bay cleanup blueprint set goals to reduce the amount of nitrogen and phosphorus that washes into rivers and streams — usually in the form of fertilizer and sewage — as well as the sediment and other pollutants that run off with urban stormwater.

All those pollutants can cloud water, blocking sunlight from reaching the grasses and stunting their growth, if not killing them.

The grasses are a key element of the bay ecosystem, oxygenating waters, creating habitat and providing food for creatures up and down the food chain. The cleanup plan set goals for ecological indicators including underwater vegetation — at the levels reported last year, the bay is 57 percent of the way toward its target — because the grasses also can help the bay better withstand future pollution.

The Chesapeake Bay Foundation cheered the report, but Beth McGee, its director of science and agricultural policy, stressed that “the recovery is fragile and proposed rollbacks to federal environmental protection regulations threaten future progress.”