As rising seas drive saltwater farther inland, Maryland officials are urging local governments, drinking water suppliers, farmers and others to start preparing now for a saltier future.
Maryland Gov. Larry Hogan’s administration in December released the state’s first plan to combat saltwater intrusion. The 76-page report doesn’t forecast how widely impacts will be felt, citing a lack of existing research, but it identifies the resources facing the highest risk, ranking agriculture at the top.
“We’re still in the dark about how much of an impact this is going to have on our coastal farms,” said Jason Dubow, a Maryland Department of Planning official and the plan’s lead author. “We do know sea level rise is accelerating, and as it accelerates, the salinization issue will accelerate as well because they’re tied together.”
Wetlands, coastal forests, freshwater streams and aquifers also are in danger of turning salty, according to the report.
Melting ice at the poles and the ocean’s thermal expansion — both triggered by climate change — are causing seas to rise across the globe, carrying salt into new places above and below ground.
Saltwater intrusion is of even greater concern in the Chesapeake Bay region, climate scientists say, because the area’s land surface is sinking — a phenomenon geologists blame on the northward retreat of glaciers after the last Ice Age. In Maryland, seas could rise up to 4.2 feet by 2100, according to the University of Maryland Center for Environmental Science.
High tides and storms are expected to inundate low-lying land more often, leaving salt behind in their wake. In such areas, farmers can no longer grow most crops, and forests slowly die. Over time, the land transforms into a salt marsh.
“Climate change is driving saltwater intrusion and [landward] marsh migration faster than ever before, so we’re going to lose more land at an unprecedented rate,” said Jim Bass, coastal resilience manager for the Eastern Shore Land Conservancy.
Considerably more research is needed to determine the extent of the intrusion so far, let alone where it will show up in the future, the Department of Planning said in the report. It calls on universities to make saltwater intrusion one of their top research priorities and for government officials and others to find ways to fund it.
Dubow said efforts should go toward helping farmers first because in low-lying portions of the Eastern Shore, they’re already experiencing the effects of saltwater intrusion.
The report urges officials to create a detailed plan to promote conservation easements for salt-ridden acreage. Those would allow farmers to get some compensation for lost production while keeping the land available for other potentially profitable opportunities, such as leasing it for hunting. The environment and the Bay would benefit because the former farmland would transition into saltmarsh, which helps to filter nutrient runoff, Dubow said.
The plan doesn’t hold out direct financial assistance to farmers. But it does suggest creating programs to inform farmers about the issue and encourage the use of water-control systems that prevent salty water from entering a field’s ditches and drainage pipes.
Kate Tully, a University of Maryland scientist who is studying saltwater’s effects on Eastern Shore farmland, said she was happy to see that the plan pushes for more research. Her team, which includes George Washington University and University of Delaware researchers, has found that 1,400 acres of farmland in Somerset County have been converted to tidal marsh from 2009 to 2017.
That amounts to 2% of the rural county’s total farmland, Tully said.
But, Tully added, until more studies are conducted, she can do little more than speculate about how those changes on the land affect water quality in the Chesapeake Bay. Salt tends to unlock nutrients from the soil, so its increasing presence could turn the phosphorus-rich farmland on the Shore into a bigger cleanup headache, she said. Phosphorus is one the nutrients responsible for fouling Bay waters.
Rising seas also are also expected to raise the level of groundwater, potentially flooding basements and causing septic systems to fail in low-lying areas, according to the report. Citing a 2016 USGS study, the administration projects a rise in the water table of up to 3 feet in most portions of the Eastern Shore below the Chesapeake Bay Bridge and on the Western Shore in lower Calvert and St. Mary’s counties.
The increased salt content of the groundwater could cause underground utility pipes to rust and fail, the authors warn. Broken wastewater pipes present a particular threat to water quality because they could spill untreated sewage into nearby waterways.
That problem is already stirring action in neighboring Virginia. Researchers and state Health Department officials are trying to get a handle on the scope of the state’s failing septic systems while lawmakers weigh whether more regulations are needed.
To combat the problem in Maryland, the plan recommends cataloging the state’s underground infrastructure within the coastal plain and developing response plans for their owners to follow.
The salt invasion presents less of a concern to drinking water than in places such as southern Florida, Dubow said, because Maryland has plenty of alternative supplies, such as deeper groundwater sources and surface waters. Some areas have already been affected — namely, the Mayo Peninsula, Annapolis Neck, Kent Island and Ocean City — but suppliers have made changes with the hope of minimizing the problems.
But utilities and farms that use underground sources for irrigation should remain vigilant of possible salinity increases over time, Dubow said.
State legislators passed a law in 2018 requiring the Department of Planning to draft the saltwater intrusion adaptation plan, setting a Dec. 15, 2019 deadline.
The plan was issued two months after another Maryland climate change-related report. That document addressed the state’s greenhouse gas emissions, calling for a 44% reduction from 2006 levels by 2030.
Unlike the emissions plan, the saltwater intrusion report doesn’t include numerical targets or deadlines for action. There isn’t enough research yet in the field to support such specifics, Dubow said.
State officials from multiple agencies helped to craft the report and plan to gather periodically to guide its implementation and track progress. State law requires the plan to be updated in 2024 and every five years in the future.