Rising waters cause high tides to mix with fence posts at Holland Cliffs Shores, Md. (Photo courtesy NOAA)

After Hurricane Isabel flooded Chesapeake Beach, Md., Wesley Stinnett’s Restaurant and Bar stood under about 6 feet of water.

The deluge did so much damage that owner Gerald W. Donovan decided not to reopen the restaurant, which had been in his family since 1936.

Though it was Isabel's high tides that finished the restaurant, Donovan describes the flood as the decisive clash in a longer battle between land and tide.

Warming global temperatures have led sea-water levels to rise a few inches worldwide in the last century, but water levels in the bay have risen faster—about a foot during the last 100 years.

As a result, low-lying land along the Chesapeake is turning into open water, and other stretches are coming further into the flood zone.

Chesapeake Bay water levels have been rising more than 3 millimeters a year on average, according to more than 60 years of measurements by the National Oceanic and Atmospheric Administration. This is fast enough to turn marshes into open water. It’s also fast enough to damage waterfronts.

“The property is more prone to flood,” Donovan said. “Even though it’s minute, over a 20-, 30-year period, it’s several inches.”

That can be a lot in the flat counties bordering the Chesapeake.

Rising Tides

In some places, land is going underwater.

One of the most visible examples is in the Blackwater National Wildlife Refuge, a 26,000-acre waterfowl sanctuary in Dorchester County, where 150 to 400 acres of marshland turn into mudflats or water every year, according to the conservation department at the National Aquarium in Baltimore.

Why Chesapeake waters are rising faster than ocean waters is murky. Court Stevenson, a professor at the University of Maryland Center of Environmental Science, and Michael Kearney, an associate geography professor at the University of Maryland, have hypothesized that the large amount of soil material washing into the bay is depressing the bay floor, causing shorelines to sink down relative to water level.

Similar situations have occurred in states further west, where dams have trapped enough sediment to sink the floors of the reservoirs, Kearney said.

The effect is magnified because the bay is so shallow, so a little increase in water level makes a big difference, Kearney said. The bay’s average depth is under 30 feet, according to the University of Maryland Chesapeake Biological Laboratory.

The bay shore may also be sinking because people are drawing water from large underground aquifers underneath, Stevenson said. A study of soil core samples and historic land survey records led Kearney and Stevenson to conclude that the bay’s water level rose dramatically after 1850--which points to human influence.

Drowning Marshes

The effects on marshes only became apparent after the 1970s, when Blackwater National Wildlife Refuge personnel asked scientists to explain extensive marsh loss at the refuge. Stevenson was one of the scientists who examined the problem.

“The land area in that part of Dorchester County is so flat that it just gets overtopped by water," said Curt Larsen, a retired research geologist for the U.S. Geological Survey.

"The plants basically drown," Stevenson said.

Larsen concluded that at current rates of water rise, most of Blackwater will be gone by 2050. Marsh loss will only accelerate after that, he said.

Some officials are looking for ways to save Blackwater and other low-lying areas, a task made more difficult because the effects of water rise are compounded by other problems.

Some developed properties along the bay, including Donovan’s, are built on former marshland that is compacting decades after buildings and parking lots were built on top of it. In Blackwater and other marshes, erosion has been hastened by large rodents called nutria.

These rodents, which can reach 20 pounds, invaded the area after being imported from South America in 1943 to boost the fur trade, according to the Maryland Department of Natural Resources. Nutria eat away the grasses that keep marsh sediment in place.

The Nutria Project Partnership, funded by a congressional grant, is working to solve the nutria problem. Meanwhile, the Army Corps of Engineers is restoring eroded marshes with sediment taken from the bay’s floor during dredging done to deepen shipping lanes.

When studies determined traditional methods could not effectively restore Blackwater’s marshes, the Army Corps turned to an experimental technique called thin-layer spraying, in which acres of marsh were brought above water level with a few inches of dredge material. Hundreds of volunteers then planted the new land with marsh grass to stabilize it, said Bev Waggoner, an organizer from Friends of Blackwater National Wildlife Refuge.

Fifteen acres of the refuge’s mudflats and open water have become marsh habitat again, as well as a few acres on Barren Island, which is south of the Choptank River and also part of the Blackwater refuge, Wagonner said. Three months after the first grasses were planted, diamondback terrapins were laying eggs there.

“The area looks fabulous now,” Waggoner said. “People (once) would be up to their knees or up to their waists in muck… Now the grasses are over our heads.”

Restoring the island is an ongoing project. Volunteers will plant 15 acres more acres of Barren Island in the summer, and the Army Corps is studying the possibility of restoring the whole Blackwater refuge, said Steven Kopecky, Army Corps project manager.

The thousands of acres of work would likely cost in the tens of millions of dollars, Kopecky said. The 20-acre original project cost $450,000.

Even then, the result might be only temporary. Orrin Pilkey, director of the Program for the Study of Developed Shorelines at Duke University, said rising sea levels just submerge the restoration work in future decades.

"You’re going to do it again and again," Pilkey said.

A Forecast of Floods

Public interest in sea-level rise is growing, Kearney said.

“Isabel was sort of a wake-up call” last September, he said. “People began imagining, if this is what Isabel could do, what if a Category 3 or, God forbid, a Category 5 hit us?”

Category 5 storms have winds over 156 mph. Isabel was a Category 2 storm as it made landfall in North Carolina, with winds between 96 and 110 mph, according to the National Oceanic and Atmospheric Administration. Around the time it passed into Maryland, Isabel was downgraded to a tropical storm, with winds between 39 to 73 mph.

But the sea level rise that concerns academics or owners of waterfront property is not something most people are talking about, even in many towns bordering the bay.

Bruce Wahl is a council member at Chesapeake Beach in Calvert County, the same town where Stinnett's restaurant was closed by Isabel. But he said he's not aware of the way water rise contributed to the problem.

“I’ve lived here for 18 years, and I suspect there’s been some rise, but I really don’t know much more than that,” Wahl said. “I think if scientifically we can prove the water level’s going to rise a certain number of inches… it would be a concern, but I also think it’s obvious we wouldn’t be able to do anything about that.”

Cities on shores across the world are using technological means like tide gates to limit the effects of sea-level rise, Stevenson said. However, the sprawling geography of the Chesapeake Bay won’t allow for such a comprehensive solution.

Bulkheads are another option, Kearney said, but they can cost hundreds of dollars a foot.

Instead, around the Chesapeake Bay, many are just doing what Donovan did after floods damaged Wesley Stinnett’s Restaurant and Bar.

Donovan just closed up and focused on the restaurants he owned that were further above the waterline.

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Copyright © 2004 University of Maryland Philip Merrill College of Journalism