NORFOLK, Va. — When Hurricane Irene was bearing down on Hampton Roads in the summer of 2011, there was a silver lining: rain. Everybody hoped a good deluge would finally douse the stubborn, smoldering fire in the Great Dismal Swamp that just wouldn't go out.
Well, it rained, roughly a foot. Problem was, the water didn't stick around long. Instead of soaking in to extinguish the largely underground fire — fueled by decayed vegetation known as peat — most of the water was funneled away by the swamp's vast network of ditches and canals. The swamp burned on and on.
"That was a real eye-opener for us," said Fred Wurster, a hydrologist at the Great Dismal Swamp National Wildlife Refuge. "Even after Irene, the fire wasn't done."
On Dec. 18, federal and North Carolina officials unveiled two structures they hope will keep more water in the swamp and make nearly 10,000 of its 113,000 acres less susceptible to fire while enhancing wetlands.
The large dam-like devices, called weirs, regulate flow at the end of two large ditches that channel water into the Dismal Swamp Canal and ultimately the Albemarle Sound. Their main job is to back up water into the swamp for several miles, which gives it time to seep into the ground, raising the water table. A higher water table means wetter peat, which suppresses fire.
"The ultimate goal is to slow the drainage of the swamp," said Chris Lowie, refuge manager.
The 2011 fire burned for 110 days, destroying 6,300 acres, which today is an apocalyptic jumble of charred stumps and spindly tree trunks in the heart of the swamp.
Lowie cautioned that the weirs won't prevent fires but should make them easier to fight. The weirs add to the network of smaller devices for water control in the refuge.
The $1.4 million project was paid for with a federal grant and state money.
The swamp is crisscrossed with more than 100 miles of ditches that allow water to flow out. They were dug to drain the swamp for farming and to access lumber.
In addition to fighting fires, officials said, keeping more water in the swamp will help restore ecosystems. For example, rare Atlantic white cedars that once covered the area need moist soil to thrive. In 2003, Hurricane Isabel leveled the last significant stand in the refuge. Dry peat had weakened the tree roots so they toppled easily in the storm.
Finally, keeping peat moist reduces greenhouse gases, officials said. Peat stores loads of carbon.
"Once the water is gone, it starts gassing off," said Will Smith, biologist for the U.S. Fish and Wildlife Service.
Refuge officials are planning to install more weirs to retain water in the swamp.
Joy Greenwood, superintendent of the Great Dismal Swamp State Park, said, "We're just trying to get back to a more natural state."