Lake Drummond is named for a former North Carolina governor who had been an ally of Governor Berkeley of Virginia, but then chose the wrong side in Bacon's Rebellion in 1676. After the rebellion collapsed, the last words of Governor Berkeley to William Drummond were "Mr. Drummond, you are very welcome. I am more glad to see you than any man in Virginia. Mr. Drummond, you shall be hanged in half an hour."1
The lake is one of just two natural lakes in Virginia. Mountain Lake (in Giles County) may have formed on Salt Pond Mountain by eroding a basin into an unusual structure in the Clinch Sandstone formation. There, cracks in the sandstone have formed a depression allowing water to seep underground, etching a lake basin in the bedrock. Intermittently, the cracks are opened (allowing Mountain Lake to drain and be replaced by a meadow) or blocked (causing the lake to reform).
The creation of Lake Drummond is even more mysterious. Geologically, Lake Drummond is an unusually large (3,108 acre) open body of water on the Coastal Plain, east of the Suffolk Scarp. The scarp marks the location of the Atlantic Ocean shoreline and barrier islands roughly 125,000 years ago, when temperatures were higher, the ice melted off the southern half of Greenland, and sea level was higher.2
The scarp is used today to separate the Outer Coastal Plain (including Lake Drummond) vs. the Middle Coastal Plain west of the scarp. The 30' high scarp separates terraces of flat sediments to the east and west. To the east, the Norfolk Formation was deposited on top of the clay-rich Yorktown Formation, and the sandy sediments provide the groundwater recharge area for the Great Dismal Swamp National Wildlife Refuge.
At normal water levels, the lake is 6-7 feet deep and the surface is 18 feet above sea level. There is little topographic relief in the area; elevation drops at one foot per mile near the lake.3
There's no obvious reason for one big lake to exist in the middle of the Great Dismal Swamp, which extended all the way to Back Bay/Albemarle Sound in the colonial era. There is no network of streams draining a watershed upstream and emptying into the lake. Lake Drummond is a high point in the middle of the remnants of the swamp.
In fact, ditches - including some dug during the time when Virginia was a colony, such as "Washington Ditch" initiated by George Washington - are supplied naturally with water that drains by gravity out of the lake. When lake level drops to 15.75 feet, the U.S. Army Corps of Engineers stops releasing water from Lake Drummond to supply the Dismal Swamp Canal. As described by the US Fish and Wildlife Service:4
The origin of the swamp dates back to the end of the last ice Age:5
Source: US Fish and Wildlife Service
Geologically, the swamp and lake formed on top of coarse sand that is very permeable, but with layers of clay and silt that block water flow. An organic layer of peat has accumulated at the surface, and is up to five feet thick. Underneath the peat is the Sandbridge Formation, with upper layer of silty clay and a lower layer of sand. The next layer down is the London Bridge Formation, mostly clay silt, and then layers of sand and silt called the Norfolk Formation. The Norfolk Formation is exposed to the west of the swamp at the Suffolk Scarp:6
One possibile way Lake Drummond was formed: a natural fire could have burned a "hole" in the peat of the Great Dismal Swamp. In 2011, during a severe drought, one of the largest wildfires in the modern history of Virginia burned over 6,000 acres of the swamp. The "Great Conflagration" of 1923-26 was probably even more significant.7
Perhaps 9,000 years ago, a lightning strike may have triggered an extraordinary fire that burned hot enough to destroy the peat layer, reaching down to the confining clay layer that keeps the water in the swamp from draining into the sand underneath. Such a fire could have carved out a bowl within the deep peat, creating a hole that developed into Lake Drummond.
Another posibility: Lake Drummond resembles may other elliptical "bays" or small lakes on the Coastal Plain of the Eastern United States, from Florida to New Jersey, with a southeast-northwest orientation. They might have formed naturally in the Pleistocene as the climate changed, perhaps comparable to the formation of modern lakes on the Arctic Coastal Plain. The elliptical pattern could have been caused by winds blowing from the southwest and forming sand ridges, which have since been vegetated (and in some cases flooded to form lakes) as rainfall increased in the last 20,000 years.8
Yet another possible cause: Lake Drummond was formed by an icy comet/meteor ("bolide") that broke up in the atmosphere and peppered the Coastal Plain. Meteorite fragments are rare in the area, so there is insufficient evidence to claim the lake is a meteor crater. However, shock waves from a comet exploding above the surface of the earth could have carved out the initial depressions, which then filled with water and have been covered with vegetation.
Fragmentation of an extra-terrestrial comet in the atmosphere might explain the regular pattern of the ellipses, their large number (roughly 500,000), and the absence of meteorite fragments. (Comets, because of their icy composition, leave no trail of "meteorites" to record their impact or disintegration in the lower atmosphere.) The Younger Dryas period of global cooling, 12,800 years ago, could have been triggered by a comet's impact. Lake Drummond could be a larger-than-usual Carolina Bay, formed recently as earth's surface was disturbed by a dying comet.9
The ground surrounding Lake Drummond includes dry land as well as swamp. The dry land is typically peat (dead vegetation that has not decomposed yet, or been compressed into lignite/coal) with sand underneath. Such soil is unsuitable for agriculture, but Atlantic White Cedar (Chamaecyparis thyoides) used to thrive in places high enough for plant roots to grow above the water table.
The cedar is a pioneer species, capable of regrowing from seed after fires/storms and forming dense stands. It is not an "old growth" species that replaces itself, perpetuating Atlantic White Cedar forests indefinitely. Without disturbance, other species such as red maple ultimately dominate land originally covered by Atlantic White Cedar trees.
As one researcher noted:10
Atlantic White Cedar has a grain that makes it easy to split/saw. The high resistance to rot also made the species a high-value target for lumber companies. Most forested areas east of the Great Dismal Swamp were harvested in the 1700-1900's, and much of the remaining timber was burned by wildfires.
Forest regeneration was blocked where land was timbered, then ditched and drained for planting crops. Efforts to drain swamps altered the hydrologic regime, triggering the growth of hardwoods and blocking reproduction of Atlantic White Cedar. By one description, the cedar forest were "mined" rather than "managed."11 By the 1950's, the Great Dismal Swamp was one of the last remaining areas with a substantial Atlantic White Cedar forest.
The Union Camp Corporation, a lumber company, donated 49,000 acres of logged-over swampland to The Nature Conservancy in 1973, and the non-government organization then transferred the property to the Federal government. Today, Lake Drummond is in the middle of the Dismal Swamp National Wildlife Refuge, managed by the US Fish and Wildlife Service in the Department of the Interior. Further land acquisition has expanded the refuge to over 110,000 acres, but that is only 10% of the size of the original swampland existing before European colonization.12
One goal of the US Fish and Wildlife Service is to re-plumb the swamp in order to restore the natural flow of water. The Federal agency, together with Dismal Swamp State Park in North Carolina, manages 42 water-control structures (and hopes to install 35 more) to undo the effects of ditches and logging roads that have created drier-than-natural and wetter-than-natural areas. The organic soils in the swamp are normally 85-95% water. When those soils dry out, the soil particles alter into a granular form that will not absorb water even after water levels rise again. The soil then oxidizes away, adding carbon to the atmosphere. Keeping the soils saturated is essential for minimizing the intensity and size of wildfires in the Great Dismal Swamp.13
Hurricanes and major forest fires, influenced by the altered drainage, alter the ecosystem even more rapidly. In 2003, Hurricane Isabel flattened 80% of the purest cedar stands in the refuge, after soil dried out and roots were unable to withstand the wind pressure. Fires - and prevention of fires - threaten the continued existence of the Atlantic white cedar plant community:14
forest with Atlantic White Cedar at Dismal Swamp
Source: US Fish and Wildlife Service National Digital Library
The 100 miles of ditches within the Great Dismal Swamp have resulted in a lower water table, draining away rainfall before it can seep into the peat. The moist soil, essential to growth of the Atlantic White Cedar, has dried out. In 2011, a fire started in early August and burned for 110 days. The 12" of rain that fell during Hurricane Irene in late August drained out of the swamp so quickly that the wildfire was not drowned by the massive amount of rain.15
In 2013, Federal land managers installed new weirs to raise water levels in the ditches, hoping to re-saturate the peat and restore the natural ecosystem over time. The US Fish and Wldlife Service proclaimed that re-watering 9,500 acres, by controlling flow in South Martha Washington Ditch and Kim Saunders Ditch, was the largest restoration project for forested wetlands east of the Mississippi River. Keeping the peat wet was predicted to trap an amount of carbon equal to what 16 million cars emit annually.16
Water levels of the lake and swamp are controlled by Federal land managers. Bear/deer hunting is authorized, so the "natural" character of the refuge is modified by human action, but insects are protected as part of the natural food chain.
A wet Dismal Swamp provides excellent habitat for beeding mosquitoes in the summer; visitors to the 113,000-acre wildlife refuge get to experience annoying as well as attractive critters. The mosquitoes are considered wildlife, like bears and birds. Because the Great Dismal Swamp National Wildlife Refuge is Federally-protected, the City of Suffolk is not allowed to spray chemicals within the refuge to kill the mosquitoes.17
The effect of that prohibition extends beyond the refuge boundaries. Mosquitoes are the primary vector that transfers Eastern equine encephalitis (EEE) and West Nile virus from birds in the refuge to horses and humans in the cities of Suffolk and Chesapeake. There is a tradeoff between protecting natural processes in natural areas vs. protecting human health. People and horses in South Hampton Roads have a higher risk of exposure to some diseases, because the habitat and animal populations (including mosquitoes) within Great Dismal Swamp National Wildlife Refuge are protected.
in 1953, the new City of Chesapeake had replaced Norfolk County on the eastern edge of Lake Drummond, but the City of Suffolk had not yet replaced Nansemond County on the west
Source: US Geological Survey (USGS), Lake Drummond 7.5x7.5 topographic map (1953)
1. Dictionary of Virginia Biography. (2010, June 9). William Drummond (d. 1677). Retrieved September 12, 2010, from Encyclopedia Virginia: http://www.EncyclopediaVirginia.org/Drummond_William_d_1677 (last checked September 12, 2010)
Jerico Ditch, Great Dismal Swamp National Wildlife Refuge
Source: US Fish and Wildlife Service, National Digital Library
Dismal Swamp National Wildlife Refuge
Source: US Fish and Wildlife Service Great Dismal Swamp National Wildlife Comprehensive Conservation Plan