In its natural state Charleston Harbor Watershed included 1400 square miles of virgin forrest, rich salt and freshwater marshland, and pristine rivers and streams. Deer, bear, elk, wild turkey, and smaller game roamed the forests. Fish, oysters, and clams were abundant in the tidally influenced portions of the Cooper and Ashley Rivers. The watershed was home about 1000 members of the Cusabo Tribe who lived off the wealth of fish and game. All that began to change in 1670 with the arrival of English settlers and the founding of Charles Town.
The Charleston Harbor Watershed’s rich and vibrant history also includes the story of the pollutants that entered the its waterways as the local population and industry grew. From the late 1800s until the early 1970s untreated sewage entered the harbor from several outfalls that ringed the peninsula. Along both sides of the Ashley River, the phosphate industry had a dramatic impact, replacing antebellum plantations with mills, wharves, drying sheds, and smokestacks. While these landmarks gradually disappeared, the legacy of pollutants they discharged remains today.
By the 1900s population growth and industrial development had taken a toll on our local waterways. Many were unfit for fishing and swimming. Past industrial land uses like the Old Gas Works at the Calhoun Park Superfund Site, the Romney Street landfill, Koppers wood treatment plant, and the Macalloy Corp. ferrochromium plant on Shipyard Creek have left a legacy of contamination still present today. More recently, a team of researchers have identified local tidal creeks as “sentinel habitat” (an early warning system) for water quality and habitat impacts from urban and suburban development activity. The critical nature of these impacts is highlighted by a recent economic study that found clean water dependent activities like commercial fishing, costal tourism, and water-based recreation have a state-wide economic impact of 10.8 billion dollars.
The Modern Charleston Harbor Watershed is very different from the on first encountered by English settlers in 1670. Today population growth and land development threaten the ability of our watershed to function naturally. Toxic chemicals like polycyclic aromatic hydrocarbons, mercury, and polybrominated diphenyl ethers are significant “stressors” for our fresh and estuarine waterways. Local dolphins have among the highest levels of some organic pollutants seen globally in marine mammals. Yet despite these sobering facts, our local waterways are an integral part of our Lowcountry lifestyle. Recent research found very high levels of participation waster-based recreational activity like swimming, fishing, and boating.
During much of its history, the Cusabo, a group of tribes with familiar names like Edisto, Kiawah, Stono, and Wando, were native to the South Carolina coast. Before English settlers arrived in the area, about 1000 Cusabo enjoyed the wealth of fish and game available in the Charleston Harbor Watershed.
The watershed familiar to the Cusabo included 1400 square miles of hardwood and longleaf pine forests, roamed by cougars, red wolves, and white-tailed deer. Salt and freshwater marshlands were drained by pristine rivers and streams. Abundant fish and oysters were found from Shem Creek up to the Wando River and along the tidally influenced portions of the Ashley and Cooper Rivers. Learn more about the history and economics of our watershed.
Salt marshes fringe estuarine waters, forming the intertidal zone (between high and low tide) along beaches and tidal rivers. South Carolina has more salt marsh than any other state on the east coast (about 400,000 acres) and Charleston County has the most salt marsh of any county in South Carolina. Salt marshes are complex and ecologically productive, with fluctuating levels of salinity and temperature as the tides move in and out.
Most low salt marsh areas (nearest to the water) are dominated by smooth cordgrass (Spartina). A mix of plants including Spartina and black needlerush (Juncus) are found in the higher areas of marsh. As the marsh grass decays in the fall, it decomposes into a rich soup of nutrients providing food for both fish and invertebrates like shrimp, blue crabs, stone crabs and clams. Fiddler crabs, marsh snails and marsh mussels are also typical marsh inhabitants.
Salt marshes also serve as high quality bird habitat, attracting, for example, blue herons and American and snowy egrets, seaside sparrows, clapper rails and marsh rails as year-round marsh residents. Waterfowl (ducks and geese) and wading birds find shelter in the marshes over the winter. Other inhabitants of our coastal marshes include muskrats, rabbits, diamond back terrapins and even alligators in less salty areas. Learn more about the Charleston Harbor watershed’s estuarine habitat.
Tidal creeks begin in uplands, draining into larger creeks until they join a tidal river or bay where their waters flow into the ocean. Tidal creeks represent about 17 percent of the state’s estuarine waters by surface area. Numerous tidal creeks like James Island and Shem Creek wind through the salt marshes of the Charleston Harbor Watershed, forming a network of highly productive habitat and serving as critical spawning areas and nursery habitat for fish, shellfish, birds and mammals. Seatrout, jack crevalle, flounder, spadefish, spot, black drum, blue crab and brown and white shrimp are among the many aquatic animals the mature in the shelter of these shallow, muddy-bottomed creeks before moving into deeper waters. Learn more about the Charleston Harbor watershed’s estuarine habitat.
The tidal rivers that flow through the salt marsh support mussels and clams as well as oysters. Oysters, common inhabitants of intertidal areas along our rivers and creeks, build reefs where small invertebrates like juvenile shrimp and larval crabs find shelter from predators. Many fish like flounder, black sea bass and Atlantic spadefish use the reefs as nursery habitat. Other fish species come to the oyster beds to feed. Learn more about the Charleston Harbor watershed’s estuarine habitat.
Before English settlers arrived in the Charleston Harbor Watershed, about 1000 Cusabo survived on subsistence farming, hunting, and fishing. These activities had a minimal impact on the watershed’s tidal creeks, salt marsh, and rivers. Population growth spurred by founding of Charles Town in 1670 led to increasing human impacts on the natural functions of the areas estuarine habitat. Rice and cotton cultivation in 1700 and 1800‘s, the Charleston peninsula’s land expansion, and the Santee Cooper Hydroelectric Project in 1939 forever altered natural functions of the Charleston Harbor Watershed’s salt marsh, tidal creeks, and rivers. Learn more about the human impacts and physical changes to our watershed.
During much of the City of Charleston’s early history, Charlestonians used privy vaults for to collect and dispose of human fecal waste. By the late 1800s, Charleston had approximately 10,000 privy vaults, of which only 10% were emptied in a given year. Drinking water cisterns were often located close to privy vaults, posing a serious health risk. Diseases like cholera were common problems.
In the late 1800s scientific advances made it clear that bacteria from fecal waste caused diseases like cholera. As a result, Charleston began constructing a sewage collection and disposal system. Work progressed in fits and starts and was finally completed in the 1940s. The system discharged untreated sewage from several outfall along the Ashley and Cooper Rivers. By the late 1960s water quality had drastically declined making many local waterways unfit from swimming and shellfishing. In the early 1970s the federal Clean Water Act required all sewage be treated before discharge. The city’s Plum Island Treatment Plant was completed in 1971 and to this day discharges treated wastewater to the Ashley River. Learn more about the history of the Charleston Harbor watershed.
The Port of Charleston
The present location of the City of Charleston was chosen because it was easy to defend and had access to the deep water of the Cooper River. By the mid-1700s, Charleston was a busy trade center exporting indigo, rice, and cotton and one of the largest ports in the American colonies. By the Civil War Charleston was the wealthiest city in the South and its commercial and cultural center.
In the years following the Civil War, Charleston’s economy languished but was buoyed by the presence of the U.S. Navy’s Charleston Naval Shipyard, naval station, and distribution center. Today, Joint Base Charleston is the Charleston area’s largest employer. The modern Port of Charleston, owned by the South Carolina Ports Authority, handles over 60 million tons of cargo annually including textiles, clothing, forest products, chemicals, machinery, vehicles, boats and aircraft, food, furniture and hardware. Learn more about the economics of the Charleston Harbor watershed.
In the 1870s deposits of phosphate were discovered Charleston’s river beds and underground. Economically pressed planters sold or rented land to the growing number of mining and fertilizer production companies. Riverbank sites were more popular than inland sites because of the ease of excavation and transport.
By the end of the 1800s more than two dozen companies, most located along the Ashley River, produced one-half of the world’s phosphates. The mining industry began to decline after the earthquake of 1886 damaged and new phosphate sources were located outside South Carolina. The mining industry was gone by 1938.
Although the mines and fertilizer plants along the Ashley River are gone the pollutants they generated are still present. Today, at some sites, old ditches can carry acidic water, lead, and arsenic into the Ashley River. Some former phosphate fertilizer plant sites along the Ashley River have been recognized by the US EPA as “Superfund” sites. Clean up and monitoring activities continue to this day. Learn more about human impacts and legacy pollutants in our watershed.
The Mosquito Fleet consisted of a small fleet of small fishing boats operated by members of the African-American community in and around Charleston. While the fleet mainly fished for commercial and subsistence purposes it also provided a ferry service across the Ashley and Cooper Rivers between the sea islands and the City of Charleston.
During its heyday the small boats with their brightly colored sails were so numerous they were said to look like a swarm of mosquito skimming over the water. In addition to commercial fishing the fleet also put on an annual race on the 4th of July. In the last known race boats like Ocean Queen, Matchme, Too Sweet My Love, and P.M. Catchem competed for the top prize. By the 1960s the Mosquito Fleet was all but gone due in part to hurricanes and higher paying jobs at the Charleston Naval Shipyard. Learn more about history and economics of our watershed.
Water-based Recreational Activity
“Underappreciated Assets: The Economic Impact of South Carolina’s Natural Resources”, a 2009 study by the University of South Carolina Moore School of Business, found water-based recreational activity and coastal tourism have a $10,840,145,849 economic impact in South Carolina. The study included both direct and indirect impacts like employment and income and concluded “well-managed” natural resources are “integral” to economic development. The Ashley/Cooper River Basins water-related natural resources not only define the region’s history and culture but also fuel the local economy and provide a high quality of life for local residents residents. Learn more about the culture and economics of the Charleston Harbor watershed.
“Underappreciated Assets: The Economic Impact of South Carolina’s Natural Resources”, a 2009 study by the University of South Carolina Moore School of Business, found commercial fishing has an annual economic impact of $33,939,909 in South Carolina. Shrimping is by far the dominant fishery, with commercial trawlers bringing in 6 million pounds annually, valued at approximately $30 million.
Shrimping has a colorful history in the Charleston area, starting with the “Mosquito Fleet” in the 1850s. These commercial shrimpers were primarily African Americans who used whatever vessels were available, netting the shrimp by hand in seives and marketing them from carts on the streets of Charleston. Since the 1920’s, the docks of Shem Creek in Mount Pleasant have been home to a fleet of high-bowed, flat-bottomed shrimp trawlers topped with outriggers that swing out on each side to lower the huge nets. The trawlers work offshore, mostly within 3 or 4 miles of the beach. Each year, a colorful local festival centers on blessing each of the fishing vessels that go in and out of Charleston Harbor.
Today a new group of “watermen” in Charleston make a living as professional shellfish harvesters. Dave Belanger (“Clammer Dave”) is one of these, farming clams and oysters for a decade in 25 acres of intertidal bottom land leased from the state near Capers Island Wildlife Refuge. His oysters are popular with local restaurant chefs and are culled by hand with a chisel, a process that dates back 200 years. For over 20 years, Toby Van Buren has pulled clams and oysters from the pluff mud in an area he leases from the state near Breach Inlet. He uses nets to protect his clam beds from predatory sting rays, crabs and flounder. These pioneers represent a new wave of sustainable shellfish growing and harvesting in our local waters. Learn more about the history and economics of the Charleston Harbor watershed.
Past Land Uses
Many past industrial and other land uses have left a legacy of contamination that impact our waterways to this day. The old Koppers wood treatment plant and Macalloy Corporation ferrochromium smelting plant sites are EPA Superfund sites. Clean up activities are complete at both sites and monitoring continues to this day. However, chromium levels in the sediment of Shipyard Creek near the Macalloy site continue to be among the highest in the world. Learn more about legacy pollutants in the Charleston Harbor watershed.
Sentinel Habitats: Tidal Creeks
In our watershed, researchers have identified the upper reaches (headwaters) of tidal creeks as “sentinel habitats,” acting as first responders to the physical, chemical, and biological changes resulting from human activities. When impervious surface in these areas is 10 to 20% of total land area or below, the physical, chemical, and biological processes of a tidal creek function normally. However, when the impervious cover exceeds 20% these processes are damaged by the rapid influx of polluted runoff and water quality, habitat quality, and the abundance of aquatic organisms declines. In addition to ecological costs impervious land cover can increase flooding, beach and shellfish bed closures, and public health risks due to bacterial contamination. Learn more about how human activity impacts the Charleston Harbor watershed.
Toxic Pollutants: Sources and Impacts
Toxic chemicals are a significant “stressor” for our fresh and estuarine waterways. Types of pollutants include: (1) organic chemicals like polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and pesticides like DDT; (2) heavy metals like lead and mercury; and (3) “emerging contaminants” like polybrominated diphenyl ethers (PBDEs) and perflourinated chemicals (PFCs) that have not traditionally been monitored or regulated. Pharmaceuticals and personal care products (PPCPs) are also sources of pollutants. Such contaminants are being found worldwide in aquatic environments, including the rivers and estuarine waters of the Ashley/Cooper River Basin.
Key local organisms can help us to understand what potential health and environmental risks these pollutants pose and whether the risks are increasing or decreasing over time. These organisms are called “sentinel species“. The results of these sentinel studies (Dolphins, Loggerhead Sea Turtles, Bivalves, Bald Eagles, Diamondback Terrapins) indicate that the toxic chemicals that enter the Ashley/Cooper River Basin and move downstream to Charleston Harbor are finding their way via the food chain into both wildlife and humans, some at concentrations that are health-threatening. Learn more about toxic pollutants in our waterways.
Mercury: Human Health and Sentinel Species
Mercury is a poisonous neurotoxin that enters the atmosphere primarily via coal-fired power plants. It can be carried great distances until it is deposited by wind and rain on land and water where it can enter the food chain. In South Carolina, most rivers and lakes have mercury-contaminated fish. In addition to issuing general consumption advisories, the state has issued guidelines regarding consumption of freshwater and certain salt water fish for high risk groups, including women of child-bearing age and children under 14, groups which represent 43% of the South Carolina’s population. For a complete list of up-to-date fish consumption advisories and information for individuals in at risk groups, see: HYPERLINK “https://www.scdhec.gov/environment/water/fish/” https://www.scdhec.gov/environment/water/fish/.
Scientists have studied both local diamond back terrapins and bald eagles as mercury sentinel organisms, animals that can alert us to pollution impacts in the environment. As predators, their bodies accumulate mercury through biomagnification (a process which increases pollutant concentration with each step up the food chain). Learn more about mercury in our waterways.
Population Growth and Land Development
As humans move into our coastal watershed and change the way land is used, the ability of estuarine habitats to function normally is challenged. The Charleston Metropolitan Area (Charleston-North Charleston-Summerville) is one of the 10 fastest growing metropolitan areas in the US. In Charleston, for example, the population grew by 40% from 1973 to 1994 while size of the urban area grew by 240%, creating urban sprawl and greatly increased impervious land cover (e.g., roads, sidewalks, driveways and parking lots that prevent water from being absorbed into the soil). The size of the urban area is expected to increase to 868 square miles by 2030, covering 65 percent of the land area.
Tidal creeks in particular are intimately linked to human land-based activities through the stormwater that runs off into them from developed land and impervious surfaces, carrying with it a cocktail of pollutants from gasoline and oil, fertilizers, pet wastes, sediments, etc. SCECAP (South Carolina Estuarine and Coastal Assessment) is an ongoing joint state and federal program that assesses the health of our coastal habitat, including our sensitive tidal creeks. Data from 1999-2008 has been analyzed and, for that period, the rivers draining into Charleston Harbor showed a persistent pattern of degraded habitat quality (based on water and sediment quality as well as the biological community). This is likely the result of a combination of historical industrial activity and high-density urban development. Learn more about human impacts in our watershed.
Recreation and Tourism
The abundant resources of the Ashley-Cooper basin fuel an enormous amount of economic activity, including recreation (e.g., swimming and sunbathing , kayaking and canoeing, motor boating, fishing, stand-up paddle boarding, surfing and kiteboarding), tourism, and commercial fishing. The results of a survey conducted by the South Carolina Dept. of Parks, Recreation and Tourism indicated that nearly two-thirds of the state’s adults used South Carolina’s beaches and over one-third participated in freshwater fishing in 2005! The number of saltwater recreational licenses nearly doubled from 2006 to 2010 when 208,204 were sold. Boating is so popular that it is estimated that there is one boat for every 12 people in the state! Learn more about the economics of the Charleston Harbor watershed.
Dolphins: Sentinels for Human Health
As long-lived fish-eating predators at the top of the food chain, bottlenose dolphins experience biomagnification of contaminants (i.e., as prey organisms are consumed, pollutants can accumulate in the predator, increasing in concentration with each step up the food chain). These mammals live year-round in Charleston waters and can act as ideal sentinels, reflecting spatial and temporal trends in the health of the marine environment.
Studies conducted by Dr. Patricia Fair and colleagues have indicated that total PCB, DDT and PBDE blubber concentrations and blood PFC levels in Charleston dolphins are among the highest reported values that have been measured in marine mammals! A total of 88% of the dolphins sampled from Charleston Harbor and the rivers and creeks of our watershed in one study exceeded the toxicity threshold for PCBs. When 82 dolphins from estuarine waters near Charleston were evaluated for health, 50% showed evidence of environmentally related symptoms and diseases. Dr. Fair and colleagues are now conducting a monitoring program measuring PFCs and other pollutants in the sediments at 42 sites in our watershed.
The high levels of organic contaminants detected in our local sentinel dolphins have raised concerns about the African-American Gullah people of the Sea Islands whose diet, like the dolphins, includes local fish. An ongoing study led by Dr. Diane Kamen at the Medical University of South Carolina is focusing on Gullah people at risk of developing the autoimmune disease lupus. Preliminary results indicate that PFCs may play a pathogenic role in triggering the disease. Learn more about the sentinel species.