The Hole Basin is part of one of the 37 hydrologic unit areas in the US where water quality is studied.All this aside, however, it becomes obvious to a visitor that these are not your usual rolling pastures and meadows. They are pockmarked with a wide assortment of grassy sinkholes, sometimes filling the landscape as far as the eye can see. From atop Muddy Creek Mountain, you look over what is known as the Sinkhole Plain, named after a landscape filled with funnel-shape dips that, except for the lush grass in them, greatly resemble a moonscape. This topography lies on the Karst Plateau of central Greenbrier County and is termed “the Great Savannah.” The sinkholes and karst topography are brought about by water dissolving the limestone bedrock over thousands of years. This process leaves a subsurface network of extensive caves, giving rise in the Greenbrier Valley to one of the heaviest concentrations of sinkholes found anyplace in the world.Aerial photographs used to measure length, width, and depth of the sinkholes reveal a distinct pattern of subsurface caves. The doline, or sinkhole, is the most dominant surface expression of a karst terrain. On average there are more than 12 sinkholes per square kilometer, ranging in depth from 1 to 33 m, in length from 26 to 800 m, in width from 26 to 533 m, and in size from perfectly round to extremely elongated.These funnel-shape depressions collect and direct surface and subsurface drainage to the groundwater aquifer. Because a significant portion of agricultural production takes place in karst areas throughout the Appalachian region, the potential for pollution of wells, springs, and groundwater generally is of immediate concern. Although karst topography comprises only 20% of the Appalachian region, more than one-third of the farms and cattle are located there, representing a similar percentage of the market value of farm production. Karst soils are nutrient-rich and good for pasture, and for this reason Greenbrier County contains the largest number of farms and cattle of all 55 counties in the state.The US Department of Agriculture (USDA) selected Greenbrier Valley as one of 37 hydrologic unit areas (HUAs) in the country. Water quality in each HUA is studied as part of a research and demonstration project under the 1990 Water Quality Initiative. Each of the watersheds was chosen because the potential for agriculture-related problems had been identified in state Clean Water Act reports to USEPA. One goal of the HUA program is to help farmers and ranchers voluntarily and affordably achieve water-quality goals to comply with state pollution management directives authorized by the federal Clean Water Act. Farmers in this area, working with the Natural Resources Conservation Service and the Greenbrier Valley Soil Conservation District, are striving to prevent farming operations from polluting the water supply and seeking solutions to pollution problems in these underground conduits. Douglas Boyer, Ph.D., a hydrologist with the Appalachian Farming Systems Research Center in Beaver, WV–part of the USDA Agricultural Research Service–is in charge of delving into the secrets of this karst terrain 200-500 ft. beneath the pastures and meadows. The project’s purpose is to ensure that surface and underground water supplies are protected through safe use of fertilizers, manure, and pesticides. “We want to understand water flow in limestone so the US Natural Resources Conservation Service can show farmers how best to protect underground water supplies,” says Boyer. “Weekly sampling checks are carried out for nitrate from fertilizer and manure, as well as herbicides.” The Agricultural Research Service’s goal is to assess the impact on water quality of current farm operations and to develop best management practices (BMPs) to mitigate any problems that become evident. These practices include conservation plans, chemical management, and animal waste management for cooperating farms.Cavers nicknamed this 6-in.-long solid gypsum crystal “the spike.” Boyer and Hall walk through a passageway in The Hole Basin also called “the spike.”Cavers dubbed this formation “Bullwinkle” because it resembles a moose head.It is one thing to observe and study a flowing river cutting across farm and woodland, where everything in its path is more or less obvious and predictable. It is quite another to understand the nature of an underground river, springs, rivulets, and tributaries completely hidden from view. A karst topography hides more secrets than will ever be uncovered by researchers, simply because of the dynamics involved. What goes on down deep in the earth as a result of dissolution of water on limestone is ever-changing. For the most part, changes are inaccessible to human eyes. Water eats into the land masses on all sides, while eroded materials and foreign matter, such as fertilizers and pesticides, flow and build and depart with the movement of underground water.We normally think of groundwater as a pool of water under the earth, but in fact it resembles streams and rivulets seen on the surface, with many small flowages feeding into main streams and these into larger streams on the surface. It is necessary to literally crawl under the earth to determine the impact of surface activities upon a karst topography and the quality of water that people depend on for drinking and other daily uses.I visited this underground wonderland with Boyer and associate Derek Hall to see firsthand a little bit of what these scientists must go through to help farmers and landowners carry out the BMPs for the protection of water and health. Our gear was cumbersome: knee pads, coveralls, safety helmets, headlamps with battery packs on our hips, gloves, and nonslip boots. In addition, Boyer carried my camera in a padded, waterproof satchel to protect it from water and general damage. I was warned to be prepared to get wet up to my waist, which I did often; not to panic when squeezing through narrow passages; and to watch my footing.Our entrance to the underground maze of passages was hidden in brush at the bottom of a sinkhole, where the opening was so small a groundhog would have had second thoughts about entering. We went into the cavity headfirst and felt our way along, adjusting our bodies slowly. Crawling on our bellies, we eventually got our hands and knees across rocks and watery pools, into eerie shadows that shrouded the caverns as the headlamps bounced their light into the unknown. There are more than a thousand caves similar to this one throughout Greenbrier County alone.As one might imagine, such caves hold a certain intrigue to young explorers, but all visitors are discouraged from entering and encouraged to do their spelunking at such commercial caves as Lost World, Smoke Hole, Organ Cave, or Seneca Caverns, all of which are relatively nearby. The danger of being lost or hurt or panicking in these caves is ever present. Sliding prostrate under overhanging rocks and wading in waist-deep water should be left to trained cavers, such as Boyer and his crew, who must do this continually to monitor water quality. The cave cricket lives in the darkest parts of the underground system.The eastern pipistrelle bats hang singly or in pairs from the moist cave walls.The cave salamander thrives in the unpolluted areas of the underground channels. Strangely enough, few of the people most intimately acquainted with the luxuriant pastures of the region associate sinkholes with underground streams, wells, and springs constantly at work under the land’s surface. Nevertheless, here is where you must come to measure the effects of land activities on groundwater so vital to the health and well-being of the population. Sampling stations must be well placed and checked often if a true picture of the entire underground complexities is to be determined. Without a proper distribution of the sampling stations, an inaccurate and distorted set of statistics could result. Semipermanent measuring devices are placed in the caves and springs for constant monitoring of pollutant levels. Monthly readings are taken in the caves and weekly readings in the springs, except during storms. Automatic samplings are taken during storms to determine the effects of heavy flows.Two drainage basins were involved in this study. One, Davis Spring Basin, covers 76 mi.2 of surface drainage and is located at Port Spring, where it empties into the Greenbrier River. The other is The Hole Basin, where we entered, which covers 5 mi.2 south of Spring Creek and west of Greenbrier River. It is drained through an extensive cave system and out of two springs, which immediately enter Spring Creek. The combination of these two springs, Burns and Blue Hole, is called Hole Springs.Both Davis Spring Basin and The Hole Basin are underlain by three main aquifers. The MacCrady-Hillsdale aquifer lies at the base of the valley at a depth of 200-500 ft. In The Hole Basin alone there are 22 mi. of known cave passages and more than 170 sinkholes in a 5-mi.2 area. The studies here involve sampling pesticides, nitrates, and animal wastes in selected springs. Atrazine, used in grain production, is by far the most widely used pesticide in the basin in terms of area covered and quantity applied. In 40% of 28 domestic wells in the area, atrazine is detectable throughout the year. Compounds such as 2,4-D (2,4-Dichlorophenoxyacetic acid) are applied in various forms for weed control in pastures. However, pesticides were always below EPA action levels. Research indicates that agriculture presents a significant potential for contamination of both surface water and groundwater. There was a time when spring water piped to the roadside served as a refreshing drink to travelers, and many people looked forward to the experience. That is rarely the case today; most of these roadside springs have warnings on them of possible contamination. As we squeezed and twisted our way into the underground labyrinth of The Hole Basin, it became obvious why karst groundwater is acutely sensitive to surface activities. We could see in these closed catchment areas where dolines funnel surface and subsurface flows to the groundwater aquifer, so that whatever finds its way into the sinkhole has a direct surface connection coupled with rapid subsurface flow through solution channels. This no doubt increases the potential for rapidly varying levels of pollutants. Understanding this variability of contamination is necessary to model the water quality of karst systems.Pathogens from manure are the most serious problem and the most difficult to deal with. Mean fecal coliform counts range from two colonies per 100 ml to more than 4,100 colonies per 100 ml. Nitrates are also difficult to deal with. A nearby dairy contributes about 60-70% of the nitrogen load in the study area. Nitrates are highest in cave streams draining the dairy and in places where cattle gather for shade and water. This karst topographic illustration depicts how these underground formations come to be. Slowly leaching springs become vast underground caverns over time.As we moved through these caverns, large and small, huge layers of hardened silt came into view, brought from aboveground through erosion. These had been deposited over the years in quieter sidelines of the caves, and from ceilings and floors of larger rooms, tiny stalactites and stalagmites are being formed. This basin contact cave system has rapid groundwater movement to two main resurgent points along Spring Creek, but there are no surface streams draining from this basin.Periodically we could walk upright, then bend, then crawl as we inched slowly through a series of down-dip streams feeding into a larger strike-oriented stream. We often went through hip-deep water, and I was never sure until I took that last step just how deep the water would be. I would imagine that a severe rainstorm aboveground would make this a precarious undertaking.Our pathway took us along feeder streams and the main stream from a gently sloping pasture with several shallow dolines. Two main streams originate from deep domes adjacent to a dairy barn and its feedlot, and nitrate levels were much higher than those observed somewhat removed from the barnyards. Water quality exhibited a high degree of variability between land-use areas.Traversing this varied and fascinating underground conduit, it becomes evident that the degree of limestone has a great bearing on size, depth, and flow of caves and streams. The more limestone, the easier water eats away and leaves the sandstone outcroppings. Having seen what subsidence does inside a coal mine, I was amazed at the few limestone cave-ins we came across. We did come upon one sinkhole that had collapsed and cut off the flow of the conduit, except for a trickle that seeped and permitted the backed-up water to escape. It was obvious from these dynamics at work underground that a pattern of down-dip streams occurred as the water table dropped over geologic time. It was awesome to speculate about just how long these processes had been taking place.Under the earth, it becomes evident that circular dolines are usually small and drain a single point, whereas elongated dolines usually result from fluvial processes intersecting a sinking point, or several smaller ones, combining to form one large doline and many sinking points. The higher rate of sinkholes is related to the number of conduits underground that can move materials out. That is what causes sinkholes: conduits that prevent materials that fall through from accumulating by moving them out as they fall.Visual evaluations can be made of the condition of underground waters by the life that exists there. One tributary contained hundreds of earthworms, which disappeared as we moved along. This was a sign of nutrient-rich water. Periodically, we found dusky salamanders and crayfish frequenting pools and tributaries, which indicated the water was good. There were areas where no life existed, indicating polluted water. Other life exists in relative abundance on the ceilings and walls of caves. Cave crickets scurry away as you near them, and eastern pipistrelle bats are commonly found hanging in singles or pairs from the ceiling. The Nature Conservancy values the flora and fauna of these complexes so much that it acquired General Davis Cave adjacent to Davis Spring Basin to protect the endangered blind salamander living there. Davis Spring holds the distinction of being the largest known spring in West Virginia.Lewisburg, Ronceverte, and Fairlea all obtain their drinking water from the Greenbrier River, as do smaller communities. The remainder of the population employs wells and utilizes groundwater as a principal water supply, so the urgency of knowing about the underground water supply is self-evident.As the original study of the springs wraps up, the job will be to relate the differences in pollutants found in springs and streams underground and in surface water. Pollutants are getting into groundwater through sinkholes, but researchers need to know whether one type of sinkhole is more vulnerable than another or whether the real problem is not so much sinkholes as it is land use. Assumptions are that it is a combination of the two. Some sinkholes are so well covered with soil that one must assume excellent filtration takes place to minimize pollutants. Some sinkholes have obvious drains or holes in the bottom that could contribute a greater amount of undiluted runoff, and some talk and money have been put into plugging. Pennsylvania and Illinois tried this, but both shut down the programs as failures. Plugging could disrupt the entire drainage process and could cause problems yet unforeseen. Some insight into plugging can be found along Interstate 64 west of Lewisburg. Periodically, after a heavy rain, a large lake could be seen there; at other times, there was no lake. When the flow of water under one sinkhole became blocked with silt and debris, the resultant flooding created the temporary lake. When dry weather returned, the lake drained and faded away. Imagine this on a grand scale of plugging sinkholes and disruption of the natural drainage.Boyer is looking into treating sinkholes as riparian zones, or hydrologic source areas, which essentially would require planting of trees or other buffering vegetation in them. This would hold the soil in place and serve as a filtering screen for solubles, especially nitrates, removing the pollutants before they reach the underground stream. Stabilizing the soil in sinkholes could also prevent accidents, such as cows falling through the bottom when soil gives away. That happened to one farmer twice before he took it upon himself to plug the hole.Volunteer-organized caving groups have been a great help to Boyer and his research. Using these cavers, the researchers were able to sample the entire cave system in one day. As might be expected, samples are normally taken at the most convenient entrances and streams because of demands of time and manpower, so having crews enter all three caves the same day expedited the survey procedure, and widespread differences in pollutant levels found from place to place help focus on problem areas. Simultaneous sampling removed variables, such as drought and excess water, that occur when one crew has to keep coming back day after day.Very little commercial fertilizer is used on these pasture fields because of the abundance of manure. The Natural Resources Conservation Service and Boyer believe the mitigation of pollution in underground streams lies in continued work with the farmers: close measurement of the amounts of fertilizers and pesticides needed and using BMPs to control animal wastes. Practices include placing collars on cattle to monitor their movements and developing strategies, such as rotational grazing and divisional fencing, to limit their proximity to the sinkholes and reduce the amount of time livestock congregate in sensitive areas. Where dairy cattle are concentrated for milking, berms are used to divert drainage from the sinkholes. Manure and milkhouse waste are also contained. Manure is stored in the fall and winter when the plants can’t use it as fertilizer, and it is distributed during the spring and summer growing season.The karst ecosystem is a completely different world from most farming areas, and as a result of these underground water studies, the farm community is anxious to find out what it can do to make greater use of this knowledge. The farmers are every bit as concerned with their spring and well water as the scientists are, so although they were resistant to any outside interference at first, they are fully cooperating now in developing and establishing these critical BMPs.As our society becomes more urban and less rural, it is important that studies such as those carried out in the beautiful Greenbrier Valley be brought before the public. Agriculture is vital to all of us and needs to know all it can about itself. Farmers are grabbing onto these studies that show what they can do to further reduce pollution of their groundwater and surface water from all sources.
