{"id":7706,"date":"2020-11-05T16:08:03","date_gmt":"2020-11-05T16:08:03","guid":{"rendered":"https:\/\/www.innovationnewsnetwork.com\/?p=7706"},"modified":"2020-12-10T08:12:37","modified_gmt":"2020-12-10T08:12:37","slug":"the-safety-of-our-freshwater-supplies","status":"publish","type":"post","link":"https:\/\/www.innovationnewsnetwork.com\/the-safety-of-our-freshwater-supplies\/7706\/","title":{"rendered":"The safety of our freshwater supplies"},"content":{"rendered":"

Professor Thomas D Shahady from the University of Lynchburg describes the growing concerns over the safety of our freshwater supplies.<\/h2>\n

A question often asked around the world is: is my water is safe? Whether it is the water flowing into a household, through a stream or lake where people swim, or water used for livestock and pets, we all have this common concern. In this article, I describe the growing concerns over the safety of our freshwater supplies.<\/p>\n

Water is the universal solvent. It readily dissolves solutes from surrounding geology often transporting them long distances. Water in your area reflects surrounding conditions and how well or poorly your community is developed. Dissolved nutrients, waste, toxins, plastics, or large woody debris flow daily from our built communities into adjacent neighbourhoods then eventually into our oceans. Dissolved elements influence water chemistry, determining how safe the water may be to drink or swim in. Larger debris such as sediment, plastics, leaves, or tree trunks journey alongside these chemicals, slowly depositing along the way until moved by the next storm event. Chemicals in the water create immediate water quality concerns, while larger debris generates longer-term pollution problems. Nutrients and waste cause bacterial and protozoan growth, while sediment and plastics degrade the habitat and critically impact aquatic life. These problems continue to grow as we develop our watersheds and generate our waste. They threaten the very quality of life and future availability of good freshwater.<\/p>\n

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Fig. 2: The same river shown at low flow and during storm stage. Sediment contaminated with E. coli and nutrients is the predominate constituent in rivers during storm stage causing considerable disturbance and disruption<\/figcaption><\/figure>\n

Waste<\/h3>\n

Waste is now an overwhelming problem threatening all sources of freshwater. By tracking the contamination of water using E. coli, nutrients, and electrical conductivity, research can predict how widespread this problem really is. My work in central Virginia, USA, suggests such problems are growing and becoming untenable to control. Comparing three differing land use areas along the same river demonstrates the problem clearly, along with the difficulty in developing any viable solution for clean-up (see Table 1).<\/p>\n

A local park where people often congregate to swim is contaminated with enough E. coli to be in violation of state standards for recreation. Here is the problem: upstream is minimally developed but contains enough contamination to be problematic. What can be controlled? To further understand this problem, molecular source tracking was used to pinpoint the exact nature of the contamination. While much of the problem stems from wildlife such as deer, human sources are also present. No identified sources of human input are located above this park, but yet it persists. While the human contribution is low, these numbers suggest enough active bacteria are in the water to create a risk for those who choose to use these waters for recreation. The problem worsens near urban centres. Greater concentrations of E. coli flow from these areas. Exiting a city while flowing back into agricultural areas, bacterial contaminations subside but contributions from human sources continue to occur. We cannot avoid human contamination throughout this river basin.<\/p>\n

And then there is storm events. It is well understood that stormwater increases the concentration of E. coli in water dramatically. This trend is consistent throughout all my studies of water quality. So, while concentrations of E. coli increase from stormwater, percent contributions from humans remains constant away from urban areas. These disturbing trends occur in urban areas where human-contributed contamination increases dramatically when it rains. This suggests these areas are poorly designed to properly treat waste to protect our water supplies. Any contact with these waters should be avoided.<\/p>\n

Therefore, consider where you are located when thinking of water cleanliness before you drink or swim etc. While contamination is ubiquitous throughout all streams in a landscape, urban development exacerbates this problem. Water at low stage flow contains proportionally less harmful pathogens suggested by low concentrations of E. coli<\/a>, it still presents a risk and does contain wastes of human origin. Any exposure to human waste risks disease or other health complications. More concerning is the fact that as rivers approach urban or concentrated areas of human development, your exposure to these contaminants increases greatly. Even more concerning, these bacteria are long-lived and can travel great distances downstream, concentrating in other areas. Unless a river is located well above human disturbance in a well-forested watershed, it is likely contaminated by human source bacteria or protozoans such as Giardia.<\/p>\n

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Fig. 3: Relationship between breast cancer and a measure of ecological integrity related to septic tank effluent. Lower scores found in areas of high septic tank usage<\/figcaption><\/figure>\n

Sediment<\/h3>\n

Sediment pollution complicates the problem. Bacteria and nutrients are attracted to sediment particle surfaces, where they grow and proliferate. If the sedimentation is clay, the electrical charge of clay particles attracts nutrients; and the flat surface area not only creates an excellent colonisation surface for bacteria, it also does not settle in the water, thus allowing long transport into bays, estuaries, and lakes. Heavier silt accumulates on stream bottoms with bacteria that will activate upon resuspension. Sediment accumulates as a blanket on river and estuary bottoms and limits sunlight penetration, destroying habitat for wildlife that maintains ecological integrity and which purify the water.<\/p>\n

While this is yet to be confirmed, research suggests sediment harbours E. coli and faecal bacteria for long periods of time. Resuspension during storms or swimming therefore increases contamination and risk of disease. Streams that are relatively clear during periods of low flow become raging torrents of sediment-infused water during storm events (see Fig. 2). This problem is incredibly pervasive and is increasing with development, meaning that the destruction will not be reversed.<\/p>\n

Now, excessive flooding exacerbated through climate change is distributing contaminated water even further throughout our communities. Work that is underway to limit the input of bacteria and nutrients into our streams is helping, but damage from stream bank erosion and stream bed sedimentation has so overwhelmed the capacity of these systems to process these inputs that not much can really be achieved. Stream water is so contaminated by nutrient- and bacteria-laden sediment that this problem will continue until development is curbed and watersheds attain equilibrium with the altered landscape.<\/p>\n

Larger debris<\/h3>\n

Further contamination occurs when plastics, trash, and other large contaminates are swept into streams during storm events. Plastics are an insidious pollutant; they are something perceived as being useful to everyday life, but when released irresponsibly into water, sunlight, and physical mixing breaks them down into microplastics. This will become one of the greatest pollution crises of our time. Microplastics are now found everywhere in soils, lakes, streams, and, most famously, the world\u2019s oceans. Yet, research now suggests freshwater streams and lakes may have even greater contamination than the oceans. These plastics cause inflammation when ingested and act as endocrine disruptors. Over time, we will soon begin to unravel what these microplastics are really doing to our environment and, more disturbingly, to us. In the meantime, we know they are disruptive to our use of freshwater and that, currently, we lack the means to remove them from consumption.<\/p>\n

Large woody debris is another problem threatening our water resources. The movement of tree trunks and other large debris scours stream bottoms, disturbing sediment and destroying habitats. When this debris becomes lodged, the stream course moves around the obstruction eroding large areas of stream banks destroying property. When debris abuts bridge crossings, it compromises the integrity of our bridges through erosion and sheer force on the expanse. This problem creates areas of potential compromise and bridge failure. It also interferes with recreation and navigation in rivers and lakes. The creation and maintenance of strong, well-developed buffers around streams is the best protective measure to combat this problem.<\/p>\n

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Table 1: Measures of waste in a river flowing through various types of land use<\/figcaption><\/figure>\n

Wells and septic systems<\/h3>\n

Septic systems and wells provide drinking water and sanitation for most of the world\u2019s rural population. This water is contained below ground in vast areas of storage know as groundwater. A key question now under consideration is the health of this groundwater:<\/p>\n