| Fresh Water Supplies At Risk, Part 3: Repairing the Water Cycle |
| Wednesday, 17 June 2009 | John Potter | Article |
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Water moves through watersheds, or drainage areas, which act like giant geographic funnels pulling all of the surrounding surface water to a river or stream. Environmental factors within each watershed directly affect the quality of water passing through it. Nature's way of purifying water is through filtration, sedimentation, organic breakdown of materials, ion-exchange, oxidation-reduction and sorption-desorption. Some of these methods are not dissimilar to those we use in purification and waste treatment, but are much better. The big difference is that nature works more slowly than man-made systems; in fact, the more slowly the process proceeds, the more effective the purification. As water moves slowly through a swamp, wetland or stream, particulate matters settle out as silt or are filtered out in percentages of around 80%. Wetlands remove between 20 to 60% of heavy metals that pass through them. Naturally occurring bacteria, fungi and algae also play a part in breaking down harmful pollutants. We usually recognize them as unsightly slime, foam or some other gross material, but these are purifying organisms altering the molecular makeup of waste into something more benign. Also within the biological heading, but generally larger, are filter feeders, which include caddisflies, black flies and shellfish. Preserving natural areas that aren't necessarily wetlands also contributes to a better, cleaner water supply. As discussed in "Fresh Water Supplies At Risk, Part 2: Groundwater," the destruction of large areas of permeable ground poses a risk to our natural aquifers. Development can prevent water from seeping into the ground; rather than recharging the aquifer, the water runs off, lowering aquifer water levels. Although the environmental method of purification requires patience, which is not one of modern man's greatest character traits, it does present significant cost savings, which should have more popular appeal. New York City considered building a new $6 billion filtration facility that was going to cost $300 million a year to operate. Instead, the city spent $1 billion on restoration and preservation of its existing natural watershed. That cost was used for land purchases, payments to land owners for maintaining natural easements, compensations for residents in the watershed region for restrictions on development, and more. Thus, the community and the environment benefited, while the city saved $5 billion plus. Science shows that protecting our ecology benefits our health through improving our water quality. Economics show that preserving the environment saves us money that we would otherwise spend on inferior methods of water purification. People living in these preserved areas may not be allowed to develop in the same ways as residents of cities, but they are encouraged to pursue tourism and recreation dollars while enjoying a higher quality of life. Unfortunately, New York City's plan to use an environmentally sound method of obtaining fresh water has encountered problems. Reports of water contamination have been reported, blamed on natural-gas drilling operations allowed near the watershed. Another example of environmental destruction leading to water-supply degradation is Fincha’a Watershed in Ethiopia. A hydropower dam was constructed in 1973, with an additional one built within the same watershed across the Amartii river in 1987. These dams have produced a reservoir that now covers a third of the watershed. Although originally heralded as a means of supplying electricity to the people, the projects have been plagued by problems. The area was originally swampland, grazing land, rivers and streams. When the dams were built, displaced residents were not properly compensated and most have been reduced to sharecropper status. Since the rivers were dammed, the flooded area of the reservoir has varied wildly, making it difficult to farm in some places and impossible in others. Soil erosion has also gotten out of control, contributing to thick layers of sediment. It can be traced to the displaced farmers from the reservoir area. Many have relocated to higher and more sloping lands, which are inappropriate for farming and prone to erosion. For all that trouble, somewhere between 12 and 20% of the population of Ethiopia now has access to electricity. Scenic river damage due to environmental destruction is also a major concern. Although some of the damage to Colorado’s Roaring Fork River can be attributed to diversion of water for irrigation and agricultural use, much of it is ironically caused by people's desire to be close to the river and enjoy its beauty. Too much pavement and construction near the river, as well as depletion of native plants and the introduction of non-native grasses for lawns, have significantly degraded the river and adversely affected water quality. Although there have been wastewater spills into the river, both individuals and the general public must accept a large degree of the blame for the degradation. The Ethiopean and Colorado situations were very different. In the former, humans were struggling to survive. In the latter, they had unlimited options of where to live. In both cases, human activity led to ecological destruction. Living in harmony with nature always requires sacrifices, yet the rewards are great. And the penalties for ignoring or trying to dominate nature are severe--sometimes even fatal. See other parts of this series: Part 1 | Part 2 | Part 4 Additional resources:
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Not all solutions to our clean-water supply problems require enormous and complex man-made engineering endeavors. The water cycle was here on Earth before man, and it has worked just fine for millennia. Sometimes the best thing we can do is return our planet to its original state (or as close as possible) and let nature repair itself. 
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