Externalities are unintended consequences which affect other people or properties. Long term negative externalities were termed the Tragedy of the Commons by the ancient Greeks. Since water is fluid and freely crosses property lines, water provides us some of the most notorious examples of externalities. To make our choices resilient and sustainable we must address each of these externalities. Here we will list the major examples.
Overuse & Depletion
Resources can only be used sustainably if the fastest average extraction rate remains lower than the typical replenishment rate. We can only achieve resilience by keeping the fastest demand smaller the slowest supply. For the rivers and reservoirs in Buncombe County this is rarely an issue. But for ground water, we are already at the point of concern.
It’s a classic example of the Tragedy of the Commons. Any well extracts water from multiple properties, not the just property that owns it. One house with one well will not drain the aquifers. But many houses with wells will draw water ground quicker than rainfall naturally replenishes it.
The excess draw is exacerbated by construction methods that interfere with the normal replenishment processes. Normally, snow and rainfall will pool in various places on the ground then percolate through the ground into the aquifers. But our construction methods create impermeable barriers at the surface and drain water away to the river quicker than the ground can absorb it. The result is that we are drawing water from the ground faster than it replenishes leaving future generations to deal with a long term ground water drought.
Flow alteration & increased runoff and flooding
The very construction practices that prevent water from percolating into ground aquifers increase the speed at which the water hits the river. This increases the impact of flash flooding downstream. It also increases the flow rate increasing erosion. Primary contributors to this include roads, parking lots, large constructions, and grading properties to prevent standing water. Again, the combined effects of small changes on many properties results in large impacts to the river which is common property.
Contamination & Pollution
Water pollution also constitutes the Tragedy of the Commons. The summation of the small actions of each of us adds up to have large long term impacts on aquatic ecosystems and the water supply. We will list a few major examples that potentially threaten the Katua water supply.
Sediments and Turbidity: If too much sediment hits the river too quickly it can kill the fish. Farming based in heavy tilling and construction loosen soil such that in washes away easier during heavy rains.
Nutrients, eutrofication, the nitrogen cascade, dead zones: Various human activities increase nutrient flow into rivers. This includes fertilizing farms, sewage, and phosphate soaps. The excess nutrients disrupt the ecosystem frequently killing most of the life through hypoxia.
Pesticides & herbicides: Although using pesticides might increase food production in the short term, they collect in the streams and aquatic ecosystems. Many have harmful effects on important parts of the food web.
Oil, solvents, & industrial wastes: Oils and solvents wash off the roads, landfills, or places they have been spilled during heavy rains. Some microbes can eat the oils, but this will not happen if they hit the rivers too quickly. Sewage treatment plants do not process oils or industrial wastes. The wastes just pass through the treatment into the rivers.
Road salts: Salt on the roads in the winter time may make driving safer. But they wash off the roads into the rivers, lakes, and aquatic ecosystems. A build up of salt over time will undermine many ecosystems destroying their ability to produce food.
Mercury, heavy metal, & acid: Mercury and heavy metals cause many health effects including brain damage. The primary source of mercury and heavy metals is coal burning power plants where they are found in the fly ash, or in the scrubbers. Other heavy industry can also emit mercury or heavy metals. Acidification of the rivers can cause the rivers to leach heavy metals out of the rocks. Heavy metals are absorbed into the fatty tissues of insects and fish. From there they proceed up the food chain concentrating in humans and birds.
Thermal pollution: The primary source of thermal pollution is power plants or other heavy industry. Thermal pollution can lead to thermal shock which kills the fish in the river. It can also make the water an improved breeding ground for pests and illnesses.
Water borne illnesses: Water borne illnesses tend to increase when human activity adds sources of germs to the water supply, such as sewage, make the water more hospitable to germs.
Above we have reviewed choices that can have a major impact on the sustainability of our water supply. If we don’t change these choices our dependence on water will become less resilient until we can no longer sustain. It is up to us as a community to mitigate each of these impacts and replace them with sustainable choices.