| Fresh Water Supplies At Risk, Part 2: Groundwater |
| Saturday, 13 June 2009 | John Potter | Article |
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Potential aquifer contamination is why gas stations have such strict rules regarding their underground tanks. Even the small puddle of oil under your car in the parking lot has the potential of seeping into the ground and coming out of your kitchen faucet. Other major threats include fertilizer leaching into groundwater, pesticide intrusion and landfill seepage. Many of these hazards are lessened by good regulation and best practices as well as improved technology, but there are many other steps that can be taken to preserve these essential underground ecosystems. Groundwater in our aquifers can be kept prisitine by preserving our natural swamps and wetlands. The mud and clay found in these areas helps purify the water--filtering out even tiny particulate matter. Also, it is important to avoid the destruction of large areas of permeable ground. In other words, where there is a big parking lot, water cannot seep into the ground. This means that rather than recharging the aquifer, the water runs off (probably contaminated with various automobile fluids and more). Overexploitation of water can lower aquifer water levels which can lead to disaster. In some places where the rock matrix that holds the water below ground is porous (caves full of water), cave-in of the aquifer is a risk. In an underground cave, around 85% of the weight of the ceiling is held up by water pressure. If the water level drops below a certain point there will be a collapse. These are called sinkholes. During a dry period in 1981, one opened up in Winter Park, Florida, 300 feet in diameter—consuming a car dealership, a public pool and a large chunk of major road in the span of 24 hours. The sinkhole is now called Lake Rose. An additional issue is saltwater intrusion—a serious problem for coastal aquifers. When water levels drop due to overexploitation, ,an aquifer close to the coast cannot hold back the salt water of the ocean. This results in inland wells that used to produce potable water now yielding saltwater. This is happening in most coastal US states (with the possible exceptions of Alaska and Oregon) and many European countries including Germany, Spain, Italy, Turkey, Denmark, Portugal, Hungary, Romania and Moldova. Misuse of aquifers can damage underground worlds we never even see (until, of course, a sinkhole devours a car dealership). However, the environment we don't see is as important to the web of life as the forests we walk through, or the air we breathe. Protection of our aquifers is essential to providing clean water to future generations, and to maintaining the balance of natural processes we too often take for granted. See other parts of this series: Part 1 | Part 3 | Part 4 Additional resources:
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Only one-percent of liquid freshwater is on the surface of the Earth; 99% is underground, held in what are called aquifers, water-bearing rock layers that serve as vast natural warehouses of fresh water. Aquifers can be found virtually everywhere on the globe, but they aren't always easily accessible, and those that are can be more susceptible to contamination. Once an aquifer has been contaminated, it is not easy to return it to its original state. The "out of sight, out of mind" quality that makes them easy to pollute also makes them difficult to clean. 
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