T Water Cycle Water C - US EPA

1 A 1 THEWATERWE VEGOTISTHEWATERWE VEGOTThe Water available to planet Earth is the samewater that has always been available and the onlywater that ever will be available. Because watercovers three-quarters of the earth s surface, itmight appear that there is plenty to go around. Inreality, however, we have a limited amount ofusable fresh Water . Over 97 percent of the earth s Water is found inthe oceans as salt Water . About two percent of theearth s Water is stored in glaciers, ice caps, andsnowy mountain ranges. That leaves only 1 per-cent of fresh Water that is readily available to usfor our daily Water supply needs. Our fresh watersupplies are stored either beneath the ground, insoil or fractured bedrock, or in surface waters,such as lakes, rivers, and use fresh Water for a variety of , agricultural uses represent the largestconsumer of fresh Water , about 42 39 percent of our fresh Water isused for the production of electricity; 11 percentis used in urban and rural homes, offices, andhotels; and the remaining 8 percent is used inmanufacturing and mining activities.

2 *THENEVER-ENDINGJOURNEYIf you think about it, Water never stays in oneplace for too long. Water is always on the move,traveling on a never-ending, cyclical journeybetween earth and sky. This journey is referred toas the Water Cycle , or hydrologic Cycle . During itsjourney, Water is continuously reused and recy-cled. It also changes form. It falls to the earth asrain, snow, sleet, or hail and evaporates from theearth back into the atmosphere as Water vapor. What form Water takes and where it goes once itreaches the earth depends on where it lands. Itmight seep into the ground and move along slow-ly with the ground Water to a nearby lake, stream,or estuary.

3 It might sink into the ground, be takenup by a plant, move through the plant to itsleaves, and evaporate back into the atmosphere(transpiration). It might land on a lake or pondand spend a season or two freezing and thaw-ing that is, changing from liquid to solid, andvice versa. It might land on a river or stream andcontinue on to the ocean. It might be heated bythe sun, evaporate into the atmosphere, condenseinto tiny droplets, and become part of a cloud for-mation. Eventually, the Water in the cloud fallsback to the earth, and the journey begins the total amount of Water on earth remainsconstant, the availability of that Water changeswith weather (for example, drought or flooding),season, and human use.

4 This problem is madeworse in situations where communities use waterfrom one location but release it into another placeafter it is used. In Massachusetts, for example,many communities in the Boston metropolitanarea drink Water from the Wachusett, Ware, andQuabbin Reservoirs located in central and westernMassachusetts, but discharge that Water as waste- Water into Boston Harbor. * Water use statistics from the National Water Summary 1987 Hydrologic Events and Water Supply and Use. GeologicalSurvey Water Supply Paper Water Cycle and Water Conservation A 2 If we understand that we have all the Water thatwe will ever have, we can better appreciate why itis so important that we keep our Water clean.

5 Thefresh Water that is available for use by people,plants, and animals must be clean. And to thisend, nature is very accommodating. The waterthat circulates between the earth and the atmos-phere is continually restored and recycled thanksto Mother Nature s impressive bag of biological,chemical, and mechanical sometimes human carelessness bogs down thesystem, loading harmful and unhealthy substancesinto the system at a rate that exceeds its naturalrestorative capabilities. When harmful substancesare discarded into the environment, they may verywell end up as part of the Water Cycle . Nature canalso stir up some environmental problems as aresult of natural events such as volcanoes, earth-quakes, and chemicals are released into the air fromsmokestacks, for example, they might well returnto the earth with rain and snow or by simply set-tling.

6 When harmful substances are discardedonto the land or buried in the ground, they mightwell find their way into ground Water or surfacewater, which may, in turn, be someone s or somecommunity s drinking Water . In nature s watercycle, all things are many ways, we, as a society, have had to learnabout managing and caring for our waterresources the hard way. By the early 1970s, manyof our nation s Water supplies had become foul-smelling and unhealthful. In 1972, recognizingthat we could no longer turn our collective backson the problem, Congress passed the Clean WaterAct, thereby setting in motion the beginning of aconcerted effort to rehabilitate the nation sdegraded waters.

7 Taking our cues from MotherNature, we have over relatively few years devel-oped biological, chemical, and mechanical tech-nologies that effectively clean wastewater before itis discharged into waterbodies. Keeping Water clean is not just our nation s prob-lem; it is a worldwide problem. Many othernations are trying to manage their waterresources. Preventing Water quality degradationfrom occurring in the first place is certainly themost cost-effective approach to Water qualitymanagement. The Water quality in some areas ofthe world has deteriorated to such an extent thatthe cost of turning the problem around hasbecome issue of Water conservation is not about saving Water it is about having enough cleanwater at any given time and place to meet ourneeds.

8 Gifford Pinchot, an American conservation-ist and politician who served as chief of the Service between 1898 and 1910, referred toconservationas The wise use of the earth and itsresources for the lasting good of men. The con-servation of our Water resources depends on ourwise use of these resources. Such wise use, without a doubt, begins at home and in ourcommunity. As we attempt to meet the Water use needs of agrowing population, issues of Water quality andquantity will gain increasing significance in yearsto come. We cannot afford to take our waterresources for granted not even here in the Water -rich Northeast. Droughts, for example, are natur-al occurrences that can cause Water shortages.

9 But human activities can cause Water availabilityproblems as well. In some instances, communitieshave had to seek other sources of drinking waterbecause their Water supply well had been contami-nated. For example, infiltration of gasoline from aleaking underground storage tank into a groundwater supply well is all it can take to render awell field unusable. Once ground Water becomescontaminated, it can take years or decades for itto clean itself Up to Speed:The Water Cycle and Water ConservationTHEWATERCYCLE ANDWATERCONSERVATIONA 3 To some extent, we all share responsibility forensuring the availability of a clean and healthywater supply.

10 We can try to reduce contaminationby keeping the Water , the ground, and the air freeof pollutants as much as possible. We can use justthe amount of Water that we need. Industries can recycle their process Water or pre-treat their wastewater so that it is easier to purifyfor drinking Water and other can educate residents about localwater resources and work together to implementland use strategies that will protect and sustainwater supplies into the future. They can developplans to handle Water shortages without waitingfor a Water emergency and can help residents dis-pose of harmful products properly by offering haz-ardous waste collection days.