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Natural Resource Systems Sample LessonNR016 Defining and Understanding Water Quality
MAIN IDEA: What is water quality and what are the factors that can upset the natural balance that keeps water quality high? To define the term "water quality," you need to give some consideration to how the water is to be used. The water in a pond may provide a very good home for a frog, a turtle or some types of fish, but it may not be safe to drink.
THE CLEAN WATER ACT The Clean Water Act requires states to conduct water quality surveys and report to the Environmental Protection Agency on how well they have met their fishable and swimmable goals. The Clean Water Act also requires that all beneficial uses comply with the goals of the Act. At a minimum, states must provide for, "the protection and propagation of fish, shellfish and wildlife" and provide for "recreation in and on water." In addition, the EPA encourages states to include a number of beneficial uses in its standards and surveys. These uses include:
Other uses may be added by states and tribes. For example, some states also apply "groundwater recharge" standards to protect groundwater uses from surface water that recharges groundwater sources. Some states also add "wildlife habitat" standards that include the use of water by land-based wildlife as well as aquatic life. In addition, some tribes include "culture" standards that maintain water bodies for their cultural and religious ceremonial uses. HOW NATURE ALTERS WATER QUALITY You have learned about the hydrologic cycle in earlier lessons. This is the natural process by which the earth recycles its fresh water supply. The cycle starts as water evaporates from oceans, lakes, soil and other surfaces. In addition, water is transpired into the atmosphere from plants. Water vapor in the atmosphere is changed from a gas to liquid by a process called condensation. As water vapor cools, it forms tiny water droplets which form clouds in the sky. As the tiny droplets bump into each other they become larger drops and fall as rain, sleet, hail or snow, called precipitation. When precipitation falls, it provides moisture for plants and animals as well as recharging lakes and streams. However, the quality of the precipitation can also influence its value for beneficial uses. Rain, sleet or snow can pick up contaminants from the atmosphere before they reach the earth. Acid rain is an example of contaminated precipitation. Filtering of water by soil is an important natural process that helps to improve water quality. Soil can screen out bacterial and viral contamination by the time it reaches 5 to 10 feet in depth. However, there are other minerals, gases and pollutants that can bypass soil filtration. Pollution from human activities cause the greatest concern. However, nature may also contaminate water in ways that make it unsuitable for some uses.
Natural contaminants of groundwater include methane and hydrogen-sulfide gasses as well as calcium, magnesium, sodium and potassium. The hardness of water is caused by mineral content. Hard water makes soaps less effective, leaves deposits on pots and pans, and coats water heater elements. HOW HUMANS ALTER WATER QUALITY Many problems with water quality also occur when human activity interferes with natural cycles. Water quality problems can begin as soon as precipitation falls to earth. Ecologists refer to the land upon which precipitation falls as the lithosphere and the plants and animals that consume water as the biosphere. Water that is not consumed by the biosphere moves into lakes, streams and groundwater. These provide sources of water for human activities, such as drinking water, washing, cleaning, power generation, industry and irrigation. Water that is used by humans and industry must go through expensive treatment before it is returned to the water cycle. The quality of water that is returned depends upon the treatment required. Water consumed for agricultural purposes is returned without treatment. Runoff water can damage water quality if it contains pollutants. The term nonpoint pollution is often used when the source of contamination cannot be clearly identified. This may include runoff from farm fields, suburban lawns, golf courses and construction sites. Runoff water may also contain contaminants such as soils, fertilizers and pesticides. Runoff from livestock farms and feedlots may contain manure which can include excess nitrogen and other elements as well as pathogens. EUTROPHICATION Eutrophication is a term scientists use for the by-product of human activities which disturb the natural balance of water quality. Eutrophication is created by the buildup of plant nutrients in a body of water. Normally it results in the excessive growth of plants, especially algae. The main element which causes eutrophication is an excessive amount of phosphorus found in freshwater sources. An eutrophicated body of water has a murky and cloudy appearance. Algae blocks out essential sunlight which limits fish life. The type of biological activities changes in ways that alter the way the water can be used. Beneficial uses are limited or eliminated. Phosphorus gets into water from a number of sources. Runoff from farm fields and feedlots is one of them, but not an important source. An estimated 70 percent of the excess phosphorus comes from household detergents. It may also get into water from construction sites and sewage discharges. Eutrophication can also be caused by thermal pollution. Many industries use water as a cooling agent. Warm water returned to the water cycle stimulates the growth of algae, which contaminates the water supply. EXERCISES: Write a brief report on water quality in your state which answers the following questions. If time is available, discuss your answers in class. 1. Get a copy of your home state's water classifications from your state's code of regulations. Find and list the beneficial uses that are covered. Select the beneficial use that is most important you and explain why. Which use is second most important? Explain. If you are unable to get a copy of your state's standards, select from the general classifications in this lessons. 2. Explain how the beneficial use you selected in Exercise #1 could be influenced by other beneficial uses listed. 3. Try to identify an example of eutrophication that has taken place in your area. Discuss what may have caused it. What do you feel could be done stop the eutrophication or reverse the process?
INTERNET RESOURCES:
** Cornelll University - Eutrophication Experiments
** U.S. Department of Agriculture - Agricultural Phosphorus and Eutrophication, 2nd edition
** U.S. Environmental Protection Agency - The Plain English Guide to the Clean Air Act
** U.S. Geological Survey - Eutrophication TEST: 1. The Clean Water Act requires states to set water quality standards for drinking, swimming, fish production and agriculture. TRUE or FALSE?
2. Which of the following are elements of state water quality standards? 3. The term anti-degradation refers to maintaining existing uses even when the water quality exceeds fishable and swimmable goals. TRUE or FALSE?
4. Which of the following terms is defined as the sphere which contains all of the plant and animal life on the earth's surface? 5. Human activities such as farming, waste disposal and building construction have been the main cause for lowering the quality of groundwater used for drinking, cooking and other household purposes. TRUE or FALSE?
----------------------------------------------------------------------------- END STUDENT SECTION NR016 Defining and Understanding Water QualityTEACHER'S GUIDEOBJECTIVE: Students will be able to explain how water quality is defined by states based upon beneficial uses under the Clean Water Act, and will be able to list and discuss factors that have an impact on water quality.PREPARATION: Review lesson content and be ready to help students identify local examples of eutrophication and discuss what may have caused it and how it could be stopped or reversed. Help students get a copy of your state's water quality classifications. In most states, water quality is handled by the Department of Natural Resources, or a water quality, environmental or ecology agency. INTERNET RESOURCES:
** Cornelll University - Eutrophication Experiments
** U.S. Department of Agriculture - Agricultural Phosphorus and Eutrophication, 2nd edition
** U.S. Environmental Protection Agency - The Plain English Guide to the Clean Air Act
** U.S. Geological Survey - Eutrophication IMPORTANT TERMS: anti-degradation statements, atmosphere, beneficial uses, biosphere, contact recreation, eutrophication, hydrologic cycle, hydrosphere, lithosphere, narrative criteria, numeric criteria, water quality. EXTENSION: As a class project, ask students to draw a large wall map of your school district. On the map, identify important bodies of surface water, such as rivers, lakes and streams. Also, ask students to create and place icons on the map that identify where beneficial uses of water such as fish propagation, fishing, swimming, irrigation, power plants, etc. are taking place. Map could also include major points at which groundwater is being used, such as municipal pumping stations and areas where irrigated farms and major industries use groundwater from wells. EXERCISE ANSWERS: 1. Answers depend on student preferences. Drinking water and recreational uses may get significant attention. 2. Student should come to recognize that some uses can cause a disruption of the ecosystem, and that some uses may come into conflict with other uses. For example, water that supports aquatic life may not be good for swimming, or safe for drinking. Use of water for agriculture may lower water levels needed for other uses. There also are positive interactions. Natural filtering of water through wetlands helps to support fish and wildlife, while filtering water sources needed for groundwater recharge, drinking and swimming. 3. Answer depends upon local situations that can be identified. A farm pond that has had runoff from fields or a feedlot is a typical example. Another typical example is a small lake that has been influenced by wastewater disposal that contains detergents. Solutions may include methods of reducing runoff, keeping wastewater out lakes and streams, and regulations on the phosphorus content of detergents. TEST KEY: 1. The Clean Water Act requires states to set water quality standards for drinking, swimming, fish production and agriculture. TRUE or FALSE? FALSE. The Act allows states to set their own standards which include selecting their own beneficial uses. It requires that the uses selected comply with goals of the Act.
2. Which one or more of the following are elements of state water quality standards? Correct answer: All are included in state standards. 3. The term anti-degradation refers to maintaining existing uses even when the water quality exceeds fishable and swimmable goals. TRUE or FALSE? TRUE.
4. Which of the following terms is defined as the sphere which contains all of the plant and animal life on the earth's surface? Correct answer: B. Biosphere 5. Human activities such as farming, waste disposal and building construction have been the main cause for lowering the quality of groundwater used for drinking, cooking and other household purposes. TRUE or FALSE?
FALSE. Groundwater often contains natural contaminants that alter its taste, odor, color and hardness. Natural contaminants of groundwater include methane and hydrogen-sulfide gasses as well as calcium, magnesium, sodium and potassium.
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