1. A. ammonia B. chlorine C. sand D. soap
46. Which substance is used in a sewage treatment system to kill harmful bacteria?
A. ammonia
B. chlorine
C. sand
D. soap

2. A. smallpox B. influenza C. cholera D. AIDS
47. Which disease that once caused many deaths has been limited due to the implementation of water quality standards?
A. smallpox
B. influenza
C. cholera
D. AIDS

3. 48. Who would MOST benefit from being educated in water stewardship?
A. families
B. a neighborhood
C. low volume water users
D. high volume water users

4. 49. Which is an action people can take to protect the water supply?
A. turn off faucets while brushing teeth
B. continue to run water while washing dishes
C. pour cooking oil down the kitchen sink
D. water outside plants during the middle of the day

5. 50. Why is it necessary to have public water treatment systems?
A. to collect and redistribute nutrients in the water cycle
B. to maintain the good health of environments and organisms
C. to manage the runoff from erosion of topsoil and city streets

6. ? A. condensation B. desalination C. evaporation D. infiltration
51. A city near the ocean wants to convert sea water into fresh drinking water. What is the process called ? ?
A. condensation
B. desalination
C. evaporation
D. infiltration

7. 52. Which is most important for protecting the quality of a local river basin?
A. reducing industrial activities in rural areas
B. planting and protecting plants around streams and lakes
C. reducing recreational activities around lakes and streams
D. planting and protecting plants in neighborhoods and parks

8. 53. Indicators of aquatic health are BEST observed under which conditions?
A. once every 10 years
B. at the surface every year
C. once a year at many depths
D. many times a year at many depths

9. 54. Why is filtration an important part of water treatment?
A. generates a clear coloring in water
B. removes small particles from the water
C. adds chlorine to water to kill bacteria
D. adds vitamins and minerals to water

10. 55. Which BEST explains why water quality standards are necessary?
A. to maintain clear water
B. to maintain fresh tasting water
C. to prevent water from having any trace of pollutants
D. to prevent water from having excessive levels of pollutants

11. 56. Which human activity has the MOST negative impact on water quality?
A. agriculture
B. flushing toilets
C. washing clothes
D. recreational boating

12. 57. Which organism uses nitrates from its fresh water habitat as a primary source of food?
A. fish
B. birds
C. algae

13. 58. Which act of stewardship MOST DIRECTLY impacts the water cycle?
A. walking to work or school
B. recycling aluminum cans
C. limiting showers to 10 minutes
D. carpooling to school or work

14. 59. How does the use of fluoride in drinking water affect the human population?
A. it helps prevent tooth decay
B. it kills the bacteria
C. it regulates pH of the water

15. 60. Why do state governments MOST LIKELY monitor the quality of their local water sources?
A. to sell water to other states
B. to help prevent global warming
C. to maintain a healthy environment
D. to save the environment for future generations