1. How do we use the freshwater available to us?
Uses of Freshwater
How do we use the freshwater available to us?

2. Farming
40% of US water usage is to grow plants and raise livestock

3. Farming
Irrigation is used to supply water from aquifers, rivers, or lakes to grow crops.
Flood irrigation: pours water through canals and waterways
Spray irrigation: sprays water onto crops

4. Industry Almost every item uses water to be made.
Cool down machines
Separate coal from dirt and rock
Factories should clean the water they use and return it to lakes/rivers

5. Transportation/Recreation
Rivers and lakes are used for transporting goods.
Great Lakes
Swimming, fishing, canoeing, etc. provide entertainment.

6. Fisheries and Aquaculture
Aquaculture: the science and business of raising and harvesting fish.
Pro: Provides cheap source of catfish, trout, and salmon
Con: excess pollution in rivers/lakes

7. Energy
Dam: structure that holds back and controls the flow of water in a river or body of water.
Water turns turbines that generate electricity
A lake behind a dam is used for freshwater (called a reservoir).
Some people rely on these for freshwater.

8. Energy
Lock: a section of waterway closed off by gates which raises or lowers the water level for boats.
Negatives:
Changes the natural way a river develops
Can damage soil
Effects the habitat for fish and other organisms

9. Society Depends on Clean/Safe Water

10. Freshwater can contain impurities that are harmful.
Small concentrations are usually safe, but larger concentrations can be harmful.
A concentration is the amount of one substance in another one.
How do we keep our water clean?

11. Environmental Protection Agency (EPA)
Agency that sets standards for clean, safe water.
If water does not meet the standards, then it has to be “treated”.

12. Treating water – Step 1
Water is sent to treatment plants in pipes.

13. Treating water – Step 2
2. Water goes through a mixer with chemicals and clumping agent.

14. Treating Water – Step 3
3. Water goes into clarifying pool and sediments sink down.

15. Treating Water – Step 4
4. Water goes through layers of sand, gravel, etc. to filter.

16. Treating water – Step 5
5. Chlorine is added to kill bacteria.

17. Waste water treatment
Waste water must also be treated before it can be reused.
Sewage system or Septic system

18. Sewage system treatment
System collects and treats waste water from a whole city or town.
Part 1: remove largest/heaviest waste and add chlorine.
Part 2: pump extra oxygen in to create bacteria that eats waste materials and add purifying chemicals.

19. Septic System Treatment
This is a smaller scale system (few homes, etc).
Waste water flows in
sludge and large particles sink
clean water flows into the ground.

20. Water Pollution
Point source pollution: pollution enters water from known sources.
Easy to spot
Laws can stop it
Non-point source pollution: pollution whose source if hard to find.

21. Preventing Pollution Industry/transportation:
Factories can clean pipes
Reuse and recycle chemicals and materials
Inspect and fix vehicles to prevent oil or fuel leaks

22. Preventing Pollution Agriculture
Keep livestock away from streams and lakes
Reduce use of pesticides
Organic farming

23. Preventing Pollution
At home:
What are your ideas??

24. The water supply EVERYWHERE is going down.
Water Shortages
The water supply EVERYWHERE is going down.

25. Why? Drought: long period of abnormally low rainfall.
Overuse: farming takes up 2/3 of the world’s freshwater, but only ½ gets used
Aquifers are emptying
Rivers are drying up

26. Conservation Use less water (repair leaks)
Reuse water (treat waste water and use for landscape)
Recycle water (use it again)

27. Desalination The process of removing salt from salt water
It is a very expensive process

28. Icebergs As we learned, icebergs contain a great deal of freshwater.
It is too expensive to bring them to the city to use, though.