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

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

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

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

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

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

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.

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

Society Depends on Clean/Safe Water

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?

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”.

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

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

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

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

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

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

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.

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.

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.

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

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

Preventing Pollution At home: What are your ideas??

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

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

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

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

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