Los Angeles Water Crisis:

Where’s the Water?

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The Truth about Fresh Water Scarcity

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What is a Water Crisis?

• Definition: the available fresh water within a region is less than that region’s demand– Causes may include

• Increased population growth• Lower-than-usual annual rainfall• Contamination of local water

supplies

– Effects may include• Government regulation on water

usage• Increased water costs• Increased food costs

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Water Crisis in Los Angeles

• Los Angeles Water Supply is NOT Sustainable– Most fresh water is imported from 100+ miles away

• Sierra Nevada mountains• Major rivers and deltas

– Less than 50% of LA water is from local sources• This can be increased in times of drought for short periods of

time

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Where Does LA’s Water Come From?

Los Angeles

San Joaquin Delta

370 miles

Colorado River280 miles

Owens River210 miles

Top 3 Sources of LA Water

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The Proposed Solution

• Reduce Use of Non-Local Water– Use local reservoir reserves

• Reduce imported water

– Increase use of groundwater (water below Earths surface)• 30% of LA water comes from groundwater (60% in a drought)

Groundwater(LA Source)

Reservoirs(LA Source)

Mountain Spring(Imported Source)

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Natural Water Requires Purification

• Passive Filtering and Purification– Gravity pulls water through filter

• Each filter stage traps different types of particles and microbes

• Has difficulty separating extremely small particles (i.e. dissolved solutions)

• Active Filtering and Purification– Pumps force water through filter

• Pressurized water can be forced through smaller filter holes

• Able to capture dissolved particles• High energy requirements = EXPENSIVE

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Water Filtration Activity• You will now…

– Build a water filtration tower with 4 filter stages• Gravel

– Traps large particles in gaps between gravel pieces• Sand

– Traps smaller solid particles in gaps between grains• Active carbon

– Traps / absorbs substances inside small holes in surface» FUN FACT: 1 gram of active carbon has more

surface area than a basketball court• Filter paper

– Very small holes strain out the smallest contaminants

– Filter different types of dirty / contaminated water– Analyze the effectiveness of the water filter tower– Use what you learn to “solve” the LA Water Crisis