A. CA’s Drought Current water infrastructure depends largely on snowpack According to UC Berkeley studies – CA may be entering worst period of dryness in 500 years – = driest record in about 1200 years UC Davis estimates agricultural economic losses to be ≈ $2 billion & roughly 17,000 jobs lost

A. CA’s Drought Biggest users of water – Farming Produce half of the fruits and vegetables in the US Produce more than 90% of the country’s grapes, broccoli, almonds, and walnuts – Alfalfa (used to feed cows) – Almonds

A. CA’s Drought CA uses 1,955,000,000,000 (6 million acre- feet) more gallons of water each year than rivers and aquifers can sustainably provide Every year, CA could save up to 4,456,000,000,000 (14 million acre- feet)…HOW?

A. CA’s Drought Agricultural Efficiency (≈5.6 – 6.6 million acre- feet) Smart irrigation scheduling (watering crops when they most need it) Expand efficient drip and sprinkler irrigation technology Water Reuse (≈1.2 – 1.8 million acre feet) Use recycled water to irrigate landscapes and crops Install graywater systems to water lawns and flush toilets Recharge groundwater with recycled water

A. CA’s Drought Stormwater capture (≈0.4 – 0.6 million acre feet) Install rainwater barrels and cisterns at homes and businesses Recharge groundwater with stormwater runoff Better urban efficiency (≈ 2.9 – 5.2 million acre feet) Replace grass with native and drought tolerant plants Replace inefficient plumbing fixtures and appliances Find/fix water leakage in buildings and homes Operate cooling towers more efficiently (in factories and offices)

B. Is All Water Usable? Millions of deaths each year caused by waterborne diseases Sewage – waste water from homes – Carries large numbers of microbes (a disease causing bacterium)

B. Is All Water Usable? Water Pollutants – Nitrates (NO 3 – ) from fertilizers dissolve easily in water  tough to remove – Older houses & water supply systems still use lead pipes  lead dissolves into the water (toxic) – Pesticides from farmers are washed or blown into streams/rivers

C. Common Water Purification Techniques Filtration – Polluted water is passed through layers of sand and gravel  “catches” particles in water Sedimentation – Chemicals added that cause tiny particles to “clump” together  allows them to be caught by filtration Chlorination – chlorine gas is injected into water  kills microbes Adsorption – adhesion of atoms, ions, or molecules onto a surface  Activated carbon often used

D. Desalination Desalination (desalinization) – removal of salt (and other minerals) from water – Reverse osmosis  water is pumped across a semi-permeable membrane (filters out unwated material) – Distillation  uses heating (evaporating water) and cooling (recondensing water) to purify

D. Desalination PROS Proven and effective method Massive amounts of ocean water Would help preserve current freshwater supply CONS Costly processes (required considerable amount of energy to desalinate water) Expensive to build desalination plants Resulting brine (very salt rich) can have a negative impact on the environment

Carlsbad Desalination Plant Set to be complete by 2016 Largest desalinization plant in the Western Hemisphere Costing taxpayers $1 billion Produces 50 million gallons of water per day Provide ≈ 7% of San Diego County’s water needs