Climate Change Impacts in the Southwest

Warmer and probably drier overall with more extreme droughts and heat waves

• Likely reduced quantities of surface water available from local runoff
• Likely reduced quantities of water available to recharge groundwater aquifers
• Very likely increased evaporative losses in inter-basin transfers of surface waters
• Changes in vegetation of watershed and aquifer recharge areas

• Altered recharge of groundwater aquifers
• Changes in quantity and quality (e.g. TOC, alkalinity) of runoff into surface waters

• Increased water temperature

• Increased evaporation and eutrophication in surface sources
• Water treatment and distribution challenges (e.g. disinfection, byproducts, regrowth)

• Increased water demand

• Increased irrigation demand
• Increased urban demand with more heat waves and dry spells
• Increased drawdown of local groundwater resources to meet the above consumption
• Increased difficulty of maintaining minimum in-stream flows in surface waters

More intense rainfall events

• Increased turbidity and sedimentation

• Loss of reseroir storage

• Shallower, warmer water; increased evaporation and eutrophication
• Potential conflicts with flood control objectives

• Water filtration or filtration/avoidance treatment challenges

• Increased risk of direct flood damage to water utility facilities

From: Implications of Climate Change for Urban Water Utilities." Association of Metropolitan Water Agencies. Washington D.C: Stratus Consulting Inc., 2007.