This is a good Q&A on water issues from The Nature Conservancy - - link. From the article:
If the definition of insanity is making the same mistakes over and over, then many cities have taken a certifiable approach to securing their water supplies — and they need some radical therapy before taking the big economic, ecological and human hits that come with a permanent state of thirst.
That’s the conclusion from a new study in the journal Water Policy, whose authors compared the water supply histories of 4 cities — San Diego, Phoenix, San Antonio and Adelaide, Australia. Among the lessons learned? Urban water conservation, recycling and desalination aren’t silver bullets. In fact, the best solution may lie upstream with farmers — saving just 5-10% of agricultural irrigation in upstream watersheds could satisfy a city’s entire water needs.
Q: Many cities take a similar pattern of water development, according to your research — going from exhausting local surface and groundwater supplies to importing water to implementing water conservation to finally recycling water or desalination. Why do you feel that this pattern is unsustainable?
Brian Richter: When we overuse a freshwater source, we set ourselves up for disaster. Each of the cities we reviewed in our study has contributed to the drying of a major river or important groundwater spring. That has obvious ecological impacts and social consequences — it affects livelihoods and human health by compromising fish production, concentrating pollution, or curtailing recreational activities.
Our research is revealing that water scarcity also causes severe economic losses by limiting or disrupting agricultural, industrial and energy production. Texas lost nearly $8 billion in agriculture last year due to water shortages; electricity generation from hydropower dams on the Colorado River in 2010 dropped by 20% due to water shortages. Some estimates suggest that China may be losing $39 billion each year due to crop damage and lessened industrial production, and hundreds of thousands of people around the globe are being forced to move due to water shortages.
Because these impacts are so pervasive and damaging, we need to begin investing in water supply approaches that don’t just minimize these adverse impacts but instead begin to reverse them.
The abstract to the referenced paper - - Tapped out - how can cities secure their water future?
Cities around the world are struggling to access additional water supplies to
support their continued growth because their freshwater sources are becoming
exhausted. Half of all cities with populations greater than 100,000 are located
in water-scarce basins, and in these basins agricultural water consumption
accounts for more than 90% of all freshwater depletions. In this paper we review
the water development histories of four major cities: Adelaide, Phoenix, San
Antonio and San Diego. We identify a similar pattern of water development in
these cities, which begins with the exhaustion of local surface and groundwater
supplies, continues with importation of water from other basins, and then turns
to recycling of wastewater or stormwater, or desalination of either seawater or
brackish groundwater. Demand management through water conservation has
mitigated, to varying degrees, the timing of water-system expansions and the
extent to which cities rely on new sources of supply. This typical water
development pattern in cities is undesirable from a sustainability perspective,
as it is usually associated with serious ecological and social impacts as well
as sub-optimal cost effectiveness. We highlight case examples and opportunities
to invest in water conservation measures, particularly through urban–rural
partnerships under which cities work with farmers to implement irrigation
conservation measures, thereby freeing up water for ecological restoration and
use by cities.