Conservation key as climate change curtails western water

Environment News Service: The drought now parching Western states is a taste of things to come, finds a new report by the Natural Resources Defense Council that assesses the effects of global warming on water supplies in the West. Drastic steps can be avoided if water managers begin preparing now, the report says.

"Global warming will make it harder for farms and cities to find water," said Barry Nelson, study co-author and co-director of NRDC's western water project. "The latest global warming science is clear - drought-like conditions are likely to increase. This means that conservation and water use efficiency will become our most important sources of new water supply," Nelson said.

Over the past eight years, the Colorado River, which supplies water to parts of Arizona, California, Colorado, Nevada, New Mexico, Utah and Wyoming, has received just over half its average flow. Southern California is experiencing its driest year on record. The state Department of Water Resources predicts that every river in the southern Sierra Nevada will receive less than half of normal runoff this year.

Global warming may cause winter precipitation to fall as rain instead of snow, reducing water supply from the snowpack. Hotter summer temperatures will cause more water to evaporate out of watersheds, rivers and reservoirs.…

Conservation tops the list of proven water supply solutions. For example, water use in the City of Los Angeles has remained steady for 30 years despite population growth due to investments such as low flow showerheads. The city can save even more water by promoting drought tolerant landscaping.

The report calls on regions to develop cooperative solutions that meet their water needs together with other benefits.

For example, groundwater de-salters in California's Chino basin produce water supplies, while cleaning up contaminated underground aquifers.

Urban stormwater retention programs designed to reduce flooding and pollution can also supply water.

The report highlights wastewater recycling as a promising solution because it will not be affected by global warming, but advises that traditional approaches - dams, diversions and groundwater pumping - are likely to perform poorly in the future.

The report concludes that global warming may increase the risk of floods, so water strategies must include ways to protect people and property.…