The short-sighted view is to focus just on short-term benefits

David Modeer contributed this Guest View. Currently Phoenix Water Service director, Mr. Modeer has been appointed general manager of the Central Arizona Project. He will take up his new position early in the new year.

When I agreed to follow-up on Sharon Megdal's sharing with us her trip to Paris, my only qualification was I would not descend into Phoenix's sewers for a photo op. That is one thing we have in common with Paris ? strolling through the Salt River Outfall sewer is not a major tourist attraction. Sharon has been a long time supporter of water conservation in Arizona, and I share her enthusiasm. Living wisely within our desert environment continues to be critical for maintaining sustainable communities in Arizona. Convincing Arizona water users to live a low-water use lifestyle will be important to sustainability. However, while we wave the water conservation flag for our customers, we need to be careful not to fall into the trap of using water savings as a new water supply.

In her review Sharon closed with "? convincing Arizona water users to do more to conserve water is a necessary and relatively low-cost way of addressing scarcity." Twenty years ago, the term scarcity meant the lack of water rights needed to meet current or projected demands. Using water conservation to lower demand was a valid response to this type of scarcity. Less demand per customer meant you could serve more customers with the same amount of water. Today, thanks to the work of Sharon and her university colleagues, we now know this is a trap.

Our view over the past 20 years of sustainable yield for surface and ground water supplies has been based on one of the wettest centuries in the last 1,000 years. Researchers have been able to reconstruct stream flows of the Colorado, Salt and Verde river systems over the last 1,000 years, revealing a much dryer past. Dry periods of 20 to 30 years were common, with all three rivers experiencing low flows together more often than not. This history and the potential future of global climate change means that droughts that reduce surface and ground water supplies are a question of when, not if. This creates a double whammy for water supplies "created" through water conservation. First, during these droughts all supplies will be reduced, including the water supply created by water conservation. Second, water conservation will have hardened demand making it more difficult to further reduce demand as a response to drought.

Avoiding this trap requires that communities set a higher standard than that used over the past 20 years. Having a sustainable water supply to meet 100 years of growth under normal water supply conditions is in reality not going to be sustainable. To be sustainable, communities must be able to meet the basic water supply needs of their communities during times of reduced water supply as well as normal.

Many communities are embracing this new standard of adaptation to long-term drought which is changing how we think about water conservation in several ways. First, demand management plans will begin distinguishing between water conservation as part of a low-water use lifestyle and water conservation that is part of drought response. A community's low-water use lifestyle should be able to meet the community's water needs during normal conditions with no negative impact on the economy, environment or desired quality of life. Water conservation during drought will have a short term negative impact on the economy, environment and desired quality of life but only to the degree that the community can quickly recover when drought conditions end. Secondly, water savings from water conservation will not be included in long-term water supply estimates for normal conditions; rather they will be included as part of a long-term drought supply. Water conservation that occurs during drought will reduce the volume of water needed to supplement reduced water supply conditions. Water saved before drought conditions will be treated as water available for banking, providing a water supply available for finite periods during times of reduce surface and ground water supplies.

Unfortunately for some communities in Arizona, the meaning of scarcity is the same today as it was 20 years ago, and water conservation is used to "create" water supplies to meet the scarcity for new or existing demands. For these communities water conservation is simply digging a big hole which will be dry when the scarcity of long term drought comes to town.

It is my strong belief that we must alter our view of water conservation and change our focus from only short-term benefits to a utilization of conservation as a strategy for providing sustainable water supplies. Failure to do this will lead to further tension regarding our water resource allocation when the time of drought and scarcity arrives.