Ask the expert: City needs second source of water

* Editor’s note: This is the second in a series of “Ask the expert” columns that will appear in the coming days, in advance of the Measure I election, regarding various technical aspects of the city’s water utility and the proposed Woodland-Davis surface water project.

The expert: George Tchobanoglous, a UC Davis professor emeritus of civil and environmental engineering. Tchobanoglous’ principal research interests are in the general areas of wastewater treatment, water reuse and solid waste management

The question: Why do you believe it is important for a city like Davis to secure a second source of water?

The answer: When thinking about acquiring a second source of water supply, Davis residents should consider the following guiding principles:

* Providing an adequate supply of high-quality water is a fundamental responsibility of a community;
* The need for secure and reliable water supply source(s) is critical;
* The value of water will rise significantly in the future; and
* Planning for future water supply should be long-range.

An adequate supply of high-quality water is essential for the long-term sustainability of a community.

Without an adequate water supply, a community is constrained in the types of choices that can be made for future development. Limited water supplies do not control growth, but result in a community at risk when drought or other threats occur to the water supply.

The current city of Davis groundwater supply system is reliable with respect to the physical delivery system, although questions remain about the long-term quality and yield of the groundwater aquifer.

Because water supply security and reliability are of paramount importance to long-term sustainability, most communities have sought to develop multiple sources of supply. The water supply options for the city of Davis are surface water, groundwater and indirect potable reuse of wastewater, in which groundwater or surface water is augmented with purified wastewater.

In the past five years, the price of water has doubled in many metropolitan areas. In California, the price of water is particularly sensitive to changing demographics, changing weather patterns and periodic drought events, such as the one California appears to be entering. The price of surface water will only increase in the future.

Water supply projects should be based on planned community growth, water use, long-term availability of regional water sources and water reuse.

Fifty years ago, the city made a decision to stay with groundwater, rather than obtain Solano Project surface water, for a variety of reasons. Today, the community must select a planning horizon, considering the quality and potential quantity limitations of the groundwater supply. The opportunity to secure surface water should not be delayed.

For the above reasons, the city of Davis’ long-term water portfolio should include surface water, groundwater and indirect potable reuse.