AWSA Planning Process Holds Forums on Economics, Science and Water Supply
The Arizona Water Settlements Act (AWSA) Stakeholders Group held three forums to further the public’s understanding of available economic tools for water planning, a potential framework for evaluating hypothetical withdrawals from the Gila River, and preliminary information on water supply in southwestern New Mexico. The AWSA planning process was established to reach consensus on how to utilize the AWSA in a cost-effective manner to balance historical and future demands for water against uncertain supply while protecting the environment.
The Gila Economic Forum was held May 28 and brought together eight experts to present a range of decision-making tools available for water planning under the AWSA. Dr. David Gutzler, climatologist at the University of New Mexico, described the predicted impacts of climate change on Gila River flows. “Streamflows in southwestern rivers, especially in snow-fed rivers like the Gila, are expected to decrease significantly in this century. It is possible that the Gila Basin could lose its snowpack altogether by the end of the 21st Century, effectively eliminating seasonal snowmelt runoff. Streamflows from late winter into early summer would decrease most markedly.” These predictions have serious implications for efforts to spend millions to divert water from the Gila River under the AWSA. If flows become significantly diminished, why build a large scale diversion project that may not be used given the constraints of the AWSA, endangered species and other considerations? Lower-cost alternatives are available to the region to meet future water needs that do not rely on an unreliable surface water supply.
Dr. John Loomis of Colorado State University discussed tools to estimate the non-market value of river instream flows, such as the Contingent Valuation Method (CVM). Non-market values are routinely used by the EPA, USBOR, and Army Corps of Engineers in their benefit-cost analyses for estimating the value of environmental goods. Although these methods are not perfect, studies have shown that the economic value of environmental goods is not zero and therefore needs to be included in benefit-cost comparisons. This is an important consideration as the AWSA planning process evaluates the benefits and costs of diverting river flows for consumptive use versus maintaining instream flows.
Dr. Jim Peach of New Mexico State University did not address demographic projections as was anticipated and only discussed historical population trends in the four-county region. This is a critical omission that will need to be addressed to estimate future water demand for the area.
Additional presentations included estimation of residential and commercial water supply benefits, water markets for river systems, estimating agricultural benefits under changing water supply conditions, and integrating science and policy for water management on the San Pedro River. A final report is available at: www.awsaplanning.com/Forum_reports.html
Comprised of six experts, the Gila Science Forum was held on June 3 to identify, discuss and recommend ways of determining the potential effects of flow modification on aquatic and riparian resources of the Gila River. A final report is still not complete, but will be available for download from www.awsaplanning.com . A critical factor in understanding the dynamic Gila ecosystem according to panel members is that any stress applied to any part of the drainage will ultimately affect all biophysical processes throughout the watershed. Characterization of the watershed is of utmost importance so that planning and implementation can be done within a robust decision-making framework where any action is least likely to cause irreversible impact. It is necessary to assemble a multi-disciplinary team to fully assess the range of potential impacts to the Gila River from any water withdrawal project.
Finally, preliminary results on southwestern New Mexico water supplies were presented to the AWSA stakeholders on June 17. A key finding included the fact that hydrologically, there is likely adequate groundwater for Silver city according to David Jordan of Interra. Silver City will need to acquire additional water rights at some point in the future, but it’s an administrative issue rather than a question of physical water availability. Although groundwater has dropped a modest half foot/year in the Deming area over the past 68 years, trends show that irrigated acreage is declining and there is also significant conversion to water conserving drip irrigation rather than flood irrigation. Additionally, Deborah Hathaway of SS Papadopulos & Associates indicated that existing uses are currently impacting stream flows on the Gila. More study would be required to determine if additional water supply can be provided from the Gila Basin without undesired impacts to river flows.
The contractors will continue to work on follow-up supply tasks over the next fiscal year. Estimation of future water demand remains a critical task for completion over the next 12 months.
An update on these reports and subsequent planning tasks will be discussed at the July 13 AWSA Implementation/Technical Committee meeting and Stakeholder’s Meeting.