New Mexico Universities Working Group on Water Supply Vulnerabilities: The Lower Rio Grande Presented to the Paso del Norte Watershed Council Phil King October 22, 2015

Background Funded by the NM State Legislature in FY 14 to: Assess the current state of water supply and demand after years of severe drought; Put the current drought into long-term context with reduced surface water, groundwater depletions, and economic activity; Develop a list of vulnerabilities and promote policy strategies to mitigate these vulnerabilities.

The Group Janie Chermak, UNM David Gutzler, UNM Peggy Johnson, NMIMT NMBGMR Phil King, NMSU Lee Reynis, UNM BBER Gwen Aldrich, UNM BBER Michael O’Donnell, UNM BBER

Average Depth to Groundwater in the Mesilla Valley, Peggy Johnson, NMT/NMBG 2015

Groundwater Elevation in the Mesilla Valley, Peggy Johnson, NMT/NMBG 2015

Groundwater Elevation in the Mesilla Valley,

Data from Connie A. Woodhouse, 2012.

Forecasting Problems:

David Gutzler, UNM 2015

Total Private Sector Employment, Indexed to 1951 Source of data: US Bureau of Labor Statistics, Quarterly Census of Employment and Wages

Principal Vulnerabilities: 1 Extended, severe drought significantly affects both surface water and groundwater supplies by disrupting the balance between precipitation and evapotranspiration in the hydrologic cycle. All credible projections of 21st century climate call for continued warming in the decades to come. Numerous assessments of groundwater vulnerability to a warming climate project that groundwater resources will be adversely affected by even small increases in temperature, regardless of changes in rainfall. The most significant adverse effects that severe drought and a warming climate have on groundwater resources are: (1) reducing the availability and distribution of groundwater recharge; (2) compounding groundwater depletions with additional pumping; and (3) intensifying groundwater declines that result in a permanent loss of groundwater storage.

Principal Vulnerabilities: 2 Recent investments and developments in the Santa Teresa, NM area will likely lead to additional businesses (re)locating to the area, and thus to additional population growth. The current water supply is anticipated to meet the area’s needs for the next decade only.

Principal Vulnerabilities: 3 Continuing drought will be increasingly detrimental to agriculture. Various strategies and technologies can be used to increase resiliency to drought, although all require additional expenses that present an additional financial burden, particularly difficult for small farms.

Principal Vulnerabilities: 4 Economic development and growth that does not consider the interactions and tradeoffs between human activity and the physical realities of water supply (and variability of supply) may result in increasingly severe constraints in times of drought that cannot easily be mitigated.

Recommendations: 1 Consider the entire spread of seasonal streamflow outlooks rather than just the median value, to explicitly account for the possibility of a continuation of forecast overestimates of snowmelt runoff. Continue assessment of the principal social and economic vulnerabilities associated with water shortages in the Lower Rio Grande, and update these vulnerabilities as the 2015 water supply situation becomes clearer. Initiate development of possible strategies for strengthening long-term resiliency to water shortages by bringing supply and demand closer to balance. Specifically, consider strategies that allow flexibility in times of shortages that consider the physical and the economic impact of the choices. Initiate development of possible strategies for addressing short-term deficiencies in surface water supplies based on prudent use of groundwater resources, and cooperate with legislators and water managers in the LRG to develop effective, resilient water policy and practices to be more responsive to short, medium, and long-term fluctuations in available water supply.

Consider better integrating the management of groundwater and surface water resources by, for example, optimizing the municipal-industrial use of groundwater during severe drought to minimize impacts to surface water and shallow aquifers. Investigate feasible means of reducing groundwater pumping and artificially enhancing groundwater recharge in order to mitigate the depletion of groundwater storage. Research and assessment of additional water sources should begin immediately. Due to stress imparted upon the region’s water supplies by the ongoing drought, it is unlikely that additional freshwaters will be available. Given the availability of brackish water, a desalination plant is an option that should be given serious consideration. Implement policies that will aid in the conversion of farmland from flood irrigation to more efficient irrigation methods such as subsurface drip. Seek to develop partnerships between farmers, Elephant Butte Irrigation District (EBID), NRCS, the Bureau of Reclamation, and other relevant agencies to plan and fund water conservation projects that address both delivery system efficiency and on- farm water conservation. Recommendations: 2