The production environment in Yuma Valley is being shaped by gradual warming and highly variable rainfall rather than a strong long-term rainfall trend. Annual precipitation does not exhibit a strong linear trend, and any increase suggested by the trendline is minor relative to year-to-year variability. In contrast, annual average maximum temperature and annual average minimum temperature indicate gradual warming. Together, these changes point to higher crop water demand and tighter irrigation margins in lettuce and leafy green production systems. These trends increase sensitivity to irrigation timing, accelerate canopy water loss during warm periods, and increase the likelihood of crop water stress. At the same time, over-irrigation can increase deep percolation and nutrient losses, complicate salinity management, and create canopy and soil conditions conducive to disease. For crop productivity and management in Yuma Valley, the overall message is that precise irrigation management, responsive crop management, and field-based Integrated Pest Management (IPM) are becoming increasingly important under warming and operationally meaningful rainfall variability. The long-term climate signal in Yuma Valley is not a simple story of more or less rainfall. It is a story of gradual warming and highly variable rainfall. Annual precipitation does not exhibit a strong long-term linear trend, and any increase suggested by the trendline is minor relative to variability. By contrast, both annual average maximum and annual average minimum temperatures indicate gradual warming. Together, these trends indicate higher crop water demand and tighter irrigation margins in lettuce and leafy green production systems. The practical implication is that existing management practices may not fully account for the impacts of these changing climate variables. Improving irrigation precision, adjusting crop management to protect crop productivity, and strengthening field-based IPM tied to crop stage, canopy conditions, irrigation practices, and short-term weather will be increasingly important for sustaining lettuce and leafy green production in Yuma Valley.

Executive Summary: Groundwater governance and management practices vary considerably across the United States. To better understand groundwater governance strategies and practices connected to water quality in the United States, a team from the University of Arizona Water Resources Research Center designed and launched a nationwide survey in 2016. The goal of the project was to identify on-the-ground practices of groundwater governance that may help to improve and enhance management of the nation’s water supplies, particularly within the realm of groundwater quality. A state water professional was recruited in each state to participate in the nationwide survey. The report was prepared as a project funded by the Ground Water Research and Education Foundation (GWREF) of the Ground Water Protection Council and benefitted from the involvement of GWREF representatives throughout the formulation of the survey. The surveys were responded to online, with no in-person interviews conducted. This report presents major findings from the survey. State water professionals identified a wide variety of groundwater concerns, including impairment of water quality and quantity, staffing and budget issues, health/vulnerability of private well users and aquifer overdraft. There are concerns about contamination of groundwater, especially in agricultural sites, but state professionals also expressed concerns about naturally occurring contaminants, underground storage tanks, Superfund/CERCLA sites, industrial sites, and septic tanks. Nitrate was the most selected contaminant of concern, followed by chlorinated solvents. More than half (53%) of respondents indicated that unconventional oil and gas exploration and production are occurring and regulated in their states. Most respondents indicated the existence of explicit groundwater quality management goals in their states and have observed significant changes to groundwater quality policy in the last 10 years. Most states share groundwater quality data with a multitude of user groups. Most states have groundwater quality standards and a groundwater classification system. States have multiple sources of funding for water quality programs, with 85% receiving some form of federal funds. However, for a majority of states, groundwater quality program budgets have decreased in the last 10 years. A majority of surveyed agencies describe the number of staff as too small. Some states rely on local and federal agencies to help implement groundwater quality regulations. Looking to the future, respondents indicated a number of issues will require more attention in the next 10 years, notably water quality/water level monitoring and increased groundwater pumping. Almost half of states anticipate that changes in groundwater regulation are likely in the next five years. This report is available at https://wrrc.arizona.edu/groundwater. A journal article based on the report's findings has been published in Water. The article “Critical Issues Affecting Groundwater Quality Governance and Management in the United States” is available at http://mdpi.com/2073-4441/10/6/735.

Excerpt from the Executive Summary: This Roadmap document is the culmination of a three-year project funded by the Nina Mason Pulliam Charitable Trust and convened by the Water Research and Planning Innovations for Dryland Systems (Water RAPIDS) program at the University of Arizona Water Resources Research Center (WRRC). The Roadmap is designed to examine possible routes, as well as roadblocks, to considering the water needs of riparian and aquatic ecosystems in Arizona water management and planning decisions. As there is little in Arizona’s legal framework to compel the consideration of water for natural areas, the WRRC sought throughout the Roadmap project to foster dialogue among water users about voluntary, stakeholder-driven options for addressing natural areas. This was done within the context of limited water supplies and existing water rights and claims.

Excerpt from the Introduction: The four scenarios presented here span the next 30 years, and demonstrate how the key drivers of change in the watershed are influenced and changed by the major uncertainties. These major uncertainties are the overarching themes for the four scenarios and include: New Mexico’s decision to divert water from the Gila and San Francisco Rivers; the tamarisk beetle; local versus federal control of the watershed; and fluctuation in cotton prices. The scenarios are written as stories to help the community think about what the future might look like and weave together information from interviews with people from the watershed and research on impacts to the watershed by elements such as tamarisk defoliation or prolonged drought. It is also important to note that while the future is full of may possibilities, these scenarios focus on likely and high-risk events that require extensive planning. For example, a return to average annual rainfall in the future is possible, but years of normal rainfall do not require the same amount of preparation as responding to prolonged drought. Increased precipitation within normal ranges, is therefore is not emphasized as strongly in this report, drought and intense storms that would cause flooding are discussed. Thinking about a future with extended droughts and intermittent flooding can be intimidating. It is important to remember that scenarios are not necessarily ideal visions of the future, we must try to use them to understand what we would like to see happen as well as what we would not like to see happen.

Executive Summary: In fall 2012, the Water Resources Research Center and the Udall Center for Studies in Public Policy at the University of Arizona initiated the project “Groundwater Governance in the U.S.” The effort aims to better understand the scope of groundwater governance across the United States today. As a first step, the project launched a national-scale survey of state agency officials in the U.S. The objective of the initial survey was to acquire baseline information regarding state-level groundwater governance practices. For the survey, a respondent was recruited from each of the 50 states and the District of Columbia. The online survey, which was conducted between November 2012 and February 2013, was designed to take approximately 15 minutes. Agency officials were identified through online research and consulting members of the National Institutes of Water Resources, a network of federally-authorized water resource research institutes at universities across the U.S. This report presents major findings from the initial survey and focuses on analyzing survey results. Depending on available funding, future efforts will expand upon this research and include a broader set of survey participants. We find great diversity in terms of the scope and extent of groundwater use across the states. In some states, as little as 3% of human water demands are met by groundwater supplies. In others, as much as 95% of human demands are met by groundwater supplies. The survey results also suggest great variation of groundwater use within states. About three-quarters (78%) of survey respondents report that reliance on groundwater use varies by region within their state in terms of relative reliance on groundwater to supply human demands. Similarly, 88% of respondents report that the proportion of groundwater use by each major groundwater-using water sector varies by region across their states. Despite this diversity by state in terms of reliance on groundwater, the vast majority of states – some 96% – report the presence of formal groundwater laws regulations, including widespread adoption of state laws addressing groundwater quality and water conservation. Most states also encourage the use of voluntary measures for addressing groundwater issues. Authority for groundwater oversight and enforcement resides largely in state agencies (98%) along with some shared authority with local agencies (64%). However, survey respondents highlight a great diversity in terms of the users of groundwater subject to state groundwater regulations. States rely on diverse tools and strategies to manage groundwater use and quantity and groundwater governance priorities vary by state. We observe less consistency across states in addressing international, interstate or Native American groundwater issues. And the role of the courts varies as well. In addition, there is significant variance in terms of the role of state law in recognizing the connection between surface and groundwater, and consideration of the water needs of groundwater dependent ecosystems. Finally, survey respondents report differences in terms of agency capacity to carry out policies and responsibilities, and the public accessibility of groundwater information. This report is posted at http://wrrc.arizona.edu/groundwater.

Excerpt: This bulletin explains the water demands of the environment in the Colorado River Region, an area including Big Sandy, Bill Williams, Gila Bend, Hualapai, Lake Havasu, Lake Mohave, Lower Gila, Parker, Sacramento and Yuma groundwater basins as well as nine other basins.

Excerpt: This bulletin explains the water demands of the environment in the North/Northeastern Arizona Region, an area including the Coconino Plateau, Grand Wash, Kaibab Plateau, Little Colorado River, Shivwits Plateau, Paria, and Virgin River groundwater basins.