The Middle San Pedro River Valley: Low Vulnerability The Middle San Pedro River Valley is an example of the significant shift towards development and urbanization that many rural towns are experiencing throughout the Southwest. In this valley, communities are struggling to stay afloat as they undergo a transition from dependence on primary industries (agriculture and ranching) to an economy fueled by services, tourism, and retirement. CLIMAS researchers’ work in this valley revealed the potential dangers of ignoring climate in a rapidly growing, semi-arid environment. While surface and groundwater availability represents one of the primary constraints to human livelihood sustainability, technology and social organization have buffered most livelihoods in such a way that residents perceive themselves as largely unaffected by climate extremes (Finan 2000). This case study identified farmers and migrant workers as stakeholders and agriculture as a sector whose climate information needs differ substantially from those of ranchers. The Sulphur Springs Valley: High Vulnerability The Sulphur Springs Valley is a region of farming and ranching communities dependent on groundwater for irrigation. In-depth interviews with a wide range of small-scale agriculturists and migrant labor revealed a community of stakeholders highly vulnerable to climate variability. The researchers also have documented that considerable diversity exists with regard to people's concerns with climate variability. For example, some vegetable growers may welcome a summer drought because this allows them to control, by irrigation, the amount of water desired. Yet consecutive years of drought can be devastating. Increased reliance on groundwater irrigation can lead to a decline in aquifer levels and a substantial increase in the costs of pumping. For many, this combination of stresses has resulted in bankruptcy and the abandonment of agriculture. For others, it has led to the development and adoption of more water-efficient irrigation systems. The Upper Gila River Valley (UGRV), a largely agricultural area in southeastern Arizona, is highly dependent on surface water from the upper Gila River and its watershed. The research conducted in the UGRV primarily focused on two stakeholder groups: the San Carlos Apache Tribe and Anglo farmers and ranchers of the Safford Valley. Resource-dependent livelihoods on the San Carlos Apache reservation include forestry and firefighting; cattle ranching; sale of hunting, fishing, and boating licenses; and backcountry and lake recreation. The research details the history of these reservation livelihoods, their current status, and the impacts of the drought on each livelihood. Vulnerabilities include bark beetle damage and higher fire risk in reservation forests; loss of forage species on the range, resulting in forced sale of cattle; and loss of lake recreation income as reservoir levels decline. Moreover, vulnerability to climate impacts overlays and magnifies vulnerabilities that are linked to historic events, institutional structures such as water rights, and political and sociocultural factors on the reservation. In the Safford Valley, the main crop is cotton, grown along the Gila River. Ranchers graze their cattle on small parcels of private land and scattered large federal and state grazing allotments. This predominantly Anglo community has generally greater access to financial resources and makes more use of government programs than the reservation does. While temperature is the primary concern of the cotton farmers, ranchers need information about both timing and quantity of precipitation that affects forage on their ranges. Cotton farmers also need localized forecasts of humidity and precipitation in addition to heat units to better manage their planting, crop management, and harvesting activities. Because the region is known for spotty rains, the preference is for information to be as localized and small scale as possible. By far the greatest vulnerability for both the San Carlos Apache Reservation and the Safford Valley is linked to the Gila River. Both communities rely on river water supplemented with groundwater. Access to Gila River water is strictly defined and hotly contested. The impacts of water allocation settlements that were based upon river flow during unusually wet years resound today, as the river has rarely provided the full apportionment to UGRV farmers, or left water of sufficient quality or quantity to meet the Tribe’s needs. As both groups of users seek to assert their water rights and make a living, drought, and even dry conditions under normal variability, exacerbates the conflict. The CLIMAS findings in the Upper Gila River Valley are consistent with those reported for the Sulphur Springs Valley (Vásquez-León et al., 2003); the role of climate and the potential for climate information to make a difference to these stakeholders are bound up in a much wider social, cultural, and institutional context. In a region where demand for water has been growing since the earliest Anglo-American settlement, water allocation is a key factor that impacts stakeholder vulnerability to climate. Reliable long-term forecasts of seasonal precipitation and temperatures could make a significant contribution to maintaining rural, resource-dependent livelihoods in an inherently challenging environment.