Assessing the Relationship Between Groundwater Availability, Access, and Contamination Risk in Arizona’s Drinking Water Sources

Groundwater is a critical drinking water source in arid regions globally, where reliance on groundwater is highest. However, disparities in groundwater availability, access, and quality pose challenges to water security. This case study employs geostatistical tools, multivariate regression, and clustering analysis to examine the intersection of groundwater level changes (availability), socioeconomic and regulatory factors (access), and nitrate and arsenic contamination (quality) across 1881 groundwater-supplied drinking water service areas in Arizona. Groundwater availability declined over 20-year and 10-year periods, particularly outside designated management areas, with mean annual decline rates ranging from −15.97 to −0.003 m/year. In contrast, increases (0.003 to 13.41 m/year) were concentrated in urban and managed areas. Karst aquifers show long-term resilience but short-term vulnerability. Non-designated areas exhibit mixed effects, reflecting variable management effectiveness. Disparities in groundwater access emerge along various socioeconomic and regulatory lines. Communities with higher Black populations are twice as likely (OR = 2.01, p < 0.001) to experience groundwater declines, while Hispanic/Latino communities have lower depletion risks (OR = 0.92, p < 0.001). Tribal oversight significantly reduces groundwater decline risk (OR = 0.62, p < 0.001), whereas state–primacy areas show mixed effects. Higher female populations correlate with increased groundwater declines, while older populations (65+) experience greater stability. Married-family households and institutional housing are associated with greater declines. Migrant worker housing shows protective effects in long-term models. Rising groundwater levels are associated with higher nitrate and arsenic detection, reinforcing recharge-driven contaminant mobilization. Nitrate exceedance (OR = 1.05) responds more to short-term groundwater changes, while arsenic exceedance persists over longer timescales (OR = 1.01–1.05), reflecting their distinct hydrogeochemical behaviors. Community water systems show higher pollutant detection rates than domestic well areas, suggesting monitoring and infrastructure differences influence contamination patterns. Tribal primacy areas experience lower groundwater declines but show mixed effects on water quality, with reduced nitrate exceedance probabilities; yet they show variable arsenic contamination patterns, suggesting that governance influences availability and contamination dynamics. These findings advance groundwater sustainability research by quantifying disparities across multiple timescales and socio-hydrogeological drivers of groundwater vulnerability. The results underscore the need for expanded managed aquifer recharge, targeted regulatory interventions, and strengthened Tribal water governance to reduce inequities in availability, access, and contamination risk to support equitable and sustainable groundwater management.