Public Health in the Rockies 2026

Background: Approximately 400,000 Coloradans rely on private wells for drinking water, leaving a significant portion of the state’s population outside the purview of the federal Safe Drinking Water Act. While the Colorado Department of Public Health and Environment (CDPHE) offers subsidized private well testing for contaminants like per- and polyfluoroalkyl substances (PFAS), heavy metals in groundwater remain a critical, yet under-monitored, public health concern. CDPHE is launching a pilot program to test heavy metals in certain private wells, and this study aimed to map high-priority well locations to support testing resource prioritization.




Methods: We developed an evidence-based strategy to predict heavy metal occurrence in private wells. We integrated historical mining data, local geology, and environmental datasets, focusing on six key analytes: Arsenic, Cadmium, Manganese, Lead, Uranium, and Zinc. Using Empirical Bayesian Kriging (EBK) Regression Prediction, we merged sparse historical data with environmental predictors to create state-wide risk maps that bridge information gaps in unsampled regions.




Results: The analysis created a series of comprehensive risk maps for each metal, alongside a generalized index map. These tools do not predict specific outcomes for individual wells, but rather identify areas of elevated concern where environmental and historical factors suggest a higher probability of naturally occurring or introduced heavy metals. By comparing these areas with permitted well locations, we can better visualize which regions may benefit most from increased community outreach and subsidized testing resources.




Implications: Colorado’s diverse mineral geology and mining legacy present ongoing concerns for groundwater contamination. By integrating these factors into spatial risk maps, CDPHE can effectively prioritize sampling and resource allocation. As funding becomes available, this data-driven framework will enable targeted outreach, testing, and health education, empowering private well users to make informed decisions about their water quality.