Elevated concentrations of metals including aluminum, arsenic, and lead were identified by Navajo Nation Environmental Protection Agency staff in the San Juan River from below the Navajo Dam, through the Navajo Nation to Mexican Hat, Utah in the Four Corners Region of the United States (Colorado, Arizona, New Mexico, Utah). An interdisciplinary team applied approaches and principles of geology, geochemistry, geomorphology, hydrology, and statistics to gain a better understanding of the tributaries supplying the source(s) of metals to the San Juan River. Water samples that were filtered with 0.45 micron filters were collected in single-siphon samplers and by grab sample at 41 ephemeral and perennial tributaries to the San Juan River in 2021 and 2022. Eighteen surface water sites along the San Juan River were sampled as grab samples in 2021 and 2022. Samples were chosen randomly for filtration to compare to unfiltered sample results. The samples were analyzed for major and trace cations by inductively coupled plasma emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS) at the US Geological Survey Analytical Chemistry Laboratory in Denver, Colorado. A sub-set of samples includes data for pH and alkalinity as calcium carbonate. A total of 282 filtered samples were collected.