This data release presents data and calculations for morphometric parameters used for the publication, "Morphometric and geologic characterization with statistical correlations for 33 tributary drainage basins of the San Juan River watershed in the Four Corners region, United States" in the Geochemistry: Exploration, Environment, Analysis journal, http://dx.doi:10.1144/geochem2024-037. Table 2. Percentage of total stream reaches (lengths) for tributary drainage basins in geologic units with potentially elevated concentrations of constituents of concern (suspended sediment concentration (SSC), aluminum (Al), arsenic (As), lead (Pb), and uranium (U)). Double dashes indicate that stream length percent is less than one. Tributary drainage basins are listed in upstream to downstream order.