This data set characterizes the thermal regime in a number of Colorado and New Mexico streams that contain populations of Rio Grande Cutthroat Trout (Oncorhynchus clarkii virginalis) or have been considered potential restoration areas for the fish. The majority of these streams had no previous record of continual temperature records. When compared to Colorado water temperature criteria (Cold Tier 1), a portion of these populations appeared to be at risk from elevated stream temperatures, as indicated by exceedance of both acute and chronic water quality metrics. Summer water temperature profiles recorded at sites within current Rio Grande Cutthroat Trout habitat indicated that although the majority of currently occupied conservation streams have temperatures that fall well below these biologically based acute and chronic thermal thresholds, several sites may be at or approaching water temperatures considered stressful to Cutthroat Trout.