The Pecos River provides an important source of water for New Mexico and Texas, US, and Mexico. Severe and prolonged drought combined with increasing temperatures during the early 21st century boosted attention on water resources and allocation management in the American West. We provide a tree-ring-based streamflow reconstruction for the Pecos River for the period 1310–2013 CE for the overarching purpose of placing the current Pecos River streamflow declines in a multi-century context. Over the past ca. 700 years, dry events ( n = 93) that lasted at least 2 years were more common than wet events ( n = 76), wherein flow was below/above the instrumental mean (61.6 m3 s−1). Although more prolonged droughts occurred during the 15th and 18th centuries, the gage record (1930–2013 CE) captures the full range and variability of flow extremes within the context of the past 700 years. The 11-year drought of 1772–1782 was the highest ranked based on magnitude + intensity below the instrumental mean, slightly edging out the 1415–1425 and 1950–1957 events. The driest events that have occurred from the 14th through the 20th centuries are challenged by flow conditions since the turn of the 21st century. The 2000–2006 and 2011–2013 dry periods ranked 6th and 13th, respectively, though the intensity (−40 m3 s−1 yr−1) of the 2011–2013 event exceeded all higher ranked droughts. The lowest single water-year flow in the reconstruction was shared by years 1904 and 2002, during which the flow of the Pecos River was estimated at 8.1 m3 s−1. Other extreme low-flow years were 1685 (9.5 m3 s−1) and 1579 (9.8 m3 s−1), but are eclipsed by 1904 and 2002 when considering the lower bounds of bootstrapped confidence limits of the reconstruction. Increased flow variability combined with projected increased temperatures and decreased precipitation will likely present new challenges to water resource managers, especially given impending anthropogenic climate change.
Chemical and isotopic evaluation of sulfur sources and cycling in the Pecos River, New Mexico, USA