No evidence for cottonwood forest decline along a flow‐augmented western <scp>U.S.</scp> river

In contrast to many other arid region rivers, streamflow in the South Platte River is heavily augmented by trans-basin water imports and irrigation return flows. Hydrological changes began 1880s, resulting channel narrowing development of a continuous Populus-Salix forest mid-twentieth century. We assessed composition, structure regeneration status riparian identified environmental variables affecting annual Populus deltoides tree growth. sampled at four sites 2015, conducted dendroecological analysis seven additional 2019. The was dominated P. deltoides, which occurred all sites, comprising 79% total basal area 62% density. Age data indicated ongoing though episodic recruitment least over past ~130 years. tested 14 linear mixed effects models describe effect climate on individual growth (modeled as log BAI, n = 237 trees). most parsimonious model selected with AICc explained 28.6% BAI variability, included hydrology factors during growing season (i.e., June–August streamflow, June–July PDSI), some aspects off-season previous November March) along age study site effects. developed response to, has been maintained by, current conditions management regimes. It may be negatively affected future change increased urban demand basin.