Predicted macroinvertebrate response to water diversion from a montane stream using two-dimensional hydrodynamic models and zero flow approximation

► We studied water withdrawal effects on invertebrates in a montane stream in Yosemite. ► We made physical measurements, sampled the benthos, and mapped the study reach. ► We studied withdrawal effects using 2-D hydrodynamic and nonlinear biological models. ► Wetted area and area-weighted faunal metrics declined sharply as flow neared zero. ► Reductions in wetted area were more important than the minimal changes to habitat.