Microinvertebrates are essential prey for larval fish, and their density can influence larval survival and subsequent recruitment. In riverine ecosystems, a primary dispersal mechanism for microinvertebrates is flow-mediated downstream drift. Understanding of the hydraulic conditions (e.g. water velocities) that entrain and transport microinvertebrates in the water column is limited and primarily supported by a small number of lab-based studies. In heavily regulated rivers like the lower River Murray, such information is critical to support restoration activities that seek to promote more natural riverine ecosystem processes and function. In December 2024, we undertook a field experiment in Pipeclay Creek (~2.5 km long, <50 m wide) in the Chowilla Anabranch and Floodplain system, South Australia, to quantify microinvertebrate drift and test critical entrainment velocity thresholds. During a pilot study, creek discharges were manipulated via an upstream regulator and water velocity–discharge relationships were established using cross-sectional velocity profile data collected with an Acoustic Doppler Current Profiler. During the experiment, microinvertebrate Haney trap sampling occurred at five sites of varying distance downstream of the regulator (50, 200, 500, 1000 and 2000 m) under six discharge settings that represented mean cross-sectional water velocities ranging from lentic (0.05 m/s) to lotic (0.4 m/s) conditions. Longitudinal and vertical changes in microinvertebrate assemblages are being investigated to address project objectives.