Fish screens can help prevent the entrainment or injury of fish at irrigation diversions, but only when designedappropriately. Design criteria cannot simply be transferred between sites or pump systems and need to be developed usingan evidence-based approach with the needs of local species in mind. Laboratory testing is typically used to quantify fishresponses at intake screens, but often limits the number of species that can studied and creates artificial conditions notdirectly applicable to screens in the wild. In this study a field-based approach was used to assess the appropriateness ofdifferent screen design attributes for the protection of a lowland river fish assemblage at an experimental irrigation pump.Direct netting of entrained fish was used along with sonar technology to quantify the probability of screen contact for aMurray-Darling Basin (Australia) fish species. Two approach velocities (0.1 and 0.5 m.sec21) and different sizes of wovenmesh (5, 10 and 20 mm) were evaluated. Smaller fish (,150 mm) in the assemblage were significantly more susceptible toentrainment and screen contact, especially at higher approach velocities. Mesh size appeared to have little impact on screencontact and entrainment, suggesting that approach velocity rather than mesh size is likely to be the primary considerationwhen developing screens. Until the effects of screen contacts on injury and survival of these species are better understood,it is recommended that approach velocities not exceed 0.1 m.sec21 when the desire is to protect the largest range ofspecies and size classes for lowland river fish assemblages in the Murray-Darling Basin. The field method tested proved to bea useful approach that could compliment laboratory studies to refine fish screen design and facilitate field validation.