Retention Rates of 2.0-Mm Fine-Mesh Traveling Water Screens: Theoretical Vs. Empirical

The biological effectiveness of fine-mesh traveling screens at cooling water intake structures (CWIS) is dependent upon their capacity to collect organisms and return them to the source waterbody with minimal stress, injury and mortality.  The retention of larval fish depends upon their morphology and the size of the screen mesh.  In the absence of empirical data, a model has been developed to predict the retention rates for a given screen mesh-size using measurements of the body size and shape of the species in question. In particular, this model postulates that head capsule depth is the critical morphometric characteristic that determines whether an organism will fit though a given screen opening. 

The effectiveness of 2.0-mm fine-mesh screens at retaining larval fish was evaluated in a laboratory study.  Test species included bigmouth buffalo (Ictiobus cyprinellus), bluegill (Lepomis macrochirus), common carp (Cyprinus carpio), golden shiner (Notemigonus crysoleucas), and white sucker (Catostomus commersonii). Theoretical estimates of retention compared strongly with the testing results for four of the five species.  These results support the accuracy of the theoretical model and indicate that measurements taken from in situ ichthyoplankton samples may be sufficient to predict retention rates at CWIS in the place of empirical data.