Abstract : The Measurement of Entrainment and Transport work unit under the Dredging Research Program's Technical Area 1, entitled 'Analysis of Dredged Material Placed in Open Water,' developed the Plumes Measurement System (PLUMES) to monitor the transport of suspended sediment from dredging and dredged material disposal operations. This acoustic system can monitor nearly synoptically, both horizontally and vertically. To determine the relationship between PLUMES acoustic measurements and suspended sediment concentrations, a laboratory sediment calibration experiment was conducted. The experiment studied acoustic backscattering from particles equivalent in size to those commonly found at dredging and dredged material disposal sites. These particles were suspended in a calibration chamber built for the study. The experiment showed that backscatterance could be predicted and concentrations calculated using Rayleigh scattering theory and an acoustic calibration of PLUMES. This report describes the experiment and the results of the experiment. Data from each calibration run are presented in the Appendices.