Development of third generation of Tidal Energy Converters (TECs) may boost the exploitation of the tidal stream energy resource in depth-limited regions. The hydrodynamic conditions of depth-limited tidal sites are highly influenced by changes in the bathymetric conditions, such as sedimentation and/or dredging operations, which are typical of these regions. Consequently, significant variations in terms of magnitude and predominant flow direction can be present during the operating life of tidal farms, which may compromise their viability. The objective of this work is to explore the potential effects caused by dredging operations on the performance of tidal farms and to propose initial threshold values for key variables (flow magnitude and direction, operating hours of TECs), to ensure the techno-economic viability of tidal farms. For this purpose, three potential tidal sites in a shallow water estuary (Ribadeo, NW Spain), were used as case study. Significant variations were found between the pre- and post-dredging scenarios in terms of energy production, with annual variations exceeding 38%, for the tidal sites present in the region. In sum, the present study highlights the importance of considering the potential bathymetric changes in the decision-making process, when planning the installation of tidal farms in depth-limited regions.