Depending on circumstances, various hydrological, environmental, ecological, and economic side effects can be realised by the implementation of a tidal inlet closure, including:
* change of tide (amplitude, flows) at the seaward side of the dam
* change in bar and gully topography, outside the dam
* removal of tides on the inner side of the dam
* change in groundwater level in adjoining areas
* alteration of drainage capacity for adjoining areas
* loss of fish and vegetation species
* loss of breeding and feeding areas for water birds
* rotting processes during change in vegetation and fauna
* stratification of water quality in stagnant reservoir
* accumulation of sediments in the reservoir
* impact on facilities for shipping
* impact on recreation and leisure pursuits
* change in professional occupations (fishery, navigation)
* social and cultural impacts.