At high tide, the dam is closed to hold the water, then at low tide, the stored water is released through a turbine to generate electric power.
(the dam; is closed then; L:At high tide) (the dam; to hold; the water) (the stored water; is released; to generate electric power)
the dam the dam the stored water
is closed then to hold is released
L:At high tide
the water
to generate electric power