Dam Ends Up on Bottom of Chespeake Bay

No, sea level rise did not overwhelm a dam, rather it was demolished and put on the bottom as a place to grow oysters: New reef created in Chesapeake Bay:

Concrete that once blocked fish from swimming up the Patapsco River to spawn has a new life as home for aquatic creatures at the bottom of the Chesapeake Bay.

Water cannons blasted chunks of the demolished Simkins Dam off a barge Wednesday, completing the structure's transition from a river barrier to an oyster reef the size of two football fields. On Thursday and Monday, the Chesapeake Bay Foundation will seed the site at the mouth of the Chester River with 4 million baby oysters..

This is a good use for old dams.  For the most part, the small dams that exist on Chesapeake Bay tributaries no longer serve much purpose.  Most are too small for much electrical generation, and relatively few are used as water sources.  Simkins dam, for example, was originally built to power a cardboard recycling plant, but hasn't been used for that purpose for decades.  Removing it (and three more unused dams, projects in the works) will allow anadromous fish access to 175 additional river miles for migration and spawning.