I’ve lived near the Chesapeake bay for several decades, and have not notice any increase in the mean water level. There are reports that the land in this area is slowly subsiding.
There was a story in the newspaper not long ago in which the Mayor of Tangier Island said claimed he could prove the island is disappearing not from sea rise, but rather by the constant washing away of the land by the bay currents over the many years.
Which leads to the question: why not sea walls and jetties.