The marble plaque is located under the S.Bartolomeo church porch, at the left of the church inlet, and marks the Tiber water level reached during the 1937 flooding.
This is the inscription: "ALLUVIONE DEL 17 DECEM 1937" [Flooding of Dec 17th 1937].
The 1937 flooding has been the last one recorded at Ripetta Hydrometer and the water level reached 16.69 meters. As the town was, at that time, flooding protected by the Tiber embankments, the 1937 flooding involved only the Tiberina Island. The only further plaque in Rome relevant to that flooding is actually on the Island, walled up in the first court of Fatebenefratelli hospital.