The southern part of the Pennsylvania Avenue district was flooded many times in the last three decades of the 19th century . Major floods occurred in October 1870 ( during which Chain Bridge was destroyed ) , February 1881 , November 1887 , and June 1889 ( the same storm which caused the Johnstown Flood ) . Floodwaters were high enough that rowboats were used on the avenue , and horse-drawn streetcars saw water reach the bottom of the trams . After a disastrous flood in 1881 , the United States Army Corps of Engineers dredged a deep channel in the Potomac and used the material to fill in the Potomac ( creating the current banks of the river ) and raise much of the land near the White House and along Pennsylvania Avenue NW by nearly . Much of the dredged material was used to build up the existing tidal flats in the Potomac River as well as sandbars which had been created by silting around Long Bridge . Reclamation occurred in three phases : Section 1 ( what is now West Potomac Park ) , section 2 ( what is now the area around the Tidal Basin ) , and section 3 ( what is now East Potomac Park ) . Congress formally designated these areas " Potomac Park " on March 3 , 1897
Johnstown Flood
Johnstown Flood
East Potomac Park