The caption on that one........with the Si castle in the middle...........was taken in 1863.....my comment about over 150 years is just a gen. estimate................now.................they say that after a 1881 flood of downtown dc...........they dredged the Potomac to make East Potomac park in 1882................the pic there was taken in 1863..............u can see Washington channel............right behind the castle..............and what looks like to me to be East Potomac Park.................I don't think they so much created an island......................they just modified stuff already there...............................b/c in this pic u can see an area of land..................so If u look at the castle................there is water right behind it.........to the west.............then land............where East Potomac park is now..............then water again.................the Potomac river.....






When Washington, D.C., was initially designed, the land currently known as West and East Potomac Park was a tidal wetland known as the Potomac Flats. In an 1863 panoramic photograph taken from the Smithsonian Castle tower showing the western view, the Potomac Flats can be seen beyond the incomplete Washington Monument (completed in 1885).

Photo courtesy of the Library of Congress, LC-USZ62-127632.

The Washington Canal, which incorporated part of Tiber Creek, ran along the north edge of the National Mall (now Constitution Avenue) connecting the Capitol with the Potomac River. The canal is clearly visible along the right side of the photo above, taken from the Capitol during the Civil War. Sewage was dumped into the canal and flowed to the river onto the flats just south of the White House grounds. Because sewage accumulated on the flats as opposed to draining out to the river, the area became extremely filthy, had a foul stench, and became a breeding ground of disease. While officials debated whether action should be taken to correct this health hazard, the final straw came in February 1881 when a huge snowfall melted causing the Potomac to flood across the Mall to the National Botanical Gardens at the base of the Capitol.