HI Tom – Good point perhaps the canal and bridges was their intent to call them Dutch Garden in association with the Van Cortlandts.
Regarding the bridges. There is a painting by Ernest Lawson (1873-1939), one of the” Eight ” artist, that is possibly a bridge in the Dutch Gardens. The painting is entitled The White Horse. There is no attribution to this site but Lawson did paint upper Manhattan and Bronx in a series dubbed Harlem River School by critics.