The Sanctuary occupies a parcel of the former Rabb Plantation a river deep enough to float light steamboats .
The former Rabb Plantation is a 19th - century sugarcane plantation on the bank of the Rio Grande - at that time .
The Sanctuary occupies a parcel of the former Rabb Plantation , a 19th - century sugarcane plantation on the bank of the Rio Grande - at that time , a river deep enough to float light steamboats .