Subject to the provisions of subsections (b), (c), and (d) of this section, those portions of Pelican Island, Texas, which are not submerged and which are within the following property descriptions, are declared to be nonnavigable waters of the United States:

Notwithstanding the declaration under subsection (a), the following portions of Pelican Island, Texas, within those lands described in subsection (a) shall remain navigable waters of the United States: