Any structures, dwellings, construction or operations existing within a watercourse, coastal wetland or tidal marsh prior to the effective date of this local law shall be exempt from this local law and permitted to continue, provided that:
A. 
No new construction, structures, dwellings or operations will be permitted after the effective date of this local law, except by permit as provided herein.
B. 
Where damage or hazardous conditions exist, the landowner may be required by the Town Board to repair such damage or remedy such hazardous conditions as the Town Board may direct.