The Secretary of State—
shall deposit maps with the appropriate agency showing what appear to him to be the fresh-water limits of every relevant river or watercourse; and
may from time to time, if he considers it appropriate to do so by reason of any change of what appears to him to be the fresh-water limit of any river or watercourse, deposit a map showing a revised limit for that river or watercourse.
It shall be the duty of the appropriate agency to keep any maps deposited with it under subsection (1) above available, at all reasonable times, for inspection by the public free of charge.
In this section "relevant river or watercourse" has the same meaning as in section 104 above.