The NRBW may at any time replace the existing main river map for Wales for the purpose of including—
a change which, pursuant to section 194(2)(b), is required by the making, amendment or revocation of a scheme under section 137,
a change to give effect to a determination under section 194C, or
a change directed by the Welsh Ministers under section 194D(5) (following an appeal against a determination).
A replacement map may not include other changes.
A replacement map must specify the date on which it takes effect.