The West of Scotland Water Authority is hereby authorized to execute the works specified in the Schedule to this Order. Subject to the provisions of this Order, during the relevant period, the Authority may, for the purposes of the undertaking, and by means of an intake, take a specified quantity of water from Lochnaw in the Rhinns of Galloway. No water shall be taken by the Authority from the said Lochnaw during any period when the water level, as measured by the gauge installed, is more than o