In 1895 the Edinburgh and District Water Trustees obtained an Act of Parliament for the introduction of a new water supply to the city of Edinburgh drawn from the Talla Water, one of the upper tributaries of the river Tweed.

The Bill as originally introduced contained provisions for giving off 4,000,000 gallons a day as compensation to the stream, and for appropriating the remainder of the water.

The Tweed Salmon Fisheries Commissioners and other proprietors interested were advised that the proposed amount of compensation was too small, and after various negotiations a clause was ultimately adjusted providing that rain gaugings should be taken over the drainage area for a period of seven years from the 1st January 1896 by the authors of this note (Mr Tait having been appointed in lieu of his predecessor), and that thereafter they should fix—taking all the circumstances into consideration—what was the available annual rainfall of the district.