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districts." These five sewerage districts, which are referred to as the Central, Southern, Eastern, Western, and Northern Sewerage Districts, are described in the " Memorandum " and are shown in the drawing No. 1 which is attached thereto. It is unnecessary to give here the full description of the sewerage districts, but we should mention that the natural drainage of the Southern District is mainly to the Manukau Harbour (a small portion draining to the Tamaki River), and of all the others mainly to the Waitemata Harbour and the Hauraki Gulf (with a small portion to the Manukau Harbour). (3) The evidence showed that as sewers, once they are constructed, cannot be economically enlarged, provision should be made to deal with the conditions which are likely to exist during a period of, say, forty years from the time of the completion of the sewers, and that treatment-works, on the other hand, can be enlarged from time to time as the need arises. We also agree with Mr. Porter's opinion that "it is more economical in general in a rapidly growing city to provide treatment-works which can be deemed to be ' productive works ' and which can easily be extended as the need arises than to provide sewers, which are essentially partly ' non-productive,' and which must be built immediately for anticipated ' ultimate load.' " It follows that it is more economical to treat and dispose of sewage in its own catchment area than to construct a sewer to convey it to a place for treatment and disposal with sewage from another area. (4) After inspecting the proposed sewerage districts and considering all the factors which we consider are relevant, we have come to the conclusion that the boundaries of the Metropolitan District should be altered in accordance with Mr. Porter's proposals. We are also of opinion that the Central and Southern Districts should comprise the Inner Area of the Metropolitan District, that the Eastern and Western Districts should be included in the Outer Area, and that the Northern District, while being brought within the Metropolitan District, should not be included within either the Inner Area or the Outer Area, but should occupy a special position in accordance with the recommendations which will be made later in Part V. The areas comprising the five sewerage districts are described in general terms in paragraphs 50 (1) and 51 (1) and Part Y. If our recommendations are adopted, a more exact description will be required for the amendments that will require to be made to the Drainage Act, but the general descriptions should afford a sufficient guide. (5) We will refer later to the proposals made by Mr. Porter for the drainage of the sewerage districts. (6) We were requested by counsel for the Metropolitan Board to recommend that the Board should have authority to divide the Inner Area into two districts for sewerage and sewage-treatment purposes. We understand that what is meant by this is that if the Board's Scheme No. 2, which is referred to in paragraph 25, is adopted, the Board should be authorized to constitute as separate sewerage districts, firstly the area the sewage from which will be dealt with at Brown's Island, and secondly the area the sewage from which will be dealt with at a site on the Manukau Harbour. It was made clear that it was not suggested that the financial provisions of the Drainage Act should be altered or that the costs of the Brown's Island and Manukau Harbour schemes should be separately borne by the respective areas served by the schemes. We have referred in subparagraph (2) above to the five sewerage districts suggested by Mr. Porter, and we have recommended that two of these districts (the Central and Southern Districts) should comprise the Inner Area of the Metropolitan District and that the Eastern and Western Districts should comprise the Outer Area. We consider also, as will be shown later, that the Northern District should constitute a separate sewerage district not forming part of either the Inner or the Outer Area. We consider that it will be convenient if the proposal made by the Metropolitan Board is carried further by subdividing the Metropolitan District into the five sewerage districts mentioned, and we accordingly recommend that this should be done and the Drainage Act amended accordingly.

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