The Secretary to the River Murray Commission has forwarded for advice the following letter:

At a recent meeting of the River Murray Commission consideration was given to a request received for advice as to the conditions under which cables for the supply of power could be placed across the River Murray in the vicinity of Koondrook. During a discussion in regard to this matter doubt was expressed as to whether the River Murray Agreement conferred upon the Commission any power to control matters such as that referred to, and I was accordingly directed to request your advice therein.

I may state that Koondrook is located on that section of the River Murray which will be rendered permanently navigable as a result of the construction of the weirs and locks provided for in the River Murray Agreement.

Following upon a discussion in the above connection, the Commission decided to invite the attention of the three Contracting State Governments to the desirability of placing under one central control the sections of the River Murray and Murrumbidgee which will be rendered permanently navigable on completion of the works set out in the Agreement, and to point out that, although the Agreement provided for the construction of weirs and locks for navigation purposes, it did not appear that the River Murray Commission had any jurisdiction over the River other than in respect of works to be carried out in pursuance of the Agreement.

The Commission at the same time directed me to submit the matter to you for favour of advice as to whether the River Murray Agreement confers upon the Commission any control in respect of that portion of the river which will be rendered permanently navigable, and, if not, what steps can be taken to give the Commission such control.

I shall be glad if you will kindly furnish me with advice in the above connection for submission to the next meeting of the Commission.

There appears to be nothing in the River Murray Waters Agreement of the 9th September, 1914, giving the Commission any power to control the erection in, on or across the River Murray of any works, other than those mentioned in the Agreement, which might obstruct the navigability of the river.

The Agreement relates to the construction of works which are designed to effect an ‘economical use of the waters of the River Murray and its tributaries for irrigation and navigation’ and in clauses 22 and 27 expressly provides that weirs and locks constructed under the Agreement shall provide at all times of the year for vessels drawing five feet of water.

The Commission has, under clause 28, power to give directions to the constructing authorities under the Agreement to ensure that the works constructed will adequately comply with the condition set out in clauses 22 and 27, but it appears to have no control over any other bodies or persons and any such directions may, I think, only be given in respect of the works specified in the Agreement.

But, if works, other than those mentioned in the Agreement, were constructed or being constructed by some body or person, other than a constructing authority, and had the effect of preventing compliance with the provisions of the Agreement as regards any particular lock or weir, the Contracting Government responsible for the construction of the lock or weir would, I think, have power to take action to prevent the construction of those works interfering with the carrying out of the Agreement. If the Contracting Government failed to take such action, the Commission would, in my opinion, have power to direct the Contracting Government to do so.

But the Commission has not, I think, any power to direct a Contracting Government to take any action with regard to works constructed in, on or across the River which might affect the navigability of the River, but do not prevent the observance of the Agreement.

The Commission not having direct control in respect of the River in any case and having indirect control in some cases only, the question then arises as to whether it may be given that control.

The River Murray is a highway of interstate commerce, and navigation on that River is, therefore, a subject on which the Commonwealth Parliament has power to legislate. (See opinion of 8.10.06 of the Attorney-General (Mr. Isaacs).⁽¹⁾)

It has been held in numerous cases in the United States that the power of Congress to legislate with regard to navigation includes the power to prevent the obstruction of navigable waters by means of bridges, dams, piers or other structures which interfere with navigation. The power of Congress with regard to navigation is, however, paramount, whereas the power of the Commonwealth Parliament does not extend to ‘abridge the right of a State or of the residents therein to the reasonable use of the waters of rivers for conservation or irrigation’ (Constitution, section 100).

Subject to that modification, I am of opinion that the power of the Commonwealth Parliament to legislate as to navigation includes the power to control the construction of works which impede or obstruct the navigation of rivers such as the River Murray.

The Commonwealth Parliament having that power, it follows that it may vest authority in any body or person to control the construction of such works and generally to regulate navigation on the River.

I am, therefore, of opinion that the River Murray Commission can, by Act of the Commonwealth Parliament be given control in respect of that portion of the River Murray which will be rendered permanently navigable by the works constructed under the Agreement.

In view however of the fact that the use of the waters of the River Murray for irrigation and navigation is the subject of an agreement between the Commonwealth and the States of New South Wales, Victoria and South Australia, I see no legal obstacle to the granting of the control in question to the Commission being provided for by a further agreement between the four Governments.

(1) Opinion No. 266.