3 At the trial, the plaintiff's argument that the Plan was invalid depended on the impugned determination being ultra vires. In their submissions as to costs, counsel for the defendants submitted that the invalidity of the impugned determination had no significance other than as a step in the plaintiff's unsuccessful argument that the Plan was invalid. I reject that submission. The invalidity of the determination will potentially be significant in relation to the exercise of discretionary statutory powers concerning Lower Pitt Water. A determination of the "protected environmental values" for an area of water pursuant to cl 10 of the State Policy amounts to an expression of policy as to the attributes and/or uses of the relevant body of water for which that body of water should be protected. According to the evidence before me at the trial, the result of the impugned determination being ultra vires is that a subsequent determination as to "protected environmental values", made by a resolution of the Board on 31 January 2003 and a resolution of the plaintiff on 4 March 2003, applies in relation to the whole of Lower Pitt Water. That valid determination is somewhat differently worded from the determination that I declared to be ultra vires. Lower Pitt Water is within the plaintiff's municipal area, and within the area covered by the Sorell Planning Scheme 1993, but there is no provision in that Scheme that prohibits or regulates any activity in Lower Pitt Water. In the event of the Scheme being amended so as to make some provision relevant to Lower Pitt Water inconsistent with the valid determination, that determination would prevail. However there has been no suggestion that the Scheme might be amended so as to include any provision relevant to Lower Pitt Water. More significantly, the valid determination is something that decision-makers, or decision-making bodies, exercising statutory power may, or sometimes should, take into account. In particular, it might be appropriate to take the valid determination into account when discretionary statutory powers are exercised in relation to Lower Pitt Water pursuant to the Marine Farming Planning Act 1995. The valid determination, as I understand it, suggests that Lower Pitt Water should be protected because of its use for swimming, diving, water skiing, boating, and fishing, as well as its aesthetic quality. However, it is not binding except when it is inconsistent with a planning scheme or a similar instrument.