Your friend who suggested that the lake should be drained was hardly worthy of the breathless implication that he/she had said something original. Rather he was merely spouting the prevailing orthodoxy which has resulted in over ninety percent of our wetlands being lost. It is up to people like you, who can see that intrinsic values are important, to continue taking up the cudgels against the relentless destruction of our heritage for commercial gain.
While, as in the case of your friend, these arguments will fall upon deaf ears help is on its way, ironically enough in the form of commercial interests. As globalisation takes hold governments and interest groups will look for more and more legal trade barriers. Tapping into a growing environmental movement offers such a legal barrier. An easy an effective way of measuring the environmental effect an industry is having is to monitor the downstream waterways. Imagine what would happen to the New Zealand dairy industry if a group of EU environmental monitors arrived to check on the Canterbury herd, only to find that the lake they had come to test had been drained and was full of cows.