The Treasury says it canât be sure the Government didnât reach a deal in the 1960s with Rio Tinto over the clean-up of the Tiwai Point aluminium smelter that has since been mislaid. A rumour was circulating at an electricity industry function hosted by Energy Minister Megan Woods in Parliament last week that a historic document setting out the smelterâs responsibilities had been lost. However, most signs appear to point to the speculation being another piece of Southland mythology â similar to the decades-old tale that the builders of the Manapouri hydro scheme mistakenly left a bulldozer in one of its tail race tunnels before they flooded it.