Newfoundland and Labrador's opposition parties are resisting the idea of building transmission lines through Gros Morne National Park in order to bring power from the Lower Churchill hydroelectric project to Newfoundland.

NDP Leader Lorraine Michael said Wednesday that building 40-metre high towers to transmit power through Gros Morne is a bad plan.

"I'm still not convinced that we even need the transmission line to come on to the island. You know I've had [provincial energy corporation] Nalcor's explanation, I've met with Nalcor and they haven't convinced me," she said.

Premier Danny Williams entered the controversy Tuesday when he said it might be too expensive to build the transmission line around the park, and that he is willing to risk Gros Morne's UNESCO designation as a World Heritage Site to cut Lower Churchill's development costs.

Opponents have warned Gros Morne could lose the designation, just as UNESCO removed it from a site in Germany over the construction of a four-lane bridge.

Liberal critic Kelvin Parsons said the Gros Morne hydro corridor is a bad first option, saying he thought it was another case of the premier "shooting from the lip."

However, Parsons said he could possibly support the plan under certain circumstances.

"Right now we have a UNESCO site there. There should be no transmission line through there unless it is absolutely necessary to go through there. And we don't know that at this point," he said.

Gros Morne visitors Becky and Russell Lyons, from Edmonton, said they came for the park's beauty, not to see power lines.

"It's nice to feel that this land is sort of sacred," Russell Lyon said.

Tourism operator Sue Rendell, who runs an adventure business in the park, said the UNESCO World Heritage Site designation has been a boon to tourism.

"To lose such a designation would be quite detrimental to the tourism industry here," she said.