Huron Bruce MPP Lisa Thompson says the current form of the Great Lakes Protection Act should not pass third reading.
Thompson joined the debate on Bill 66 in the House yesterday.
She's concerned that it gives too much power to the minister of environment and climate change to override municipal decision making powers, especially when it come to zoning.
The PC Caucus has submitted a list of 31 amendments but 30 were rejected.
Thompson says a PC amendment to prohibit offshore industrial wind turbines in the great lakes was voted down by the Liberal government.