Michigan voters could decide as early as November 2006 whether to prohibit new diversions from the Great Lakes.
A constitutional amendment approved Thursday by a state House committee would prohibit new withdrawals that aren't already operating legally.
Some environmentalists and House Democrats said the measure doesn't go far enough to regulate large withdrawals and puts off the debate until the next general election.
But Representative Dave Farhat of Fruitport says it's important to put the measure in the Michigan Constitution so state lawmakers could not change it in the future.
Only a vote of the people can change the constitution.
The measure now goes to the full House, which could consider it as early as next week.