Item number 13 on this week's Austin City Council agenda involves a vote to spend a little more than $3 million for excavation and storm water facilities at the site of Water Treatment Plant #4.

But, Thursday's vote is much bigger than what is on the agenda, as it could very well be the beginning of the end to a very long argument about the future of Austin's water needs.

"If we vote to tunnel, move forward with this project, to tunnel under Lake Travis, I think it's the point of no return," Mayor Pro Tem Mike Martinez said.

On one side, Mayor Lee Leffingwell, Mayor Pro Tem Martinez and Council Member Sheryl Cole believe Austin needs to start building a new water treatment plant now.

"From a policy prospective, it's the best thing we can do for our water infrastructure right now," Martinez said.

On the other side, Council Members Laura Morrison, Chris Riley and Bill Spelman hold a different opinion.

"I don't believe we need it now and I believe it's to our detriment to build it now," Morrison said. "Some of the statistical analysis and the projections suggest very strongly that we can put it off for some years."

Up until Tuesday afternoon, Council Member Randi Shade was the swing vote.

"I think it's reasonable to think we're not in crisis mode yet, but it's not too far off. I think the time is right for this project," Shade said.

The fight over the $500-million treatment plant goes far beyond City Hall.

"We owe it to the rate payers to consider more affordable options for our water future," Colin Clark, with Save Our Springs, said.

Water customers will end up covering the cost of the project.

The three council members against the plant will try and pass
a water management plan that attempts to make Austin a national leader in water conservation by 2020.