The Austin City Council took a field trip Wednesday morning to the construction site of the controversial Water Treatment Plant 4.

The council learned from the sites construction manager that the $500 million project is about 15 percent complete.

Once operational, the treatment plant will basically suck water out of Lake Travis, via massive underground tunnels, treat the water and then distribute it to Northwest Austin.

Construction has been under way for about a year. The council narrowly gave the green light to start the project back in 2008.

Since then the council's swing vote, Randi Shade, has been replaced by Kathie Tovo. She has said she would not have voted for the plant in the first place.

Those against the plant, say it’s a waste of money and the city does not need it because water demand has been decreasing or staying flat since 2001.

Those for the plant, including Mayor Lee Leffingwell ,say the city can not and should not gamble with its future water supply.

Last month in a 4-2 vote, the council told the city staff to figure out how much it would cost to stop construction for a 5-10 year period.

“I think it’s important for us to see the level of construction that has taken place and the level of activity here on the site,” Tovo said. “So, it is definitely an important piece of information to factor into our decision making process.”

City staff is expected to have that number for the council early next month.

Depending on how big the number is, there is a chance some council members could move forward with a vote to try and stop construction.