Austin city officials are planning a final, $300 million vote next week on a controversial water treatment plant the city is building near Lake Travis.

The money represents the additional amount necessary to finish the treatment plant. The decision would presumably be the last of numerous council votes on the plant, unless costs balloon or council members have a sudden change of heart after heavy construction begins.

This vote "will allow us to do the project more efficiently," said Council Member Randi Shade , who is among those who say the treatment plant is necessary to meet Austin's future water needs. "But this will still be a contentious issue, and I think there will be arguments over it for a while."

A split City Council gave the decisive go-ahead to the treatment plant more than a year ago, and the city has since spent more than $100 million on it. The site has been cleared, and the foundation will be poured soon. But the debate has continued. Critics now say the city is trying to curb public scrutiny of a project they consider unnecessary and potentially harmful to the environment.

"They're trying to pull a fast one," said Bill Bunch , executive director of the Save Our Springs Alliance. "They're giving the city staff a blank check and committing the money before they've finished their environmental assessments \u2026 and I just can't see how they can do that and say, 'OK, now do honest science.'\u2009"

Next week's vote would be a change from the way the city has handled decisions about the treatment plant. The council had been approving each of the numerous contracts with planners, engineers and construction companies individually during public meetings — an unusual process that gave the public more detailed information about the city's biggest public works project since it built Austin-Bergstrom International Airport. Critics also had the opportunity to oppose individual portions of the project.

But the process added eight weeks or more to each contract negotiation so that various city boards and commissions could review the terms. It also created the risk of delays and missed contracting opportunities, water officials say.

"We'll keep giving the council regular updates and doing public engagement," said Greg Meszaros , director of the Austin Water Utility. "But by breaking the project up into many pieces like we've been doing, we're not maximizing our ability to deliver it on time and on budget."

If the council authorizes the $300 million , the opposition will probably not disappear.

Residents of Northwest Austin's Spicewood Springs neighborhood still object to the city digging a wide shaft on a small parcel of undeveloped parkland there. The shaft would be an entry point to a 6-mile tunnel the city plans to dig to carry water from the treatment plant to other parts of town. The city is planning to hold a public hearing on the matter in December.

In addition, the city is facing two federal lawsuits from environmental activist groups.

One lawsuit, filed by the Save Our Springs Alliance and Environment Texas , asks the courts to stop the treatment plant until the city finishes all of its environmental studies. City officials contend the lawsuit is baseless and say some studies must happen during the designing and early phases of construction.

The second lawsuit, being prepared by the Sierra Club's Austin chapter and Save Our Springs, is more complicated but has the same basic aim: to force a halt to the treatment plant.

Bunch has said that if the lawsuits do not ultimately prevent the project, he hopes they will at least delay it until the May City Council election, allowing the possibility of electing new council members who are opposed to the treatment plant.