An environmental study is beginning on a plan to cut a mile-long tunnel through the north slope of Provo Canyon, but some believe the study is coming a little late because design plans have already been set.

The $8 million to $10 million tunnel would replace a mile-long stretch of the green Olmstead Aqueduct that is occasionally damaged by landslides near Canyon Glen.Critics of the tunneling plan point out that a conclusion on construction procedures was announced in December, almost five months before the public was invited to comment on possible environmental effects or alternatives to the tunneling proposal.

"I feel like decisions have been made without public input," said Danielle Davis, a Provo Canyon resident speaking for the Utah County League of Women Voters.

The pipeline was owned and operated by Utah Power & Light until it was condemned by the Bureau of Reclamation and turned over to the Central Utah Water Conservancy District more than one year ago for use as a feature of the Central Utah Project.

Conservancy district officials called a public meeting in Orem Tuesday evening to solicit input on the tunneling proposal and two other pipeline repair options, but General Manager Don Christiansen made it clear at the meeting the district was only considering the tunneling option.

"The fix that we would like to pursue on this pipeline is a tunnel," he said. "Investigation into many concerns led us to believe the tunnel is, at very least, equal to other alternatives that could be used in fixing the pipeline."

Burying part of the pipeline in a trench or rerouting the pipeline by crossing the Provo River are the other two options that were considered.

Lillian Hayes, representing the Sierra Club, told the Deseret News she is concerned a tunnel might disrupt springs Provo relies on for culinary water supplies.

She has criticized the Bureau of Reclamation and the conservancy district for not pursuing the environmental assessment process outlined by the National Environmental Policy Act, as she interpreted it, before proceeding with design work. At the Tuesday meeting, she told district representatives that delaying a report on environmental impacts until final design work was under way violates NEPA requirements.

But the bureau's environmental staff chief in Provo, Lee Swenson, said that while the conservancy district and its consulting engineers were responsible for providing environmental-impact information to the bureau, the bureau's regional director would have to concur with a finding that no significant environmental impacts exist before construction could begin.

If the bureau approves a draft environmental assessment, further environmental studies could be required if potential impacts are identified during a 30-day public comment period.

"If there are impacts, a full-blown environmental impact statement would be done," Swenson said. "But the district is pretty certain the impacts of the (tunneling) proposal are minimal."

Swenson added that he has yet to see the consulting engineer's environmental report and probably won't until summer.

Christiansen said the tunnel would benefit the environment in the canyon because a hidden tunnel would replace a segment of the green pipeline, and the replaced segment would be dismantled and removed from the hillside.

Christiansen said the tunnel would also be the cheapest repair option under consideration. The tunneling plan also incorporates sound engineering principles and would resolve the problem with the line for at least 100 years.

Provo city officials also have questions about the effect the tunneling work will have on the city's springs in Provo Canyon.

Public Works Director Merril Bingham told the Deseret News he has written a letter with Provo's concerns that he wants included in the district's record.

"Our concern is that the tunneling process not interfere with those springs. We've asked them to address that specifically in their engineering and geologic report," Bingham said, adding that he is also interested in knowing how Provo's water would be replaced if the tunneling work did interfere with the city's springs.

"We're in a position where we can't afford to have those springs impacted negatively, and we have asked them to address that more specifically," Bingham said.