Authorities estimate more than $1 million in damage was done by the wall of water that engulfed parts of Lindon after the banks of the Murdock Canal failed Sunday.

But no one knows why the canal failed, and answers aren't likely to come for at least several days - if they can be found at all.Residents and an estimated 300 volunteers were busy again Tuesday morning pumping water from basements, shoveling muck from front lawns and trying to clean muddy high-water marks from walls.

According to a preliminary damage estimate released Monday by Pleasant Grove Police Chief Mike Ferre, some 40 homes, several city streets, portions of a U.S. highway and the Lindon City Park suffered the brunt of flood damage done by the break, which occurred at 4:50 p.m. Sunday.

Only one minor injury has been attributed to the incident, and authorities say warnings to nearby residents by emergency personnel and quick reactions by numerous volunteers kept the injury toll from being much higher.

A news reporter was injured Monday when the ground collapsed as she stood near barricades set up to keep spectators from venturing too close to the break. She was treated for rib injuries and released.

Authorities have given no word on a possible cause for the canal failure, and investigators still are trying to determine what happened, Pleasant Grove police dispatcher Sherrie Atwood said.

There have been unconfirmed reports that seepage was seen Sunday near the section of the canal bank that collapsed. But by the time those reports were made to police, the banks had failed.

Jack Gardner, superintendent of the Provo River Water Users Association, which owns and operates the canal, said the non-profit water corporation has hired a Salt Lake geotechnical engineering firm to help it rebuild the failed section.

The engineers will attempt to find the cause of the failure and will perform soil tests that will assist in rebuilding, Gardner said. The association has two contractors ready to begin rebuilding as soon as the engineers' reports are made, possibly later this week.

Until those reports come back, no one will know why the canal failed or how much it will cost to rebuild, he said. However, once reconstruction is under way the project could be finished within a week to 10 days.

Repairs to homes and streets will take longer, and just how homeowners will be compensated isn't known yet.

The water users association called in attorneys and engineering consultants at an emergency meeting Monday morning after examining the damaged canal and the flooded neighborhood downstream.

"We talked about houses that had been hurt," Gardner said. "The water overloaded the sewer, and there's street cleanup and road repair."

The canal, built by the federal Bureau of Reclamation in 1938, has no recent history of failure, and none on this scale. The canal failed near Point of the Mountain a decade ago, before the project was turned over to the association, Gardner said.

The canal, which supplies irrigation water to much of Salt Lake and northern Utah counties, is being dammed ahead of the break so irrigation water can be diverted and delivered to some association stockholders through other systems.

Only stockholders between the break and Point of the Mountain will be without water after Tuesday, Gardner said. Those who don't get water until the canal is rebuilt will probably suffer lower yields per acre because of the interrupted irrigation, but rainfall could make up a portion of the lacking irrigation water.

Gardner said he's confident the canal wasn't carrying more water than it should have, nor did water top the bank.

"It can take 375 second-feet at the head (at the mouth of Provo Canyon). It had 342 in it, so we weren't even up to capacity. It can deliver 240 second-feet to the Jordan Narrows, and we had 120 there. We had about 300 second-feet where it went out, which is normal."