Slideshow: Deadly floods swamp Colorado John Wark / AP Days of heavy rainfall flooded Colorado mountain towns, obliterating roads and leaving many people stranded. Launch slideshow

Severe damage from the deadly floods that swept Colorado could keep residents of one town out of their homes for up to six months, officials said.

E. coli bacteria contaminated the drinking water system for Lyons, and the wastewater system suffered at least $1 million in damage, town administrator Victoria Simonsen told the crowd at a meeting Thursday, the Longmont Times Call reported.

To the north in Larimer County, at least 82 people were still unaccounted for after the flooding last week, and Larimer County sheriff's spokesman John Schulz said some of those eventually would be added to the official list of missing.

"We certainly expect that a number of people on that list will be listed as missing rather than unaccounted for and will turn up dead,” Schulz told Reuters. “We hope that will be a low number."

The list of people who are unaccounted for statewide has been steadily falling from 1,200 a few days ago, Reuters reported, as families reunite, evacuees register and rescue teams reach areas cut off by the floods.

The official death toll stands at seven: four in Boulder County, two in El Paso and one in Clear Creek County. But at least three others are presumed dead, and Reuters said search dogs were combing a large debris field near Loveland in the Big Thompson River canyon, where a 1976 flood killed more than 140.

As Colorado begins the slow recovery from more than a week of massive floods, pet owners who were airlifted to safety witnessed something that gives them hope. They saw the National Guard's determination -- that no PETS would be left behind. NBC's Mike Taibbi explains.

When torrential rain and flooding began last week across the central part of the state, homes were destroyed, roads washed away and vital infrastructure damaged. The flooding also hit oil fields on the state’s Front Range, and authorities said Friday that at least 22,000 gallons of oil had spilled from tanks, complicating the cleanup effort.

Authorities in areas downstream in Nebraska warned residents to avoid contact with flood water.

Property losses could hit $2 billion, the catastrophe modeling firm Eqecat said Wednesday in its first comprehensive estimate.

In Lyons, one casualty of flooding was the Planet Bluegrass Ranch, home of a couple of well-known music festivals – RockyGrass and the Rocky Mountain Folks Festival. But employee Brian Eyster told the Denver Post that organizers plan to repair and rebuild in time for next summer’s events.

"Just on the emotional power alone, it'll be the best RockyGrass ever,” Eyster told the Post. “It has to be."

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