Flooding across western Iowa has damaged levees and forced some communities to evacuate. The floodwaters have even put water treatment systems at risk.

Floodwaters from the Missouri and Nishnabotna rivers forced the evacuation of about three-quarters of the population in the Fremont County city of Hamburg on Sunday. Hamburg is home to about 1,100 people.

The Missouri River in southwest Iowa crested about 2 feet higher than the previous record from 2011.

Water inundated Hamburg's treatment plant Monday morning, so the roughly 300 residents that remain in the city have been given bottled water. The city and the Iowa Department of Natural Resources are asking people to avoid using their washing machines and dishwashers.

“The floodwaters can carry some microbiological and chemical contaminants,” said Ryan Young, an environmental specialist with the Department of Natural Resources in southwest Iowa. “And the water treatment plants that we have down here, they’re not used to treating things like that. They’re used to treating groundwater.”

Around 5 p.m. Sunday, environmental officials were notified the power was shut off at Hamburg’s water treatment plant because floodwaters had begun entering it. The city's wells are also inundated.

It’s unclear how long the city could be without its water treatment plant. But Young said this is a unique situation.

“We don’t typically see it as wells and water plants are built to be above the 100-year flood level,” Young said.

Young said a few communities have reported bypasses of wastewater or water main washouts, but Hamburg is the only city experiencing “a complete loss of the treatment plant” due to flooding.

When flooding began to affect the city, Fremont emergency management officials put up a shelter at Hamburg Elementary. Because the water supply was compromised, they had to look at other options, said Mike Crecelius, director of Fremont County Emergency Management.

“Once the water supply was contaminated, we had to move the shelter from Hamburg to one of the churches at Sidney,” Crecelius said.

When a water treatment system is inundated, it could take some time to bounce back, Young said. The DNR and the city will have to wait for water levels to drop before they remove mud and debris, test the equipment, collect bacteria samples.

Once bacteria is no longer there, they'll use the clean water to flush out the distribution system and sample the system again to make sure the water is safe to drink.

Over 30 miles north from Fremont, floodwaters have surrounded the Glenwood Municipal Utility water plant in Mills County. Both Glenwood, and the city of Pacific Junction which also uses the plant, were asked to reduce their water use and avoid turning on their washing machines or dishwashers.

The Glenwood plant serves about 5,700 people between the two towns.