High ammonia levels threaten Des Moines' water

Manure and commercial fertilizers spread on frozen ground contributed to record ammonia levels in water supplies across Iowa this spring, threatening tap water in Des Moines and harming fish and other aquatic life, officials said.

Sampling by the Iowa Department of Natural Resources found sharply elevated readings across the state, prompting environmental groups to urge new restrictions for farmers who use the fertilizers.

"We're alarmed about the ammonia levels Des Moines Water Works has had to deal with," said Roger Wolf, who works on river issues on behalf of the Iowa Soybean Association and a consortium called Agriculture's Clean Water Alliance. "We're trying to identify the sources so we can do something about it."
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The levels reached record highs because heavy ice cover acted like a lid on a pot, trapping ammonia from the manure and fertilizer runoff that otherwise might have naturally worked its way into the atmosphere, state biologists said. The same went for ammonia from decaying plant matter in the rivers. The ammonia built up to levels considered damaging to river life.

The ammonia problem was so pronounced in early March that Des Moines Water Works was forced to draw on alternative water sources to provide enough water for the metro area, said interim general manager Randy Beavers.

Because of the rising ammonia levels in the Raccoon River, plant operators feared they wouldn't be able to add chlorine fast enough during the treatment process to kill all bacteria and pathogens.

At times, the utility had to draw water from the shallow aquifer next to the city's treatment plant and from its backup plant at Maffitt Reservoir to keep taps running.

"We consider this a very serious situation," said Beavers.

"It made the Raccoon River basically unusable. We would have had a serious situation if we had lost the Des Moines River as a source because of a pump failure or something."

The spikes in ammonia forced Des Moines Water Works to quadruple the amount of chlorine used to disinfect the water it draws from the Raccoon and Des Moines rivers, which usually provide the area's drinking water. Waterworks in cities such as Council Bluffs and Panora had to take similar measures to ensure the safety of their water.

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