What’s that smell? Rotten-egg odor from ponds is nasty, but natural | VailDaily.com
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What’s that smell? Rotten-egg odor from ponds is nasty, but natural

Eagle River Water & Sanitation officials were at this pond in Arrowhead on March 23 testing oxygen levels in the water. Results show oxygen depletion in the pond, causing in a vulgar odor coming from it.
Eagle River Water & Sanitation | Special to the Daily |

What’s that smell?

Odors from high alpine ponds may occur from a natural process known as oxygen depletion, or “turnover.”

A pond turns over when the water mixes due to changes in temperature — or seasons. Oxygen is pulled out of the water creating sulfide gas, which smells like rotten eggs.

The process occurs every year in certain ponds in Eagle County.

EAGLE COUNTY — Diane Johnson has been busy the past several days, explaining pond turnover to residents concerned about a rotten-eggs smell coming from local ponds.

Johnson, the community information officer for the Eagle River Water & Sanitation District, is also easing the public’s concerns that the smell is not from any of the district’s treatment plants, wastewater collection systems nor anything else that’s part of its infrastructure.

“We’re explaining pond turnover, but I’m sure it’s new to many people and I think they’re kind of uncertain,” Johnson said in an email.

The ponds have no effect on the public water supply, Johnson said, adding that the district — which serves residents from East Vail to Edwards, including Minturn — uses no ponds as a source of drinking water.

“While pond turnover is a natural process, we’d encourage owners of ponds that are emitting smells to do some testing of the water.”Diane JohnsonEagle River Water & Sanitation

Odors from the Edwards/Arrowhead area were traced back to a pond in Arrowhead, Johnson said, and the district received a similar report of strong odors and dead fish at Nottingham Lake in Avon.

What is pond turnover?

Ponds at higher elevations often put off a vulgar smell this time of year due to oxygen depletion, a natural process. As winter turns to spring, the ice thaws and oxygen is pulled out, creating sulfide gas, which smells like rotten eggs.

“It’s not hazardous at all to the environment, it’s just a lack of oxygen in the water causes the sulfur dioxide gas to be given off,” said Pentti Tofferi, general manager at Country Club of the Rockies in Arrowhead. “Every year around this time it happens. This year it happened a little bit earlier just because of the earlier melt.”

While oxygen depletion can be hazardous to plants, algae and fish, the pond in Arrowhead does not stock fish because it is too shallow and freezes nearly top to bottom in the winter.

After talking with homeowners near the pond, Tofferi said it has been putting off the foul odor ever since it and the golf course were built. However, he said, this year might be worse than others for the smell.

Tofferi said he has been out by the pond recently and hadn’t smelled the odor, but wasn’t certain if it was gone for good.

“In the summertime, that pond is crystal clear and healthy,” he said.

Joint effort

Eagle River Water & Sanitation officials are working with town of Avon representatives about the status of Nottingham Lake, as the public is concerned about summer recreation.

Country Club of the Rockies is also working with Eagle River Water & Sanitation and performing tests on the pond water to make sure it’s nothing more than oxygen depletion. Tofferi said while depletion is a natural process, he is also looking into ways to possibly prevent the smell in the future.

Results from Eagle River Water & Sanitation’s test at the pond in Arrowhead showed the “dissolved oxygen is very low.”

“While pond turnover is a natural process, we’d encourage owners of ponds that are emitting smells to do some testing of the water,” Johnson wrote.

Reporter Ross Leonhart can be reached at 970-748-2915 and rleonhart@vaildaily.com. Follow him on Instagram at colorado_livin_on_the_hill.


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