Boise & Garden City

How E. coli got into Boise’s ponds and what the city’s doing to stop it from happening again

Geese poop targeted with dogs and remote controls

Geese poop has been a major cause of E. coli found in Boise park ponds. Here's how goose overpopulation is being addressed.
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Geese poop has been a major cause of E. coli found in Boise park ponds. Here's how goose overpopulation is being addressed.

After E. coli closed popular swimming holes in two Boise parks last month, the city launched a three-pronged attack to get rid of the harmful bacteria.

The first two prongs were aimed at reducing — if not eliminating — the main sources of E. coli in Quinn’s Pond and two ponds in Esther Simplot Park: dog and goose poop. The third is a flush of water through all three ponds.

The multi-faceted approach appears to be working, at least so far. Tests over the past few weeks indicate a reduction of E. coli in Quinn’s Pond and both Esther Simplot Park ponds, according to city of Boise data obtained by the Idaho Statesman.

Boise Parks and Recreation director Doug Holloway re-opened Quinn’s Pond June 30. As of Friday, he had no immediate plans to re-open the other ponds.

Before opening them, Holloway said, he wants his boss, Mayor David Bieter, and Idaho Department of Environmental Quality to agree with his assessment that the ponds are safe. And he wants to make sure that once he opens the ponds, he won’t have to close them again.

“We don’t want to get into that whipsaw, back-and-forth, ‘it’s open today, closed tomorrow’ kind of a thing,” Holloway said. “But we’re heading in the right direction.”

Holloway said he wants to see five to seven consecutive days with E. coli levels well below the threshold of what’s considered safe for humans before re-opening Esther Simplot Park’s ponds.


E. coli is a bacteria that thrives in the guts of warm-blooded animals. Some types of E. coli sicken and can even kill humans who are exposed to it.

Quinn’s Pond and the two ponds in Esther Simplot Park are the only public ponds in Boise where swimming is allowed. The city tests the ponds for E. coli once a week between April and October, until a high level of bacteria is detected, Holloway said. After that, it tests the ponds daily to determine whether to close or, later, re-open them.

Both Esther Simplot ponds and Quinn’s Pond, which are adjacent to each other, showed bacterial cultures above state water quality standards for recreational use during a test last week.

Part of the reason public agencies test for E. coli is that it’s a good indicator of other dangerous bacteria, said Graham Freeman, watershed coordinator for the Department of Environmental Quality’s regional office in Boise. When E. coli reaches a certain concentration, Freeman said, there’s a greater chance that other bacteria are flourishing.

E. coli levels at Quinn’s Pond and Esther Simplot Park looked fine through April and May, said Haley Falconer, environmental division manager for Boise’s Public Works Department. Toward the end of May, the numbers started creeping up.

A few times, initial readings showed concentrations well above Idaho’s water quality standard for recreational use, but subsequent samples failed to confirm those levels.

Still, the arc was clear: As the weather warmed, E. coli levels in Quinn’s Pond and Esther Simplot Park were rising.

A laboratory in Florida tested three samples Quinn’s Pond and Esther Simplot Park samples, Holloway said. The lab determined that goose and dog feces were the source of the E. coli, he said. One of the ponds showed a trace of human feces. Dog feces was the main culprit.

On June 19, Falconer said, the city started doing daily testing in the ponds.

Holloway closed them two days later. It was a setback for a park complex that’s among the most attractive in Idaho and one of the most popular recreation spots in Boise.

“It’s very disappointing, not only to the city but to the public that has been waiting for this park to open,” he said. “That’s why we moved so quickly to identify the sources and then moved so quickly to start managing those sources.”

Tests never confirmed that Quinn’s Pond had E. coli levels above the DEQ threshold, Falconer said, though they were close.


The same day Holloway re-opened Quinn’s Pond, Boise Parks and Recreation announced that dogs are no longer welcome in the Quinn’s-Esther Simplot complex, except from Nov. 1 to Feb. 28.

During the summer months, dogs have never been allowed off-leash in either park. But people often broke the rules, letting their dogs run free and swim in the ponds.

“Even if there’s dog waste up on the could either be washed into the water; it could be stepped on by somebody and taken into the water; it could be stepped on by another dog and taken into the water,” Holloway said. “And so, the only way to really manage it is to say, ‘No dogs.’”

Officers who patrol the parks will allow people to walk their dogs through them on their way to and from the Boise River Greenbelt, Holloway said.

“You just can’t linger in the park,” he said.

On the goose front, Parks and Recreation has deployed staffers to clean up the birds’ feces on the ground around the two ponds, Holloway said. The city also hired a contractor who’s using dogs to condition geese to stay out of the parks. Holloway said the approach seems to be working, since the geese have stopped hanging around the parks in the evenings. Only a small flock was visible Wednesday morning when the Idaho Statesman observed the goose conditioners in action.


The third prong was to flush E. coli out of Quinn’s Pond and Esther Simplot Park. In 2012, during construction of the first phase of a whitewater park in the Boise River just west of Quinn’s Pond, the city bought a small water right from the Thurman Mill Irrigation Company, which owns a nearby canal.

When the ponds’ E. coli levels rose this year, Parks and Recreation ran that water through a pair of 12-inch pipes under the whitewater park and into Quinn’s Pond, Holloway said. From there, water flows into Esther Simplot Park’s ponds.

It’s not much water — about four cubic feet per second, compared to around 1,000 in the river — but it appears to have pushed E. coli out of Quinn’s Pond, which the city re-opened June 30.

Readings have shown E. coli declined in Esther Simplot Park, too.

“We’re watching those numbers closely, and we believe it’s starting to have an impact now,” Holloway said. “We’re cautiously optimistic that we’re moving in the right direction.”

Parks and Recreation is working on one more tool stop E. coli from closing the ponds again: a filtration system — perhaps something like a French drain — that would keep contaminants on the land from draining downthill into the ponds.

Between that, flushing the ponds and reducing dog and goose poop, Holloway said, Boise should be able to avoid future E. coli problems.

“Now, are we going to be able to keep it pristine all the time? Probably not,” Holloway said. “But we're certainly going to make a very strong effort to keep it cleaned up.”


In February 2015, Mayor Bieter and Scott Simplot signed the final development agreement for Esther Simplot Park.

Simplot was representing the J.R. Simplot Foundation, which paid to develop the park. Part of the agreement required Boise to keep water temperatures in Quinn’s Pond and the closest Esther Simplot Park pond no colder than 70 degrees between June 15 and Oct. 15, and at least 75 degrees between July 16 and Sept. 15.

“Should water conditions deteriorate and bacterial levels increase to potentially unsafe levels, the city may post warning signs at the ponds, but shall allow swimmers and other users of the amenities to use the same at their own risk,” the agreement reads.

Holloway said he wasn’t sure how that affects his authority to close the ponds. He said the minimum temperature requirement received support from swimmers and other water enthusiasts in Boise.

The Simplot Foundation wanted water to be a centerpiece of Esther Simplot Park’s recreation activities, Scott Simplot said.

“That remains our goal,” he said in an email sent through a J.R. Simplot Company spokesman. “We’re happy to discuss any solutions the city may have to solving this problem and trust that their water specialists will help us find a way to use the ponds as soon as possible.”

Did warmer temperatures in Quinn’s Pond and Esther Simplot Park increase the amount of E. coli in them?

Probably not, said Robert Voermans, microbiology manager for the Idaho Bureau of Laboratories, a division of the Idaho Department of Health and Welfare.

In an extremely polluted — nutrient-rich — environment, raising the temperature of the water likely would lead to faster replication of E. coli and other bacteria, Voermans said. But that would require much dirtier water — think cesspool — than what’s in Quinn’s Pond on Esther Simplot Park, he said.

In those ponds, Voermans said, higher temperatures might actually lead to faster dissipation of E. coli because the bacteria would more quickly exhaust the scarce nutrients at their disposal. Generally, he said, E. coli doesn’t last long in water, unless it’s far more polluted than Quinn’s Pond and Esther Simplot Park.

Holloway said this year’s E. coli encounter doesn’t necessitate a change to the minimum temperature requirement.

“Because I think, in the middle of summertime, we don’t have a choice anyway,” he said. “The water temperature is going to be significantly higher, regardless of what we do.”