Amid complaints, city offers details on DNA testing from Boise ponds hit by E. coli

The city of Boise has shed more light on the DNA testing methods it used to determine that dog feces were the primary cause of an E. coli outbreak at two popular Boise swimming ponds.

Boise Parks and Recreation was roundly criticized on social media after choosing to ban dogs from both Quinn’s Pond and nearby Esther Simplot Park following the test results. Some complainants expressed disappointment at losing a spot for pets to play — others offered skepticism that dogs were the main cause of the ponds’ elevated E. coli levels.

According to a press release from Parks and Rec, samples from ponds at both parks were sent to Source Molecular, a Florida-based laboratory that analyzes fecal bacteria in a practice called microbial source tracking to determine the bacteria’s origin.

“The basis for these source tracking techniques is that there are characteristics unique to the fecal bacteria from a particular animal and these characteristics allow for the identification of a source,” the Parks and Recreation press release said.

The department is still conducting tests on the ponds (one of which reopened last week), but officials said two weeks’ worth of test results decidedly show dog feces as the main culprit — followed by goose feces and small amounts of human feces, as well.

General testing of both ponds turned up evidence of dog feces in both Quinn’s Pond and Esther Simplot Park ponds, while goose feces biomarkers were found only in Quinn’s Pond, results showed. Targeted sampling along shorelines of the ponds showed a significant jump in biomarkers for dog feces at Quinn’s Pond in particular. Biomarkers for human feces were detected in shoreline testing at Esther Simplot ponds.

While dogs are no longer welcome in either park (including Esther Simplot Park’s previously designated off-leash area), dog owners can still walk their pets along the Greenbelt that stretches along the parks.

“We ask that citizens obey all posted signs, stay out of closed areas and keep their pets leashed,” Parks and Recreation officials said in the release.

In addition, the department said it’s doing more to haze geese away from the parks, as well as increase the frequency of cleaning goose feces from the areas.

As for the incidence of human feces, Parks and Recreation officials urged swimmers to be hygienic — including parents with small children. The department asked that children wear swim diapers to avoid potentially leaking waste into the water.

Quinn’s Pond reopened for recreational use last week; however, Esther Simplot Park ponds remain closed until testing shows that bacteria levels have dropped below the state threshold for safety.

Parks and Recreation will continue testing the water at both parks daily.

This story was originally published July 2, 2017 at 10:00 AM with the headline "Amid complaints, city offers details on DNA testing from Boise ponds hit by E. coli."