Sunday, July 02, 2017

DNA source test results for Quinn's Pond and Esther Simplot Park Ponds

The City of Boise is releasing DNA test results that identify the sources of fecal bacteria in Quinn’s Pond and Esther Simplot Park ponds. City staff members are committed to making the ponds a safe place for citizens to enjoy while also educating the public about the source of the bacteria.

As was previously reported, E. coli bacteria testing by City staff showed high levels of the bacteria in both Quinn’s Pond and Esther Simplot Park ponds during the month of June – levels in Esther Simplot Park pond continue to test above state water quality standards for recreation.

Since the initial E. coli warning, the Central District Health Department has received several reports of associated illness linked to swimming in the ponds, which the City takes very seriously.

Subsequent DNA testing, performed by Florida-based laboratory Source Molecular, has allowed the City of Boise to determine the sources that contributed fecal bacteria associated with the high levels of E. coli in the ponds.

Those DNA test results point to three main causes of fecal bacteria in the ponds: dog feces, goose feces and human feces, although human feces only showed up in the second round of testing.

To mitigate the source of the bacteria, the City of Boise will no longer allow dogs at Quinn’s Pond or Esther Simplot Park, including the ponds and the previously designated dog off-leash area. The City is also ramping up efforts to haze the geese in the ponds in order to move them out and is increasing the frequency of goose feces removal at both parks. Finally, the Boise Parks and Recreation Department will continue to educate the public about the importance of using swim diapers when children are recreating at the ponds.

Here is a brief description of the DNA testing methods along with the test results:

In addition to enhanced E. coli sampling and site investigations, the City of Boise contracted with a laboratory that performs microbial source tracking (MST) (also called bacterial or fecal source tracking) to help determine the sources of fecal bacteria in Quinn’s Pond and the ponds at Esther Simplot Park.  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 contract laboratory, Source Molecular, used fecal Bacteroidetes, a phylum of bacteria found primarily in the intestinal tracts and mucous membranes of warm blooded animals for source tracking, to identify the fecal bacteria sources. For example, certain categories of Bacteroidetes have been shown to be predominantly detected in dogs while others are predominantly detected in geese, so the laboratory uses those categories to identify a source. The laboratory also runs positive and negative controls alongside its analysis for quality control purposes.

The City of Boise is still collecting data to complete a robust study, but tests two weeks in a row confirmed the presence of dog and goose fecal biomarkers in the ponds.

 

Waterbody

DNA Analytical Results, source detected

Marker Quantified (copies/100 mL)

Week 1 (whole pond)

Quinn’s Pond

Dog

Goose

< 10

< 10

Esther Simplot Pond

Dog

< 10

Week 2 (targeted shoreline)

Quinn’s Pond

Dog

Goose

1250

< 10

Esther Simplot Pond

Dog

Goose

Human

< 10

< 10

< 10


In the first week, dog fecal biomarkers were detected in both Quinn’s and Esther Simplot Park pond surveys, while goose fecal biomarkers were only detected in Quinn’s Pond.

The second week of sampling concentrated the sample efforts along the pond shorelines.  DNA results detected the presence of dog and goose biomarkers in both ponds as well as human biomarkers in Esther Simplot Park pond.

While biomarker copies per 100 mL were still low for geese in both ponds, the dog feces biomarker was significantly higher.  Although the City is still collecting data, these preliminary analyses, in conjunction with field surveys, confirmed that dogs are a significant source of fecal bacteria to both ponds.

The conclusion that dogs are a significant source of fecal bacteria in the ponds and contributed to the high E. coli concentrations is based on the fact that dog feces biomarkers were detected in the ponds; that biomarkers indicated that dog feces was the primary source of fecal bacteria in Esther Simplot Park pond one week, and genetic biomarkers for dog fecal bacteria were more prevalent (1250 vs. <10 copies per 100 ml) than other sources in Quinn’s Pond the following week.

Dog owners can continue to use designated Greenbelt paths through Esther Simplot Park for connectivity, but we ask that citizens obey all posted signs, stay out of closed areas and keep their pets leashed.

“The health and safety of our citizens is paramount and the decision was made to keep dogs out of Quinn’s Pond and Esther Simplot Park to help manage bacteria levels and prevent sickness,” said Doug Holloway, director of the City of Boise’s Parks and Recreation Department.

While Quinn’s Pond has been reopened for recreation, the ponds in Esther Simplot Park remain closed because test results continue to show E. coli bacteria levels above state water quality standards for recreation, meaning it is unsafe for swimming or wading.

The Boise Parks and Recreation Department appreciates the public’s continued cooperation as we work to maintain these popular city parks and make the ponds safe and enjoyable places for citizens to recreate in.