Tracy Clark, who lives on Big Horn Avenue just below Beacon Hill Road, blames what she terms “toxic levels” on subdivision septic systems and sewage. Clark contacted the Wyoming Department of Environmental Quality, which tested the water last month.
The DEQ will conduct a triangulation study in the spring.
Although a state official said one location test was high, he also said there is no reason for alarm, though the DEQ is taking it seriously.
The theory is irrigation runoff is likely transporting the E. coli to the river from non-point (unidentified) sources. The DEQ is conducting a TMDL — total maximum daily load — project on the Shoshone from Buffalo Bill Reservoir downstream to Yellowtail Reservoir. Sage Creek is included in the project.
The DEQ has set E. coli standards. For primary-contact recreation use from May 1 to Sept. 30, concentrations of E. coli bacteria cannot exceed a geometric mean of 126 organisms per 100 milliliters.
The secondary contact recreation season runs Oct. 1 to April 30, and during that time, E. coli cannot exceed 630 organisms per 100 milliliters.
On Oct. 22, the DEQ collected samples in three locations east and north of Cody.
Below the Belfry Bridge on Wyo. 120 just north of Cody, the E. coli count was 5.2 organisms per 100 milliliters. Below Cooper Lane on the east end of Cody the count was 11 organisms per 100 milliliters.
But below the Corbett Bridge on U.S. 14-A, east of Cody, the count was much higher. The DEQ found 461.1 organisms per 100 milliliters, said Jason Martineau, DEQ senior environmental analyst in Sheridan.
Primary recreation use can entail a human’s full immersion and it is nearly impossible for people not to ingest a little water when immersed, Martineau said.
The Corbett Bridge count captured the DEQ’s interest, he said.
“It was high,” Martineau said. “That’s why we’re going back.”
The DEQ will return in mid-May to a collect geometric mean. They will take five samples from each of the three above locations over the course of 30 days, Martineau said.
A geometric mean means getting an average or trend. In this scenario, obtaining the average number of E. coli organisms per 100 milliliters.
The Corbett Bridge count may be high, but that doesn’t mean people are at risk, according to the DEQ.
“It’s no reason for alarm, I don’t think,” Martineau said.
Clark blames subdivisions on Cooper Lane and near the Greybull Highway (U.S. 14-16-20) and sewer ponds below Cooper Lane West on the outskirts of Cody for the higher than normal count.
The E. coli is from irrigation runoff flowing into Sage Creek and then into the Shoshone, said Mack Frost, chairman of the Cody Conservation District in Cody.
Septic systems in some subdivisions near Sage Creek Road (Road 3EX) may not be in compliance, Frost said. The sewer pond is not part of the problem, he said.
“That is absolutely totally in compliance,” Frost said.
The two ponds or “aerated lagoon system” below Cooper Lane West are in full compliance, said Keith Viles, solid waste superintendent for the city of Cody.
Monitor wells are on site. The wells are tested at the city’s lab and the results are sent to the DEQ. And, the DEQ inspects the facilities and records regularly.
“We’re in full compliance with all areas of our discharge permit,” Viles said.
But Clark said everyone living downstream of Sage Creek should be worried.
“I wouldn’t put my toe in there and it’s coming from Sage Creek,” she said.
Martineau said even in wilderness areas, water is not 100 percent pure. “There is always some E. coli in streams,” he said.
“Escherichia coli (E. coli) bacteria normally live in the intestines of healthy people and animals,” said the Mayo Clinic’s website. “Most varieties of E. coli are harmless or cause relatively brief diarrhea. But a few particularly nasty strains, such as E. coli O157:H7, can cause severe abdominal cramps, bloody diarrhea and vomiting.”
Healthy adults usually recover from infection of E. coli O157:H7 within a week, but young children and older adults can develop a life-threatening form of kidney failure, said the clinic.