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RIVERTON — A private lab's test results released Friday show that a particular toxin is absent in secondary water contaminated with blue-green algae, or cyanobacteria, leading city officials here to turn on irrigation supplies for residents and farmers.
The Utah Department of Agriculture and Food lifted its advisory warning people to refrain from watering crops, gardens or livestock with water from canals or Jordan River water in Salt Lake County, but kept it in place for livestock consumption of Utah Lake water.
"We are cautiously optimistic that continued water test results will bring good news for our growers and consumers," said LuAnn Adams, Utah's commissioner for agriculture and food.
The Salt Lake County Health Department stressed, however, that people still need to exercise caution, apply water at nighttime hours to limit exposure and avoid direct contact with water from Utah Lake and Jordan River.
"We are looking at continuing aggravating conditions," said Royal Delegge, director of the agency's environmental health division, noting that triple digit temperatures forecast through next week will present ideal conditions for the cyanobacteria to continue to flourish.
The algal bloom that infested Utah Lake and spread to the Jordan River and a network of canals in Salt Lake County can produce four groups of toxins that in certain levels can cause adverse health impacts to people who are exposed. Three of the four toxins were already ruled out as being present at harmful concentrations, while test results on the remaining toxin came in Friday.
The presence of cyanobacteria — which has been documented in Utah Lake and the Jordan River at dramatic rates well over safe exposure thresholds put out by the World Health Organization — does not mean the toxins are present, or that they couldn't be produced at a later time.
Riverton officials convened an emergency meeting Friday to determine if the delivery of secondary water should be resumed after the system was turned off on Saturday as a precaution. Other cities, such Herriman and South Jordan, also ceased delivery of secondary water on advice of state health and water quality officials pending laboratory results.
"That is the difficulty of this decision," said Riverton Mayor Bill Applegarth. "There are so many unknowns. … We are flying blind."
The mayor and council members were prepared to meet later Friday to decide on resuming secondary water service pending the arrival of more recent, conclusive results, even as they acknowledged they were caught up in a frustrating wait-and-see determination.
"I think that we are always going to be seven days later," said council member Paul Wayman. "If we keep delaying we will never know the toxins levels and it could be nonexistent by the time we get results."
Delegge said Utah lacks the any laboratory capacity to test the water for these groups of toxins and must wait on the work of a private laboratory in Florida, which takes days and creates uncertainty over current conditions of the water.
Sampling of water tested July 14-19 at Utah Lake and the lower Jordan River showed "non detect" for a potent neurotoxin called saxitoxin, which causes a human illness known as paralytic shellfish poisoning.
Delegge said no one should ever consume untreated secondary water even under normal circumstances, but the infestation of cyanobacteria at unprecedented levels at Utah Lake and Jordan River is cause for heightened concerns for exposure.
The Utah Poison Control Center has fielded more than 500 calls from people suspecting exposure to the blue-green algae, with 85 percent of those from Utah County.
Delegge said no drinking water supplies have been contaminated, and there's no evidence pointing to any infestation in Davis County.
Fears that the bloom could worsen and the toxin levels could change continues to cause alarm for state agencies.
State agriculture department officials have taken 11 samples from potentially impacted fruit and vegetables and sent those to the Florida lab to determine what, if any risks, might be present.
City council member Brent Johnson said the algal bloom has created a situation full of uncertainty because the presence of toxins can fluctuate and test results have time delays.
"This is just a chase game," he said. "The whole thing is a frustration because we are trying to make good decisions based on data we don't have. As soon as we see spikes, then we will have to make the best, informed decision that we can."
