SALT LAKE CITY — Toxic blue green algae infecting Utah Lake continues to put a stranglehold on secondary water supplies in multiple southern Salt Lake County communities, even as the oozing blooms are growing worse.
The Utah County portion of the Jordan River was closed Tuesday, as was the Liberty Park Pond in Salt Lake City as a precaution. Utah Lake has been closed since Friday.
The Utah Department of Environmental Quality is sampling for levels of harmful cyanobacteria at Utah Lake, the Jordan River, Big Cottonwood Creek and the lower Spanish Fork River. As a precaution, testing is also moving north to impounded wetlands at the Great Salt Lake and Farmington Bay and to the Provo River south.
Fueled by excess levels of phosphorus and nitrogen, rapid proliferation of algal growth predominately occurs in warm weather at slow-moving bodies of water.
The blooms contain harmful levels of toxins that in high enough concentrations can be deadly, especially for pets and livestock given more chance of inadvertent exposure. Humans can begin experiencing physiological responses to cyanobacteria at 20,000 cells per milliliter. Samples taken Saturday show a count of 737,924 cells per milliliter at Jordan River and Bangerter Highway, and nearly 260,000 at Big Cottonwood, according to the state.
Walt Baker, who heads up the water quality division for the state, said an individual conducting monitoring at Utah Lake became violently ill, heightening concerns over the safety of response teams.
"They've observed that conditions on the bloom are worse now than they were last week," he said. "We need to find out how to do this monitoring without putting our people at risk."
About 20 percent of the more than 300 cases of exposure documented by the Utah Poison Control Center involve people who developed actual symptoms such as nausea, headaches, diarrhea and vomiting. Slightly more than half of those exposed were 20 or younger, the state reports.
The Utah Department of Agriculture and Food is advising people to refrain from consuming fruit or vegetables irrigated with contaminated water and have told farmers to look for alternative sources of water.
While there is evidence cyanobacteria can infect plant systems, agricultural officials can't know the degree of contamination that may exist because of so many variables — the actual type of watering system used, the time between potential exposure and consumption of the food, and the density of toxins in the contaminated water.
The warnings, the agency stressed, are being issued out of caution.
Luke Petersen, who farms 100 acres in southwest Salt Lake County, uses a drip irrigation system for his crops and trees with barriers that eliminate the plants' contact with water other than the root system.
After consultation with the U.S. Department of Agriculture, the Utah State University Extension Service, environmental scientists and health officials, the secondary water to his farm is now back on.
"We are pumping and keeping the water off the plants themselves," he said. "There is really no data about the secondary impacts of cyanobacteria. There are no documented instances of transfer from the plants. The plants change it to a biologically inactive form."
State water quality officials believe the extremely low levels of Utah Lake — it is down 4 feet from last year — are contributing to the scope and persistence of the blooms, which they say are unprecedented and covered 38 square miles of the lake's surface.
Baker said if this is a toxic species of algal, the degree of toxins in the water will increase as the single-cell plants die off. As the plants start to decompose, the dissolved oxygen levels in the water will go down. Excess organic matter in water consumes the dissolved oxygen needed by fish and other aquatic species to survive. In extreme situations, the water can become a hypoxic dead zone.
Nationally, algal blooms impact 65 percent of the country's major estuaries, costing $2.2 billion each year, according to the U.S. Environmental Protection Agency. There are an estimated 166 coastal hypoxic dead zones.
A state of emergency was declared earlier this month for southern Florida after blooms from the state's largest freshwater lake, Lake Okeechobee, spread to the coastal region and prompted beach closures.
Pyramid Lake was shut down this summer in Los Angeles County, California, and last year, a 636-mile stretch of the Ohio River was blanketed with scum. Drinking water supplies were impacted when the intake at Lake Erie was covered with algae last August.
So far, none of Utah's drinking water supplies have been impacted, but state water officials are warning against "cross connections" to secondary systems because of risk of spreading the contamination.
Phosphorus and nitrogen occur naturally, but excess amounts can develop in waterways because of human activities, including stormwater runoff, runoff from agricultural production and discharges from wastewater treatment plants.
There is no national, numerical limit for the amount of phosphorus or nitrogen that can be "safely" discharged into a waterway, but Utah has developed a phosphorus limit for wastewater treatment plants that takes effect in 2020.
The rule was developed after a multiyear process of working with cities and treatment plants. The upgrades are costly — Salem just received a $13 million state loan for a new treatment plant — but Baker said the algal blooms underscore the need for action.
Petersen said the algal blooms at Utah Lake are a repeat problem — they were extensive enough to kill a family's dog two years ago — so he hopes there's better preparation the next time.
"I think all along the whole system, everybody needs to be asking themselves how to be prepared the next time this happens," he said. "That is the farm way."
Contributing: Nicole Vowell