A round of testing of Rogue River water in June found none of the toxic bacteria that prompted health alerts about a reservoir that serves the city of Salem.
“At this point, we’ve had no detections in the Rogue,” said Brad Taylor, Medford Water Commission general manager.
His agency will continue testing for the toxin, cyanobacteria, as the summer progresses even though early samples didn’t detect any problems.
“It’s still a possibility,” he said. “That’s why we need to pay attention to it.”
The state has issued a list of 100 public water systems that might be susceptible to harmful algae blooms, referred to as HABs by water agencies. Algae blooms are an indicator of the toxin, which is a byproduct of a bacteria that is similar to algae.
Cyanobacteria can make people and animals sick, and in large doses can cause liver damage and attack the nervous system.
Starting July 1, the state has required testing for cyanobacteria after health alerts in Salem caused by an algae bloom in Detroit Lake in May.
Gold Hill, Emigrant Lake, the city of Rogue River and the Medford Water Commission, which serves Medford and other local communities, have been identified by the state as having the potential to see these algae problems.
Lost Creek Lake in Jackson County has been found to have the toxins practically every year since 2007. But the lake is about 20 miles from where the intake pipe is located for the Water Commission’s treatment plant.
Taylor said that under the new requirements the source of the water must first be tested. If harmful algae is found in the test, then additional testing is conducted after the water is treated.
At the Water Commission’s treatment plant, Rogue River water goes through ozone disinfection before it is put into municipal pipes.
“Ozone is the best treatment method for algae toxins,” Taylor said.
Ben Klayman, director of water quality and treatment, said his agency has tested for cyanobacteria for years and hasn’t found any problems in Rogue River water.
“In past years, when Lost Creek Lake is blooming, we haven’t detected toxic bacteria here,” he said.
Even though the state now requires testing of water from the source, the Water Commission has routinely tested finished water, which has been treated, to make sure it’s safe for public consumption. As part of the testing, the commission looks for cyanobacteria.
During the winter, the source of the water is Big Butte Springs, which provides 26 million gallons a day. Apart from a little chlorine, the spring water doesn’t need treatment.
In the summer, when consumption increases, treated Rogue River water is mixed in, requiring the injection of liquid oxygen and the application of an electrical current. Testing for cyanobacteria occurs every two weeks out of the Rogue.
Klayman said the liquid oxygen treatment would kill the cyanobacteria if it were present in the water.
There is about a 50-50 mixture of Rogue River and spring water in the summer, Klayman said.
Blue-green algae blooms typically break out in stagnant water that gets heated during the summer.
Because the Rogue is a relatively cold body of water, it tends to get fewer algae blooms and is less susceptible to the creation of cyanobacteria, Klayman said.