A stretch of the American River in Northern California contains significant levels of E. coli bacteria, a sign of fecal contamination, according to Sacramento County officials.
Tiscornia Beach, an area on the lower American River frequented by summer visitors, tested 7.5 times higher than the safety threshold on Tuesday, according to data from the county and the Central Valley Regional Water Quality Control Board.
Samples of river water taken two weeks earlier at nearby Discovery Park tested almost 5.5 times higher than the safety threshold.
The Central Valley water board has tested the river's water for bacteria for about 10 years, and weekly results have been published online since December 2017.
"We knew there was a problem, " Adam Laputz, an assistant executive officer with the water board, said of the E. coli findings.
While most E. coli strains are harmless, some can sicken humans, with symptoms ranging from diarrhea to respiratory distress, according to the Centers for Disease Control and Prevention.
The bacteria live in the intestines of healthy people and animals and can be found in feces, but officials aren't sure where the E. coli in the American River is originating.
According to a Sacramento Bee report, homeless encampments line the banks of the river, and there is a widespread lack of bathroom access in the area.
But the contamination also could be a result of geese excrement. One goose can produce up to three pounds of feces per day, according to the Bee.
Sacramento County and the Central Valley water board are now preparing a years-long study to determine the exact source of the fecal matter using DNA analysis, Laputz said.
Until the origin of the bacteria is determined, officials can't say how they will handle the pollution, according to Liz Bellas, director of Sacramento County Regional Parks.
She said it is unlikely, though, that additional portable restrooms would be added in areas near homeless camps. Portable bathrooms in remote areas are more difficult to service in a timely manner and are often vandalized or tipped over, causing an even greater public health hazard, she said.
No one is known to have become sick after swimming in the river, Bellas said, but the county is still taking precautions. It has posted signs warning against drinking or cooking with river water and advising swimmers not to get in the water with cuts or open sores and to wash their hands and shower after taking a dip.