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Wildlife are main source of bacterial contamination in lower American River new study shows

Dogs and birds have also been deemed to be large fecal contaminators in some areas along the American River.

SACRAMENTO, Calif. — As thousands of cubic feet of water rush down California's American River every second, a problem murks the clear waters of the stream, which cuts through the city of Sacramento. 

Fecal contamination in the popular river, used recreationally by thousands each year, has been studied for years but a new study released Tuesday sheds more light on the cause of the contamination. 

According to the State's Water Board, humans are not the main cause of fecal contamination in at least 3 miles of the 30-mile-long river.

According to the study, which took samples from the lower American River between Paradise Beach and Sutter's Landing Regional Park, wildlife, birds and dogs are the main sources of bacterial or fecal contamination. 

The study used DNA testing to identify the leading causes of E.coli contamination. It found that most locations sampled met statewide water quality thresholds for bacteria. At Sutter's Landing, however, 100% of the samples exceeded water quality thresholds.

Birds, in particular, were found to be the largest and most consistent source of contamination. Dogs were also found to be consistent in contaminating that stretch of the American River with feces. On the left bank of Paradise Beach, contamination from dogs was detected in more than 60% of samples.

Two detections of human fecal matter were observed in the area but, according to the study, "both detections were at very low levels and not quantifiable."

The areas most impacted by fecal matter contamination are along banks and in shallow water areas, according to the study. The main channel of the Sacramento River was found to be meeting bacterial objectives and of "high quality."

Read the full study here.


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