Nevada County authorities are still working to determine the source of contamination after discolored water in the South Yuba River tested positive for “dangerous” levels of E. coli over the weekend, prompting a no-swim advisory.
The Yuba River is being tested and monitored closely after murky, yellow waters appeared in two separate segments of the river starting Friday. E. coli bacteria was detected in one stretch of the South Yuba River in Nevada County, but a separate contaminated stretch along the middle fork of the Yuba River was declared “all clear” Sunday by Yuba County health officials.
The Nevada County Office of Emergency Services first issued a no-swim advisory, “due to unknown sediments in the water, and dangerous levels of E.coli” detected Friday evening near the Highway 49 bridge. E. coli levels tested at double the level considered acceptable for recreational waterway use by the Environmental Protection Agency, according to a news release by Nevada County health officials.
The no-swim advisory, from the town of Washington through and including Englebright Lake, was still in place as of Monday afternoon. People are also urged to keep their animals away. Nevada County’s environmental health department found that contamination levels had increased by Saturday evening, leading officials to expand the no-swim order to include the lake.
“The source appears to be above the State Highway 49 Bridge on the South Yuba River,” Nevada County said in a Saturday evening news release, based on a helicopter survey performed with assistance from the California Highway Patrol. “Officials continue to work on confirming a direct source, but it appears to be a plume that is moving downriver.”
Generally speaking, E. coli bacteria in water is an indication of fecal contamination, often caused by either sewage or high concentrations of animal waste. Earlier this month, an investigation by The Sacramento Bee discovered high levels of E. coli bacteria along the lower stretch of the American River, where there are high concentrations of homeless encampments.
Nevada County is working with numerous local, state and federal agencies and with help from volunteers to determine the source of the contaminant, and to gather samples to test for E. coli as well as toxic metals.
Toxic levels of arsenic, lead and mercury can sometimes flow into the river due to the area’s extensive history of mining operations. Mining sediment could account for discolored or murky waters, but not for E. coli. Results from metal testing take about three to four days.
The county is partnering with the South Yuba River Citizens League to get the message out about the no-swim advisory, according to Nevada County Emergency Services Manager Jeff Pettitt, who is also a captain for the Nevada County Sheriff’s Office.
“We both understand what a valuable resource the South Yuba River is for our community and have been working collaboratively to identify the cause,” Pettitt said.
Middle Fork of Yuba River is ‘all clear’
The Yuba County Office of Emergency Services issued its own no-swim advisory, this one for the Middle Fork of the Yuba River, starting Sunday morning after yellow sediment was observed there Saturday.
The water returned to a clear state by Sunday, with no unhealthy levels of contaminants found during testing, and the no-swim advisory was lifted just after 5 p.m. Sunday, Yuba County said in a news release. The brief swim restriction had affected Rice’s Crossing water access, Missouri Bar and Lower Missouri Bar.
Environmental health workers “spoke to someone who indicated there may have been a small mining operation that caused sediment to be stirred up,” according to Sunday’s news release by Yuba County.
Yuba County also posted before and after pictures of the river’s middle fork. Sure enough, the water was “all clear,” both visually and according to E. coli test results.
“It looked very much like what was happening on the Yuba River South Fork in Nevada County this past week, but the duration was very, very short,” the news release said.