November 27, 2019 – After reports of a yellow discoloration of the South Yuba River on Friday, September 20th, local officials from Nevada County, South Yuba River Citizen’s League (SYRCL), State Parks, and Nevada County Consolidated Fire District met to discuss and respond to the incident. CHP performed a helicopter fly over of the South Yuba River that same day and identified a distinct area of the River that changed coloration in the proximity of the 13000 Block of Kilham Mine Road.

Nevada County Environmental Health immediately began efforts to make contact with the Central Valley Regional Water Quality Control (State Water Board) and met with them on Monday, September 23rd, with the CEO Alison Lehman and OES Director Captain Jeff Pettitt. With the information and video footage collected by CHP, State Water Board Storm Water Investigators along with County personnel and the Sheriff’s Department inspected and sampled the 13000 Block of Kilham Road property. Environmental Health took surface water and soil/sediment samples along the South Yuba beginning Friday, September 20th, through Sunday, September 29th, that did not show toxic metals or high levels of E.coli.

Investigation Update and State Report

On October 23rd, the State Water Board submitted an Inspection Report of Findings to the Kilham Mine Road property owner. They found no evidence of a sediment discharge from the property that matches the characteristics of the plume in the South Yuba River was observed.

“The nature of the plume was particularly concerning due to the immense quantity of sediment that visibly traveled the Yuba for over 20 miles before diluting into Englebright Reservoir. We are grateful the sediment did not contain high concentrations of toxic metals that are prevalent in our watershed due to past hydraulic mining; next time we may not be so lucky,” said Melinda Booth, SYRCL’s Executive Director. “The State’s report confirmed our concern that the Yuba River watershed is still at high risk for future events and the South Yuba River Citizens League’s (SYRCL) 20 year monitoring history supports that conclusion.”

However, land disturbances greater than one acre that require coverage under the Construction Storm Water General Permit and code violations were observed during the inspections. The State Water Board findings from site inspections conducted on September 24th and September 30th indicated staff observed three graded areas and regrading of an access road that measured to be over one acre in total. The property owner was required to enroll under the Construction Storm Water General Permit and stabilize the disturbed areas at the site and was issued a Storm Water Notice of Non-Compliance.

Next Steps

In continued efforts to pinpoint the source of the plume, the State Water Board will now investigate 2 miles upstream from the Kilham Mine Road location and include investigations of Blue Tent on Bureau of Land Management (BLM) property along with shoreline investigations along the South Yuba River. The State will be conducting fly overs of the same area after the first significant rain fall.

Freshly graded pad along the Northern Access Road.

Although the State Water Board continues their investigation to find the source of the plume, the local history of numerous old mine sites, including abandoned debris control dams, tunnels, and holding ponds, can be a threat to our community’s health, the quality of our water, and the watershed as a whole. These sites tell us stories about our past, ones that include not only the prosperous history of that time but also the negative environmental and cultural impacts. September’s yellow plume event brought the past into the present.

As the State continues to conduct their official investigation into the source of the plume, the County will continue to work with both the State Water Board and local organizations SYRCL and Sierra Fund on the investigation to find the source of the plume.