Ruth Dam Hydraulic Oil Spill Threatens Mad River Water Supply

A mechanical failure at Ruth Dam has sent hydraulic oil into Ruth Lake and the Mad River, raising questions about water quality for Humboldt County communities that draw from the river, even as Trinity County officials maintain there is no known risk to the public.

According to a hazardous materials spill report filed with the California Governor's Office of Emergency Services, the trouble began March 3, when a flap gate at the dam's intake structure failed and hydraulic oil escaped from its containment system. Responders observed an oil sheen roughly 200 feet long and 10 feet wide on the surface of Ruth Lake. The amount of hydraulic fluid visible on the water was estimated at about 15 gallons. Absorbent pads were deployed while response crews traveled to the scene, and divers were scheduled to inspect the structure and identify the precise source of the leak.

Yet Trinity County's public account tells a different story about when the problem came to light. In a press release dated March 12, the county stated it was notified of the hydraulic oil release on March 11 at approximately 2:00 p.m. That is more than a week after the mechanical failure described in the spill report. Kym Kemp of Redheaded Blackbelt noted that "the difference between the March 3 mechanical failure described in the spill report and the county's statement that officials were notified March 11 was not explained in the county's announcement." Redheaded Blackbelt reached out to the Humboldt Bay Municipal Water District, which operates the R.W. Matthews Dam at Ruth Lake and is coordinating with Trinity County on the response, but the district had not replied before publication.

Trinity County Environmental Health is leading the local response in coordination with the California Department of Fish and Wildlife's Office of Spill Prevention and Response and the North Coast Regional Water Quality Control Board. Response teams have deployed containment booms to capture the oil and limit its spread downstream. Trinity County Environmental Health expects additional hydraulic fluid releases to continue until repairs are completed on March 18, when the damaged components are expected to be fixed.

"The health and safety of our community is Trinity County's number one priority," the county's press release stated. "At this time, ongoing assessments indicate there is no known risk to the public."

What remains unanswered is whether any water-quality sampling has been conducted on Ruth Lake, the Mad River, or intake points used by the Humboldt Bay Municipal Water District. No confirmed test results or water supply advisories had been issued as of this reporting. The district had not addressed whether Humboldt County water customers face any near-term supply disruptions, or confirmed how much total hydraulic fluid has entered the system beyond the surface estimate of roughly 15 gallons. With repairs still days away and additional releases expected in the interim, the containment booms now deployed between Ruth Lake and the downstream Mad River corridor represent the last line of defense for a water supply that serves residents across portions of Humboldt County.