New Colgate Powerhouse breach: What do the longer-term impacts look like?

It has been more than two weeks since a major environmental incident broke out in the Yuba County foothills.

A penstock pipe at the new Colgate Powerhouse suffered a catastrophic failure on Feb. 13, flooding the facility located south of New Bullards Bar Reservoir and forcing workers to evacuate.

The 14-foot-diameter pipe carried water from the reservoir through a tunnel into the powerhouse for hydroelectric power generation.

Officials said 10 people had been working at the facility. Five managed to escape on foot, while the others had to be rescued by helicopter. One worker suffered serious injuries and was hospitalized, but has since been released to recover at home.

The rupture also triggered a mudslide, sweeping sediment and oily debris into the North Yuba River — home to populations of spring and fall-run Chinook salmon and steelhead. 

Recovery efforts are currently underway and reporting progress. As of March 3, the state Office of Spill Prevention and Response reported nearly all large, oily debris has been recovered from Englebright Lake, totaling about 1,440 cubic yards.

But much work still remains.

Yuba Water’s response

The powerhouse is operated by the Yuba Water Agency, which was established in 1959 to manage flood risk, water supply and wholesale power generation. Officials said the facility produces enough power for 300,000-400,000 homes in Northern California.

General Manager Willie Whittlesey told Insight Host Vicki Gonzalez crews were able to reach New Colgate last week to take stock of the facility. He said a lot of work needs to be done to restore the plant, but “it’s not as bad as we thought it was.”

“The top area of the powerhouse is covered in sediment and debris from the landslides and erosion. But inside the powerhouse and the generators themselves, they’re not inundated with mud like you might think,” Whittlesey explained.

When asked about a potential repair timeline, Whittlesey said the best case scenario is “a year to two years.” He explained that crews will need to dig out and dry the powerhouse, as well as restore access on a nearby road that was blocked by mudslides. 

Whittlesey said the agency had been doing months of maintenance at New Colgate when the rupture happened. “We were in the process of restoration or return to service,” Whittlesey said. “We were filling the penstock, we were filling the tunnel.”

He said Yuba Water was following procedures and planning to do a final inspection when the penstock burst. “We’ve never experienced anything like this; it’s an absolute abnormality,” Whittlesey said.

When asked about the cause of the penstock rupture, Whittlesey said it is currently under investigation. “We’re committed to a root cause analysis,” he said, adding that an engineering team will conduct a forensic analysis to identify any flaws.

Investigation and financial hits

California workplace safety officials have also begun an investigation into the incident. The state’s Division of Occupational Safety and Health (Cal/OSHA) told CapRadio last week it has begun an inspection of the Yuba County Water District.

A spokesperson for the agency said its investigation must be completed within six months, and it will “issue citations if violations of workplace safety regulations are identified.”

Whittlesey said Yuba Water has been in contact with Cal/OSHA. “We will cooperate with Cal/OSHA and be completely transparent on what had transpired with this incident. I have no concerns about a safety violation,” he said.

Whittlesey said his agency will need to reassess its finances in the wake of the penstock breach. “Not having the revenue created from hydroelectric generation at Colgate Powerhouse, we’re probably missing out on 80% of our normal annual revenue,” he said.

“It’s a significant source of generation in Northern California, the CAISO grid will see a lack of the megawatts that we put out at least this summer, and likely summer of 2027.” 

The environmental impact

Aaron Zettler-Mann is the Executive Director of the South Yuba River Citizens League (SYRCL), which protects the Yuba River watershed and responded to the breach.

Zettler-Mann called the incident a “tragic disaster,” and something that has never happened on the Yuba before.

“We focused initially on dissolved oxygen, pH, temperature, and then turbidity,” he explained. “Very quickly after a couple of days, we were confident that most of those variables… weren't any concerns.”

Zettler-Mann said turbidity, or water cloudiness, was elevated following the landslide. “We saw a very, very muddy river,” he said, calling it “a dark, kind of chocolate milk” color. The organization said the sediment plume moved downstream of the disaster, and hung around for days at a time.

A researcher with the South Yuba River Citizens League takes a sample of muddy water from the Yuba River following a penstock rupture at the New Colgate Powerhouse on Feb. 13, 2026.Courtesy of South Yuba River Citizens League

Elevated turbidity can be harmful to the fish that call the Yuba River home. SYRCL said the sediment can affect feeding behaviors and obscure their vision, leading to poor health and potential death.

The breach also had a much more direct impact directly on salmon themselves. Whittlesey said the incident caused a power outage at Yuba Water’s Narrows Powerhouses downstream of Englebright Dam and took them offline.

He said an operator at New Colgate would usually open a bypass valve to increase flows to the Lower Yuba, but said in this case the worker was evacuating. “There was about two hours where the flow in the Lower Yuba River did decrease,” Whittlesey said, which resulted in a significant fish kill.

SYRCL representatives said many salmon fry were stranded when the water levels dropped. “Hundreds, probably thousands of juveniles were stranded in rock and gravel. This was not, and is not a water quality issue,” Zettler-Mann said.

He said the ultimate impact on vulnerable salmon populations will take time to figure out, estimating the time frame at “about four years, about one life cycle.”

“It’s hard for all of us because we have together put so much effort into restoring.. .we saw record returns this year, highest numbers in a decade,” he explained. “To feel like our projects were working and moving the needle some, it’s been pretty tough.”

The Yuba Water Agency gave $300,000 to SYRCL shortly after the powerhouse disaster, which Zettler-Mann said will be used for a habitat restoration project along the Lower Yuba River.

“We will continue to push this forward,” he said. “How that looks in the future we don’t know, but it doesn’t change our shared interest in getting this good work done.”