In part two of our coverage of the ongoing disaster at the Colgate Powerhouse, in Yuba County, Zeke Lunder and guests discuss the collapse of the Colgate penstock in Yuba County, California, following a major spill when the penstock which feeds the powerhouse ruptured. The disaster, which occurred after significant upgrades, has impacted water management and flood control in Northern California. The Yuba County Water Agency had been replacing the penstock and tunnel, with work scheduled through March 2026. The failure occurred during the refilling process, causing extensive damage. The discussion also covers the broader implications for hydropower operations, sediment management, and fish populations, highlighting the need for better infrastructure maintenance and public safety measures.
At 350 megawatts, the Colgate Powerhouse is one of the largest hydropower generation stations in California. It is fed by a 5 mile-long tunnel which can carry up to 3,500 cubic feet per second of water (1.5 million gallons per minute). The only other outlet on New Bullards Bar Reservoir once it drops below spillway height is a 1,200 CFS outlet at the bottom of the dam. With the tunnel/penstock out of action for the foreseeable future, the Yuba County Water Agency has lost 75% of their ability to deliver water from the dam to downstream users.
Introduction and Apology for Previous Inaccuracies
- Zeke apologizes for inaccuracies in the previous day’s video about the Colgate powerhouse and penstock collapse.
- This episode includes a discussion with some of his smartest hydrology and river type friends, Eric Ginney and Dave Steindorf, to get more accurate information.
Overview of the Disaster and Geographical Context
- The broadcast provides an overview of the disaster, which occurred in Yuba County, California.
- It explains the geographical context, including the Yuba River watershed and its three branches: North, Middle, and South Yuba.
- The disaster involved the collapse of the penstock, which resulted in millions of gallons of water flooding down the mountain and burying the powerhouse in debris.
Details of the Pen Stock Collapse and Repair Work
- The Yuba County Water Agency has been doing upgrades to the Colgate tunnel and penstock pipe, with active work through March 2026.
- A new section of specially fabricated penstock pipe was successfully delivered over the summer.
- The disaster occurred during the refilling process of the tunnel and penstock, with the new protective valve failing.
- A five-mile tunnel that had to be drained following the rupture.
Impact on Water Management and Flood Control
- The disaster has regional implications on water management and flood control in Northern California.
- During the summer. The Colgate Powerhouse is typically operated at peak capacity for about 16 hours a day, and idled in the early morning hours.
- This creates a whipsaw effect in river flows, below, which would be bad for fish and the aquatic environment at large if it extended downstream to the Lower Yuba River.
- Englebright Lake, directly downstream of the powerhouse, is used to moderate these fluctuations. Releases from Englebright are kept at a relatively steady level.
Interview with Dave Steindorf and Eric Ginney
- Zeke introduces Dave Steindorf and Eric Ginney, who have extensive experience with California rivers and hydrology.
- Dave explains the history of the New Bullards Bar Dam, which was commissioned by Yuba County for flood control, consumptive water, and power production.
- Eric provides a detailed account of the disaster, including the failure of the new protective valve and the impact on the powerhouse and switch yard.
- They discuss the limitations of the low-level outlet at the dam and the challenges of managing water flow without the powerhouse.
Fisheries and Sediment Management
- Zeke and the guests discuss the impact of the disaster on fisheries, including Chinook salmon and steelhead in the Yuba River.
- Eric explains the historical context of hydraulic mining in the Yuba River watershed and the role of Englebright Dam in trapping sediment.
- Many stretches of the Yuba River which are below dams are deprived of sediment, which gets trapped behind the dams.
- Many millions of dollars have been spent hauling in gravel and cobble to restore spawning beds for salmon downstream of Englebright.
- Englebright Dam was actually built to trap sediment, not store water.
Public Safety and Infrastructure Maintenance
- Dave emphasizes the importance of public safety and the need for significant investment in hydro infrastructure.
- He mentions that many California hydro projects were originally gold mining ditches and are now falling apart without proper maintenance.
- The guests discuss the economic challenges of operating hydro projects and the impact of negative power prices during peak solar production, midday, on their viability.
- They highlight the need for better public disclosure of dam safety issues and the potential risks of large uncontrolled releases of water.