Things are not going well at Spaulding, contrary to a press release sent by the utility corporation last week. The repairs to both Spaulding Powerhouse #1 and Powerhouse #2 are now joined by a new issue, the lower intake tower which is underwater and brings water to both powerhouses. When PG&E dewatered the tunnel again to start repairs on the second discharge horn in Spaulding #1, they found a piece of this steel grate in the tunnel, according to NID’s General Manager Jennifer Hanson.
No water from Lake Spaulding is available during the repairs, according to PG&E. The repairs are slated to be completed by late June, then testing of the repairs will take place. Normal flows from Spaulding #1 are planned for early August. Spaulding #2, which predominantly feeds Scotts Flat, has repairs slated for 2026.
A bypass at Spaulding #2 was supposed to deliver some water flows during the repairs. However, the flange installed over the intake tunnel appears to be leaking and PG&E had to dewater the tunnel completely.
In order to safely perform the remaining repairs at Spaulding 1, PG&E needs to drain the tunnel. These safety requirements will prevent the flow of water through the Spaulding 2 PRV until the work is completed.
PG&E press release dated March 6, 2025
Intake tower?
We asked PG&E to describe the intake tower and Spokesperson Paul Moreno responded via email:
There are two separate intakes for the power tunnel at Spaulding. The upper intake is a large hole in the side of the rock wall with a grizzly/trash rack over it. The Lower Intake is deeper in the lake and has a cage-like steel structural tower built over the top of it. The tower is approximately 45’ tall and has multiple trash rack panels that let water in and keep debris out. The Lower Intake is currently out of service pending a physical dive inspection to confirm condition. A tension strap from the tower was discovered in the power tunnel when it was drained and inspected at the start of the Spaulding 1 outage. The inspection will take place simultaneously with the ongoing work to repair the liners to the second water discharge horn.
Extraordinary Event?
Meanwhile, PG&E has been sending cost estimates to both NID and PCWA for repairs on the discharge horns, claiming the repairs should be Reimbursements for Extraordinary Events. “The facilities damaged as part of the Spaulding Main Tunnel Extraordinary Event are being repaired by PG&E and include both discharge horns for PRV A and PRV B and the structural columns and foundations within the discharge chamber.”
In a letter to NID dated Feb. 14, 2025, PG&E estimated the costs for the repairs at $59,415,822 – with cost to date being $24,415,882 and an additional $35,000,000 estimated costs.
A similar cost sharing agreement exists with PCWA. Neither water agency has received the root cause analysis for the failure of the discharge horns, making it impossible to ascertain if these repairs are an extraordinary event or just lack of maintenance. NID has repeatedly asked for the document and was told by PG&E in October that they wouldn’t disclose it.
Some background
A search of public documents on the Federal Energy Regulatory Commission (FERC) website shows the pressure relief valve being flagged by FERC during a dam safety inspection in July 2023, according to a letter sent to PG&E on August 24, 2023.
The FERC letter reads, in part:
Corrosion was observed on the turbine shutoff valve (TSV) and pressure regulator valves (PRV) at Powerhouse No. 1. PG&E should clean and recoat these valves or describe the maintenance program for doing so.FERC letter to PG&E dated August 24, 2023
PG&E filed a response to FERC on October 9, 2023 – due to the response containing critical energy/electric infrastructure information (CEII), the details are not available. We requested an update from PG&E about their proposed fix on March 25, 2024.
PG&E spokesperson Paul Moreno got back to us on March 26 and stated:
PG&E, FERC, and independent consultants inspected the valve bodies of the turbine shutoff valve (TSV) and pressure regulating valves (PRV) during a routine planned 5-year detailed inspection of the Lake Spaulding Project. Surficial coating issues and minor corrosion were identified on the exterior of the valve bodies by FERC. The external coating issue of the valve bodies is not related to the emergency work on the downstream discharge horns which are embedded in concrete and submerged during normal operation.
PG&E reported the current PRV damage at Spaulding #1 to FERC on March 8, 2024. One of the two discharge horns was repaired in 2024, the second horn is being repaired now. There is no firm date for repairs at Spaulding #2 at this time.
