Raising the height of the Shasta Dam has been under consideration for at least a decade. The U.S. Bureau of Reclamation wants to expand it by 18 feet, adding an additional 13% storage capacity to the largest reservoir in California.
This extra storage would allow for more water to be delivered to farmers in Southern California during dry seasons, which is something that President Donald Trump has worked toward during both his terms.
Alastair Bland is a climate reporter who has written about the potential impacts of raising the Shasta Dam for CalMatters.
He said a recent federal budget bill allocated $2 billion for enhancing surface water storage — likely for Shasta Dam.
“Raising the dam by 18 feet would flood almost another mile of the McLeod River where it enters the lake. So, it would inundate some important cultural sites for the tribe.”- Alastair Bland, CalMatters reporter
“That $2 billion is almost exactly the most recent estimate of the cost of the Shasta Dam project,” Bland said. “So experts do believe that that $2 billion allocation – although it does not mention Shasta Dam – is specifically earmarked for the Shasta Dam enlargement.”
That budget bill has passed the U.S. House, and is now awaiting review in the Senate.
Bland said the Shasta Dam project has been controversial since it was proposed. There are concerns about the cost, effectiveness and environmental impacts.
Supporters and critics both say their side will support chinook salmon, which are threatened and have been declining drastically for decades.
Those in favor say the increased depth of water in the reservoir will keep water colder, which salmon need. On the other hand, opponents say raising the dam would flood many essential salmon habitats.
The potential flooding is also a major concern for Indigenous tribes in the area.
Bland said 90% of the Winnemem Wintu Tribe’s territory was flooded when the Shasta Dam was built.
“Raising the dam by 18 feet would flood almost another mile of the McLeod River where it enters the lake,” he said. “So, it would inundate some important cultural sites for the tribe.”
Bland said even if the funding is approved, local and state laws will likely be obstacles.
“The California Wild and Scenic Rivers Act … specifically prohibits building a new reservoir on the lower reach of the McLeod River,” Bland said. “And this is exactly what that would do. So, it plainly violates that law.”
The interactions between state and federal laws can be complicated, Bland said. If the funding is achieved, there could still be years of legal battles ahead before the project can begin.
“President Trump has made vows through executive orders to increase the amount of water delivered to users in the Central Valley, in spite of any state laws that might stand in the way,” Bland said.
In the end, he said a cost-benefit analysis might not justify the expense.
“It would substantially increase the capacity of the reservoir. However, it's hard to fill a reservoir that size in California, and just because it's a bigger reservoir does not mean it will be a full reservoir.”- Alastair Bland, CalMatters reporter
“The estimate from the Bureau of Reclamation is that this project would only increase the deliveries from their Central Valley Project to recipients in the Central Valley by about 1% of the average,” Bland said.
The Central Valley Project delivers about 5 million acre-feet of water for agricultural use each year. It includes 20 dams and reservoirs across California.
Shasta Dam has a current storage capacity of 4.55-million-acre-feet. The proposed 18-foot expansion would create 634,000 acre-feet of potential water storage.
“It would substantially increase the capacity of the reservoir,” Bland said. “However, it's hard to fill a reservoir that size in California, and just because it's a bigger reservoir does not mean it will be a full reservoir.”
