These are notes that I am writing to help me learn our industrial history. They are my best understanding, but that does not mean they are a correct understanding.
Friday, April 23, 2021
1945 Shasta Dam on Sacramento and Pit Rivers near Shasta Lake, CA
Work on the dam began in 1937. (Construction started in 1938) Many of the people that helped build Hoover Dam moved to help build this dam. Since many of those people then went off to help fight WWII, women helped finish the dam by 1945. [nps-history] So many of the 4,700 men [nps-shasta] were actually women. People need to learn to use the term "workers" or "employees" instead of "men."
The dam is on the Sacramento River, but it is built just below the Pit River confluence so that it creates a big reservoir in both rivers. It is an arch-gravity hybrid design that is 602' high. The nameplate capacity appears to be 676 MW (2*125+3*142), but it generates electricity only when water is needed downstream. (Update: 710 MW [WaterEducation] and 663 MW [usbr-details]) After meeting the electrical needs for water supply such as pumping, it earns $50m annually for the federal government. [usbr-plan] It uses Francis turbines and has a plant factor of 33.1%. [usbr-details] I assume the plant factor is the percentage of what it would generate if it operated at full capacity all of the time.
usbr.gov-projects The water stored in the reservoir is about 41% of the storage for the Central Valley Project. [Overview] The net generation is 1.8 billion kwh. At 1065' reservoir elevation, the spillway capacity is 186 kcfs and the outlet works can pass 81.8 kcfs. The maximum lake level is 1076.2'. [Details]
WaterEducation It holds about 4.5 million acre-feet. In a typical year, it supplies 7 million acre-feet of water, which is about 20% of the states developed water.
Shasta Lake posted Here's a drone shot of the great Shasta Dam. By. Tony Hord Fhotography
nps-shasta Lake Shasta has a 365-mile shoreline. [Google Maps labels it Shasta Lake, but this article called it Lake Shasta. No wonder I'm confused about the name. Most sources use Shasta Lake, the same name as the nearby town.]
nps-shasta It was built with 5' lifts in 50' x 50' blocks. A 9.6-mile conveyor was built from from a quarry to supply the aggregate needed to feed the concrete batch mixing plant that was built at the base of this cable headtower. "Shasta Dam is 883 feet thick at its base, 30 feet thick at its crest, and contains 6.5 million cubic yards of concrete weighing 15 million tons. At 487 feet long, its spillway was the largest manmade waterfall in the world, though it is eclipsed today by those at other dams, including Three Gorges Dam in China and Itaipu in Brazil."
Slide 13 of a 24-slide virtual tour via TrainOrders The concrete buckets held 8 cubic yards. [Slide 15] To put that in perspective, the ready-mix concrete trucks with the chute at the back that we see today hold 9 cubic yards. (The ones with the chute at the front hold 11 cu. yd.)
City of Shasta Lake posted Today’s Flashback Friday takes a look back at this early color photo of the initial construction of the Cable Head Tower at Shasta Dam. As most locals know, the tower was cut down below the water line and becomes exposed as the lake goes down beyond a certain level. The head tower at completion was 460 feet high. The cables which operated from the head tower to several tail towers carried cable cars and buckets which supplied materials (primarily mixed concrete) to the construction areas of the dam. In the lower left of the photo one can see the early grading for the five the power plant penstocks that would ultimately supply water to the power turbines. Paul Jevert shared Building Shasta Dam
This old topo map shows that the Southern Pacific used to closely follow the Sacramento River north of Redding, CA.
1901 Redding Quadrangle @ 1:125,000
One of the first things they built was a tunnel through the west side of the valley by the dam site so that they could move the railroad out of the dam site to start digging the dam's abutments. While the dam's abutments were being built, the permanent relocation of the railroad out of the river valley was built. The relocated line headed north from Redding, CA, and joined the old route south of today's Pollock, CA. The old route downstream of the dam became a spur to supply the dam construction. It is now abandoned.
In 1958 the downstream part of the original route and the new route both existed. And we see that today's I-5 was built as US-99.
1958 Redding Quadrangle @ 1:250,000
When the new railroad route became available, they built a division dam that sent the river's water through what had been the railroad tunnel. This made the entire dam site dry.
And 2018 must have been wet because the reservoir is still full near the end of the dry season. The reservoir is supposed to be at its lowest level in December to provide flood control.
In the photo below they are pulling water from the lowest outlet level in the reservoir. I assume they are doing this to get cooler water to meet downstream water temperature requirements. "Downstream water temperature requirements required bypasses of outflows around the powerplant and resulted in around 2,000,000 megawatt-hours of lost generation." [usbr-plan] They release warmer water from the upper layers to maintain river flows and save the colder water for the winter-run Chinook salmon migration and spawning. [WaterEd-release] The Bureau of Reclamation runs fish hatcherie killed 75% of the eggs and fry in 2014 and 2015 because they didn't release enough cold water. [WaterEd-kill]
Is the statement about wasting 2,000,000 Mwh of generation capacity still true after they built this structure in 1997? And what went wrong in 2014-15 that caused so many of the endangered salmon to be killed?
This photo explains why I could not find any street views from the top of the dam. I presume that Homeland Security had declared a high alert level. Normally, the road is supposed to be open during the day.
The Bureau of Reclamation wants to raise the dam 18.5' to add about 14% more capacity. I assumed the one advantage of doing this is that it would provide more water for the State Water Project. But this report indicates it would be less! It also discovered that the bureau didn't bother to mention the earthquake risks in its 2015 Environmental Impact Statement. People have listed many disadvantages of raising the dam. One would be cost. In addition to the obvious cost of adding more concrete to the dam, there would be the cost of again raising the roads and railroads and their bridges. The bureau's 2015 estimate was $1.4b. And we know that figure is only going to go up. Many want the project officially terminated because, as the threat of the expansion continues, the value of the properties around the lake is reduced.
In some areas, rather than raise I-5 or the UP railroad, they would build dikes around them.
usbr-2018, p8 [These viewgraphs are "Public Outreach Material" and the bureau is still not admitting that there are any cons to the one pro of supposedly more water. (I still don't understand how the State Water Project would end up with less water with a larger dam. And hiding earthquake risk seems particularly bad.)]
Active NorCal posted, Aug 21, 2021 Shasta Lake is so low, you can kayak through a historic train tunnel. (via @lovemykayak/IG) Steven Wiser: Put in at Sugarloaf and go down to Beehive on the Sacramento arm. Matt Fisher: Forrest Hopson that's the old southern pacific railroad line before they relocated it to higher ground. Barbara Barrett-Jerpe: This is tunnel #5. Near Lakehead. Debra Moore-Stenger: Takes 1 gallon of water to grow 1 almond. Where the water go? Flooded orchards!!! [I knew almonds were a water consumption issue. It is nice to have some information about them.] [I didn't even notice the panda until I read some comments. I looked at just 50 of the 741 comments.]
Mark Frazier shared Drought revels lost train tunnel. [I tried to find tunnel #5 and the bridge on a topo map. But the oldest available is 1945, and it shows the new SP alignment.]
Norcal FireWeather posted Karen Yuhasz: Mount Shasta is looking good too. When I drove through there last summer, the lake was so low and the mountain had very little snow. This is great!
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