Big Creek Hydroelectric Project

Big Creek Hydroelectric Project
Company type	Subsidiary project
Industry	Hydroelectric power generation
Founded	1911
Founder	John S. Eastwood
Headquarters	Sierra Nevada, California, United States
Area served	California
Key people	John S. Eastwood (engineer), Henry E. Huntington (financier)
Products	Electricity
Owner	Southern California Edison

The Big Creek Hydroelectric Project stands as a significant hydroelectric power installation situated on the upper reaches of the San Joaquin River within California's Sierra Nevada region. Managed and owned by Southern California Edison (SCE), this system exploits the elevation drop of the San Joaquin River, along with its South Fork and Big Creek, spanning a vertical descent of , which has earned it the title "The Hardest Working Water in the World."

Initially established to provide electricity to the swiftly expanding city of Los Angeles, the project was conceived by engineer John S. Eastwood and initially financed through Henry E. Huntington’s Pacific Light and Power Company (PL&P). Construction commenced in 1911, with the first electricity generation beginning in 1913. After Southern California Edison acquired PL&P in 1917, the project grew to encompass 27 dams, an extensive network of tunnels, and 24 generating units housed within nine powerhouses, achieving over 1,000 megawatts (MW) of installed capacity by 1987. The six principal reservoirs collectively offer more than in storage capacity. The entire complex was added to the National Register of Historic Places in 2016.

At present, Big Creek produces close to 4 billion kilowatt hours (KWh) annually—accounting for approximately 90 percent of SCE’s hydroelectric production and nearly one-fifth of its overall generating capability—equivalent to around 12 percent of California’s hydroelectric output. Beyond electricity generation, its reservoirs play vital roles in irrigation, flood mitigation for the Central Valley, and recreational uses. The project has also encountered environmental and societal issues, including disruptions to fish migration patterns and submersion of historic Native American sites.

Background

The origins of the Big Creek Project trace back to California engineer John S. Eastwood, who conducted surveys along the upper San Joaquin River during the late 1880s to identify potential reservoir sites and locations for hydroelectric plants. In 1895, while serving as chief engineer at the San Joaquin Electric Company, Eastwood attempted a hydroelectric installation on the North Fork of the San Joaquin River; however, this effort failed due to insufficient funding and drought conditions.

Undaunted, Eastwood established Mammoth Power Company with plans to construct a rockfill dam on the main stem of the San Joaquin River. Nevertheless, investors were deterred by high expenditures—particularly for a proposed tunnel—and he abandoned this scheme by 1901. Subsequently, Eastwood designed a more extensive hydroelectric network covering the entire upper San Joaquin basin, utilizing several smaller reservoirs to generate power incrementally rather than relying on a single large dam and tunnel. This strategy eventually attracted financial backing.

In 1902, Eastwood presented his concept to Southern California entrepreneur William G. Kerckhoff, who was linked to Henry E. Huntington, founder of Pacific Light and Power Company (PL&P). Huntington aimed to increase generating capacity in response to Los Angeles’ rapid expansion and surging electric rail demand, which consumed about 80% of regional electricity by the early 20th century. Hydropower from the San Joaquin River represented a cost-efficient alternative compared to thermal power plants. Although initially hesitant, Huntington employed Eastwood at PL&P, awarding him 5,400 shares to conduct comprehensive surveys from 1902 through 1905.

While PL&P swiftly secured water rights claims, it postponed construction work in favor of developing thermal plants since anticipated hydroelectric output surpassed immediate needs. By 1905, Eastwood’s design incorporated a large reservoir and two powerhouses along Big Creek—a major tributary of the San Joaquin—and introduced the multiple-arch dam design that would later influence dam engineering throughout the Western United States.

By 1907, PL&P was prepared to begin construction but was delayed by economic turmoil caused by the Panic of 1907. In 1910, Huntington removed Eastwood from his position as chief engineer—likely due to disagreements over authority or profit distribution and investor apprehensions regarding multiple-arch dam safety compared with gravity dams. By 1912, Eastwood forfeited his stake in PL&P after failing to fulfill a $27,000 share payment required for project financing. Despite this setback, PL&P retained Eastwood’s original Big Creek development plans.

Financing and initial groundwork

The Big Creek Project’s construction commenced in February 1910 under the leadership of George Ward, with the Boston-based engineering firm Stone & Webster managing the building process. To fund the endeavor, PL&P issued a $10 million bond; however, by October 1911, only $2.5 million had been purchased. The remaining bonds were subsequently sold at 85% of their face value to a syndicate headed by investment bankers William Salomon & Co.

Negotiations led by Huntington with San Joaquin Valley farmers, including prominent landowners Miller & Lux who controlled nearly a vast expanse of land, secured an agreement in August 1906. This deal permitted reservoir construction on their property in exchange for guaranteed water flow through their lands.

One significant logistical challenge was transporting laborers and materials. Initially dependent on mule teams, the company decided to construct the San Joaquin and Eastern Railroad. This line branched off from the Southern Pacific Railroad at El Prado and extended deep into the Sierra Nevada to reach the company town of Big Creek.

Railroad construction began on February 5, 1912. Featuring 1,078 curves, 43 bridges, and steep inclines up to 5.2%, it earned the nickname "Slow, Jerky and Expensive." The last mile, dubbed the "Miracle Mile," alone cost over $1 million. Completed in an unprecedented 157 days by July 1912, the route required specialized geared Shay locomotives from Ohio’s Lima Locomotive Works to handle its sharp curves and steep grades.

Initial phase: 1913–1914

Starting in summer 1912, construction focused on three concrete dams—Big Creek Nos. 1, 2, and 3—that formed Huntington Lake at an elevation close to . This reservoir supplied water to two hydroelectric plants: Big Creek Powerhouses No. 1 and No. 2, situated on forebay dams Dam 4 and Dam 5 respectively. By late summer, approximately 3,500 workers were active across twelve camps scattered throughout the High Sierra. Budget limitations necessitated swift completion to enable revenue generation; thus, gravity dams were chosen despite requiring more concrete than the originally planned multiple-arch design.

A labor strike in January 1913 over working conditions forced PL&P to replace nearly 2,000 employees, causing project delays. Powerhouse No. 1 began operations on October 14, 1913; Powerhouse No. 2 followed on December 8 after a fire postponed its completion. In November of that year, following a failure at PL&P’s Redondo plant, power from Big Creek was transmitted for the first time via one of the world’s longest transmission lines. The engineering challenges involved were likened to those encountered during Panama Canal construction.

Most construction activities halted during World War I between 1914 and 1919, with only limited excavation of a tunnel for Powerhouse No. 3 completed. In 1917, PL&P merged into Southern California Edison (SCE), consolidating regional energy assets under one company.

Second phase: 1921–1929

Postwar economic recovery spurred renewed expansion efforts. By January 1921, after raising and enlarging Huntington Lake dams in 1919, plans were approved to boost powerhouse capacity by diverting additional water from the upper San Joaquin River basin. Big Creek Powerhouse No. 8 was built to harness the final drop in elevation before Big Creek merges with the San Joaquin River.

Dam 6 was finished in 1923 on the San Joaquin River below Big Creek’s confluence; this dam created a reservoir serving as Powerhouse No. 8’s afterbay. Its construction involved innovative engineering solutions such as rerouting river flow via a suspended flume due to the canyon’s restrictive geography.

Powerhouse No. 3 also commenced operation in 1923 as the largest hydroelectric facility west of the Mississippi at that time, boasting a capacity of 75 megawatts. That year saw transmission voltage upgraded from 150 kV to a groundbreaking commercial level of 220 kV worldwide. By 1925, Powerhouses Nos. 1 and 2 were expanded to accommodate increased flows diverted from the larger South Fork San Joaquin River.

The Ward Tunnel—stretching thirteen miles—began channeling South Fork water into Huntington Lake in April 1925. Construction of Florence Lake Dam followed in 1926 utilizing Eastwood’s multiple-arch design; this enabled year-round storage for diversions completed in 1927 from Mono and Bear Creeks through a large siphon traversing a deep valley.

To compensate for limited reservoir capacity compared to annual runoff (approximately 1.7 million acre-feet), Shaver Lake was constructed between 1925 and 1927 on Stevenson Creek to store surplus water from Huntington Lake; although connected by tunnel initially it lacked an associated power station.

Work started in 1926 on Powerhouse No. 2A as an extension of Powerhouse No. 2 designed to generate electricity from releases at Shaver Lake; it discharged into Dam 5’s forebay reservoir. The second phase concluded with an expansion of Powerhouse No. 8 in 1929; most construction camps had shut down by late 1926.

At peak activity during this phase, over 5,000 workers were employed under enhanced safety protocols implemented following a fatal accident in 1924. Despite ongoing high turnover rates among laborers, SCE invested significantly in community infrastructure.

Phase two resulted in a sixfold increase in generating capacity—from approximately seventy megawatts to four hundred twenty-five megawatts—and nearly an eightfold rise in annual production—from two hundred thirteen gigawatt-hours in 1914 to sixteen hundred gigawatt-hours by 1928—making Big Creek responsible for up to ninety percent of power supplied to Los Angeles through much of the mid-20th century.

Construction activities paused again during the Great Depression; by 1933 most sections of the Big Creek railroad used for logistics had been dismantled and converted into roadways.

Third phase, 1948–1960

Following the conclusion of World War II, construction activities recommenced in 1948 with the enlargement of Powerhouse No. 3. By July 1949, efforts had commenced on Redinger Dam located at the outlet of Powerhouse 3, alongside the development of Big Creek Powerhouse No. 4, which began operations between June and July 1951 as the project’s lowest elevation facility.

During the 1950s, Southern California Edison (SCE) increased the project’s capacity by erecting its two largest dams. The first was Vermilion Valley Dam on Mono Creek, initiated in 1953 and completed by October 1954. This earth-fill dam captures floodwaters to support downstream power generation during dry spells. The resulting reservoir was named Lake Thomas A. Edison in tribute to the famed inventor.

Technological progress in low-head turbines facilitated the construction of the Portal Powerhouse from 1954 to 1955 at the outlet of Ward Tunnel near Huntington Lake. Its distinctive open-air structure and automated control systems contributed additional flexible generation capacity.

Construction of Mammoth Pool Dam began in early 1958 on the San Joaquin River above where it merges with Big Creek. This rockfill dam, completed by October 1959, is the tallest within the project and supplies water to the Mammoth Pool Powerhouse, which commenced operations in March 1960 near Powerhouse 8.

The third stage of development concluded with the finalization of Mammoth Pool Dam, representing near completion of Big Creek Project’s principal infrastructure.

Fourth phase, 1983–1987

The mid-1980s saw the creation of Big Creek’s largest powerhouse through the Balsam Meadows Project. The Eastwood Powerhouse, boasting close to 200 MW capacity, was constructed at the outlet of the diversion tunnel connecting Huntington Lake to Shaver Lake. This pumped-storage facility functions by transferring water from Shaver Lake up to Balsam Meadows Forebay during periods of low electricity demand and generating power during peak load times.

Situated within a granite cavern approximately deep underground, Eastwood significantly improved Big Creek’s ability to meet peak power requirements. Completed in 1987, this development raised both generation capacity and output to present-day levels.

Project data and statistics

Big Creek consists of a series of interconnected facilities governed under seven Federal Energy Regulatory Commission licenses. Major operational elements include:

The dam at Florence Lake collects runoff from the South Fork San Joaquin River and channels it through Ward Tunnel toward Big Creek. This flow is augmented by diversions from Mono and Bear Creeks. Vermilion Valley Dam forms Lake Thomas A. Edison on Mono Creek, managing water supply. Ward Tunnel then discharges into Huntington Lake, feeding the Portal Powerhouse.

Huntington Lake is created by Big Creek Dams Nos. 1, 2, and 3 along with a saddle dam at Big Creek’s headwaters. It stores waters from both Big Creek and South Fork San Joaquin River, releasing them through a tunnel with a vertical drop of to Big Creek Powerhouse No. 1 at a forebay known as Dam 4. Water continues via tunnel dropping further to Big Creek Powerhouse No. 2 situated on Dam 5.

Located on Stevenson Creek south of Huntington Lake, Shaver Lake primarily receives overflow from Huntington Lake. Water is diverted through a tunnel leading to Balsam Meadows Forebay before descending to Eastwood Powerhouse on Shaver Lake. During off-peak periods, water is pumped back uphill to Balsam Meadows to improve peaking capabilities. From Shaver Lake, water drops — representing the project’s greatest hydraulic head—to Big Creek Powerhouse 2A on Dam 5.

From Dam 5, combined flows pass through a tunnel with a drop of to Big Creek Powerhouse No. 8 on Dam 6, located at the junction of Big Creek and San Joaquin River.

Mammoth Pool Dam forms Mammoth Pool Reservoir roughly upstream from Dam 6 on the San Joaquin River, regulating flow for enhanced downstream power production. Water travels through a tunnel dropping to Dam 6 before reaching Mammoth Pool Powerhouse.

From Dam 6, water descends by to Big Creek Powerhouse No. 3 at Redinger Dam (Dam 7). It then continues through a final tunnel dropping further to Big Creek Powerhouse No. 4 situated on Kerckhoff Dam reservoir—a component of an independent Kerckhoff hydroelectric system owned by Pacific Gas and Electric.

Reservoirs and Forebays

Key Reservoir Data
Dam(s)	Reservoir	River	Dam Height	Storage Volume	Surface Area	Elevation	Year Constructed
Big Creek Dam No. 1 Big Creek Dam No. 2 Big Creek Dam No. 3	Huntington Lake	Big Creek	170 ft (52 m)	89,800 acre.ft (110,000 dam³)	1,440 acres (583 ha)	6,950 ft (2,118 m)	1913
Big Creek Dam No. 4	Dam Four Lake	Big Creek	75 ft (23 m)	99 acre.ft (122 dam³)	4 acres (2 ha)	4,810 ft (1,466 m)	1913
Big Creek Dam No. 5	Dam Five Lake	Big Creek	60 ft (18 m)	74 acre.ft (91 dam³)	10 acres (4 ha)	2,943 ft (897 m)	1921
Big Creek Dam No. 6	Dam Six Lake	San Joaquin River	155 ft (47 m)	1,730 acre.ft (2,134 dam³)	23 acres (28 ha)	2,230 ft (680 m)	1923
Florence Lake Dam	Florence Lake	South Fork San Joaquin River	154 ft (47 m)	64,600 acre.ft (80,000 dam³)	296 acres (120 ha)	7,328 ft (2,234 m)	1926
Mammoth Pool Dam	Mammoth Pool Reservoir	San Joaquin River	411 ft (125 m)	123,000 acre.ft (152,000 dam³)	1,100 acres (445 ha)	3,330 ft (1,015 m)	1959
Redinger Dam (Big Creek Dam No. 7)	Redinger Lake	San Joaquin River	250 ft (76 m)	35,000 acre.ft (43,200 dam³)	620 acres (251 ha)	1,403 ft (428 m)	1951
Shaver Lake Dam	Shaver Lake	Stevenson Creek	185 ft (56 m)	136,000 acre.ft (168,000 dam³)	2,190 acres (886 ha)	5,370 ft (1,637 m)	1927
Vermilion Valley Dam	Lake Thomas A. Edison	Mono Creek	165 ft (50 m)	140,000 acre.ft (173,000 dam³)	1,910 acres (773 ha)	7,643 ft (2,330 m)	1954
Aggregate Water Data	(at full capacity)			590,303 acre.ft (727,444 dam³)	7,593 acres (3,071 ha)

Diversion Dams

Overview of Diversion Dams
Name	Purpose Served	Elevation
Adit No. 8 Creek	Powerhouse No. 2	(4,816) ft (1,468 m)
Balsam Creek	Powerhouse No. 2	(4,881) ft (1,488 m)
Bear Creek	Mono–Bear Diversion	(7,350) ft (2,240 m)
Bolsillo Creek	Ward Tunnel	(7,535) ft (2,297 m)
Camp 62 Creek	Ward Tunnel	(7,257) ft (2,212 m)
Chinquapin Creek	'Ward Tunnel'	(7,273) ft (2,217 m)
'Crater Creek'	'Florence Lake'	(8,762) ft (2,671 m)

|- |Ely Creek |Powerhouse No. 2 |(4,845) ft (1,477 m) |- |'Hooper Creek' |'Florence Lake' |(7,350) ft (2,240 m) |- |'Mono Creek' |'Mono–Bear Diversion' |(7,355) ft (2,242 m) |- |'North Slide Creek' |'Florence Lake' |(7,350) ft (2,240 m) |- |'Pitman Creek' |'Eastwood Powerhouse' |(6,998) ft (2,133 m) |- |'Rock Creek' |'Mammoth Pool Powerhouse' |(3,336) ft (1,017 m) |- |'Ross Creek' |'Mammoth Pool Powerhouse' |(3,359) ft (1,024 m) |- |'South Slide Creek' |'Florence Lake' |(7,345) ft (2,239 m) |- |'Tombstone Creek' |'Florence Lake' |(7,365) ft (2,245 m) |- |'Warm Creek' |'Lake Thomas A. Edison' |(8,004) ft (2,440 m) | }

Power generation facilities

Summary of powerplant data

Facility	Installed Capacity (MW)	Hydraulic Head	Yearly Output (MWh)
Big Creek 1	88.15	Template:Nts ft (649 m)	Template:Nts
Big Creek 2	66.5	Template:Nts ft (566 m)	Template:Nts
Big Creek 2A	110.0	Template:Nts ft (737 m)	Template:Nts
Big Creek 3	174.45	Template:Nts ft (252 m)	Template:Nts
Big Creek 4	100.0	Template:Nts ft (127 m)	Template:Nts
Big Creek 8	75.0	Template:Nts ft (217 m)	Template:Nts
'Mammoth Pool'	190.0	Template:Nts ft (335 m)	Template:Nts
'Eastwood'	199.8	Template:Nts ft (408 m)	Template:Nts
'Portal'	10.8	Template:Nts ft (70 m)	Template:Nts
Aggregate	1,014.7	--	3,932,576

Works cited

External links