Misplaced Pages

Crystal Springs Dam: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editContent deleted Content addedVisualWikitext
Revision as of 22:45, 14 December 2024 editGreenMeansGo (talk | contribs)Autopatrolled, Extended confirmed users, Page movers, File movers, New page reviewers, Pending changes reviewers, Rollbackers64,306 edits →External links: {{Commons category|Crystal Springs Dam}}← Previous edit Latest revision as of 01:45, 9 January 2025 edit undoWikiCleanerBot (talk | contribs)Bots928,066 editsm v2.05b - Bot T19 CW#25 - Fix errors for CW project (Heading hierarchy)Tag: WPCleaner 
(29 intermediate revisions by 7 users not shown)
Line 6: Line 6:
| name_official = Lower Crystal Springs Dam | name_official = Lower Crystal Springs Dam
| dam_crosses = ] | dam_crosses = ]
| res_name = ] | res_name = ]
| location = ] | location = ]
| operator = ] | operator = ]
Line 13: Line 13:
| dam_width_base = {{convert|40|ft|m|abbr=on}} | dam_width_base = {{convert|40|ft|m|abbr=on}}
| construction_began = | construction_began =
| opening = {{start date and age|1888}} | opening = {{start date and age|1889}}
| cost = | cost =
| res_capacity_total = {{convert|57910|acre.ft|m3|abbr=on}} | res_capacity_total = {{convert|57910|acre.ft|m3|abbr=on}}
Line 22: Line 22:
}} }}


'''Crystal Springs Dam''' is a ] constructed across the ] in ], ]. It impounds water to form the ] which sits atop the ] in a rift valley created by the fault. The dam itself is located about 300 yards (273 meters) east of the fault.<ref></ref><ref></ref> It was among the first concrete gravity dams built in the western United States.<ref name="auto">Advanced Dam Engineering for Design, Construction, and Rehabilitation, by Robert B. Jansen, page 117</ref> ] runs over the dam, which also forms the trailhead of the popular ]. '''Crystal Springs Dam''' is a concrete ] constructed across the ] in ], ]. It impounds water in a rift valley created by the ] to form the ]. The dam itself is located about {{Convert|1100|ft|m}} east of the fault. The dam is owned and operated by the San Francisco Public Utilities Commission, and stores drinking water for the City of San Francisco. The current dam is 140 feet high with a crest length of 600 feet.


It was first mass concrete gravity dam built in the United States. Upon its completion, it became the largest concrete structure in the world and the tallest dam in the United States. A 2024 review by ASCE and the Institution of Civil Engineers in Great Britain indicated that it is likely the oldest mass concrete dam in the world.<ref name=":0" /> Construction techniques used at the dam, including washing aggregate and staggered joints, influenced the development of future gravity dams, such as ] and ]. In December 2023, it was recognized as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers (ASCE).
==History==
⚫ ], the private utilities corporation that eventually developed the Crystal Springs Dam, was formed in 1858 to provide the rapidly expanding port city of ] with a reliable water source. Under the leadership of George Ensign, a prominent ], it quickly established a monopoly on the San Francisco water market.<ref>{{Cite web |title=Spring Valley Water Company - FoundSF |url=https://www.foundsf.org/index.php?title=Spring_Valley_Water_Company |access-date=2024-11-29 |website=www.foundsf.org}}</ref> Quickly understanding that any potential water source would have to come outside of the naturally barren city limits, Ensign turned towards adjacent ], along with its largely undeveloped mountains and streams. Over the next three decades, Spring Valley Water Works constructed a variety of conduits, dams, and tunnels to connect the San Andreas Valley watershed to San Francisco. Despite this, there was still a desire for a larger reservoir to ensure that San Francisco had a more reliable long-term water source.<ref name=":0">{{Cite journal |last=Magura |first=Lawrence M. |date=2024-03-01 |title=A Concrete Dam for the Ages |url=https://ascelibrary.org/doi/10.1061/ciegag.0001712 |journal=Civil Engineering Magazine Archive |language=EN |volume=94 |issue=2 |pages=32–37 |doi=10.1061/ciegag.0001712}}</ref>


⚫ The dam has undergone multiple repairs and improvemnts throughout its lifetime, and has survived both the ] and the ] with minimal damage, despite being located approximately {{Convert|1100|ft|m}} from the San Andreas Fault.
⚫ ], a German immigrant who moved to California in 1864 as a prospective civil engineer, quickly rose the ranks to become Chief Engineer of the Spring Valley Water Company. Cognizant of the growing desire for a reservoir, Schussler encouraged the Company to acquire as much watershed property as possible. By the time that Schussler began considering the development of a dam to impound the ], the Company had already acquired over {{Convert|100,000|acre|km2}} of prime property across the ]. <ref name=":0" />


==Background==
⚫ The location of the proposed dam site had its benefits and downfalls: located in a {{Convert|700|ft|m}} valley formed by San Mateo Creek, sandstone cliff walls rose over {{Convert|200|ft|m}} from the creekbed. The dam encloses a larger valley that spreads outwards both east and west of the dam itself. Schussler's initial design created a lake approximately {{Convert|9|mi|km}} long.<ref name=":1" /> Geological testing was conducted using ] techniques, which disclosed that the valley was favorable towards the dam's construction: the foundation was hard blue sandstone that contained no cracks nor fissures.
⚫ ], the private utilities corporation that eventually developed the Crystal Springs Dam, was formed in 1858 to provide the rapidly expanding port city of ] with a reliable water source. Under the leadership of George Ensign, a prominent ], it quickly established a monopoly on the San Francisco water market.<ref>{{Cite web |title=Spring Valley Water Company - FoundSF |url=https://www.foundsf.org/index.php?title=Spring_Valley_Water_Company |access-date=2024-11-29 |website=www.foundsf.org}}</ref> Quickly understanding that any potential water source would have to come outside of the naturally barren city limits, Ensign turned towards adjacent ], along with its largely undeveloped mountains and streams. Over the next three decades, Spring Valley Water Works constructed a variety of conduits, dams, and tunnels to connect the San Andreas Valley watershed to San Francisco. Despite this, there was still a desire for a larger reservoir to ensure that San Francisco had a more reliable long-term water source.<ref name=":0">{{Cite journal |last=Magura |first=Lawrence M. |date=2024-03-01 |title=A Concrete Dam for the Ages |url=https://ascelibrary.org/doi/10.1061/ciegag.0001712 |journal=Civil Engineering Magazine Archive |language=EN |volume=94 |issue=2 |pages=32–37 |doi=10.1061/ciegag.0001712}}</ref>


⚫ ], a German immigrant who moved to California in 1864 as a civil engineer, quickly rose the ranks to become Chief Engineer of the Spring Valley Water Company. Cognizant of the growing desire for a reservoir, Schussler encouraged the company to acquire as much watershed property as possible. By the time Schussler began considering the development of a dam to impound the ], the company had already acquired over {{Convert|100,000|acre|km2}} of prime property across the ].<ref name=":0" />
⚫ Schussler's designs called for a projected height of {{Convert|140|ft|m}}. At the time there were only 17 constructed dams in the world taller than {{Convert|95|ft|m}}, and all were located outside the United States. A majority of these dams were either ]. This approach, however, could not work for Schussler's design, as there were no suitable quarries to procure materials from.<ref name=":0" /> However, during the search a large outcrop of ] was located, especially conductive for concrete. As such, Schussler switched to a design using ].<ref>{{Cite book |last=Schussler |first=Hermann |url=https://www.google.com/books/edition/The_Water_Supply_of_San_Francisco/mLo2AQAAMAAJ?hl=en&gbpv=1&bsq=Crystal%20Springs%20Dam |title=The Water Supply of San Francisco |date=1909 |publisher=Journal of Electricity, Power and Gas |language=en}}</ref>


⚫ The location of the proposed dam site had its benefits and disadvantages: located in a {{Convert|700|ft|m}} valley formed by San Mateo Creek, sandstone cliff walls rose over {{Convert|200|ft|m}} from the creekbed. The dam encloses a larger valley that spreads outwards both east and west of the dam itself. Schussler's initial design created a lake approximately {{Convert|9|mi|km}} long.<ref name=":1" /> Geological testing was conducted using ] techniques, which showed that the valley was favorable for the dam's construction: the foundation was hard sandstone that contained no cracks nor fissures.
⚫ At the time, the United States had no large-scale manufacturer of cement, leading to the ] being transported via ship from ],England,<ref name=":0" /> which at the time was the biggest Portland cement manufacturing plant in the United Kingdom.<ref>{{Cite web |title=Cement Kilns: John Bazley White & Brothers |url=https://www.cementkilns.co.uk/cc_jbw.html |access-date=2024-11-30 |website=www.cementkilns.co.uk}}</ref> The dam was constructed by separately pouring large blocks of the structure in place, and allowing them to set before pouring the adjoining blocks. This enabled the bricks to set and harden individually, while also ensuring that the concrete would not crack during the curing process. An important design feature is that neither the horizontal nor the vertical joints line up. This helps the structure act as a single monolithic construction despite being made of thousands of individual blocks, while also enhancing its structural stability.<ref name=":1" />

== Construction ==
]
⚫ Schussler's designs called for a projected height of {{Convert|140|ft|m}}. At the time there were only 17 constructed dams in the world taller than {{Convert|95|ft|m}}, and all were located outside the United States. A majority of these dams were either ]. This approach, however, could not work for Schussler's design, as there were no suitable quarries to procure materials from.<ref name=":0" /> However, during the search for quarry sites, a large outcrop of ] was located, especially conducive for concrete. As such, Schussler switched to a design using ].<ref>{{Cite book |last=Schussler |first=Hermann |url=https://www.google.com/books/edition/The_Water_Supply_of_San_Francisco/mLo2AQAAMAAJ?hl=en&gbpv=1&bsq=Crystal%20Springs%20Dam |title=The Water Supply of San Francisco |date=1909 |publisher=Journal of Electricity, Power and Gas |language=en}}</ref>

At the time, the United States had no large-scale manufacturer of cement, leading to ] being transported via ship to San Francisco from ], England,<ref name=":0" /> which at the time was the biggest Portland cement manufacturing plant in the United Kingdom, before being sent via rail to San Mateo.<ref>{{Cite web |title=Cement Kilns: John Bazley White & Brothers |url=https://www.cementkilns.co.uk/cc_jbw.html |access-date=2024-11-30 |website=www.cementkilns.co.uk}}</ref><ref name=":2">{{Cite book |last=Svanevik |first=Michael |url=https://archive.org/details/sanmateocountypa00svan/mode/2up |title=San Mateo County parks : a remarkable story of extraordinary places and the people who built them |last2=Burgett |first2=Shirley |date=2001 |publisher=Menlo Park, Calif. : San Mateo County Parks and Recreation Foundation |others=Internet Archive |isbn=978-1-881529-67-5 |pages=27}}</ref> Sand was brought in from San Francisco beaches via ship to ], before using a team of horse-led wagons to bring the sand up to the canyon construction site. In total, almost a million barrels of sand were used in the construction of the dam.<ref name=":2" />

⚫ The dam was constructed by separately pouring large blocks of the structure in place, and allowing them to set before pouring the adjoining blocks. This enabled the blocks to set and harden individually, while also ensuring that the concrete would not crack during the curing process. An important design feature is that neither the horizontal nor the vertical joints line up. This helps the structure act as a single monolithic construction despite being made of thousands of individual blocks, while also enhancing its structural stability.<ref name=":1" />


Schussler ensured that each block of the dam was poured with concrete made to the exact proportions of his mix specifications. Schussler ensured that each block of the dam was poured with concrete made to the exact proportions of his mix specifications.


The structure was completed in 1888 at a height of {{Convert|120|ft|m}}.<ref name=":0" /> However, a wet winter in 1889-1890 caused the dam to overflow, leading to an addition to bring the total height of the dam to {{Convert|145|ft|m}}, making it the tallest dam in the United States at the time.<ref name=":1">{{Cite web |date=1898-12-17 |title=Scientific American Volume 79, Issue 25 |url=https://www.scientificamerican.com/issue/sa/1898/12-17/ |access-date=2024-11-30 |website=Scientific American |language=en}}</ref> At the time of its completion, with {{Convert|4239000|cuft|m3}} of concrete,<ref name=":0" /> it was the largest concrete structure in the world.<ref name="SFE-690511">{{cite news |date=May 11, 1969 |title=Peninsula's Bridge Open May 28 |url=https://www.newspapers.com/newspage/460217440/ |access-date=12 May 2021 |newspaper=San Francisco Examiner}}</ref> The structure was completed in 1889 at a height of {{Convert|120|ft|m}}.<ref name=":0" /> However, a wet winter in 1889-1890 caused the dam to overflow, leading to an addition to bring the total height of the dam to {{Convert|145|ft|m}}, making it the tallest dam in the United States at the time.<ref name=":1">{{Cite web |date=1898-12-17 |title=Scientific American Volume 79, Issue 25 |url=https://www.scientificamerican.com/issue/sa/1898/12-17/ |access-date=2024-11-30 |website=Scientific American |language=en}}</ref> At the time of its completion, with {{Convert|157,000|cuyd|m3}} of concrete,<ref name=":0" /> it was the largest concrete structure in the world.<ref name="SFE-690511">{{cite news |date=May 11, 1969 |title=Peninsula's Bridge Open May 28 |url=https://www.newspapers.com/newspage/460217440/ |access-date=12 May 2021 |newspaper=San Francisco Examiner}}</ref>


In 1976, the dam was designated as a California Historic Civil Engineering Landmark by the ] (ASCE).<ref>{{cite news |author=<!--Staff writer(s)/no by-line.--> |title=State Pays Tribute to San Mateo's Dam |work=San Mateo Times |date=21 May 1976}}</ref><ref>{{cite news |last=Bohan |first=Suzanne |date=14 April 2006 |title=Water System Vulnerable Then And Now |url=https://www.eastbaytimes.com/2006/04/14/water-system-vulnerable-then-and-now/ |work=East Bay Times |access-date=30 January 2021}}</ref> The dam was later designated as a ] by ASCE in 2023.<ref>{{cite news |last=Lopez |first=Sierra |date=7 December 2023 |url=https://www.smdailyjournal.com/news/local/san-mateo-countys-crystal-springs-dam-receives-national-historic-engineering-landmark-status/article_14740274-94ae-11ee-b0e1-3708fb7cfc51.html |title=San Mateo County's Crystal Springs Dam receives National Historic Engineering Landmark status |work=San Mateo Daily Journal |access-date=3 December 2024}}</ref> In 1976, the dam was designated as a California Historic Civil Engineering Landmark by the ] (ASCE).<ref>{{cite news |last=Bohan |first=Suzanne |date=14 April 2006 |title=Water System Vulnerable Then And Now |url=https://www.eastbaytimes.com/2006/04/14/water-system-vulnerable-then-and-now/ |work=East Bay Times |access-date=30 January 2021}}</ref> The dam was later designated as a ] by ASCE in 2023.<ref>{{cite news |last=Lopez |first=Sierra |date=7 December 2023 |url=https://www.smdailyjournal.com/news/local/san-mateo-countys-crystal-springs-dam-receives-national-historic-engineering-landmark-status/article_14740274-94ae-11ee-b0e1-3708fb7cfc51.html |title=San Mateo County's Crystal Springs Dam receives National Historic Engineering Landmark status |work=San Mateo Daily Journal |access-date=3 December 2024}}</ref>


] ]


==Operations and repairs==
⚫ The dam survived both the ] and the ] with only minor damage – despite its location about {{Convert|300|yd}} east of the ]. It was subject to severe shaking in both earthquakes.<ref name="auto"/>


Two outlet towers were constructed near the dam, the first being built in 1891. The Crystal Springs Pump Station was built alongside the dam and gatehouse, and was designed to pump up water from the Crystal Springs Reservoir to nearby ], where it could thereafter be distributed across San Francisco. Upon completion, the outlet works had a flow capacity of 25 million gallons per day.
==Repairs==


The City of San Francisco purchased the Spring Valley Water Company in 1928, through a $41,000,000 bond approved by voters. Through this, all of Spring Valley's water rights, dams, reservoirs, and watersheds were transferred to the city, including Crystal Springs.<ref>{{cite book |title=Hetch Hetchy and its Dam Railroad |first=Ted |last=Wurm |publisher=Trans-Anglo Books |year=1990 |isbn=0-87046-093-5 |page= 229}}</ref> Another public funding grant from the City of San Francisco in 1933, intended to develop and expand the ] Project, led to repairs and upgrades to the pump station, enabling it to pump a maximum of 70 million gallons per day to San Andreas Reservoir.<ref>{{Cite book |last=Hanson |first=Warren D. |url=https://archive.org/details/sanfranciscowate1994hans/page/16/mode/2up |title=San Francisco water and power : a history of the Municipal Water Department and Hetch Hetchy system |date=1994 |publisher= |others=San Francisco Public Library |pages=16–17}}</ref> The first delivery of water from Hetch Hetchy reached the ] on October 28, 1934.<ref>{{cite book |title=Hetch Hetchy and its Dam Railroad |first=Ted |last=Wurm |publisher=Trans-Anglo Books |year=1990 |isbn=0-87046-093-5 |page= 235}}</ref>
⚫ The ] began the process of renovating the dam in 2003. A major step in the renovation process, doubling the width of the main spillway and raising the dam to increase the water storage capacity, was completed in 2012. The renovations, which are intended to improve the reliability of the system in the event of an earthquake, were completed in 2016. ], the road on top of the dam, was closed for the construction of a new replacement bridge in October 2010. Along with the replacement bridge, the parapet wall was raised by nine feet, the dam's spillway was widened, and power lines were relocated to the underside of the bridge. Construction completed in late 2018 and the roadway was reopened in January 2019.<ref>{{cite web|author=County of San Mateo Public Works|access-date=2017-12-11|title= Crystal Springs Dam Bridge Replacement Project - Traffic Advisory|url=http://publicworks.smcgov.org/crystal-springs-dam-bridge-replacement-project-traffic-advisory}}</ref><ref name="SF_Examiner">{{cite news |last1=Bay City News |title=Roadway atop Crystal Springs Dam reopens after 8-year project |url=http://www.sfexaminer.com/roadway-atop-crystal-springs-dam-reopens-8-year-project/ |access-date=17 March 2019 |publisher=San Francisco Examiner |date=14 January 2019 |archive-url=https://web.archive.org/web/20190114221754/http://www.sfexaminer.com/roadway-atop-crystal-springs-dam-reopens-8-year-project/ |archive-date=14 January 2019 |language=English}}</ref>


Before the construction of the original Crystal Springs Bypass Tunnel in 1969, Crystal Springs Dam was the penultimate destination for Hetch Hetchy water before being distributed. Currently, the dam impounds a combination of Hetch Hetchy water and water from its own catchment area.
<gallery>

⚫ File:Crystal Springs Dam Leeside.jpg|Crystal Springs Dam from downstream
⚫ The ], who owns the 23,000 acre watershed of the reservoir,began the process of renovating the dam in 2003. A major step in the renovation process, doubling the width of the main spillway and raising the dam to increase the water storage capacity, was completed in 2012. The renovations, which are intended to improve the reliability of the system in the event of an earthquake, were completed in 2016. ], the road on top of the dam, was closed for the construction of a new replacement bridge in October 2010. Along with the replacement bridge, the parapet wall was raised by nine feet, the dam's spillway was widened, and power lines were relocated to the underside of the bridge. Construction completed in late 2018 and the roadway was reopened in January 2019.<ref name="SF_Examiner">{{cite news |last1=Bay City News |title=Roadway atop Crystal Springs Dam reopens after 8-year project |url=http://www.sfexaminer.com/roadway-atop-crystal-springs-dam-reopens-8-year-project/ |access-date=17 March 2019 |publisher=San Francisco Examiner |date=14 January 2019 |archive-url=https://web.archive.org/web/20190114221754/http://www.sfexaminer.com/roadway-atop-crystal-springs-dam-reopens-8-year-project/ |archive-date=14 January 2019 |language=English}}</ref>
⚫ File:Crystal Springs Reservoir.jpg|Lower Crystal Springs Reservoir

⚫ File:Crystal Springs Reservoir aerial view, February 2018.JPG|Aerial view of the Crystal Springs Reservoir from the southeast
=== Earthquake risks ===
The Crystal Springs Dam has survived both the ] and the ] with inconsequential damage. It is unclear if Hermann Schussler, the chief engineer of the project, was aware of the existence of the ] {{Convert|1100|ft|m}} away from the dam. The dam is classified with an "Extremely High" downstream hazard rating by the ] in the event of a breach.<ref>{{Cite web |title=Web Map Viewer |url=https://fmds.water.ca.gov/webgis/?appid=dam_prototype_v2 |access-date=2024-12-31 |website=fmds.water.ca.gov}}</ref><gallery>
⚫ File:Crystal Springs Dam Leeside.jpg|Crystal Springs Dam and Crystal Springs Pump Station, viewed from downstream.
⚫ File:Crystal Springs Reservoir.jpg|Lower Crystal Springs Reservoir, formed by Crystal Springs Dam.
⚫ File:Crystal Springs Reservoir aerial view, February 2018.JPG|Aerial view of the Crystal Springs Reservoir from the southeast.
File:Crystal Springs Dam from under highway 35.jpg|View from under the ] roadway that was added atop the dam File:Crystal Springs Dam from under highway 35.jpg|View from under the ] roadway that was added atop the dam
</gallery> </gallery>
Line 60: Line 73:


==References== ==References==
{{reflist}}
⚫ * {{cite web | author=Department of Water Resources | title=Station Meta Data: Lower Crystal Springs Dam (CRY) | url=http://cdec.water.ca.gov/cgi-progs/profile?s=CRY&type=dam | work=California Data Exchange Center | publisher=State of California | year=2009 | access-date=2009-04-01}}
{{Refbegin}}
⚫ *{{cite web | author=Department of Water Resources | title=Station Meta Data: Lower Crystal Springs Dam (CRY) | url=http://cdec.water.ca.gov/cgi-progs/profile?s=CRY&type=dam | work=California Data Exchange Center | publisher=State of California | year=2009 | access-date=2009-04-01}}
* {{cite gnis |type=retired| id = 233747 | name = Crystal Spring Dam | entrydate = 19 Jan 1981 * {{cite gnis |type=retired| id = 233747 | name = Crystal Spring Dam | entrydate = 19 Jan 1981
| access-date = 2009-06-11 }} | access-date = 2009-06-11 }}
* {{cite web|author=U.S. Geological Survey |title=Crystal Springs Reservoir |url=http://3dparks.wr.usgs.gov/3Dbayarea/html/CrystalSprings.htm |publisher=U.S. Department of the Interior |date=24 November 2003 |access-date=2009-04-01 |url-status=dead |archive-url=https://web.archive.org/web/20081206034220/http://3dparks.wr.usgs.gov/3Dbayarea/html/CrystalSprings.htm |archive-date=December 6, 2008 }} * {{cite web|author=U.S. Geological Survey |title=Crystal Springs Reservoir |url=http://3dparks.wr.usgs.gov/3Dbayarea/html/CrystalSprings.htm |publisher=U.S. Department of the Interior |date=24 November 2003 |access-date=2009-04-01 |url-status=dead |archive-url=https://web.archive.org/web/20081206034220/http://3dparks.wr.usgs.gov/3Dbayarea/html/CrystalSprings.htm |archive-date=December 6, 2008 }}
* {{cite web | author=Ron Horii | title=Bay Area Biking: Crystal Springs Trails | url=http://pages.prodigy.net/rhorii/xtalsprg.htm | archive-url=https://web.archive.org/web/20001012111214/http://pages.prodigy.net/rhorii/xtalsprg.htm | url-status=dead | archive-date=12 October 2000 | work=Bay Area Back Page | date=1 October 2003 | access-date=2009-04-01 }} * {{cite web | author=Ron Horii | title=Bay Area Biking: Crystal Springs Trails | url=http://pages.prodigy.net/rhorii/xtalsprg.htm | archive-url=https://web.archive.org/web/20001012111214/http://pages.prodigy.net/rhorii/xtalsprg.htm | url-status=dead | archive-date=12 October 2000 | work=Bay Area Back Page | date=1 October 2003 | access-date=2009-04-01 }}
{{reflist}} {{refend}}


==Further reading== ==Further reading==
Line 81: Line 96:
] ]
] ]
] ]
] ]

Latest revision as of 01:45, 9 January 2025

For the dam in Arkansas, see Crystal Campground. Dam in San Mateo County, California
Crystal Springs Dam
Official nameLower Crystal Springs Dam
LocationSan Mateo County, California
Coordinates37°31′43″N 122°21′44″W / 37.5285°N 122.3622°W / 37.5285; -122.3622
Opening date1889; 136 years ago (1889)
Operator(s)San Francisco Public Utilities Commission
Dam and spillways
ImpoundsSan Mateo Creek
Height140 ft (43 m)
Length600 ft (180 m)
Width (base)40 ft (12 m)
Reservoir
CreatesCrystal Springs Reservoir
Total capacity57,910 acre⋅ft (71,430,000 m)
Catchment area29.4 sq mi (76 km)
Surface area1,323 acres (5.35 km)

Crystal Springs Dam is a concrete gravity dam constructed across the San Mateo Creek in San Mateo County, California. It impounds water in a rift valley created by the San Andreas Fault to form the Crystal Springs Reservoir. The dam itself is located about 1,100 feet (340 m) east of the fault. The dam is owned and operated by the San Francisco Public Utilities Commission, and stores drinking water for the City of San Francisco. The current dam is 140 feet high with a crest length of 600 feet.

It was first mass concrete gravity dam built in the United States. Upon its completion, it became the largest concrete structure in the world and the tallest dam in the United States. A 2024 review by ASCE and the Institution of Civil Engineers in Great Britain indicated that it is likely the oldest mass concrete dam in the world. Construction techniques used at the dam, including washing aggregate and staggered joints, influenced the development of future gravity dams, such as Hoover Dam and Grand Coulee Dam. In December 2023, it was recognized as a National Historic Civil Engineering Landmark by the American Society of Civil Engineers (ASCE).

The dam has undergone multiple repairs and improvemnts throughout its lifetime, and has survived both the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake with minimal damage, despite being located approximately 1,100 feet (340 m) from the San Andreas Fault.

Background

Spring Valley Water Works, the private utilities corporation that eventually developed the Crystal Springs Dam, was formed in 1858 to provide the rapidly expanding port city of San Francisco with a reliable water source. Under the leadership of George Ensign, a prominent land baron, it quickly established a monopoly on the San Francisco water market. Quickly understanding that any potential water source would have to come outside of the naturally barren city limits, Ensign turned towards adjacent San Mateo County, along with its largely undeveloped mountains and streams. Over the next three decades, Spring Valley Water Works constructed a variety of conduits, dams, and tunnels to connect the San Andreas Valley watershed to San Francisco. Despite this, there was still a desire for a larger reservoir to ensure that San Francisco had a more reliable long-term water source.

Hermann Schussler, a German immigrant who moved to California in 1864 as a civil engineer, quickly rose the ranks to become Chief Engineer of the Spring Valley Water Company. Cognizant of the growing desire for a reservoir, Schussler encouraged the company to acquire as much watershed property as possible. By the time Schussler began considering the development of a dam to impound the San Mateo Creek, the company had already acquired over 100,000 acres (400 km) of prime property across the San Francisco Peninsula.

The location of the proposed dam site had its benefits and disadvantages: located in a 700 feet (210 m) valley formed by San Mateo Creek, sandstone cliff walls rose over 200 feet (61 m) from the creekbed. The dam encloses a larger valley that spreads outwards both east and west of the dam itself. Schussler's initial design created a lake approximately 9 miles (14 km) long. Geological testing was conducted using boring techniques, which showed that the valley was favorable for the dam's construction: the foundation was hard sandstone that contained no cracks nor fissures.

Construction

A plaque on the Crystal Springs Dam honoring Hermann Schussler.

Schussler's designs called for a projected height of 140 feet (43 m). At the time there were only 17 constructed dams in the world taller than 95 feet (29 m), and all were located outside the United States. A majority of these dams were either rock-filled or earth-filled dams. This approach, however, could not work for Schussler's design, as there were no suitable quarries to procure materials from. However, during the search for quarry sites, a large outcrop of indurated sandstone was located, especially conducive for concrete. As such, Schussler switched to a design using mass concrete blocks.

At the time, the United States had no large-scale manufacturer of cement, leading to Portland cement being transported via ship to San Francisco from Swanscombe, England, which at the time was the biggest Portland cement manufacturing plant in the United Kingdom, before being sent via rail to San Mateo. Sand was brought in from San Francisco beaches via ship to Coyote Point Wharf, before using a team of horse-led wagons to bring the sand up to the canyon construction site. In total, almost a million barrels of sand were used in the construction of the dam.

The dam was constructed by separately pouring large blocks of the structure in place, and allowing them to set before pouring the adjoining blocks. This enabled the blocks to set and harden individually, while also ensuring that the concrete would not crack during the curing process. An important design feature is that neither the horizontal nor the vertical joints line up. This helps the structure act as a single monolithic construction despite being made of thousands of individual blocks, while also enhancing its structural stability.

Schussler ensured that each block of the dam was poured with concrete made to the exact proportions of his mix specifications.

The structure was completed in 1889 at a height of 120 feet (37 m). However, a wet winter in 1889-1890 caused the dam to overflow, leading to an addition to bring the total height of the dam to 145 feet (44 m), making it the tallest dam in the United States at the time. At the time of its completion, with 157,000 cubic yards (120,000 m) of concrete, it was the largest concrete structure in the world.

In 1976, the dam was designated as a California Historic Civil Engineering Landmark by the American Society of Civil Engineers (ASCE). The dam was later designated as a National Historic Civil Engineering Landmark by ASCE in 2023.

Crystal Springs Dam overflowing, in February 1911

Operations and repairs

Two outlet towers were constructed near the dam, the first being built in 1891. The Crystal Springs Pump Station was built alongside the dam and gatehouse, and was designed to pump up water from the Crystal Springs Reservoir to nearby San Andreas Lake, where it could thereafter be distributed across San Francisco. Upon completion, the outlet works had a flow capacity of 25 million gallons per day.

The City of San Francisco purchased the Spring Valley Water Company in 1928, through a $41,000,000 bond approved by voters. Through this, all of Spring Valley's water rights, dams, reservoirs, and watersheds were transferred to the city, including Crystal Springs. Another public funding grant from the City of San Francisco in 1933, intended to develop and expand the Hetch Hetchy Project, led to repairs and upgrades to the pump station, enabling it to pump a maximum of 70 million gallons per day to San Andreas Reservoir. The first delivery of water from Hetch Hetchy reached the Crystal Springs Reservoir on October 28, 1934.

Before the construction of the original Crystal Springs Bypass Tunnel in 1969, Crystal Springs Dam was the penultimate destination for Hetch Hetchy water before being distributed. Currently, the dam impounds a combination of Hetch Hetchy water and water from its own catchment area.

The San Francisco Public Utilities Commission, who owns the 23,000 acre watershed of the reservoir,began the process of renovating the dam in 2003. A major step in the renovation process, doubling the width of the main spillway and raising the dam to increase the water storage capacity, was completed in 2012. The renovations, which are intended to improve the reliability of the system in the event of an earthquake, were completed in 2016. Skyline Boulevard, the road on top of the dam, was closed for the construction of a new replacement bridge in October 2010. Along with the replacement bridge, the parapet wall was raised by nine feet, the dam's spillway was widened, and power lines were relocated to the underside of the bridge. Construction completed in late 2018 and the roadway was reopened in January 2019.

Earthquake risks

The Crystal Springs Dam has survived both the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake with inconsequential damage. It is unclear if Hermann Schussler, the chief engineer of the project, was aware of the existence of the San Andreas Fault 1,100 feet (340 m) away from the dam. The dam is classified with an "Extremely High" downstream hazard rating by the California Department of Water Resources in the event of a breach.

  • Crystal Springs Dam and Crystal Springs Pump Station, viewed from downstream. Crystal Springs Dam and Crystal Springs Pump Station, viewed from downstream.
  • Lower Crystal Springs Reservoir, formed by Crystal Springs Dam. Lower Crystal Springs Reservoir, formed by Crystal Springs Dam.
  • Aerial view of the Crystal Springs Reservoir from the southeast. Aerial view of the Crystal Springs Reservoir from the southeast.
  • View from under the California State Route 35 roadway that was added atop the dam View from under the California State Route 35 roadway that was added atop the dam

See also

References

  1. ^ Magura, Lawrence M. (2024-03-01). "A Concrete Dam for the Ages". Civil Engineering Magazine Archive. 94 (2): 32–37. doi:10.1061/ciegag.0001712.
  2. "Spring Valley Water Company - FoundSF". www.foundsf.org. Retrieved 2024-11-29.
  3. ^ "Scientific American Volume 79, Issue 25". Scientific American. 1898-12-17. Retrieved 2024-11-30.
  4. Schussler, Hermann (1909). The Water Supply of San Francisco. Journal of Electricity, Power and Gas.
  5. "Cement Kilns: John Bazley White & Brothers". www.cementkilns.co.uk. Retrieved 2024-11-30.
  6. ^ Svanevik, Michael; Burgett, Shirley (2001). San Mateo County parks : a remarkable story of extraordinary places and the people who built them. Internet Archive. Menlo Park, Calif. : San Mateo County Parks and Recreation Foundation. p. 27. ISBN 978-1-881529-67-5.
  7. "Peninsula's Bridge Open May 28". San Francisco Examiner. May 11, 1969. Retrieved 12 May 2021.
  8. Bohan, Suzanne (14 April 2006). "Water System Vulnerable Then And Now". East Bay Times. Retrieved 30 January 2021.
  9. Lopez, Sierra (7 December 2023). "San Mateo County's Crystal Springs Dam receives National Historic Engineering Landmark status". San Mateo Daily Journal. Retrieved 3 December 2024.
  10. Wurm, Ted (1990). Hetch Hetchy and its Dam Railroad. Trans-Anglo Books. p. 229. ISBN 0-87046-093-5.
  11. Hanson, Warren D. (1994). San Francisco water and power : a history of the Municipal Water Department and Hetch Hetchy system. San Francisco Public Library. . pp. 16–17.
  12. Wurm, Ted (1990). Hetch Hetchy and its Dam Railroad. Trans-Anglo Books. p. 235. ISBN 0-87046-093-5.
  13. Bay City News (14 January 2019). "Roadway atop Crystal Springs Dam reopens after 8-year project". San Francisco Examiner. Archived from the original on 14 January 2019. Retrieved 17 March 2019.
  14. "Web Map Viewer". fmds.water.ca.gov. Retrieved 2024-12-31.

Further reading

  • Postel, Mitchell (1994). San Mateo: A Centennial History. San Francisco: Scottwall Associates, Publishers. ISBN 0-942087-08-9.

External links

Categories: