Difference between revisions of "Nacimiento Dam"

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A [[Summaries of Environmental Topics in California's Central Coast Region|Environmental Topics]] summary by the [[ENVS 560/L Watershed Systems]] class at [[California State University Monterey Bay|CSUMB]].
 
A [[Summaries of Environmental Topics in California's Central Coast Region|Environmental Topics]] summary by the [[ENVS 560/L Watershed Systems]] class at [[California State University Monterey Bay|CSUMB]].
  
This page provides a brief overview of the history, purpose, design, and use-cases of the Nacimiento Dam.  
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This page provides a brief overview of the history, purpose and design of the Nacimiento Dam.  
  
 
==Summary==
 
==Summary==
The dam was completed in 1957 and is under the jurisdiction of the California Department of Water Resources. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>
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The Nacimiento Dam was completed in 1957. Although it is located in northern San Luis Obispo County, it is owned by the [[Monterey County Water Resources Agency]]. It is located about 20 miles from the coast, and 4.4 miles away from the [[San Antonio Dam]]. Both were created for the primary purposes of groundwater recharge and flood control. <ref name="Salinas Valley Water Project Engineer's Report"> Monterey County Water Resources Agency [https://digitalcommons.csumb.edu/cgi/viewcontent.cgi?article=1000&context=hornbeck_cgb_6_b Monterey County Water Resources Agency Engineering Reports] Updated July 21, 2017. </ref> The Nacimiento Dam and [[San Antonio Dam]] are currently involved in the recently created [[Salinas Valley Water Project]] and they provides opportunities for recreation. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>  
  
The Nacimiento Dam is located at 35°45′31″ N, 120°53′6″ W. <ref name="Nacimiento Dam USGS"> USGS Feature Report: Nacimiento Dam [https://geonames.usgs.gov/apex/f?p=gnispq:3:::NO::P3_FID:1693269 USGS Feature Report: Nacimiento Dam] </ref>
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The Nacimiento Dam creates the Nacimiento Reservoir, which has the ability to store water from winter storms for the dry season. At an elevation of 800 feet, the reservoir has the capacity to store 377,900 acre-feet of water when it is full. It is roughly 18 miles long, and has about 165 miles of shoreline available for recreation. The maximum flood stage elevation is 802 feet. The maximum temporary capacity during a flood event is 538,000 acre-feet, with a surface area of 7,149 acres.
  
Nacimiento Dam and its reservoir, Nacimiento Reservoir, are located in northern San Luis Obispo County, about 20 miles from the coast, in central California. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>
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==Purpose==
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The primary function of the Nacimiento Dam is to provide an instrument for groundwater recharge and flood control in the [[Salinas Valley]]. <ref name="Salinas Valley Water Project Engineer's Report"> Monterey County Water Resources Agency [https://digitalcommons.csumb.edu/cgi/viewcontent.cgi?article=1000&context=hornbeck_cgb_6_b Monterey County Water Resources Agency Engineering Reports] Updated July 21, 2017. </ref> The Nacimiento Dam and [[San Antonio Dam]] are also essential parts of the more recent [[Salinas Valley Water Project]] and they provide opportunities for water recreation in southern [[Monterey County]] and northern [[San Luis Obispo County]]. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>  The Nacimiento Dam spillway drains into the [[Salinas River]] groundwater system, and this watershed contributes to the [[Salinas Valley]] water supply.<ref name="Nacimiento Dam Report #79"> CalWater [https://www.yumpu.com/s/KIull25otL6gJKwn Nacimiento Dam Report #79] Published 2014. </ref> It is an instrumental in maintaining water supply during the dry season, and was modified in 2010 to raise the flood elevation to 800 feet. <ref name=Salinas Valley Water Project"> Monterey County Water Resources Agency. [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/salinas-valley-water-project-svwp Salinas Valley Water Project] Updated 2020. </ref>  
  
When the reservoir is full (elevation 800 feet) it has a maximum storage capacity of 377,900 acre-feet, is 18 miles long, and has about 165 miles of shoreline. The maximum elevation during flood stage is 825 feet, with a maximum temporary capacity of 538,000 acre feet and a temporary surface area of 7,149 acres.
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Further downstream, near the mouth of the [[Salinas River]], the [[Salinas River Diversion Facility]] captures some of this released water, and creates an artificial dam to store additional water. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref> This timed-release and gradual groundwater recharge helps to slow the rate of [[Salinas Valley Seawater Intrusion| seawater intrusion in the Salinas Valley]]. <ref name="Seawater Intrusion in Monterey County"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/programs/seawater-intrusion-monitoring Monterey County Water Resources Agency: Seawater Intrusion Monitoring] Updated 2020. </ref>
  
Dam Type as determined by the California Department of Water Resources: ERTH - Earth
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==Statistics==
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*The Nacimiento Dam is located at 35°45′31″ N, 120°53′6″ W. <ref name="Nacimiento Dam USGS"> USGS Feature Report: Nacimiento Dam [https://geonames.usgs.gov/apex/f?p=gnispq:3:::NO::P3_FID:1693269 USGS Feature Report: Nacimiento Dam] </ref>
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*Dam Type as determined by the California Department of Water Resources: ERTH - Earth
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*Dam Usage as determined by the California Department of Water Resources: FC,DOM,IRR,MUN,POW - Flood Control, Domestic, Irrigation, Municpial, Power <ref name="California Data Exchange Center: Dam Definitions"> California Data Exchange Center [http://cdec.water.ca.gov/misc/damInfo.html CDEC: Dam Definitions] Updated 2017. </ref>
  
Dam Usage as determined by the California Department of Water Resources: FC,DOM,IRR,MUN,POW - Flood Control, Domestic, Irrigation, Municpial, Power <ref name="California Data Exchange Center: Dam Definitions"> California Data Exchange Center [http://cdec.water.ca.gov/misc/damInfo.html CDEC: Dam Definitions] Updated 2017. </ref>
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==Current Issues==
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According to a 2019 report and independent audit conducted by GEI Consultants, Inc., the Nacimiento Dam safety program is deficient. It has an outdated program document, insufficient staff and a long list of overdue safety repairs. This maintenance is estimated to cost more than $50 million, and needs to be addressed as soon as possible. The report noted that staff is overworked and undertrained, accompanied by a myriad of workload and funding issues. Additionally, the safety program is inadequate for a structure built more than six decades ago. The Nacimiento Dam has been identified by the state Division of Safety of Dams as an “extremely high hazard,” regarding these repairs. <ref name="johnson"> Johnson, Jim. [https://www.mercurynews.com/2019/07/18/report-nacimiento-dam-safety-needs-expensive-upgrade/ Monterey County’s Nacimiento Dam Needs Safetey Upgrades] Published July 18, 2019. </ref>.
  
==Purpose==
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If the dam failed and flooded, it would cause substantial damage. Peak flows through the breach are estimated to be 3,300,000 cubic feet per second (cfs) and are projected to occur one hour after dam failure. The flood wave would take roughly one day to reach the mouth of the [[Salinas River]], and the flow rate would be approximately 700,000 cfs. The simulation predicts flooding in portions of Camp Roberts and San Miguel, Bradley, the San Ardo oil field, San Ardo, and portions of King City, Spreckels, [[Salinas]], Castroville and Moss Landing. <ref name="Monterey County Office of Emergency Services"> Monterey County Office of Emergency Services [https://www.co.monterey.ca.us/government/departments-a-h/administrative-office/office-of-emergency-services/ready-monterey-county/hazard-ready/dam-failure Monterey County Dam Safety] Updated 2020. </ref>
The primary function of the Nacimiento Dam is to provide groundwater recharge for agriculture, control floods, conserve water and to contribute to the water supply in the Salinas Valley in accordance with the goals of the [[Salinas Valley Water Project (SVWP)]]. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resource Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>
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The secondary function of the Nacimiento Dam is to provide a recreation area for boating, fishing, and camping.
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The Nacimiento Dam is owned and operated by the [[Monterey County Water Resources Agency (MCWRA)]].
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Water released from the Nacimiento Dam percolates into the Salinas River groundwater system, contributes to our region's water supply. <ref name="Nacimiento Dam Report #79"> CalWater [https://www.yumpu.com/s/KIull25otL6gJKwn Nacimiento Dam Report #79] Published 2014. </ref>
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===Current Issues===
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==Dam Subdivisions And Applications==  
According to a 2019 report and independent audit done by GEI Consultants, Inc., Monterey County’s Nacimiento Dam safety program is seriously deficient with an outdated program document, insufficient staff and a long list of outstanding dam safety repairs and maintenance estimated to cost more than $50 million that needs to be addressed in short order. The report noted that staff is overworked and undertrained, accompanied by a myriad of workload and funding issues. Additionally, the safety program is inadequate for a structure built more than six decades ago. The Nacimiento Dam is identified by the state Division of Safety of Dams as “extremely high hazard.<ref name="johnson"> Johnson, Jim. [https://www.mercurynews.com/2019/07/18/report-nacimiento-dam-safety-needs-expensive-upgrade/ Monterey County’s Nacimiento Dam Needs Safetey Upgrades] Published July 18, 2019. </ref>.
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In the San Antonio Dam, operational pools refer to management of water being stored in the reservoir. There are a few different operational pools related to storage, release, and conservation.
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*Physical minimum pool - maximum height: 670 feet. At this elevation or lower, water cannot flow out of the reservoir.
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*Operational minimum pool - maximum height: 687.8 feet. Any water below this elevation is reserved for fish habitat, as well as a water entitlement for [[San Luis Obispo]] County.
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*Conservation pool - maximum height: 787.5 feet. Water is "conserved" to be later released into the [[Salinas River]] for groundwater recharge, fish passage, and operation of the [[Salinas Valley Water Project (SVWP)| Salinas Valley Water Project]].
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There is one additional pool known as the flood pool, which is from the concrete spillway to an elevation of 801 feet (or 1 foot above the top of the spillway gate). <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>
  
==Use Cases==  
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==Hydroelectric Power==
===Operational Pools===
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There is a 4-megawatt powerplant constructed at the right dam abutment. The power plant contains both large and small turbines that operate in the optimal range of 25 cfs to 400 cfs. <ref name="MCWRA: Dams and Reservoirs"> Monterey County Water Resources Agency [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/ MCWRA: Dams and Reservoirs] Updated 2020. </ref>
Operational pools have been created to aid in the management of water being stored in the reservoir. The conservation pool which extends from the minimum pool to the concrete spillway elevation of 787.75 feet is the operational pool used to store water for later release to the Salinas River for groundwater recharge, fish passage, and the operation of the [[Salinas Valley Water Project (SVWP)]]. The flood pool extends from the concrete spillway to an elevation of 801 feet or 1 foot above the top of the inflated Obermeyer spillway gate. The flood pool is intended to provide winter flood protection by maintaining the ability of the spillway to pass the Probable Maximum Flood without overtopping of the dam.<ref name-"MCWRA"> https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/</ref>
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===Power===
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A 4-megawatt powerplant is constructed at the right dam abutment. The plant contains both large and small turbines that operate in the range of 25 cfs to 400 cfs. To maximize power production, two sets of runners have been provided. One set is used at low reservoir elevations and the second at high reservoir elevations.<ref name-"MCWRA"> https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/</ref>
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==Dam Safety==
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==Nacimiento Dam Measurements==
===Overview===
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A dam failure is the structural collapse of a dam that releases the water stored in the reservoir behind the dam. A dam failure is usually the result of the age of the structure, inadequate spillway capacity, or structural damage caused by an earthquake or flood. The Nacimiento Dam is classified as “Extremely High” downstream hazard potential dams by the Division of Safety of Dams of the California Department of Water Resources.<ref name-"Monterey County Office of Emergency Services">https://www.co.monterey.ca.us/government/departments-a-h/administrative-office/office-of-emergency-services/ready-monterey-county/hazard-ready/dam-failure</ref>
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===Dam Failure Simulation Results===
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The peak flow through the breach is estimated to be 3,300,000 cfs and is estimated to occur one hour after the dam begins to fail. It is estimated that ZZZ of reservoir storage above the TTT-foot level will be discharged RRR days after failure begins. The flood wave would take an estimated 24 hours to reach the mouth of the Salinas River where the flow rate would be approximately 700,000 cfs. The simulation predicts flooding in portions of Camp Roberts and San Miguel, Bradley, the San Ardo oil field, San Ardo, portions of King City, Spreckels, portions of Salinas, and portions of Castroville and Moss Landing.<ref name-"Monterey County Office of Emergency Services">https://www.co.monterey.ca.us/government/departments-a-h/administrative-office/office-of-emergency-services/ready-monterey-county/hazard-ready/dam-failure</ref>
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===Spillway Failure Simulation Results===
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The peak flow is estimated to be 216,000 cfs and estimated to occur 6 minutes after spillway failure begins. An estimated 205,000 acre-feet of reservoir storage will be discharged within 3.5 days of failure, and the flood wave would take about 2 days to reach the mouth of Salinas River. The peak flow there would be about 40,000 cfs. Most of the flow would remain within the Salinas River channel and the FEMA 100-year flood plain, and most of the flood plain would drain within one week after failure. The simulation predicts a community adjacent to San Lorenzo Park in King City may experience some flooding, mostly in the streets, and there would also likely be shallow flooding along the southern edge of the City of Salinas.<ref name-"Monterey County Office of Emergency Services">https://www.co.monterey.ca.us/government/departments-a-h/administrative-office/office-of-emergency-services/ready-monterey-county/hazard-ready/dam-failure</ref>
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==Data==
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===Current Data===
 
===Current Data===
As of April 6th, 2020, the [[Monterey County Water Resources Agency (MCWRA)]] publishes observed data for preceding 10-day periods for the following metrics: Percentage of Capacity, Elevation(feet), Depth(feet), Storage(acre-feet), Lake Surface Area(acres), Length of Lake(miles), Releases(cfs), Rainfall Past 24 hours(in.), Rainfall to Date Last year(in.), and Total Rain Last Season(in.). This information can be found at [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/historical-data (MCWRA Reservoir Data)]
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The [[Monterey County Water Resources Agency (MCWRA)| Monterey County Water Resources Agency]] publishes observed data for preceding 10-day periods for the following metrics: Percentage of Capacity, Elevation(feet), Depth(feet), Storage(acre-feet), Lake Surface Area(acres), Length of Lake(miles), Releases(cfs), Rainfall Past 24 hours(in.), Rainfall to Date Last year(in.), and Total Rain Last Season(in.). They also include historical data from 1958-present for the same parameters. This information can be found at [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/historical-data (MCWRA Reservoir Data)]
 
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===Historical Data===
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As of April 6th, 2020, the [[Monterey County Water Resources Agency (MCWRA)]] publishes historical data from 1958-present for the following: Elevation Graph, Daily Elevation Data (PDF), Daily Elevation Data (text), Storage Graph, Daily Releases. This information can be found at [https://www.co.monterey.ca.us/government/government-links/water-resources-agency/projects-facilities/dams-and-reservoirs/historical-data (MCWRA Reservoir Data)]
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==References==
 
==References==

Latest revision as of 13:10, 12 April 2020

Image 1. Nacimiento Dam.

A Environmental Topics summary by the ENVS 560/L Watershed Systems class at CSUMB.

This page provides a brief overview of the history, purpose and design of the Nacimiento Dam.

Summary

The Nacimiento Dam was completed in 1957. Although it is located in northern San Luis Obispo County, it is owned by the Monterey County Water Resources Agency. It is located about 20 miles from the coast, and 4.4 miles away from the San Antonio Dam. Both were created for the primary purposes of groundwater recharge and flood control. [1] The Nacimiento Dam and San Antonio Dam are currently involved in the recently created Salinas Valley Water Project and they provides opportunities for recreation. [2]

The Nacimiento Dam creates the Nacimiento Reservoir, which has the ability to store water from winter storms for the dry season. At an elevation of 800 feet, the reservoir has the capacity to store 377,900 acre-feet of water when it is full. It is roughly 18 miles long, and has about 165 miles of shoreline available for recreation. The maximum flood stage elevation is 802 feet. The maximum temporary capacity during a flood event is 538,000 acre-feet, with a surface area of 7,149 acres.

Purpose

The primary function of the Nacimiento Dam is to provide an instrument for groundwater recharge and flood control in the Salinas Valley. [1] The Nacimiento Dam and San Antonio Dam are also essential parts of the more recent Salinas Valley Water Project and they provide opportunities for water recreation in southern Monterey County and northern San Luis Obispo County. [2] The Nacimiento Dam spillway drains into the Salinas River groundwater system, and this watershed contributes to the Salinas Valley water supply.[3] It is an instrumental in maintaining water supply during the dry season, and was modified in 2010 to raise the flood elevation to 800 feet. [4]

Further downstream, near the mouth of the Salinas River, the Salinas River Diversion Facility captures some of this released water, and creates an artificial dam to store additional water. [2] This timed-release and gradual groundwater recharge helps to slow the rate of seawater intrusion in the Salinas Valley. [5]

Statistics

  • The Nacimiento Dam is located at 35°45′31″ N, 120°53′6″ W. [6]
  • Dam Type as determined by the California Department of Water Resources: ERTH - Earth
  • Dam Usage as determined by the California Department of Water Resources: FC,DOM,IRR,MUN,POW - Flood Control, Domestic, Irrigation, Municpial, Power [7]

Current Issues

According to a 2019 report and independent audit conducted by GEI Consultants, Inc., the Nacimiento Dam safety program is deficient. It has an outdated program document, insufficient staff and a long list of overdue safety repairs. This maintenance is estimated to cost more than $50 million, and needs to be addressed as soon as possible. The report noted that staff is overworked and undertrained, accompanied by a myriad of workload and funding issues. Additionally, the safety program is inadequate for a structure built more than six decades ago. The Nacimiento Dam has been identified by the state Division of Safety of Dams as an “extremely high hazard,” regarding these repairs. [8].

If the dam failed and flooded, it would cause substantial damage. Peak flows through the breach are estimated to be 3,300,000 cubic feet per second (cfs) and are projected to occur one hour after dam failure. The flood wave would take roughly one day to reach the mouth of the Salinas River, and the flow rate would be approximately 700,000 cfs. The simulation predicts flooding in portions of Camp Roberts and San Miguel, Bradley, the San Ardo oil field, San Ardo, and portions of King City, Spreckels, Salinas, Castroville and Moss Landing. [9]

Dam Subdivisions And Applications

In the San Antonio Dam, operational pools refer to management of water being stored in the reservoir. There are a few different operational pools related to storage, release, and conservation.

  • Physical minimum pool - maximum height: 670 feet. At this elevation or lower, water cannot flow out of the reservoir.
  • Operational minimum pool - maximum height: 687.8 feet. Any water below this elevation is reserved for fish habitat, as well as a water entitlement for San Luis Obispo County.
  • Conservation pool - maximum height: 787.5 feet. Water is "conserved" to be later released into the Salinas River for groundwater recharge, fish passage, and operation of the Salinas Valley Water Project.

There is one additional pool known as the flood pool, which is from the concrete spillway to an elevation of 801 feet (or 1 foot above the top of the spillway gate). [2]

Hydroelectric Power

There is a 4-megawatt powerplant constructed at the right dam abutment. The power plant contains both large and small turbines that operate in the optimal range of 25 cfs to 400 cfs. [2]

Nacimiento Dam Measurements

Current Data

The Monterey County Water Resources Agency publishes observed data for preceding 10-day periods for the following metrics: Percentage of Capacity, Elevation(feet), Depth(feet), Storage(acre-feet), Lake Surface Area(acres), Length of Lake(miles), Releases(cfs), Rainfall Past 24 hours(in.), Rainfall to Date Last year(in.), and Total Rain Last Season(in.). They also include historical data from 1958-present for the same parameters. This information can be found at (MCWRA Reservoir Data)

References

  1. 1.0 1.1 Monterey County Water Resources Agency Monterey County Water Resources Agency Engineering Reports Updated July 21, 2017.
  2. 2.0 2.1 2.2 2.3 2.4 Monterey County Water Resources Agency MCWRA: Dams and Reservoirs Updated 2020.
  3. CalWater Nacimiento Dam Report #79 Published 2014.
  4. Monterey County Water Resources Agency. Salinas Valley Water Project Updated 2020.
  5. Monterey County Water Resources Agency Monterey County Water Resources Agency: Seawater Intrusion Monitoring Updated 2020.
  6. USGS Feature Report: Nacimiento Dam USGS Feature Report: Nacimiento Dam
  7. California Data Exchange Center CDEC: Dam Definitions Updated 2017.
  8. Johnson, Jim. Monterey County’s Nacimiento Dam Needs Safetey Upgrades Published July 18, 2019.
  9. Monterey County Office of Emergency Services Monterey County Dam Safety Updated 2020.

Links

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.