Difference between revisions of "Los Padres Reservoir Capacity Issues"

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A stage-volume study completed by the CSUMB Watershed Institute in 2008 measured the reservoir capacity at 1,785 acre feet. <ref name= "stage"/>
 
A stage-volume study completed by the CSUMB Watershed Institute in 2008 measured the reservoir capacity at 1,785 acre feet. <ref name= "stage"/>
 
 
  
 
== Resources at Stake ==
 
== Resources at Stake ==

Revision as of 01:11, 9 April 2013

A watershed-related issue examined by the ENVS 560/L Watershed Systems class at CSUMB.

Summary

The Los Padres Dam was built in 1949 as an alternate water storage facility in response to sediment accumulation in the downstream San Clemente Dam (built in 1921). The Los Padres Reservoir had an initial storage capacity of 3,130 acre-feet. Water stored in the Los Padres Reservoir is released to the Carmel Valley Aquifer during low-flow season where it is pumped out by California- American Water Co. and is used by nearly all of the Monterey Peninsula. By 2008, the Los Padres Dam had lost almost half of its capacity to heavy sediment accumulation [1].

Los Padres 2009.png
Los Padres.png

The Los Padres reservoir serves as the primary source of water storage for the Monterey Peninsula. If the reservoir has a large increase in sediment accumulation and subsequent decrease in storage capacity, the Monterey Peninsula's water storage may be significantly reduced.

Location

The Los Padres Reservoir is part of the Carmel Valley Watershed in Central California. The reservoir is located 30 km southeast of the city of Carmel, and is bounded by the Santa Lucia Range to the south, Jacks Peak to the north and Sierra de Salinas to the east.

Capacity Changes

The Los Padres Reservoir was constructed with an initial capacity of 3,130 acre feet is subject to sedimentation under natural conditions due to the steep, unstable granitic slopes of the reservoir being highly susceptible to erosion. [2]

In August 1977, the Marble-Cone fire burned approximately 178,000 acres in the Santa Lucia Mountains, affecting virtually all of the Carmel watershed above Los Padres Reservoir. The US Forest Service estimated that over half the watershed was left with less than 10% vegetative cover remaining. Unusually heavy rainfall in the months following the fire led to increased erosion, and deposition in the reservoir in the three years following the fire was about equal to the total of the previous thirty years. By October 1980, the reservoir was left with a capacity just under 2000 acre feet. [3]

Sediment was removed from the reservoir in 1984, leading to a temporary increase in capacity to 2,179 acre feet. Cite error: Closing </ref> missing for <ref> tag of the watershed above the Los Padres reservoir. There was concern that the impact of this fire would lead to a further increase in sedimentation similar to that of the Marble-Cone fire, but further study showed that no increase in sediment flows occurred, probably due to the low rainfall years that followed the fire. [4]

A stage-volume study completed by the CSUMB Watershed Institute in 2008 measured the reservoir capacity at 1,785 acre feet. [5]

Resources at Stake

  • Water supply for the Monterey Peninsula is at stake. Increased sediment in the Los Padres reservoir decreases water storage capacity.
  • Steelhead trout habitat is at stake. Increased sediment accumulation may degrade water quality and pose as a threat to essential habitat for steelhead trout [6]. Each year a certain amount of water is released from the dam during the low flow season [7]. If there is less water storage, there may be a decrease in the volume released and habitat could be threatened.

Proposed Solutions

Stakeholders

Laws, Policies, & Regulations

  • After the Basin Complex Fire, measures to address potential erosion and post-fire land management policies were outlined in the Burned Area Emergency Response (BAER)report [8].
  • The 10 year comprehensive survey plan (2002) [9] addresses the need for wildland fire and restoration strategies to protect communities, forests and rangelands from the effects of wildland fires.
  • CalAm and the Monterey Peninsula Water Management District (MPWMD) have proposed a new dam called Carmel River Dam and Reservoir Project (CRDRP)to replace Los Padres Dam [10] and have also proposed increasing the capacity of Los Padres Reservoir [11].* More that could be described, e.g.:
    • SWRCB order against Cal-Am
    • ESA
    • DWR & Dam Safety

Systems

  • Dynamics of rainwater flow and sediment flow on recent burn areas i.e. hydrophobic soils.

Science and Technology

Projects and technologies that can be applied to capacity issues at the reservoir include:

  • The USGS and USFS both have projects assessing burn events:
    • The USGS gathers information to assess debris flow, water degradation, flood risk, and ecosystem damage. USGS Debris Flow Project
    • Through the Department of the Interior, the US Forest service and USGS work cooperatively to form Burned Area Emergency Response(BAER) teams that rapidly assess burn areas using remote sensing and satellite imagery [13].
  • Geologists, hydrologists and biologists continue to study erosion, siltation, fish habitat and hydrology in relation to water storage, water supplies and river ecosystems.
  • Hydrologic Computer Modeling [14].
  • Aerial photography and satellite imagery ( AVHRR ) can be used to monitor burn areas and landslides.
  • LIDAR data can be merged with multibeam bathymetry data to create high resolution digital elevation maps to quantify change [15].

Future research

  • Future work should involve quantifying current sediment load in the Los Padres Reservoir and assess the impacts of increased sediment accumulation. This should aid MPWMD in future water management decisions.
  • Potential future CWSP MS thesis topic:
    • Analysis of pre/post fire LIDAR and multibeam bathymetry data of Los Padres Reservoir to quantify sediment change.

References

  1. http://ccows.csumb.edu/pubs/reports/CCoWS_MPWMD_LosPadres_StageVol_2008_090508.pdf
  2. http://ccows.csumb.edu/pubs/reports/CCoWS_CRWC_CarmAssPhysHyd_041101.pdf
  3. http://books.google.com/books?hl=en&lr=&id=UhjbO_CC_VoC&oi=fnd&pg=PA134&dq=hecht+1981+upper+carmel+river&ots=O-ekwa5F3L&sig=c1XTZtc_f-sx31cvj64roifYXqY#v=onepage&q=hecht%201981%20upper%20carmel%20river&f=false Hecht 1981
  4. http://hydro.csumb.edu/Doug/html/SaraKelly_Carmel_fireImpacts_capstone_120509.pdf
  5. Cite error: Invalid <ref> tag; no text was provided for refs named stage
  6. Newcombe CP, MacDonald DD. 1991. Effects of Suspended Sediments on Aquatic Ecosystems. North American Journal of Fisheries Management 11 (1):72-82
  7. http://www.mpwmd.dst.ca.us/gmletters/2009/20090508/20090508.pdf
  8. http://ca.water.usgs.gov/webcams/bigsur/09_22_Basin_2500-8redacted.pdf
  9. http://www.westgov.org/wga/initiatives/fire/implem_plan.pdf
  10. http://www.mpwmd.dst.ca.us/seir/execsum.htm
  11. http://www.mpwmd.dst.ca.us/asd/board/boardpacket/2008/20081020/18/item18_exh18a.pdf
  12. Palmieria A Shahb F Dinara A. 2001. Economics of reservoir sedimentation and sustainable management of dams. Journal of Environmental Management 61 (2):149-163
  13. http://www.fws.gov/fire/ifcc/esr/home.htm
  14. Beeson PC Martens SN Breshears DD. 2001. Wildfire: Mapping Vulnerability to Landscape Disturbance. Hydrological Processes 15 (15):2917 - 2930
  15. http://ccows.csumb.edu/pubs/reports/CCoWS_MPWMD_LosPadres_StageVol_2008_090508.pdf

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.