Los Padres Reservoir Capacity Issues

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

Summary

Los Padres Reservoir is filling up with sediment. 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). 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 2008 Basin Complex fire (See Basin Complex Fire Erosion and Debris Flows) burned 64% [2] of the watershed above the Los Padres reservoir. Burned areas leave behind hydrophobic soils and denuded landscapes which erode quickly given precipitation [3]. Elevated erosion rates may lead to increased sediment accumulation in the Los Padres Reservoir.

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 bounded by the Santa Lucia Range to the south, Jacks Peak to the north and Sierra de Salinas to the east.

Resource/s 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 [4]. Each year a certain amount of water is released from the dam during the low flow season [5]. If there is less water storage, there may be a decrease in the volume released and habitat could be threatened.

Stakeholders

Laws, policies, & regulations

  • After the Basin Complex Fire, measures to address potential erosion and post-fire land management policies were addressed in the Burned Area Emergency Response (BAER)report [6].
  • The 10 year comprehensive survey plan (2002) [1] protects communities, forests and rangelands from the effects of wildland fires by addressing the need for wildland fire and restoration strategy.
  • 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

  • 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 [2]. USGS debris flow project (http://landslides.usgs.gov/research/wildfire/07sca/).
    • The US Forest service and USGS work cooperatively to form Burned Area Emergency Response (BAER)[3] teams that rapidly assess burn areas using remote sensing and satellite imagery.

Scientific Tools

  • Hydrologic Computer Modeling [4]
  • 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.

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://cpoabigsur.org/Images/SEAT_REPORT_Fourth_Draft_9_17_08.pdf
  3. http://www.tucson.ars.ag.gov/ICRW/Proceedings/Pierson.pdf
  4. Newcombe CP, MacDonald DD. 1991. Effects of Suspended Sediments on Aquatic Ecosystems. North American Journal of Fisheries Management 11 (1):72-82
  5. http://www.mpwmd.dst.ca.us/gmletters/2009/20090508/20090508.pdf
  6. http://ca.water.usgs.gov/webcams/bigsur/09_22_Basin_2500-8redacted.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.