Difference between revisions of "Los Padres Reservoir Capacity Issues"

Revision as of 12:28, 6 February 2009

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 1999, the Los Padres dam had lost half of its capacity to heavy sediment accumulation [1].

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 which erode quickly given precipitation. This may exacerbate erosion rates and 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 so any big increase in sediment accumulation may be detrimental.

Location

The Los Padres Reservoir is part of the Carmel Valley Watershed which is bounded by the Santa Lucia Range to the south, Jacks Peak to the north, Sierra des Salinas to the east in Central Coastal California.

Resource/s at stake

• Water supply for the Monterey Peninsula is at stake. Increased sediment in the Los Padres reservoir decreases water storage capacity, directly affecting the water supply for the residents of the Monterey Peninsula.
• Increased sediment accumulation may also degrade water quality, posing as a threat to essential habitat for steelhead trout.
• <What about quality of life for nearby residents who could be affected by reservoir management and modification operations?>

Stakeholders

• California-America Water Company ( Cal-AM )[3]
• Monterey Peninsula Water Management District ( MPWMD )[4]
• Monterey Peninsula Residents
• Steelhead trout interests (e.g. NOAA-NMFS, CDFG, CRSA)

Laws, policies, & regulations

• One of the main factors that determines the amount of sediment accumulation in the Los Padres Reservoir is the amount of rainfall after fire events. Due to difficult nature of predicting rainfall, policies have been implemented to address the management of burn areas.^[1]
• The 10 year comprehensive survey plan (2002) [5] 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 [6]. 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)[7] teams that rapidly assess burn areas using remote sensing and satellite imagery.

Scientific Tools

• Hydrologic Computer Modeling [8]
• 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. ↑ Need source

• Basin Complex SEAT report
  • (http://cpoabigsur.org/Images/SEAT_REPORT_Fourth_Draft_9_17_08.pdf)
• Basin Complex Fire BAER Report
  • (http://www.fs.fed.us/r5/lospadres/fire/baer/gallery/basin-rehab.pdf)
• MPWMD's memorandum to raise Los Padres Dam to increase storage capacity
  • (http://www.mpwmd.dst.ca.us/asd/board/boardpacket/2008/20081020/18/item18_exh18a.pdf)
• MPWMD's short report on wildfire impacts. Old but, the concepts are similar.
  • (http://www.mpwmd.dst.ca.us/newsrels/fireqa1099.htm)
• Ten Year Comprehensive Strategy
  • (http://www.westgov.org/wga/initiatives/fire/implem_plan.pdf)

Links

• Other Watershed Issues

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.