The purpose of the Calabazas Creek Capacity Improvement Project is to identify improvements to channel sections on Calabazas Creek, to achieve one-percent flood protection between San Francisco Bay and Miller Avenue, to obtain a Letter of Map Revision (LOMR) from the Federal Emergency Management Agency (FEMA), and to stabilize the channel between Lawrence Expressway and Miller Avenue. A one-percent flood is an event which has a one percent chance of occuring in any given year (also known as a 100-year flood).

These channel improvements will remove 2,250 parcels from the existing one-percent floodplain, extending over portions of the cities of Santa Clara, San Jose, and Cupertino and stabilize the channel invert.

Calabazas Creek Capacity Improvement Project (Miller Avenue to Central Expressway) fact sheet (PDF 447KB)

Project contact:
For more information about this project, contact Project Manager Tony Ndah, Santa Clara Valley Water District, at (408) 265-2600, ext. 2679.

Check here for:

• Project goals
• Proposed project work
• Map of project area
  • Flood protection work (JPEG 1.2 MB) (Central Expressway to El Camino Real)
  • Erosion repair work (JPEG 1.5 MB) (Lawrence Expressway to Miller Avenue)
• Project status
• Project timeline
• Project history and background
• Projects to protect the community from flooding
  VIEW MAP (JPEG 1.2 MB)

Project goals:

• Provide continuous one-percent flood protection between San Francisco Bay and Miller Avenue to remove 2,250 parcels from the one-percent floodplain.
• Stabilize channel invert along Calabazas Creek between Lawrence Expressway and Miller Avenue.

Proposed project work

The project will provide continues one-percent flood protection and consist of the demolition of an existing maintenance ramp downstream of Central Expressway (PDF 170 KB); the demolition of an existing maintenance ramp upstream of Kifer Road (183 KB); the demolition of a flow separation wall downstream of the Union Pacific Railroad bridge (PDF 164 KB); the construction of a low flow channel beginning just upstream of Machado Avenue (PDF 211 KB) to about 640 feet downstream; and the construction of a low flow channel 500 feet upstream and downstream of El Camino Real (PDF 395 KB).

Work also includes stabilizingthe channel by constructing grade control structures (PDF 1.5 MB) along 11,150 feet of channel between Lawrence Expressway and Miller Avenue.

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Project status

• Prepared Problem Definition Report
• Evaluated feasible alternatives to meet project objectives
• Selected the preferred project alternative
• Installed three grade control structures in Summer 2005 along Calabazas Creek at Homestead Road, Pruneridge Avenue, and Stevens Creek Boulevard
• Filed Notice of Exemption (Categorical Exemption) for CEQA in June 2006
• Submitted Conditional Letter of Map Revision (CLOMR) application to FEMA in August 2006
• Public meeting was held on September 12, 2006
  
  

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Project timeline

Project construction will be begin in April 2007 and be completed by December 2007.

The project will require several Board actions to complete the anticipated work. Below is a list of the Board actions required and when these items are estimated to be brought to the Board.

• Approve Draft Engineer’s Report for public circulation: October 2006
• Adopt final Engineer's Report: December 2006
• Advertise contract documents for construction: February 2007
• Obtain LOMR from FEMA: August 2008
  

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Project history and background


One-percent flood protection improvements were constructed on Calabazas Creek from San Francisco Bay to Miller Avenue between 1994 and 1999. Upon completion of these improvements, two revegetation projects were implemented in order to satisfy mitigation requirements.

Following the completion of the projects, the Water District began preparation of the Letter of Map Revision (LOMR) application for submittal to the Federal Emergency Management Agency (FEMA) to revise the Flood Insurance rate map of Calabazas Creek. As part of the draft LOMR application, hydraulic analyses of the improvements were performed using an “as-built” hydraulic model developed in late 2002. The analysis indicated that the creek did not have the capacity to contain a one-percent flood in some locations. In addition, high flows have severely eroded the creek bottom between Miller Avenue and Lawrence Expressway and threaten to undermine the concrete footing supporting the concrete-lined and gabion channel sides’ slopes. Staff obtained a special permit from the Department of Fish and Game in summer 2004 to conduct emergency repairs to stabilize some sections of this reach prior to the wet season.

The Calabazas Creek Capacity Improvement Project was initiated in the fall of 2004 to address these issues. The Calabazas Creek Capacity Improvement Project will result in the removal of 2,250 parcels from the one-percent floodplain and provide a permanent solution to resolve the significant invert erosion problem along the channel downstream of Miller Avenue.

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Projects to protect the community from flooding

Calabazas Creek Flood Protection Project – Phase 1
(Lawrence Expressway to Homestead Road)
– Completed November 1996

Calabazas Creek Flood Protection Project – Phase 2
(Guadalupe Slough to Arques Avenue)
– Completed December 1995

Calabazas Creek Flood Protection Project – Phase 3
(Central Expressway to Lawrence Expressway)
– Completed February 1996

Calabazas Creek Flood Protection Project – Phase 4
(Homestead Road to Miller Avenue)
– Completed March 1999

Calabazas Creek Capacity Improvement Project – Phase 5 (Central Expressway to Miller Avenue)
- Anticipated construction June 2007

Calabazas Creek Planning Study (Miller Avenue to Wardell Road)

Bollinger Road Bridge Replacement Project (Bollinger Road)
- Anticipated construction April 2007

Calabazas Creek Planning Study (Comer Drive)

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