Flood protection project
Upper Llagas Creek

Project description:

The project extends approximately 13.6 miles from Buena Vista Avenue upstream to just beyond Wright Avenue. The project will provide 100-year level of flood protection in the urban areas of Morgan Hill, as well as an approximate 5-10 year level of flood protection in the agricultural areas of Gilroy and Morgan Hill. In addition, the project will provide channel stabilization measures, thus reducing erosion and sedimentation.

Goals and objectives:

To provide flood protection for residential, commercial, and agricultural developments in southern Santa Clara County, including expanding residential communities that support Silicon Valley; to protect and improve water quality in the watershed, and to preserve and enhance the river's habitat, fisher and wildlife.

Check here for:

• Fact Sheet
  

• Llagas Creek Flood Protection Project status report 2007
  

• Briefing Memo - 3-06
  

• Map of the project

Project contact:
For more information about this project, contact: Marc Klemencic, Manager, Uvas/Llagas Watersheds, at (408) 265-2607, x2084 or Bal Ganjoo, Senior Project Manager, Upper Llagas, at (408) 265-2607, x3117 at the Santa Clara Valley Water District.

Description of the Lower Llagas Creek and Upper Llagas Creek project
The Llagas Creek Watershed Project was initiated in 1954, approved by local sponsoring agencies in 1968, and authorized by Congress in 1969 under Public Law 83-566 (PL-566). With a total drainage area of 104 square miles, the project extends approximately 16.6 miles from the Pajaro River south of Bloomfield Road upstream to just beyond Wright Avenue. The project will provide 100-year level of flood protection in the urban areas of Morgan Hill and Gilroy, and an approximately 10-year level of flood protection in the agricultural areas. In addition, the project will provide channel stabilization measures, thus reducing erosion and sedimentation. Structural measures will include the replacement of more than 35 bridges and culverts at road crossings.

The Llagas Creek project was originally a joint Soil Conservation Service (SCS)-Santa Clara Valley Water District (SCVWD)-Loma Prieta Resource Conservation District (LPRCD) effort. The Project Engineers Report and EIS/EIR were completed in 1982. Subsequently, construction of the Lower Llagas Creek portion, from Buena Vista Ave to the Pajaro River, was completed in 1996. In 1999, due to Natural Resources Conservation Services (NRCS, formerly the SCS) funding constraints Congress authorized the Army Corps of Engineers to assume responsibility for completing the project. The NRCS, SCVWD, and LPRCD will continue to cooperate as sponsors with the Corps serving as the lead agency.

The remaining project costs will be cost shared with the Army Corps of Engineers. The November 2000 passage of Measure B (Clean, Safe Creeks and Natural Flood Protection Measure) ensured local funds were available.

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Project timeline

Flooding history
Encompassing a watershed of 104 square miles in southern Santa Clara County, the Llagas Creek Flood Protection Project will protect residential, commercial, and agricultural areas in
San Martin, Morgan Hill, and Gilroy. Floods in 1937, 1955, 1958, 1962, 1963, 1969, 1982, 1986, 1996, 1997, and 1998 damaged existing homes and businesses within these communities. The
largest recorded flood, estimated to be a 33-year event, occurred in December 1955.

At the time of the 1982 report, an estimated 1,123 residential buildings, 64 mobile homes, 463 commercial establishments, and 24 industrial buildings were located in the flood-prone area.
At that time, related damages from a 1 percent or 100-year flood were estimated to be $8.5 million.

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