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The Wiedemann Ranch Geologic Hazard Abatement District (GHAD) encompasses the Norris Canyon Estates development in Contra Costa County and the Henry Ranch development in San Ramon, California. Norris Canyon Estates is located along the southern side of Norris Canyon Road, west of the intersection of Norris Canyon and Bollinger Canyon Roads. The development is bordered to the east, south and west by undeveloped land. The Henry Ranch development is located to the west of San Ramon Valley Boulevard. This development is bordered by undeveloped land to the west, residential properties off Duberstein Drive, Duncan Hill Court, and Minerva Way to the north, and residential properties off of Pine Valley Place and Terraced Hills Court to the south.

The Wiedemann Ranch GHAD was formed in 1998 and the Henry Ranch development was annexed into the Wiedemann Ranch GHAD in 2000. The Board of Directors for the Wiedemann Ranch GHAD are the members of the Contra Costa County Board of Supervisors.

The Wiedemann Ranch GHAD is responsible for prevention, mitigation, abatement, and control of geologic hazards within the GHAD boundaries including mitigating or abating landslides and erosion hazards that could directly affect properties within the GHAD boundaries. This includes maintaining geologic stabilization features and managing surface and subsurface drainage facilities and improvements located in open space areas. The Wiedemann Ranch GHAD water quality maintenance responsibilities include monitoring and maintaining the two detention basins and select creek banks within the GHAD boundaries.

The GHAD is not responsible for general maintenance of open-space areas (weed abatement, trail maintenance, fire control, etc.). The role of the GHAD is limited to overseeing and supervising the HOA’s general physical maintenance of the open-space areas to prevent, mitigate, control or abate erosion, sedimentation, and potential landslide hazards.

As listed in the Plan of Control, the guidance document for the Wiedemann Ranch GHAD, site improvements for which the Wiedemann Ranch GHAD provides monitoring and maintenance are provided below.

• Detention basins
• Concrete-lined drainage ditches in open space areas
• Subdrains and subdrain outlets
• Storm drain inlets, outfalls and pipelines within the open space area
• Restored and unaltered creek corridors
• Developer constructed retaining walls
• Debris benches
• Slopes

The Wiedemann Ranch GHAD is financed through the collection of supplemental tax assessments from homeowners within the GHAD. Revenue is typically split between an ongoing operations/maintenance fund and the accumulation of a reserve for less frequent major repair items. The 2000 Engineer’s Report serves as the basis for the annual operating budget. Each year, an annual budget is considered and adopted by the Wiedemann Ranch GHAD Board of Directors.


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