Chapter I — Hillside, Creek, and Ridgeline Areas

Contents:

D5-1 - Purpose

D5-2 - Applicability

D5-3 - Exemptions

D5-4 - Hillside, Creek, and Ridgeline Area Development Standards

D5-5 - Design Guidelines D5-6 - Slope Methodology

D5-1 - Purpose

This Chapter provides standards for the protection and preservation of hillside, creek, and ridgeline areas. The purpose of this Chapter is to:

1. Preserve significant features of hillsides, creeks, and ridgeline areas in essentially their natural state;

2. Preserve existing vegetation, soils, geology, slopes, and drainage patterns;

3. Preserve the natural topography, including swales, canyons, knolls, ridgelines, and rock outcrops, wherever feasible;

4. Minimize grading and cut and fill practices to retain the natural terrain and character of the hillsides and ridgelines;

5. Avoid development that would result in unacceptable fire, flood, slide, or other safety hazards;

6. Avoid unwarranted, high maintenance costs for public facilities;

7. Provide a mechanism for flexible design of development projects so that development may be clustered to allow environmentally sensitive areas to be preserved as open space;

8. Encourage design of street systems and driveways that blend with the natural contours and minimize extensive grading; and

9. Provide adequate buffer areas between creek corridors and adjacent development, to retain the creek corridors as valuable natural, scenic, and recreational amenities as appropriate.

Definitions of technical terms and phrases used in this Section may be found in Division D8 (Glossary) under “Resource Management.”

D5-2 - Applicability

The provisions of this Chapter apply to proposed development, other than Public Works projects, on any sites as identified below:

1. The Resource Management Area and Creeks as identified in General Plan Figure 8-3 (Resource Management); or

2. All property over 500 feet in elevation; or

3. Property with a natural gradient in excess of 10 percent; or

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4. Property within 1,000 feet of a major or minor ridgeline;

D5-3 - Exemptions

The provisions of this Chapter shall not apply to:

1. The Built Urban Land as identified in General Plan Figure 8-3 (Resource Management).

(Ord. No. 522, § 6, 12/12/2023)

Effective on: 1/11/2024

D5-4 - Hillside, Creek, and Ridgeline Area Development Standards

• A. Development standards. Development proposed within the Hillside, Creek, and Ridgeline Areas shall comply with the development standards of the primary zone, except as follows.

  1. Density. The density on all developable and undevelopable land shall be limited to the following densities based upon the existing natural slope as determined by the method described in Section D5-6 (Slope Methodology).

Densities on undevelopable land may be exercised only upon transfer to developable land. Undevelopable land is defined by Zoning Ordinance Division D8 (Glossary) as:

• a. Land with an existing, natural slope in excess of 20 percent with a minimum elevation differential of 40 feet and a minimum contiguous area of three acres; or

• b. Riparian corridors or associated vegetated areas of creeks, intermittent streams, perennial streams, or lakes.

2. Height Limit. Structures shall be limited to 32 feet in height measured from the lowest to the highest points of the structure which are above the ground. The review authority may allow up to a 15 percent increase in height for multi-family development projects that incorporate sustainable building and development practices similar to Leadership in Energy and Environmental Design (LEED) Gold or Platinum certifications.

3. Building prohibited on “undevelopable land.” No building shall be allowed on undevelopable land, as defined in Zoning Ordinance Division D8 (Glossary) under "Resource Management," and the land shall not be included in density calculations that establish the development potential of a site. However, permanent open space dedication may include “undevelopable land” (see General Plan Table 4-4). Streets, driveways, non-residential accessory structures, park and recreation facilities and utilities may be constructed on undevelopable land. The review authority may allow minor grading (three acres or less) with review to create buildable lots on otherwise undevelopable land if a corresponding amount of contiguous land with slopes less than 20 percent is retained by deed restriction as permanent open space.

   • a. Exception: A single-family dwelling shall be permitted on a lot created prior to October 25, 2012, provided there is a suitable building site and all structures, driveways and grading conform to the standards of this Section.

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4. Ridgeline setback. No structure shall be located within 100 feet, measured vertically, of the centerline of a major ridge, or within 50 feet, measured vertically, of the centerline of a minor ridge. For purposes of this Section, the ridge centerlines shall be as identified in General Plan Figure 8-3 (Resource Management), unless the review authority approves a more precise delineation, based on a topographic map with a contour interval of not more than 10 feet.

measured vertically, of the centerline of a major ridge, or within 50 feet, measured vertically, of the centerline of a minor ridge. For purposes of this Section, the ridge centerlines shall be as identified in General Plan Figure 8-3 (Resource Management), unless the review authority approves a more precise delineation, based on a topographic map with a contour interval of not more than 10 feet.

Where structures are proposed within 1,000 feet of a major ridge as identified in General Plan Figure 8-3 (Resource Management), the building pad shall be graded and the building designed so that the structure maintains a low-profile appearance and conforms to the natural grade of the hillside, as determined by the review authority.

• a. Exception: Within pocket areas, as defined in Zoning Ordinance Division D8 (Glossary) under "Resource Management," the vertical ridge setback may be reduced by up to 50 percent and buildings may project, measured vertically, up to 33 percent into the reduced ridge setback area on not more than 25 percent of the lots upon making the following special Variance findings in addition to the Variance findings in Zoning Ordinance Section D6-29 (Variances):

  • i. The pocket development will not significantly impact visually, neighboring communities; and

  • ii. The exception meets the intent of the Zoning Ordinance.

5. Street and driveway grades. Maximum street grades shall be 12 percent, and maximum driveway grades shall be 15 percent. Special streets, including one-way streets, split-level streets, and dead-end streets, and minor variations from the maximum grade standard, may be allowed when the review authority determines that their use is justified by detailed engineering and traffic circulation studies submitted by the applicant and approved by the City Engineer finding that the streets are necessary to achieve the purposes of this Section.

6. Creek setback. No habitable structure shall be located within 100 feet of the centerline of a creek or stream channel identified in General Plan Figure 8-3 (Resource Management) plus any additional horizontal distance to be determined by an approved drainage report; provided that no habitable structure shall be located midslope or within the 100 year flood plain plus one foot of free board. Improvement within the setback areas shall be limited to open space and recreation amenities and access roads incidental to achieving effective circulation patterns.

   • a. Exception: A required creek setback may be modified to avoid a “taking” of private property if the review authority can make the following special Variance findings in addition to the Variance findings in Zoning Ordinance Section D6-29 (Variances):

     • i. The modification is consistent with the General Plan;

     • ii. Riparian vegetation comprises less than 50 percent of the plant species within the normal 100-foot setback area;

     • iii. There is no historical evidence that riparian vegetation could be easily reestablished within a five-year period; and

• iv. A reduced setback will not expose structures to bank erosion, or flooding damage, increase downstream flooding, flood hazard or impair access to the creek or stream channel for maintenance.

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Figure 5-1 – Creeks Setback for Waterways as shown in General Plan Figure 8-3

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7. Creek Setback Development Standards. Development within a creek setback shall meet the following development standards:

   • a. Alteration of natural features. No grading or filling, planting of exotic/non-native or non-riparian plant species, or removal of native vegetation shall occur within a creek or creekside setback area, except where authorized for flood control purposes and by the proper permits issued by the California State Department of Fish and Game, all other applicable State and Federal agencies having authority over the creek

   • b. Design of drainage improvements. Where drainage improvements are required, they shall be placed in the least visible locations and in manners that achieve natural appearance through the use of river rock, earthtone concrete, and landscaping with native plant materials.

   • c. Use of permeable surfaces. The proposed development should incorporate permeable surfaces (for example, wood decks, sand-joined bricks, and stone walkways) where feasible, to minimize off-site flows and facilitate the absorption of water into the ground.

   • d. Creek bank stabilization. Development or land use changes that increase impervious surfaces or sedimentation may result in channel erosion. This may require measures to stabilize creek banks.

     • i. Creek rehabilitation is the preferred method of stabilization, with the objective of maintaining the natural character of the creek and riparian area. Rehabilitation may include enlarging the channel at points of obstruction, clearing obstructions at points of constriction, limiting uses in areas of excessive erosion, and restoring riparian vegetation.

     • ii. Concrete channels and other mechanical stabilization measures shall not be allowed unless no other alternative exists.

     • iii. If bank stabilization requires other than rehabilitation or vegetative methods, hand-placed stone or rock rip-rap are the preferred methods.

   • e. Physical and visual access. The following physical and visual access standards shall apply unless a resource agency establishes a different standard for the project:

     • i. Public access and visibility to creeks should be provided through the use of singlelane width frontage roads adjacent to creeks, but outside of the creek setback. Structures or lots that back-up to creeks or creek frontage roads are discouraged.

     • ii. The provision of multipurpose creekside trails and public open space is encouraged. Open space areas should include planting for riparian enhancement with native shrubs and trees, paths and trails, lighting, benches, play and exercise equipment, and trash receptacles outside of the riparian habitat area, where appropriate.

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• iii. Where streets are not used, frequent access to creekside trails and public open space should be provided at least every 300 feet, and may occur at the end of culde-sacs.

D5-5 - Design Guidelines

• A. Design Guidelines. Development proposed within the Hillside, Creek, and Ridgeline Areas shall consider the following guidelines:

  1. Natural terrain alteration. Alterations of existing natural or artificial contours of land shall be minimized. Any natural contour altered by grading shall be rounded and shaped to simulate natural terrain, unless on an individual site this would diminish open space or significant natural features of the site. Grading shall follow the natural topographic contours as much as possible, allowing for multi-level foundations to accommodate differences in grade.

  2. Viewshed Criteria. Development within the Hillside, Creek, and Ridgeline Areas shall consider the following viewshed criteria to promote architecture and designs that are compatible with the natural hillside terrain and minimize visual impacts:

     • a. Retain a significant portion of natural on-site vegetation to naturally screen structures;

     • b. Design and install landscaping to substantially screen structures;

     • c. Design project and site lighting to minimize off-site visibility and glare;

     • d. Blend the exterior color and materials with the surrounding vegetation and landforms;

     • e. Use of non-reflective windows and trim; and

     • f. Design roof angles and composition to conform to existing landforms and landscape

Additional photosimulations, studies, and/or other submittal items may be required by the review authority to determine compliance with the viewshed criteria.

3. Building and structure design standards. The following standards are intended to ensure that the design of structures conform to the natural land form and enhance the character of the site.

   • a. The use of multi-level foundations (floor levels separated by a minimum of four feet) shall be encouraged as the standard design for residential structures located on natural hillsides with slopes of 15 to 20 percent. This requirement does not apply to lots created prior to October 25, 2012.

   • b. Roof lines shall relate to the surrounding slope and topography.

   • c. Second-story levels of structures shall incorporate a variety of bays, recesses, overhangs, or setbacks, at the downhill side of the structure so that the appearance of vertical mass and the visual impact on the surrounding area are reduced.

   • d. All fencing shall be designed and located to be compatible with existing and proposed buildings and surrounding open space.

   • e. Exterior mechanical equipment shall be screened from public view. Equipment to be screened includes heating, air conditioning, refrigeration equipment, plumbing lines, ductwork, and transformers. Screening of the top of equipment may be required if necessary to protect views from a Residential Zone.

• f. Exterior structural supports and undersides of floors and decks not enclosed by walls or otherwise screened and more than 12 feet high may be approved only if the Review Authority finds that no alternative type of construction is feasible, and fire-safety and design considerations have been adequately addressed.

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• g. A driveway serving three or more residences and that is not entirely visible from both ends shall have passing turnouts. Each driveway shall comply with minimum widths prescribed by the City Engineer.

• h. A dwelling unit adjoining a street where parking is prohibited on both sides shall provide adequate guest parking as required by the Zoning Ordinance.

D5-6 - Slope Methodology

• A. The purpose of this section is to establish slope methodology standards to achieve consistent application of the Hillside, Creek, and Ridgeline Development Standards in Section D5-4.

  1. Grid. On a subject property, apply a 200 ft. by 200 ft. grid. Grids shall be placed as close as parallel as possible with the existing contour lines. Contour lines shall be drawn with a maximum interval of 10 ft. with 5 ft. intervals preferable.

  2. Slope. Determine the average slope of each individual grid square. The average slope is determined by taking three (3) slope measurements within each grid square as follows:

     • a. Along the left boundary;

     • b. Along the right boundary, and

     • c. Along the center.

Average slope is determined by dividing the sum of the three measurements by three (3).

Figure 5-2 – Example Average Slope Calculation

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3. Allowed Density. Determine the allowed density for all full grid squares and partial grid squares based upon Section D5-4.A.1. The total density shall equal the sum of the allowed density for all full grid squares and partial grid squares.

4. Net Developable Area. Determine the net developable area by deducting from the gross area the following areas on which buildings and/or structures are prohibited:

   • a. Existing natural slopes greater than 20 percent;

   • b. Major and minor ridge and creek setback areas as identified in General Plan Figure 8-3 (Resource Management)

5. Net Density. Determine net density as the Allowed Density divided by the Net Developable Area.

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6. General Plan Density. Compare the Net Density with the permitted General Plan density.