TO: HONORABLE MAYOR AND MEMBERS OF THE CITY COUNCIL
FROM: David Chantarangsu, AICP Development Services Director
PREPARED BY: Chris Tracy, AICP Senior Planner, Advanced Planning
SUBJECT: title
Hillside Updates (DCA-2021-2396) - Workshop 4
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RECOMMENDATION
recommendation
Receive a presentation by staff, receive public comments, discuss the proposed ordinance; and
Provide direction related to policy options under the proposed ordinance framework.
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PRIOR ACTION/VOTE
On March 29, 2022, the City Council directed staff to review the hillside development standards (Non-Action Item).
On June 28, 2023, the Planning Commission recommended the introduction and first reading of an Ordinance updating the hillside development standards, amending Murrieta Municipal Code (MMC) Chapters 8.20 and 15.52, and updating portions of Title 16 (Vote 4-0-1) (Attachment 1).
On August 15, 2023, the City Council hosted a workshop on this item. The City Council requested additional information, so the workshop was continued to a future meeting date (Attachment 2).
On March 5, 2024, the City Council hosted a second workshop on this item. Due to additional time needed for the discussion and feedback, the workshop was continued for a second time (Attachment 3).
On June 17, 2025, the City Council hosted a third workshop on this item. The direction from Council was that more detailed examples were needed to assist the Council with moving forward, in particular with retaining wall criteria (Attachment 4).
CITY COUNCIL GOAL
Maintain a high performing organization that values fiscal sustainability, transparency, accountability and organizational efficiency.
BACKGROUND
The City Council directed staff at its annual priority and goal-setting workshop on March 29, 2022, to review the hillside development standards, as there were concerns about how they were being interpreted and implemented at the project level. The City’s existing hillside development standards, contained in Chapter 16.24 (Hillside Development) of the Murrieta Development Code (MDC), were added in 1997 to support the City’s 1994 General Plan land use goals and policies associated with the City’s hillside features. The General Plan continues to contain goals and policies in hillside areas to “maintain the natural character and the environmental and aesthetic values of sloped areas.”
For details about the historical context of the hillside development standards and why these updates are being brought forward, please refer to the “Background Section” as provided within Attachments 1, 2, 3, and 4. Staff is bringing forward these updates in a continued workshop format for the City Council to review the proposed standards and provide input ahead of a future public hearing.
DISCUSSION / NEXT STEPS
The primary objective of these updates is to revise the development standards to make them clearer and more precise, ensuring both applicants and staff can apply them effectively when applicable. By simplifying the language and improving accuracy, staff’s approach aims to reduce or eliminate confusion and streamline the review process, ultimately saving time and resources for everyone involved.
In the context of the General Plan, the following statements are made that encourage good stewardship of the City’s hillside resources:
Land Use Element Goal LU15-1.1: Encourage the preservation of natural and visual resources within Los Alamos Hills, such as rock outcroppings and scenic views of the local hills and valleys, to the greatest degree practicable.
Conservation Element Goal CSV-5: Hills and ridges are protected for their environmental and aesthetic values.
Conservation Element - Policy CSV-5.1: Promote compliance with hillside development standards and guidelines to maintain the natural character and the environmental and aesthetic values of sloped areas.
Ultimately, the recommended regulations should not impose excessive burdens on property owners or project applicants. These standards must strike a balance between protecting community interests as described in the General Plan language above, and support reasonable development in hillside areas so that development is responsible and achievable.
Focus Topic - Applicability of Standards
At the June 17, 2025, City Council meeting several members of the City Council expressed interest in re-visiting the applicability of the ordinance and its potential impact on property rights. Similar comments were raised during the public comment period. Staff has designed this workshop to focus on the areas of the City where the standards should apply.
1. Identifying The City’s Hillside Areas: 20 Percent Slope Versus 25 Percent
As described below the MDC indicates that any areas that have a slope of 20 percent or greater or are mapped by the Planning Division are subject to the hillside ordinance:
16.24.020 “Applicability”
“ A. Hillside Area. The standards contained in this chapter apply to uses and structures within areas that have a slope of twenty (20) percent or greater and/or are designated on the significant features map on file with the department.”
As currently written in the MDC, the Hillside Area criteria apply to all areas of the City that are 20 Percent or greater and/or are designated on the significant features map on file with the department.
Pros
• If the objective is to maximize hillside preservation across the City, this approach is advantageous, as it includes a larger number of properties for analysis and establishes a broader baseline for potential area preservation.
• Including more properties helps maintain the scenic quality and natural aesthetics of hillside neighborhoods.
• A larger number of properties provides a stronger foundation for evaluating trade-offs and prioritizing areas for conservation versus development.
Cons
• The definition references a map that doesn’t exist, and requires parcel-by-parcel analysis as property owners submit applications. Further, staff does not have the tools to measure slopes independently.
• Elsewhere in the MDC, a conflicting 25 percent baseline for a Hillside Area/Condition is referenced, creating confusion and inconsistency with how the definition is currently framed.
• The City does not presently have a codified hillside slope map or significant features map.
• Subjecting a larger number of properties to the hillside requirements means additional costs, more data collection, technical reports, and review, which can be time-consuming for property owners and staff to prepare and review.
• Properties that might otherwise be buildable as a non-hillside property could face restrictions, such as unusable lot area.
• Reviewing and enforcing hillside criteria across a wider set of properties increases permitting delays.
• More extensive technical and environmental review may extend timelines for development approvals.
2. 25 Percent Slope Criteria
The following language specifies a 25% Slope Criteria in the Development Code:
a. MDC Section 16.24.020(D). The development standards, guidelines and provisions of this chapter shall be applied to those portions of land with a predominance of significant natural slopes exceeding twenty-five (25) percent and areas that are integrally contiguous, or slopes determined as significant by the director. The provisions of this chapter shall apply to projects relating to subdivisions, permits, uses, structures, specific plans, master development plans, and associated site plans for development review except as specifically exempted by Section 16.02.020 <https://codelibrary.amlegal.com/codes/murrieta/latest/murrieta_ca/0-0-0-24072>.”
b. MDC Section 16.24.040(D) Slope Analysis Map. A slope analysis map for the purpose of determining the amount and location of land as it exists in its natural state and for calculating average slope categories. A base topographical map of the site shall be prepared and shall have a scale of not less than one inch to two hundred (200) feet. The base topographical map shall include adjoining properties within one hundred (100) feet of the site boundaries to portray the site's context. Slope bands in contrasting colors shall be delineated in the range of zero to twenty-five (0-25) percent, twenty-six to fifty (26-50) percent, and fifty (50) percent or greater. A tabulation of the land area by slope percentage shall also be provided.
The exact method for computing the percent slope and area of each slope category shall be sufficiently described and presented so that a review can be readily made. A heavy solid line indicating the twenty-five (25) percent grade differential shall be clearly marked on the plan. An eight and one-half by eleven (8 1/2 x 11) inch legible acetate reduction of the slope analysis with appropriate legend shall also be provided.
c. MDC Section 16.24.060(A) identifies slopes up to 25 percent as a non-hillside condition and slopes between 25 and 50 percent as a hillside condition.
d. MDC Chapter 16.110 - Hillside. Land with an average rise or fall of twenty-five (25) percent or greater or a vertical rise of thirty (30) feet or more.
e. MDC Chapter 16.110 - Slope, Significant Natural. A slope that is not man-made that exceeds twenty-five (25) percent and a vertical rise of thirty (30) feet or more.
As noted above, an area qualifies as a “Hillside Area” if it meets or exceeds a 25 percent slope threshold, which determines its classification as a hillside condition. This 25 percent threshold is referenced five times in MDC Chapter 16.24 in relation to the application criteria that define a hillside condition.
Prior Direction
• During the 2022 City Priorities Workshop, staff received direction that the 25 percent criteria should apply versus the other described criteria in the MDC, and only to designated hillside areas depicted on a non-codified map.
• It was explained to staff by the Mayor and Council at the time of the Workshop it was never intended to apply on a citywide basis. However, the original ordinance’s administrative record contains no information. The lack of a clear standard has led to unequal application of the hillside standards.
• A potential recommendation to clarify the conflicting language would be to revise the definition in Section 16.24.020 and adopt the map (Attachment 5) within the Municipal Code to depict the areas to which the Hillside Overlay applies (Attachments 6 through 17 for detailed discussion).
Pros
• It has been noted five times as a baseline numeric percentage across Chapter 16.24 in comparison to the lone 20 percent association.
• A number of properties will remain for analysis under this condition for potential areas of hillside preservation/grading techniques as a baseline condition.
• Implementation of the 25 percent threshold still helps the City meet the City’s General Plan Goals and Objectives as relates to the preservation of hillside areas.
• This has been a main area of confusion versus the 20 percent/citywide thresholds.
• There could still be some cost for homeowners/project applicants versus having no standard.
• Adoption of a hillside map would resolve questions concerning the applicability of the hillside standards to a property
• By clearly defining and mapping the specific areas of where it applies, the result will be reducing potential confusion, streamlining the review process, and minimizing costs and delays for homeowners and project applicants.
Cons
• Adoption of a proposed hillside map utilizes a less precise methodology for measuring slope than the City’s current average slope formula, but still provides an effective tool for identifying hillside properties.
• If the hillside standards remain in effect citywide, and not to focused areas of the City, all projects would require slope analysis, which would increase costs on non-hillside development projects.
Key Policy Questions to Resolve Concerning Slope
Based on the background information from the MDC above, how should hillside slopes be defined and applied?
Should the hillside slope definition apply on a Citywide basis, or only to areas specified by an adopted hillside map?
Is there agreement that the 20 percent threshold for a hillside area seems to be an anomaly whereas the 25 percent criteria is more consistently referenced as criteria?
3. Specific Plans
At a previous workshop, a speaker suggested identifying the City’s Specific Plans in relation to the Hillside Area Overlay (Attachment 5). This could mean making properties within Specific Plans subject to the Hillside Ordinance. Alternatively, it could mean identifying Specific Plans on the Hillside Map in order to make clear that those areas are not subject to the Hillside Ordinance because hillside standard were addressed as part of the Specific Plan.
Pros
• Including Specific Plans within the Hillside Area Overlay, can provide further clarity on what standards apply.
Cons
• There might still be some confusion about what standards would apply at times.
• Making Specific Plan areas subject to the Hillside Ordinance risks overturning that were previously made within the context of a specific development area.
Recommendation
Staff agrees that mapping these Specific Plans alongside the overlay area would be the most effective approach for cross-referencing. To support this, staff recommends including a note in the draft ordinance directing users to consult the applicable Specific Plan for hillside development criteria. Staff recommends that Specific Plans are not subject to the Hillside Ordinance because hillside standards were already addressed during the Specific Plan process.
Key Policy Question To Resolve Concerning Specific Plans
Does the Council concur with the proposed approach to incorporate Specific Plans into the Hillside Overlay Exhibit Map, along with the corresponding cross-referencing framework?
Does Council concur that Specific Plans would supersede the general Hillside Ordinance if and when there are conflicting standards for Hillside Development?
4. Use Of Geographic Info. Systems (GIS) And Average Slope Formula
Geographic Information Systems (GIS)
GIS analyzes slope by using ground elevation data (such as Digital Elevation Models (DEMs)) to calculate slope at random points. It compares elevation changes across grid cells to create a slope map, showing steepness as a percentage. GIS enables rapid and visual slope analysis; however, its accuracy relies on the quality of elevation data.
Pros
• It provides efficiency in that large areas can be analyzed quickly.
• It provides objectivity in that it reduces subjective or manual slope calculations.
• It combines easily with other spatial data (e.g., soils, vegetation, zoning).
• It provides greater precision when evaluating a subject site, especially with the sourcing of high-resolution data that is available from software vendors in the GIS industry.
• City staff widely use GIS on a daily basis.
Cons
• Slope algorithms vary slightly between software platforms, which may produce different results for the same dataset.
• Interpolation errors may arise when converting contour data into GIS data, resulting in slope distortions.
• Parcel boundaries rarely align perfectly with raster grids, which can introduce data distortions at the edge of a parcel.
• Small or narrow parcels may contain too few raster cells to allow for meaningful slope analysis, particularly at coarser resolutions.
• A property that might be just over the threshold of being subject to the hillside standard would lose the benefit of the more precise average slope formula that potentially places the property’s slope under the threshold.
Alternative Option - Average Slope Formula in conjunction with the use of AutoCAD
MDC Chapter 16.24 currently has an Average Slope Formula for determining the slope at a subject property. It is a commonly used method across municipalities (local examples include the Cities of Riverside, Menifee, and Calimesa, and Riverside County) to quantify the overall steepness of a parcel of land. This measurement is critical for determining land suitability for development, enforcing hillside regulations, and managing environmental impacts.
The average slope formula is defined as follows:
16.24.030 “Definitions”
Pros
• It provides a simple and easy-to-calculate method using basic elevation and distance data.
• It provides a clear, single metric for comparing terrain steepness, especially if there is disagreement with the outcomes from a GIS analysis.
• Can be efficient for early planning, screening, or regulatory classification of sloped areas,
• AutoCAD and similar drafting programs are widely available and used by engineers and architects.
Cons
• Requires survey data from a process that may oversimplify terrain by masking local variations or steep sections.
• May not accurately represent irregular or complex topography.
• The results can vary depending on data resolution or calculation method.
Recommendation
As proposed, the use of Geographic Information Systems (GIS) mapping data is proposed to replace the traditional average slope calculation methodology. As presently proposed, in the event that there is a discrepancy or a dispute with how this information is documented, the City Engineer may permit an alternative method for demonstrating this information, such as a CAD-based program with the utilization of the Average Slope Formula.
Key Policy Question To Resolve Concerning Average Slope
Is there concurrence to use a City, GIS-generated slope map to replace the average slope formula approach, but allowing it to remain as an alternative?
Conclusion
In conclusion, by revisiting the original intent of these updates and carefully evaluating the best path forward, staff remains committed to developing clear, balanced, and practical standards for a future draft ordinance. These refinements are intended to support responsible hillside development that aligns with the City’s General Plan Goals and Policies, reflects community input, and facilitates a more efficient and transparent review process for all stakeholders.
The primary focus remains on revising development standards to make them clearer, more precise, and easier to apply at the project level for homeowners, project applicants, and staff. Simplifying the language and enhancing accuracy will help reduce confusion and streamline the review process, ultimately saving time and resources for homeowners and project applicants. These improvements are designed to create a more transparent and efficient system that benefits everyone involved.
At the same time, staff recognize the importance of recommending regulations that avoid placing undue burdens on homeowners and project applicants. The standards must strike a careful balance between protecting hillside areas while still enabling reasonable, achievable hillside development. This result would foster a responsible approach to the updates for responsible growth that respects existing environmental conditions while supporting the community’s long-term vision to manage development in hillside areas.
Once the Key Policy Questions pertaining to ordinance applicability are resolved, the next workshop will concentrate on an in-depth review of standards related to hillside development, such as retaining walls and landscaping requirements. It will also cover any outstanding issues that need further discussion or evaluation to ensure all matters are fully addressed prior to returning with an ordinance for adoption.
FISCAL IMPACT
None.
ATTACHMENTS
1. Planning Commission Ordinance Introduction Staff Report, June 28, 2023
2. City Council Workshop 1 Staff Report, August 15, 2023
3. City Council Workshop 2 Staff Report, March 5, 2024
4. City Council Workshop 3 Staff Report, June 17, 2025
5. Citywide - Hillside Overlay Map Exhibit - With Specific Plans
6. Focused 1 - Hillside - Los Alamos Hills Area 1
7. Focused 2 - Hillside - Los Alamos Hills Area 2
8. Focused 3 - Hillside - Los Alamos Hills Area 3
9. Focused 4 - Hillside - Greer Ranch Area 1
10. Focused 5 - Hillside - Greer Ranch Area 2
11. Focused 6 - Hillside - Greer Ranch Area 3
12. Focused 7 - Hillside - Greer Ranch Area 4
13. Focused 8 - Hillside - Murrieta Hills Area 1
14. Focused 9 - Hillside - Murrieta Hills Area 2
15. Focused 10 - Hillside - Bear Creek Area
16. Focused 11 - Hillside - Copper Canyon
17. Focused 12 - Hillside - Westside
18. Draft Ordinance - Title 16 - Strikeout-Underline
19. Correspondence - Prior to Workshop 3