June 23, 2026
Via Email:
Citycouncil@cityofsanmateo.org
planningcommission@cityofsanmateo.org
zoningupdate@cityofsanmateo.org
Subject: Key Issues for Comprehensive Zoning Code Update
Dear Mayor Loraine and Members of the San Mateo City Council, Planning Commission and City Staff,
The Sierra Club Loma Prieta Chapter's Sustainable Land Use Committee (SLU) advocates on land use issues in San Mateo and Santa Clara Counties.
SLU offers the comments below as an overview of some key issues that we believe need to be addressed in the Comprehensive Zoning Code Update (CZCU). We appreciate the White Papers as a strong starting point for the Comprehensive Zoning Code Update (CZCU). Below are our recommendations to help guide the update process.
Housing Production Emphasis needed, with a Strong Emphasis on Affordable Housing
The Comprehensive Zoning Code Update (CZCU) should prioritize housing production over new commercial office development, with particular emphasis on expanding affordable and workforce housing. As noted in the February 23, 2026 Staff Report, the CZCU is intended to modernize the City's Zoning Code and incorporate current best practices. It should also simplify the development of new housing by reducing unnecessary costs and delays while maintaining appropriate environmental review, public safety protections, and input from residents, whenever possible.
Prioritize Affordable Housing
Expanding affordable housing and preventing displacement should be among the highest priorities of the CZCU. Affordable housing has consistently been the most difficult housing type to produce, as reflected in the City's failure to meet affordable housing goals, while market-rate housing targets have generally been achieved. Most recent residential development has focused on market-rate as well as luxury housing, thereby contributing to rising housing costs, gentrification, and the displacement of lower- and moderate-income residents.
To increase the supply of affordable housing, the City should provide special additional incentives for 100% affordable housing projects and projects with a higher percentage of affordable units, including the following:Making publicly-owned land available at reduced or no cost,
Actively acquiring existing apartment buildings for preservation or conversion to permanently affordable housing,
Protecting existing affordable housing from demolition or conversion,
Reducing or waiving development fees, and
Providing expedited review and approval processes.
These improvements should result in more affordable housing being approved and built.
Comments on “Building Heights” White Paper
Use building height strategically to increase open space.The CZCU should encourage the strategic use of building height to create more meaningful open space at the ground level. In appropriate locations, allowing increases in building height—without increasing overall development density—can reduce a building's footprint and preserve larger areas for parks, landscaping, tree canopy, habitat, and other common open spaces.
The City should consider offering incentives for projects to exceed minimum open space requirements. Potential incentives could include modest height flexibility, reduced setbacks where appropriate, or other development bonuses in exchange for publicly accessible parks, greenways, trails, urban forests, natural habitat areas, or other high-quality green infrastructure.
Comments on “Open Space” White Paper
The policy paper should begin with a clear statement of why people in urban areas need open space. It is important to note that the benefits of nature and living plants extend well beyond just space for recreation or gathering places for people. Urban parks and green spaces—with living plants and open sky—are vital for public health, mental well-being, and environmental health.
A. Improve Terminology
The term Open Space is currently used too broadly, combining two fundamentally different land use categories. The CZCU should clearly distinguish between areas intended for public recreation and those intended primarily for habitat protection and conservation. The definitions should differentiate:
- Human-centered open spaces: Parks, plazas, urban green spaces, and other areas designed primarily for public recreation and community use. Maybe use “Recreational Open Spaces”
- Natural conservation areas: Habitat lands, limited-access conservation areas, and permanently protected open space, such as Sugarloaf Open Space, that are managed primarily for ecological preservation rather than recreation. Maybe use “Natural Open Spaces”
Making this distinction will provide greater clarity, improve land use planning, and help ensure that environmentally sensitive areas are managed and protected according to their conservation purpose.
B. Recognize Parks and Natural Open Space as Ecological Infrastructure
The CZCU should recognize parks and natural open space not only as places for recreation, but also as essential ecological infrastructure that provides critical environmental services. These areas support biodiversity, improve climate resilience, enhance public health, and preserve natural ecosystems.
The City's policies should distinguish between recreational parks and open space designated primarily for habitat conservation and environmental protection. Open space should not be defined solely as land intended for public access or active recreation. Protected natural areas that are not intended for human use provide significant public benefits, including the following:
Wildlife habitat and biodiversity conservation,
Air quality improvement and carbon sequestration,
Stormwater retention and groundwater recharge,
Reduced runoff and flooding,
Noise attenuation,
Wind protection,
Privacy screening, and
Climate resilience and urban heat reduction.
Examples include habitat preserves, vegetated freeway buffers, green corridors, riparian areas, street tree corridors, wildlife movement corridors, and landscaped buffers between buildings and major transportation corridors. Wide vegetated buffers of mature trees and native vegetation can substantially reduce air pollution, mitigate traffic noise, capture stormwater, provide windbreaks, and support wildlife, even where public access is neither practical nor appropriate.
The CZCU should therefore recognize these natural landscapes as critical infrastructure deserving long-term protection and enhancement, rather than evaluating them solely for their recreational value.
To further strengthen the City's green infrastructure network, the CZCU should incorporate the principles outlined in the Sierra Club Sustainable Land Use Committee's Guidelines for a Sustainable Green Street Network, which explains how best to create a connected system of safe, slow, tree-lined streets that prioritize pedestrians and bicyclists while expanding urban canopy, habitat connectivity, and climate resilience.
C. Emphasize the Urban Forest as a critical aspect of the City’s Open Space
The CZCU should recognize the urban forest as a fundamental component of the City's open space and green infrastructure network. Livability comes not from empty land, but from trees, vegetation and biodiversity within it. For example, Detroit has abundant vacant land, however, Barcelona, which is much denser, is richer in street trees, greenery and livability.
Existing stands of mature trees and native vegetation are invaluable community assets that contribute significantly to the urban canopy and biodiversity. They should be preserved through stronger tree protection and landscape conservation ordinances that minimize unnecessary removal during development and promote long-term biodiversity. Urban forests provide the following:
Shade and urban heat reduction,
Improved air quality and carbon sequestration,
Stormwater capture and groundwater recharge,
Reduced runoff and flooding,
Wildlife habitat and biodiversity,
More attractive, walkable streetscapes, and
Improved public health, comfort, and quality of life.
D. Increase Parks as Density Grows and Population Increases
As the City plans more housing and higher density, it must also simultaneously significantly increase parks and public open space. Creative solutions should also be explored, to improve livability, including: Green Streets, Green Corridors, Pocket green parks, Rooftop and podium green space, Linear parks and trail connections
Comments on White Paper “Setbacks and Buffers”
There is much good information in this white paper. We have only a few observations.
A. Setbacks should be designed to create usable green space, tree planting zones, and visual buffers rather than leftover paved strips. With more high density housing required to meet RHNA targets and to meet the housing deficit, including green open space is increasingly important for quality of life in a dense urban context.
See Sierra Club Loma Prieta’s Guidelines for Open Space for High Density Housing for some important suggestions on this topic.
B. The CZCU should seek to provide incentives to encourage more off-street parking and this is noted in the Staff Report of June 9, 2026. The ideas listed in the Staff Report regarding Tandem Parking, Parking in Required Setbacks and Parking Exempt from FAR Calculation are good concepts to consider as well as other ideas that may meet the objective of encouraging off-street parking. In addition, since currently each single family site is allowed to support up to six dwellings (SB-9 plus ADUs) and recent code changes allow some enclosed garages to convert to living space for ADUs, additional parking space is needed.. Encouraging more off-street parking will allow more use of the public right-of-way for future safe bike lanes, improved pedestrian access, etc. See Guidelines for a Sustainable Green Street Network.
C. Balconies or decks should, if possible, not overhang required open space. Open space loses value when covered by another deck or roof, though resulting rain protection has some value. Alternating left-right balcony placement can reduce shading. Similar standards should apply to commercial office developments.
15-Minute Neighborhood Strategy in White Paper
Consider a citywide planning approach based on the 15-minute neighborhood concept. Areas that are more than a half mile from transit should be evaluated for neighborhood nodes with the following possibilities:
Mixed-use buildings. Ground-floor commercial, or other uses, with housing above.
Small-scale retail,
Cafés and seating
Secure package lockers e.g. Amazon,
Mailboxes,
Shared EV charging,
Spaces for Car-share,
Autonomous taxi parking zones, and
“Missing Middle” housing: allow 3-story buildings, at nodes, in 2-story neighborhoods.
A network of neighborhood centers can reduce vehicle trips and greenhouse gas emissions, improve access to everyday goods and services, encourage walking and bicycling, strengthen neighborhood identity, and support future transit expansion. The CZCU should provide zoning flexibility and development incentives to encourage the creation of these complete, walkable neighborhoods while respecting the scale and character of adjacent residential areas.
Climate Resilience, Sea Level Rise and Associated Ground Water Rise
Consider a Sea Level Rise Overlay Zone
Sea level rise adaptation should be integrated into the CZCU and General Plan. Applicable areas could require higher finished floor elevations, flood-resilient site design and consideration of groundwater rise. The Bay edge may be suitable for nature-based adaptation measures offering near-term flood reduction, lower long-term costs and greater resilience benefits.
The overlay zone could include areas directly impacted by SLR as well as related impacts like creeks backing up with higher tides and causing flooding. It could also include a timeline for capital outlays to raise roads and, especially, utilities out of corrosive rising brackish ground water.
The Health and Safety Element of the General Plan may also need modification to recognize the impacts of flooded infrastructure and other health and safety impacts of flooding from rising sea levels and ground water levels.
Biological Safety Levels (BSL)
In office, commercial, manufacturing, life science, and similar zoning districts, only Biosafety Level 1 (BSL-1) and Biosafety Level 2 (BSL-2) laboratories should be permitted. Higher-risk laboratory operations should be prohibited in these areas due to the potential for biological accidents, including the potential for exposure to unknown viruses or other infectious disease agents. For additional public safety protection, zoning standards should also require appropriate setbacks from residential uses, schools, childcare facilities, and other sensitive receptors.
The City of San Carlos has already adopted this approach by limiting life science facilities to BSL-1 and BSL-2 laboratories.
The City of Redwood City takes a further step in its Downtown Precise Plan (DPP) area, which includes high-density mixed-use development. There, BSL-1 and BSL-2 laboratories are allowed only as conditional uses, enabling additional review of health, safety, and nuisance impacts associated with laboratories operating in close proximity to 24-hour residential and commercial uses.
Based on these precedents, we recommend that life science and laboratory zoning be limited to BSL-1 and BSL-2 facilities, consistent with the San Carlos ordinance. In addition, Redwood City’s conditional-use framework should be considered as a model for mixed-use areas to ensure appropriate oversight and safeguards where laboratories are located near sensitive uses.
We recommend that in the zoning for Life Sciences and Laboratories, safety levels be restricted to BSL-1 and BSL-2 as in the San Carlos ordinance1. Redwood City’s more detailed conditional use ordinance for BSL-1 and BSL-22 should be considered for Mixed-Use zones.
SLU looks forward to further discussions with you on the CZCU.
Respectfully,
Gita Dev, FAIA, Chair, Sustainable Land Use Committee
Chair, Conservation Committee
Sierra Club Loma Prieta Chapter
Cc: James Eggers, Chapter Director, Sierra Club Loma Prieta Chapter
1 See San Carlos Code Chapter 18.07 INDUSTRIAL DISTRICTS Table 18.07.020: Land Use Regulations- Industrial Districts
2 Redwood City Downtown Precise Plan Section 2.2.4. Use Permit Process