Diamond Bar Town Center Specific Plan

4 Documents in Project


SCH Number
Lead Agency
City of Diamond Bar
Document Title
Diamond Bar Town Center Specific Plan
Document Type
NOP - Notice of Preparation of a Draft EIR
Present Land Use
The 45-acre Planning Area is designated by the Diamond Bar General Plan 2040 as Town Center Mixed Use. The Planning Area is zoned by the City as Regional Commercial (C-3), Community Commercial (C-2), and Neighborhood Commercial (C-1). Currently, the Planning Area has 510,000 square feet of existing commercial space comprised of retail, dining, and medical office, as well as 97 existing hotel rooms.
Document Description
The City of Diamond Bar (City), as the Lead Agency pursuant to the California Environmental Quality Act (CEQA), intends to prepare a Supplemental Environmental Impact Report (SIR) to the December 17, 2019, certified Diamond Bar General Plan Update (Diamond Bar General Plan 2040) and Climate Action Plan Program EIR (Certified EIR) (State Clearinghouse No. 2018051066), as amended on August 11, 2022, with adoption of the 2021-2029 Housing Element Update, for the proposed Diamond Bar Town Center Specific Plan (proposed project). The Diamond Bar General Plan 2040 established a new vision for a pedestrian-oriented “Town Center” that provided housing opportunities, food-oriented retail, restaurants, and entertainment. The proposed Specific Plan would guide the development of the Diamond Bar Town Center, implementing the goals and policies related to reestablishing the Town Center as a mixed-use civic area promoting walkability, through the planning horizon of the Diamond Bar General Plan 2040. A General Plan Amendment and a Zoning Amendment would be required to increase the maximum density and floor area ratio (FAR) allowed within the Specific Plan’s Planning Area to allow the Specific Plan’s proposed density, to establish development and design standards for development within the Planning Area, and to rezone the Planning Area parcels for the Specific Plan’s proposed uses. An SIR is needed to address changes to the Town Center not discussed in the certified EIR to evaluate the degree to which there would be any new significant impacts or substantially more adverse impacts caused by adoption of the Diamond Bar Town Center Specific Plan than have already been evaluated in the certified EIR. In accordance with §15082 of the State CEQA Guidelines, the City has prepared this Notice of Preparation (NOP) to provide Responsible Agencies and other interested parties with information describing the proposed project and to identify its potential environmental effects pursuant to State requirements. The NOP and related documents can be reviewed on the City website at: www.diamondbarca.gov/towncenter. The Specific Plan would serve as both a policy and regulatory document to guide the transformation of the Town Center area from a nondescript suburban-style neighborhood commercial area into a vibrant, pedestrian-oriented, mixed-use district that serves the community, adding to the identity and quality of life in Diamond Bar. The Specific Plan involves the phased redevelopment of approximately 45 acres of existing suburban-style retail shopping centers along Diamond Bar Boulevard between Golden Springs Drive and the SR-60 overpass. The Specific Plan would have a maximum buildout of: • 2,055 housing units (805 more units than adopted General Plan; 2,055 more units than existing land use); • 150 hotel rooms (53 more hotel rooms than existing land use); • 40,000 square feet of public open space (40,000 square feet more open space than existing land use); and • 415,000 square feet of commercial space including retail, dining, entertainment, office, community, and cultural uses (95,000 square feet less commercial space than existing land use). The actual rate and amount of development as a result of the Specific Plan may differ but would be within the maximum allowed. Actual buildout of the Specific Plan would involve the development of new roads within the Planning Area in addition to the development associated with housing, hotels, and commercial space. The proposed Specific Plan also includes supporting infrastructure through the adoption of the Specific Plan and associated entitlements. As part of the infrastructure improvements, the Specific Plan would implement a “road diet” to narrow Diamond Bar Boulevard by decreasing lane widths from an existing 12-foot width to 11 feet for travel lanes and 10 feet for left turn pockets. The changes to Diamond Bar Boulevard would also remove the right lane in each direction to create right turn pockets and add a protected bike lane. The Specific Plan proposes to reduce the number of through lanes on Diamond Bar Boulevard between Gentle Springs Lane / Palomino Drive and Golden Springs Drive. This road diet would eliminate one through lane in each direction (from three to two), remove the center median, and narrow the remaining lanes. The direct benefits of a road diet include shorter pedestrian crossing distances and more space on the existing public right-of-way for alternative use such as bicycle lanes, wider sidewalks, bus turnouts, and additional landscaping. The SIR will address potential impacts of the proposed road diet.

Contact Information

Grace S. Lee
Agency Name
City of Diamond Bar
Job Title
Senior Planner
Contact Types
Lead/Public Agency


Diamond Bar
Los Angeles
Southern California
Cross Streets
Diamond Bar Boulevard and Golden Springs Drive
Total Acres
Parcel #
See NOC Attachment 1.A
State Highways
60, 57
Metrolink Riverside Line
See NOC Attachment 1.B
San Jose Creek, Diamond Bar Creek
San Bern

Notice of Completion

State Review Period Start
State Review Period End
State Reviewing Agencies
California Air Resources Board (ARB), California Department of Conservation (DOC), California Department of Fish and Wildlife, South Coast Region 5 (CDFW), California Department of Forestry and Fire Protection (CAL FIRE), California Department of Housing and Community Development (HCD), California Department of Parks and Recreation, California Department of Transportation, District 7 (DOT), California Department of Water Resources (DWR), California Highway Patrol (CHP), California Natural Resources Agency, California Public Utilities Commission (CPUC), California Regional Water Quality Control Board, Los Angeles Region 4 (RWQCB), Department of Toxic Substances Control, Office of Historic Preservation, San Gabriel and Lower Los Angeles Rivers and Mountains Conservancy (RMC), State Water Resources Control Board, Division of Drinking Water, State Water Resources Control Board, Division of Drinking Water, District 7, California Native American Heritage Commission (NAHC)
State Reviewing Agency Comments
California Native American Heritage Commission (NAHC)
Development Types
Residential (Residential on 34 acres minus acreage for 150 hotel rooms)(Units 2055, Acres 34), Recreational (40,000 square feet of public open space), Other (415000 SF commercial retail, dining, office, ent, comm, cultural)
Local Actions
General Plan Amendment, Specific Plan, Rezone
Project Issues
Aesthetics, Agriculture and Forestry Resources, Air Quality, Biological Resources, Cultural Resources, Cumulative Effects, Drainage/Absorption, Energy, Flood Plain/Flooding, Geology/Soils, Greenhouse Gas Emissions, Growth Inducement, Hazards & Hazardous Materials, Hydrology/Water Quality, Land Use/Planning, Mandatory Findings of Significance, Mineral Resources, Noise, Population/Housing, Public Services, Recreation, Schools/Universities, Septic System, Sewer Capacity, Solid Waste, Transportation, Tribal Cultural Resources, Utilities/Service Systems, Vegetation, Wetland/Riparian, Wildfire
Local Review Period Start
Local Review Period End


Draft Environmental Document [Draft IS, NOI_NOA_Public notices, OPR Summary Form, Appx,]
State Comment Letters [Comments from state reviewing agencies]

Disclaimer: The Governor’s Office of Planning and Research (OPR) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. You may also contact the OPR via email at state.clearinghouse@opr.ca.gov or via phone at (916) 445-0613. For more information, please visit OPR’s Accessibility Site.

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