Portola Valley, CA
Home MenuPopular Searches
Geologic & Ground Movement Potential Maps
The Town's geologic maps (links below) have been prepared by the Town based on the study of aerial photographs, field investigations, and other available geologic studies. These maps portray geologic conditions with considerable accuracy. Given this level of data, the Town Council found it appropriate to adopt these maps as policy, to have them serve as guidelines for administering the affairs of the Town and to modify them from time to time as better information becomes available.
It is the Town Council's intention that these maps and related land use policies be employed as guides in all Town decisions to which they are relevant and shall be adhered to unless modifications to the geologic maps or deviations are permitted.
For questions, please contact the Town's Planning Department by sending an email to planning@portolavalley.net
- Geologic Map (5.1MB PDF, approved by Town Council on November 8, 2017)
- Ground Movement Potential Map (6.6MB PDF, approved by Town Council on November 8, 2017)
Resolution No. 2746-2017 - Land Use Policies for Lands Shown on Said Maps
Map Amendments
Since 2017, the Town Planning Commission has approved amendments to the maps as part of planning and building permit reviews. The List below includes the File Number for each Geologic Map Modification (GMM) Project, the Assessor's Parcel Number (APN) associated with each GMM, the address associated with each GMM, and the Planning Commission Resolution number associated with each GMM.
| File Number | APN | Address |
Planning Commission Resolution Number |
| PLN_GMM0003-2017 | 77080360 | 380 Escobar Drive | 2018-11 |
| PLN_GMM0002-2017 | 76237020 | 171 Trinity Lane | 2017-08 |
| PLN_GMM0001-2017 | 79092150 | 30 Holden Court | 2017-14 |
| PLN_GMM0002-2018 | 77273010 | 207 Westridge Drive | 2019-03 |
| PLN_GMM0001-2022 | 79021020 | 350 Grove Drive | 2022-02 |
| PLN_GMM0001-2021 | 79030150 | 214 Grove Drive | 2021-10 |
| PLN_GMM0001-2018 | 80020080 | 5577 Alpine Road | 2018-05 |
| PLN_GMM0001-2025 | 77212160 | 145 Deer Meadow Lane | 2025-05 |
| PLN_GMM0001-2020 | 77011120 | 195 Ramoso Road | 2021-14 |
The public may access the Town Records including the Planning Commission Resolutions for each GMM Project for more information. This information is very valuable for the public and property owners when they consider purchasing properties or construction on these properties.
The Town Planning Division staff is working on creating updated map files that include these amendments. We will post them when available in approximately Summer 2026.
Development and Permitting Requirements
The Town has requirements for geologic review of permit applications. Please review the requirements and contact the Planning or Building Divisions for assistance.