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Ordinance No. _____
Ordinance of the Council of the City of Palo Alto Repealing and Replacing Section 18.40.140 (Stream Corridor Protection and Review) of the Palo Alto Municipal Code
SECTION 1. Findings and Declarations. The City Council of the City of Palo Alto finds and declares as follows:
A. On November 13, 2017, the City Council adopted the 2030 Comprehensive Plan, which recognizes the value of its creeks and riparian areas for habitat, connectivity, design, and flood control. Specifically, Policy N3.3 aims to mitigate development impacts on creeks by establishing setback requirements and preserving their function as habitat corridors.
B. On March 5, 2024, a virtual Community Information Session was conducted to inform residents about proposed updates to the stream protection ordinance and to receive feedback from the community.
C. On April 4, 2024, an informational report was prepared to inform the Architectural Review Board about the ordinance update effort.
D. On August 14, 2024, the Planning and TransportaƟon Commission conducted a study session and provided feedback and direcƟon in preparing for the draŌ ordinance.
E. On October 9, 2024, the Planning and TransportaƟon Commission reviewed a draŌ ordinance and provided comments.
F. On February 6, 2025, a hybrid Community Workshop was conducted to solicit community feedback on the draŌ ordinance.
G. On August 27, 2025, the Planning and TransportaƟon Commission reviewed a draŌ ordinance and provided feedback but conƟnued the discussion to a date uncertain.
H. On May 13, 2026, the Planning and TransportaƟon Commission recommended that the City Council adopt the draŌ ordinance.
I. The updated Stream Corridor ProtecƟon Ordinance intends to preserve and strengthen riparian resources, protect improvements from damage caused by potenƟal stream flooding and bank erosion, and minimize storm water polluƟon. ***Not Yet Adopted***
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J. The updated Stream Corridor ProtecƟon Ordinance provides a balance between development and conservaƟon by establishing varying streamside setback distances for different areas of the City.
SECTION 2. Section 18.40.140 (Stream Corridor Protection and Review) of Chapter
18.40 (General Standards and Exceptions) of Title 18 (Zoning) of the Palo Alto Municipal Code is repealed in its entirety and replaced as follows:
18.40.140 Stream Corridor Protection and Review
(a) Purpose. The purpose of the natural resources protection measures specified below is to preserve and strengthen water and riparian resources, protect improvements from damage caused by potential stream flooding and bank erosion, and minimize storm water pollution. (b) Definitions. Whenever the following terms are used in this chapter, they shall have the meaning established by this section:
(1) “Bank” means any embankment, dike, levee, wall or similar feature of natural or manmade origin which adjoins or parallels any watercourse, and which has as a function the confinement of the water of said watercourse.
(2) “Baylands Area” means the area within the City Limits that is east of Highway 101. (3) “Central Area” means the area within the City Limits that is between Foothill Expressway and Highway 101.
(4) “Fence” means an artificially constructed barrier or wall of any material or combination of materials erected to physically separate properties, provide privacy, or provide security or confinement.
(5) “Fence, Wildlife-Friendly” means a fence that allows for safe passage of wildlife over or under the fence and is visible especially to hooved animals and birds, meeting all of the following specifications:
(A) Distance from ground to top of fence shall not exceed 40 inches (total fence height);
(B) The distance from the ground to the bottom of the fence shall be at least 18 inches;
(C) Fence posts shall be spaced at intervals of no less than 8 feet; (D) Fences shall be constructed with a solid top rail (such as wooden or vinyl plank or metal bar) for visibility and to prevent entanglement; and (E) Fences shall have at least one gate which can be opened in the event an animal becomes trapped and needs to be released.
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(6) “Floodwall” means an artificial barrier that extends above the top of bank, usually made of concrete, that is designed to increase the capacity of a creek to contain water during high flow events and prevent flooding.
(7) “Hillside Area” means “the area within the City Limits that is west of Foothill Expressway.
(8) “Qualified Biologist” means a professional who possesses at minimum a relevant college bachelor’s degree and the appropriate education, training, and at least two years of relevant work experience to expertly evaluate project impacts on living organisms and biological resources. This individual must have demonstrated regional expertise and the practical capacity to conduct biological surveys, monitor project activities, provide environmental education to construction personnel, and prepare regulatory compliance documents like CEQA reports.
(9) “Riparian Vegetation” means native plant life that occurs in and/or adjacent to watercourses, typically growing on or in the vicinity of the banks, in soils that exhibit wetness characteristics during part of the growing season. This vegetation is structurally or floristically distinct from nearby, non-streamside plant communities and relies on riparian water sources for soil moisture levels greater than what is available through local precipitation alone.
(10) “Riparian Vegetation, Woody” means vegetation that are distinguished from herbaceous vegetation by the presence of “tough, fibrous stems and branches covered with bark,” such as trees, shrubs, and vines.
(11) “Service Road” means roads that limit general public access, primarily designed and used to provide personnel and equipment from public agencies like Santa Clara Valley Water District with access to their facilities for operation, maintenance, and repair. (12) “Slope Stability Protection Area" means the area where development is generally prohibited, to preserve riparian vegetation, strengthen the streamside ecosystem, and protect against bank instability. The slope stability protection area shall extend to a point measured at the rise over run ratio of 1:2 landward from the toe of the bank, but no less than the following distance from the top of the bank:
(A) 20 feet for Central Area, or
(B) 25 feet for Baylands Area and Hillside Areas.
(13) “Stream” means any number of natural watercourses flowing from the hill areas to San Francisco Bay in which water flows at least periodically or intermittently through a bed or channel having banks; usually characterized by a distinct channel and a band of dense vegetation along the banks. This may include watercourses having a surface or subsurface flow that supports or has supported riparian vegetation, fish and/or aquatic life.
The presence of a stream is determined by one or more of the following criteria:
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(A) As designated by the City of Palo Alto as shown on maps maintained by the City; (B) As designated by a solid line or dash and three dots symbol on the largest scale of the USGS maps most recently published or any replacement to that symbol; (C) As designated by the Santa Clara Valley Water District as shown on maps maintained by the District;
(D) As designated on the most recent maps maintained by Santa Clara County; (E) As determined by a survey of the property by a licensed land surveyor; or (F) On a site plan which may be required by a permitting agency using the Criteria to Verify or Identify a Watercourse as a Stream set forth in the Santa Clara Valley Water Resources Protection Collaborative User Manual Guidelines and Standards for Land Uses Near Streams, or criteria set forth by the permitting agencies. (14) “Stream, Channelized” means a stream or portion of a stream whose course has been intentionally altered, usually straightened or enlarged for the purposes of storm runoff control, flood control, or ease of navigation. Alterations may include widening, deepening, straightening, or lining the channel with materials like concrete. (15) “Streamside Setback” means the area measured from top of bank in which the siting of structures, impervious surfaces, outdoor activity areas, and landscaped areas is regulated by this Section.
(16) “Toe of Bank” (Figures 1 and 2) means the point in a channel where the slope of the bank meets the streambed.
(17) “Top of Bank” (Figures 1 and 2) means a stream channel boundary, which is determined as follows:
(A) "Stream with Defined Bank.” Top of bank is the line connecting all the points where there is substantial grade change between the stream bank and the adjacent land, as determined by a qualified biologist or otherwise determined by the Director. For channelized streams, where a fully engineered channel exists, the top of the bank is defined as the highest edge of that channel. (B) “Stream without Defined Bank.” Where there is no defined bank and the slope from the streambed is less than the rise over run ratio of 1:2, top of bank is considered the one-hundred-year water surface elevation calculated by a qualified hydrologist or hydraulics engineer.
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FIGURE 1: TOP OF BANK, STREAM WITH DEFINED BANK
FIGURE 2: TOP OF BANK, STREAM WITHOUT DEFINED BANK
(18) “Wall, Retaining” means a structural wall designed to hold in place a mass of soil so that it can be retained at different levels on each side of the wall, and/or restrain a slope.
(c) Applicability. The following types of developments are subject to this Section:
(1) Development in all zoning districts except the R-1, R-2, and RMD districts. (2) Development in the R-1, R-2, or RMD zoning districts that:
(A) Requires discretionary planning approval (including, but not limited to Single Family Individual Review, Home Improvement Exceptions, and Conditional Use Permits); or (B) Proposes to locate closer to a stream than the existing condition. ***Not Yet Adopted***
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(d) Exemptions. Notwithstanding subsection (b), the following projects are exempt from this Section, except that they shall remain subject to the slope stability protection area requirements in subsection (g):
(1) Interior construction or alterations;
(2) Retaining walls less than three feet in height that are located outside of the Slope Stability Protection Area;
(3) Less than 3 cubic yards of earthwork associated with: (i) landscaping with riparian vegetation that is native to the region or (ii) remedial stream bank stability work deemed necessary by the Director of Public Works;
(4) Replacement of utility service laterals where location outside the protected areas is not available;
(5) Accessory Dwelling Units (ADUs) or Junior Accessory Dwelling Units (JADUs) pursuant to Chapter 18.09. ADUs and JADUs may be constructed within the Slope Stability Protection Area without seeking an exception under Section 18.40.140(h)(2); (6) Projects located in the Central Area on properties separated from the stream by a public or private street, alley, paved public trail, or paved service road; (7) Any properties that are directly abutting floodwalls that were installed or maintained by regional agencies like the Santa Clara Valley Water District, or; (8) Any single-family properties adjacent to San Francisquito Creek and fronting on Edgewood Drive. These properties shall be allowed to install fences and ornamental ***Not Yet Adopted***
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landscaping within the Slope Stability Protection Area without seeking an exception under Section 18.40.140(h)(2).
(e) Streamside Setback. The Streamside Setback distances are outlined in Table 1 as measured from top of bank.
Table 1: Streamside Setback
Central Area 25 feet(1)
Hillside Area(2) 150 feet(1)
Baylands Area 150 feet(1)
(1) Applicable properƟes must comply with both the streamside setback and the Slope Stability ProtecƟon Area requirements (see SecƟons 18.40.140(b) and (g)). Where the required Slope Stability ProtecƟon Area distance exceeds the streamside setback, the greater distance shall govern. (2) Within the Hillside Area, properƟes zoned RE (Real Estate) shall be allowed to apply the Streamside Setback of the Central Area.
(f) Streamside Setback Requirements. Unless otherwise required under Section 18.40.140(g), the following requirements shall be applicable within the Streamside Setback areas:
(1) Vegetation
(A) The following vegetation shall be allowed:
(i) Native riparian vegetation.
(ii) Non-riparian or non-native vegetation, provided that such species are:
(I) non-invasive;
(II) located on the structure side of any existing or future fencing (away from the stream); and
(III) irrigated in a manner that will not adversely affect mature oaks and other woody riparian vegetation within the setback area. (B) The following vegetation shall be prohibited:
(i) Invasive species
(ii) Prohibited plant material as listed in the Santa Clara Valley Water Resources Protection Collaborative's User Manual Guidelines and Standards for Land Uses Near Streams.
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(iii) Other species that are deemed detrimental to the area by the City. (C) Existing Riparian Vegetation, including Woody Riparian Vegetation, shall be retained to the maximum extent possible. Replacement of Riparian Vegetation shall be required if removal was approved by the Director.
(D) For any trees removed, replacement with native riparian trees shall be required following the replacement ratio pursuant to Chapter 8.10. (E) The following requirements shall be applied to the soil area:
(i) No synthetic cover or fill shall be allowed and shall not be covered with synthetic cover or fill, including but not limited to plastic (nylon, polypropylene or polyethylene, rubber) and ground cover such as artificial turf or weed barriers.
(ii) Irrigation systems shall be designed to prevent soil erosion. (iii) For irrigation systems within outboard stream bank slope, it must be bubbler or drip-type systems and used for establishment purposes only. (2) Fences.
(A) New fences in the Streamside Setback shall conform to Chapter 16.24. (B) Within the Hillside Area and the Baylands Area, only Wildlife-Friendly Fences shall be permitted within the Streamside Setback area.
(3) Structures and improvements.
(A) No new Buildings, Structures, or similar improvements (excluding fences) shall be permitted in the Streamside Setback without an exception pursuant to Section
18.40.140(h)(1).
(B) No more than 25 percent of the Streamside Setback area or 2,500 square feet, whichever is less, of impermeable paving or surface shall be allowed. (C) Loading docks, trash enclosures, chemical storage areas, stationary noise-producing mechanical equipment, septic tanks, and leach fields shall be located a minimum of 50 feet from the top of bank.
(4) All permitted improvements shall be constructed in a manner consistent with the current version of the Santa Clara Valley Water Resources Protection Collaborative User Manual Guidelines and Standards for Land Uses Near Streams. (g) Slope Stability Protection Area Requirements. In addition to the requirements under
18.40.140(f), the following requirements shall be required within the Slope Stability Protection Area:
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(1) Only native riparian vegetation shall be allowed.
(2) No new ornamental landscaping shall be permitted.
(3) No new Buildings or Structures, including but not limited to, fences; decks of any height; swimming pools, spas, sports courts, and hot tubs; and parking lots or impermeable paving, shall be allowed unless an exception is granted by the Director of Public Works pursuant to 18.40.140(h)(2).
(h) Exception Requests
(1) General Findings. Applicants requesting an exception from a required Streamside Setback must submit documentation supporting all of the following findings:
(A) A qualified biologist has prepared an environmental assessment that identifies any Riparian Vegetation, including Woody Riparian Vegetation, affected by the project, delineates habitat and work limits, and prescribes avoidance/minimization measures and, if necessary, compensatory mitigation; and
(B) There is no physically or legally feasible alternative for the proposed project configuration that completely avoids or minimizes the encroachment into the setback area.
(2) Slope Stability Protection Area Exceptions. No structures are permitted within the Slope Stability Protection area unless an exception is granted by the Director of Public Works. (A) The applicant must provide a geotechnical slope stability analysis demonstrating that maintenance and repair of the stream could be provided with the proposed development in place, and at least one of the following:
(i) The proposed development would not threaten the stability of the streambank slope; or
(ii) The proposed development includes the introduction of hardscape to maintain the streambank slope; or
(iii) The proposed development would not be at risk of damage from future bank instability or erosion.
(B) The exception shall be subject to compliance with the following requirements:
(i) New fences shall be constructed with a minimum of five feet landward from the top of bank.
(ii) Loading docks, trash enclosures, chemical storage areas, and stationary noiseproducing mechanical equipment shall be located a minimum of 50 feet from the top of bank of a stream, provided that the Director may allow equipment closer than 50 feet where site conditions or other setback requirements make strict compliance not possible; the Director shall not allow noise-producing (50 ***Not Yet Adopted***
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dBA or greater) equipment closer than 50 feet unless located within an enclosure to reduce noise impacts.
(iii) All permitted improvements shall be constructed in a manner consistent with the current version of the Santa Clara Valley Water Resources Protection Collaborative User Manual Guidelines and Standards for Land Uses Near Streams.
(3) Exception Review Process. Notwithstanding Section 18.77.075(a), exception requests shall follow the review process set forth in 18.77.075. If the request is combined with another permit application that requires a greater level of review than the procedures described in Section 18.77.075, the exception request will be reviewed in accordance with the process for review of the other permit application(s). (i) Capital Improvement Programs or other Projects Performed by Public Agencies. (1) Capital Improvement Programs or any other projects performed by the City or other public agencies, including but not limited to Cities of Menlo Park or East Palo Alto, San Mateo County Flood and Sea Level Rise District, Santa Clara Valley Water District, Midpeninsula Regional Open Space District, Caltrain, and California Department of Transportation (Caltrans), shall comply with the requirements of this Section to the extent feasible. The Director may grant adjustments or exemption to any applicable requirements for such facilities if the adjustment is necessary for the efficient operation, maintenance, or safety of the facility, or to ensure public safety and security; and is consistent with the overall intent and purpose of this Section. A written request for an adjustment or exemption, including supporting documentation, shall be submitted and shall be reviewed according to the applicable review procedures in Chapter 18.77 associated with the proposed development.
(2) Routine maintenance in accordance with regulatory permits and done within the creek as part of repair or restoration in advance of or following storms events shall be exempted from the requirements of this Section.
(j) Non-complying Facilities. Any facilities, including fences, rendered legal and nonconforming or non-complying by this Section shall be subject to Chapter 18.70, which covers requirements for maintenance, repair, and replacement. (k) Lot Measurement Along Watercourses. No portion of a lot which is located within the easement lines, or top of the banks in the event such easement lines cannot be ascertained, of any natural watercourse, river, stream, creek, waterway, channel, or flood-control easement or drainage easement shall be included in the determination of lot area and lot dimensions. In the case of any such lot which is bounded, in whole or in part, by any such natural watercourse, river, stream, creek, waterway, channel, or flood-control easement or drainage easement, for those portions of the lot so bounded, all measurements and dimensions specified by this title and related to or determined from lot lines shall be measured from said easement line, or top of the bank, of such watercourse. Provided the ***Not Yet Adopted***
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expansion of an existing easement over a lot adjacent to San Francisquito Creek and fronting on Edgewood Drive in favor of the Santa Clara Valley Water District (or its successor in interest) on or after January 1, 2002 shall not alter the calculation of lot area. Lot area, lot dimensions, and setbacks shall be calculated for such lots as if the post-January 1, 2002 easement had not been created. Lot area shall be defined per 18.04.030 (85). (l) Additional Provisions and Conflict Precedence. Other requirements applicable to development near streams by the Building Code, Fire Code, regulations of other regional agencies with purview, or state or federal law shall be applied in conjunction with the requirements of this section, unless these requirements necessarily conflict with the aforementioned Codes, regulations, and laws. In the event of a conflict, the standards in the applicable Codes, regulations, and laws shall prevail.
SECTION 3. If any section, subsection, sentence, clause, or phrase of this Ordinance is for any reason held to be invalid or unconstitutional by a decision of any court of competent jurisdiction, such decision shall not affect the validity of the remaining portions of this Ordinance.
The City Council hereby declares that it would have passed this Ordinance and each and every section, subsection, sentence, clause, or phrase not declared invalid or unconstitutional without regard to whether any portion of the Ordinance would be subsequently declared invalid or unconstitutional.
SECTION 4. The Council finds that the Ordinance is exempt from the California Environmental Quality Act (CEQA) pursuant to CEQA Guidelines Section 15308 because adoption of this ordinance is an action to protect the environment.
SECTION 5. This Ordinance shall be effective on the thirty-first date after the date of its adoption.
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SECTION 6. This Ordinance shall not apply to any project application deemed complete prior to the effective date of this Ordinance. Any project completed pursuant to such application and rendered non-complying by this Ordinance shall be deemed a legal non-conforming structure and/or use, subject to the provisions of Palo Alto Municipal Code Chapter 18.70.
INTRODUCED:
PASSED:
AYES:
NOES:
ABSENT:
ABSTENTIONS:
ATTEST:
____________________________ ____________________________ City Clerk Mayor
APPROVED AS TO FORM: APPROVED:
____________________________ ____________________________ Assistant City AƩorney City Manager
____________________________
Director of Planning and
Development Services