Chapter 8.134 — RM DISTRICT (RESOURCE MANAGEMENT DISTRICT)

The purposes of this chapter are to carry out the objectives and policies of those San Mateo County General Plan Chapters that fulfill the requirements for State-mandated Open Space and Conservation Elements, as well as other elements adopted as part of the General Plan of San Mateo County, to meet the requirements of Section 65910 of the Government Code of the State of California requiring formulation of an open space zoning ordinance, and to ensure consistency between the General Plan and the zoning ordinance.

(Prior code § 6310 Amd. Ord. 3872; 01/19/99)

The Resource Management District (hereinafter the RM District) shall supplant and replace in name those F-1, A-1, and A-2 Districts that are combined with S-13 and S-11 Districts. The RM District may also be applied to other areas of the County when they are rezoned to such district.

These regulations shall not apply to a building or structure or portion thereof or use of building or land which does not conform to the zoning regulations and which lawfully existed at the time these regulations, with which it does not conform, became effective.

All parcels 5 acres or larger in size which were legally in existence at the time of the enactment of this ordinance shall continue to be legal parcels. Parcels smaller than 5 acres in size shall continue to be legal parcels only if no adjacent property was in the same ownership at the time of enactment of this ordinance, or if a potable on-site water supply had been developed on the parcel at the time of enactment of this ordinance. When such parcels can be aggregated to a minimum of 5 acres, each 5-acre aggregation shall constitute one legal parcel.

The regulations of this district are included in seven (7) major ordinance elements: (1) Maximum forms of development and type of use, as indicated in Section 8.134.070 (2) Development Review Procedures and Criteria, as indicated in Section 8.296; (3) General Review Criteria, as indicated in Section 8.292.030 (4) Supplementary Review Criteria for Primary Resource Areas, as indicated in Section 8.292.100; (5) Supplementary Review Criteria for Special Hazards Areas, as indicated in Section 8.292.180; (6) Primary Resource Areas and Hazard Areas; and (7) the applicable portions of the Zoning District Map, as included in the San Mateo County Zoning Ordinance.

(Prior code § 6312 Amd. Ord. 3872; 01/19/99)

All developments proposed for a location within a RM District shall require the issuance of a permit, pursuant to the Development Review Procedure specified in Chapter 8.296.

For purposes of Chapters 8.134, 8.292, and 8.293, but excluding those uses defined below, “development” shall mean the construction of any significant structure on land, or in or under water; the discharge or disposal of any significant dredged material or any gaseous, liquid, solid or thermal waste; the division or subdivision of land into two or more parcels; reconstruction or substantial alteration of any significant structure, including any facility of a private, public or quasi-public utility; and any major removal of vegetation.

Excluded from this definition of development and from Development Review Permits and Procedures are uses defined in Section 8.296.090 and commercial logging which is controlled under regulation of the Timber Harvesting Ordinance, Chapter 8.408 of the San Mateo County Ordinance Code; topsoil operations which are subject to regulations of the County Ordinance Code, chapter 8.412, quarrying operations which are subject to regulation of the County Ordinance Code, Chapter 8.420; oil and gas well regulations, Chapter 8.424 and grading and excavating operations which are subject to regulations of the County Ordinance Code, Chapter 10.64, Regulation of Grading and Excavating Operations: agricultural utility poles; single pump houses of less than 800 cubic feet in size, fences under 4 feet in height constructed of single wire or open wood rail, necessary repairs or maintenance of existing structures, agricultural uses that did not require a permit prior to adoption of this ordinance, and harvesting and conversion of land for agricultural use, unless said use or land falls within a Primary Wildlife or Primary Natural Vegetative Area, except that vegetation forming a significant part of the viewshed as seen from urban areas or public roads and trails shall be deleted from the definition of Primary Natural Vegetative Areas in consideration of conversion of land for agricultural use.

For purposes of this ordinance, “Significant Structures” shall be defined as a structure for human occupancy or use such as a single-family residence, multiple-family residences, trailer park structures, structures for overnight accommodations, restaurants, churches, private and public club structures, and schools, roads, bridges, public facilities and utilities, nonagricultural utility poles and structures, dams, breakwaters, mineral extraction buildings and constructs, harbors, docking facilities, recreation buildings and facilities, campground structures, dude ranch structures and similar types of structures.

(Prior code § 6313 Amd. Ord. 2347; 01/20/76)

(Prior code § 6313 Amd. Ord. 3872; 01/19/99)

• (a) The Director of Planning shall be responsible for notifying and furnishing information to interested persons and agencies, for coordination, accumulation and presentation of data to the Planning Commission and Board of Supervisors, for making recommendations relating to the overall design, and for assuring compliance with the provisions of this Ordinance.

• (b) The County Engineer and Road Commissioner shall be responsible for making recommendations pertaining to public and private roads, all such improvements within road rights-of-way including but not limited to storm drainage, sewer, water, traffic control, street lighting and public utilities facilities, and for making recommendations in connection with site development, grading erosion control, and matters related to soil stability and geology of the development. They shall be responsible for the review of reports, final maps and improvement plans required.

• (c) The County Health Officer shall be responsible for: (1) submission of a report stating the recommendations and conditions that must meet the standards and requirements pertaining to water supply, sewage disposal, and other environmental health matters, (2) certification that the quality and quantity of the domestic water supply meets County and State regulations, and (3) final approval of the method of sewage disposal, including consideration of state and local requirements.

• (d) The County fire authorities shall be responsible for making recommendations pertaining to fire prevention and means for protection from fires.

• (e) Officers shall submit their reports to the Director of Planning for submission to the Planning Commission and Board of Supervisors. Each of said officers shall be responsible for making necessary inspections with regard to the matters for which they are responsible to insure compliance with the requirements of this Chapter and the conditions of approval.

The following provisions relating to use, density and intensity of development ensure that development is consistent with levels of services which reasonably can be provided, will conserve natural features and scenic values, and that areas hazardous to development or life are left in open or limited use. These provisions are maximum limits and, where applicable, more restrictive requirements imposed by the application of review criteria under Chapter 8.292 shall supersede Sections 8.134.070 through 8.134.090.

The following uses only shall be permitted in the RM District, except those subject to the provisions of Section 8.280 which require a Use Permit:

• (a) Agricultural uses and accessory structures, on-site sales of agricultural products.

• (b) Nurseries and greenhouses.

• (c)* Temporary trailer parks and other housing for farm laborers.

• (d) Livestock raising and grazing.

• (e) Dairies.

• (f)[1 ] Kennels or catteries.

• (g)[2] Timber harvesting and commercial woodlots, providing that no commercial timber harvesting shall occur within 1,000 feet of any legal dwelling in existence on June 18, 1991, except under the following circumstances:

  • (1) Timber harvesting operations for which all permits had been received on or before June 18, 1991, may complete operations in accordance with the terms and conditions of such permits.

  • (2) Timber harvesting operations may occur within the 1,000-foot buffer zone with prior written approval of the owner of the affected dwelling, subject to the prior recordation of the statement specified in Chapter 8.360.

  • (3) Normal forest maintenance may be conducted within the 1,000-foot buffer zone, but shall be limited to: (a) removing dead, dying, or diseased trees and snags; (b) salvaging downed wood; (c) cutting trees for the purposes of developing viewsheds or landscape aesthetics in accordance with other applicable provisions of Title 8, of San Mateo County Ordinance Code; or (d) clearing for firebreaks, in accordance with requirements of the County Fire Marshal or other applicable fire authority having jurisdiction.

Notwithstanding the above, access roads to the site of timber harvesting operations may be constructed, improved, and used within the 1,000-foot buffer zone. The limitation on harvesting within 1,000 feet of an existing dwelling shall not apply to a dwelling located on the parcel which is proposed for timber harvesting.

For the purpose of this section, the distance from a dwelling shall be measured along the surface of the ground.

• (h)[4] Quarries and waste disposal sites.

• (i) Single-family residences.

• (j) Multi-family residences.

• (k)* Hotels, motels and restaurants.

(l)* Churches.

• (m)* Schools.

• (n)* Fire stations.

• (o)* Public and private clubs.

• (p) Public recreation.

• (q)* Commercial recreation, including but not limited to stables and riding academies, golf courses, campgrounds, dude ranches, and motorcycle parks in accordance with adopted policies on motorcycle parks and related facilities.

• (r)[3] Oil and gas exploration, production and storage.

• (s) Home occupations.

• (t)* Wineries; provided that the annual storage capacity shall not exceed 10,000 gallons, the annual fermentation capacity shall not exceed 5,000 gallons, and the annual bottling shall not exceed 2,500 cases of wine; the only retail sales permitted will be those of wines produced on the premises.

• (u)* Exotic animals for which a Use Permit has been obtained in accordance with Chapter 6.08 of the San Mateo County Ordinance Code are permitted in addition to those animals otherwise permitted by this Chapter.

• (v)* Scientific/Technical Research and Test Facilities, provided a Use Permit shall only be issued for this use upon the following findings:

  • (1) That the use is of a low-intensity nature with a minimum of permanent construction required, no permanent on-site personnel or permanent on-site vehicles.

  • (2) That the nature of the operation requires an open, isolated, and radio frequency interference-free environment.

  • (3) That no manufacturing or industrial activities are involved.

  • (4) That the size, location and design of any proposed facility as well as level of activity on the site are compatible with the policies of the Local Coastal Program.

  • (5) That the proposed use does not impair existing or potential agricultural uses on the site or on surrounding properties. The applicant shall demonstrate how agriculture will not be impaired, including provisions for leasing portions of the site for agricultural uses.

  • (6) That the proposed use of facility does not create a potential for any health or safety hazard.

  • (7) That the applicant for such a facility shall describe the manner in which other users might be accommodated in sharing the proposed facility so as to avoid the duplication of such facilities in the future.

• (w) Keeping of pets in association with a one-family dwelling.

• (x) Limited keeping of pets in association with a second unit, farm labor housing unit or multiple-family dwelling unit.

• (y) Animal fanciers.

• (z)* Veterinary hospitals for small animals.

• (aa)* Veterinary hospitals for large animals.

• (ab) Keeping of confined animals.

*Uses allowed subject to a use permit

1Allowed subject to a kennel/cattery permit

2Allowed subject to timber harvesting permit

3Allowed subject to oil well permit

4Allowed subject to quarry permit

(Prior code § 6315(f) Amd. Ord. 3449; 12/15/92 (Prior code § 6315(g) Amd. Ord. 3381; 04/14/92) (Prior code § 6315(t) Ord. 2340; 04/12/77)

(Prior code § 6315(u) Ord. 2522; 07/18/78)

(Prior code § 6315(v) Ord. 2872; 01/17/84) (Prior code § 6315(w) Ord.3449; 12/15/92) (Prior code § 6315(x) Ord. 3449; 12/15/92) (Prior code § 6315(y) Ord. 3449; 12/15/92) (Prior code § 6315(z) Ord. 3449; 12/15/92)

(Prior code § 6315(aa) Ord. 3449; 12/15/92)

(Prior code § 6315(ab) & Footnote (ab)5 Rep. Ord. 4844; 05/04/21)

(Prior code § 6315(ab) Ord. 3791; 10/21/1997)

(Prior code § 6315(ac) Ord. 4075; 11/06/01)

See Chapter 8.392 for provisions to allow second dwelling units to locate in the RM District.

(Prior code § 6316 Ord. 3038; 06/18/85)

In the RM District, for purposes of determining the maximum total number of dwelling units permissible on any parcel, the following system shall be used:

The total parcel shall be compared against the criteria of this section in the order listed. Any segment of a parcel to which a criterion first applies shall be allowed a maximum accumulation of that density. Once considered under a criterion, a segment of the parcel shall not be considered under subsequent criteria. When the applicable criteria have been determined for each of the areas, any portion of the parcel, which has not yet been assigned a maximum density accumulation, shall be assigned a density of one dwelling unit per 5 acres.

The sum of densities accrued under all applicable categories shall constitute the maximum density of development permissible under this section. If the fractional portion of the number of dwelling units allowed is equal to or greater than .5, the total number of dwelling units allowed shall be rounded up to the next whole dwelling unit. If the fraction is less than .5, the fractional unit shall be deleted.

The provisions of this section will not apply to farm labor housing or other structures considered to be accessory to agriculture under the same ownership.

• (a) On lands falling within a 100-year floodplain as defined by USGS, dwelling units may be accumulated at a maximum of one unit per 40 acres. Where previous actions have eliminated such flood areas, the provisions of this subsection shall not apply.

• (b) For remote lands, defined as those lands over one mile from an existing all-weather through public road, density accumulation shall be limited to one dwelling unit per 40 acres.

• (c) Density accumulation in agricultural preserves or the exclusive Agricultural Districts as defined in the adopted Resource Conservation Area Density Matrix policy, designated for the production of specialty and other crops, shall not exceed one dwelling unit per 40 acres.

• (d) For areas within any of the three least stable categories (Categories V, VI and L) as shown on the U.S. Geological Survey Map MF 360, “Landslide Susceptibility in San Mateo County,” density accumulation shall be limited to one dwelling unit per 40 acres.

• (e) All areas located within the rift zone or zone of fractured rock of an active fault as defined by the U.S. Geological Survey and mapped on USGS Map MF 355, “Active Faults,” probably active faults, and associated fracture zones in San Mateo County shall be limited to a maximum density accumulation of one dwelling unit per 40 acres.

• (f) That portion of a parcel which has a slope in excess of 50% shall have density accumulation limited to one dwelling unit per 40 acres; that portion of a parcel having a slope in excess of 30% but not exceeding 50% shall have density accumulation limited to one dwelling unit per 20 acres; that portion of a parcel having a slope in excess of 15% but not exceeding 30% shall have density accumulation limited to one dwelling unit per 10 acres. Slope is determined by dividing the change in elevation between contours (lines of equal elevation) by the horizontal distance between the respective contours.

• (g) Lands within the adopted Skyline State Scenic Highway corridors shall be limited to a density accumulation of one dwelling unit per 10 acres.

• (h) Areas designated by the U.S. Department of Agriculture, Soil Conservation Service as Class I or II soils, or Class III soils rated “good” or “very good” for artichokes or Brussels sprouts and within the climatic zone suitable for artichokes and Brussels sprouts shall be limited to a maximum density accumulation of one dwelling unit per 10 acres.

Any map referenced in this section can be challenged for accuracy. Where maps referenced in this section can be proved inaccurate by more detailed study, the appropriate density accumulation shall be allowed.

Require, after any land divisions, that the applicant grant to the County (and the County to accept) a conservation easement containing a covenant, running with the land in perpetuity, which limits the use of the land covered by the easement to uses consistent with open space (as defined in the California Open Space Lands Act of 1972 on January 1, 1980). The boundaries of the conservation easement may be modified by the parties for purposes of health, safety and maintenance of the uses allowed at the time of the subdivision provided that the original intent and purposes of the conservation easement are maintained.

The land subject to a conservation easement is that land which is not designated for development under a Master Land Division Plan under the requirements of Chapter 8.296 (Development Review Procedure). The boundaries between the land designated as a conservation easement and the land available for development shall be chosen, at a minimum, so that improvements allowable at the time of subdivision may be made in areas outside the conservation easement, provided however, that no increase in density credits is implied or created and any development planned under this provision will be subject to the State laws and County regulations in place at the time the development is sought to be implemented. For purposes of Section 8.134.090(a), a “land division” does not include:

• (a) A lot line adjustment unless the proposed lot line adjustment will increase the intensity of use or density credits of the master parcel.

• (b) A land division resulting from a transfer of land to a public agency or non-profit organization for public recreation or open space purposes provided that the land acquired by the government agency or non-profit organization is dedicated as public open space or parkland in perpetuity.

(Prior code § 6317A Ord. 4388; 09/11/07)

Where it is demonstrated that a development will further the goals and policies of the Open Space and Conservation Element of the San Mateo County General Plan, increases in the maximum allowable density may be permitted.

• (a) Developments where over 80% of the contiguous and compact parcel area is kept free from alteration (except as required for natural resource management purposes) and held in permanent common open space through appropriate forms of restrictions or public dedication, shall be encouraged by granting a bonus density of up to 10% beyond that permitted by the provisions of Section 8.134.090.

• (b) An additional bonus of up to 10% shall be granted if one or more of the following criteria are also met:

  • (1) Auxiliary transportation modes will be used either to reduce the total land area devoted to structures and paved surfaces or to preserve areas of special open space value.

• (2) Building and site design, structural systems and construction methods will be employed which both reduce the land area to be altered from a natural state and preserve the overall natural appearance and scale of the area.

• (3) Housing units will be constructed of a type, price and in a location which would help promote the objectives of the Housing Element of the San Mateo County General Plan.

In the RM District, no residential or commercial structure shall exceed three stories or 36 feet in height except as allowed by use permit provisions in Chapter 8.336 of the San Mateo County Ordinance Code.

In the absence of more restrictive provisions within this ordinance and with the exception of setbacks determined under the provisions of Section 8.134.140 of this Ordinance Code, the minimum yards required in the RM District shall be as follows:

Front: 50 feet Side: 20 feet Rear: 20 feet

Main and accessory buildings shall be located at least thirty (30) feet apart.

(Prior code § 6319B Amd. Ord. 4496; 04/27/10)

• (a) Decision Making Authority: In order to grant a reduction of the required setbacks as allowed by this section, the decision making authority of the Resource Management Development Review Permit, pursuant to Section 8.134.040 of this Chapter, must make the finding that the proposed development complies with the criteria listed in this section at the time of permit approval.

• (b) The front setback (yard) may be reduced to a minimum of 20 feet, and side setback(s) (yards) may be reduced to a minimum of 10 feet, if all of the following apply:

• (1) The project preserves an area of open space that significantly enhances the protection of visual, habitat, or open space resources. The preservation of open space is accomplished by a conservation easement.

• (2) The project is located in an urban area, as shown on Map 8.1M of the San Mateo County General Plan.

• (3) The home sites are located immediately contiguous to an existing developed area.

• (4) The reduced setbacks are appropriate to conform the proposed development to existing development, thereby helping to integrate the new development into the surrounding neighborhood.

• (5) The reduced setbacks will allow for increased open space by:

  • a) Reducing the front setback allows for shallower parcels, and thereby allowing for increased open space and/or conservation easement area to be preserved in the rear area of the project or subdivision, and/or

  • b) Reducing the side setback(s) will promote clustering of proposed residences thereby allowing more open space and/or conservation easement area to be preserved in the project or subdivision.

• (6) The project will comply with the following development standards:

  • a) Minimum Lot Width of 75 feet.

  • b) Maximum Building Site Coverage Ratio of 40%.

  • c) Accessory buildings and structures will comply with Chapter 8.348 (Detached Accessory Buildings) of this Ordinance Code, except that structures will maintain the minimum 20-foot rear setback and a minimum side setback of 10 feet.

• (7) The project will minimize grading.

• (8) The reduction of required setbacks does not adversely impact community character, public health, safety or welfare.

(Prior code §, 6310- 6319B, Chap 20A Ord 2229; 12/20/73)

(Prior code § 6319C Ord. 4496; 04/27/10)