101 local rules on file · Pop. 4,406 · San Mateo County
Showing ordinances that apply to Emerald Lake Hills, CA
Emerald Lake Hills is an unincorporated community with a population of approximately 4,406 in San Mateo County, California. Because Emerald Lake Hills is not an incorporated city, it does not have its own municipal government or city code. Instead, San Mateo County ordinances apply directly to residential and commercial properties here. The rules below are the county-level regulations that govern your area. Nearby incorporated cities in San Mateo County may have different rules.
San Mateo County enforces weed abatement under California Government Code §§39560-39588 and Health & Safety Code §14875, combined with PRC §4291 defensible space in fire hazard zones. The County Fire Marshal and Department of Public Works issue annual pre-season LE-100 notices to vacant-lot and hillside property owners, typically between April and May. Failure to clear results in County contractor abatement and a lien on the property.
Unincorporated San Mateo County permits artificial turf installation. Civil Code §4735 preempts HOA bans. Drainage must comply with stormwater regulations. Coastal zone installations may require Coastal Development Permit for larger areas.
These unincorporated areas are also governed by San Mateo County ordinances.
Rainwater harvesting for non-potable residential use (garden irrigation, lawn watering, toilet flushing with treatment) is legal in San Mateo County and encouraged by local water districts. Small rain barrels and above-ground cisterns up to 5,000 gallons generally do not require a permit. Larger systems, connections to plumbing, or potable-use systems trigger plumbing and building permits. Cal Water, BAWSD, Coastside County Water District, and other local agencies offer rain barrel rebates ($100-$300).
San Mateo County requires a building permit from the Planning & Building Department for all in-ground swimming pools, spas, and hot tubs. Plan review covers setbacks (typically 5 ft from property lines and structures), electrical (GFCI per CEC Article 680), drainage, and barrier compliance with California Building Code Chapter 31 and the Swimming Pool Safety Act (Health & Safety Code §§115920-115929). Surveys are required as part of permit review to verify setbacks.
Unincorporated San Mateo County requires electrical permit for hot tub/spa 240V installations. Locking safety cover meeting ASTM F1346 satisfies barrier requirement under H&S §115921(b). Setbacks per Zoning Regulations typically 5 feet from side/rear property lines.
Above-ground pools over 18 inches deep in unincorporated San Mateo County require a building permit. All permanent pools must comply with California Pool Safety Act fencing requirements. Consult County Building for specific situations.
Pool fences in unincorporated San Mateo County must comply with CA H&S §115920: minimum 60-inch barrier, self-closing/self-latching gates, ground clearance under 2 inches, no gaps over 4 inches. Two drowning prevention features required.
New pools in unincorporated San Mateo County require a building permit. Pools must meet CA Building Code and the Pool Safety Act. Setback and slope compliance required. Anti-entrapment drains (Virginia Graeme Baker Act) required.
San Mateo County follows California Title 24 Part 6 (CALGreen) EV readiness requirements for new construction. Residential Level 2 chargers require electrical permit only. HOAs cannot prohibit owner-installed EV chargers under Civil Code §4745.
Unincorporated San Mateo County has no general overnight parking ban on most streets. Specific residential neighborhoods may have permit parking. California Vehicle Code §22651(k) allows towing vehicles parked over 72 hours in same spot.
Unincorporated San Mateo County enforces CVC §22651(k) for vehicles on public streets (72 hours) and Ordinance Code Chapter 4.48 for inoperable vehicles on private property (must be enclosed or screened from view within 72 hours of notice).
Parking in unincorporated San Mateo County is governed by Title 7 (Vehicles and Traffic) of the county code. CVC 72-hour rule applies. Many unincorporated areas have narrow roads with limited parking and posted restrictions.
Commercial vehicle parking in residential zones of unincorporated San Mateo County is regulated under Title 7. Large vehicles are prohibited from residential areas. Home businesses must comply with county home occupation rules.
Vehicles in unincorporated San Mateo County must be parked on legal paved parking areas. Blocking public roads or private easements is prohibited. Many hillside communities have very limited off-street parking.
Unincorporated San Mateo County restricts oversized vehicle parking under Title 7. RVs and trailers are subject to the 72-hour street parking rule. Hillside and coastal communities have significant road width restrictions.
San Mateo County requires 100 feet of defensible space around all structures in State Responsibility Areas (SRA) and designated Very High Fire Hazard Severity Zones (VHFHSZ) per California Public Resources Code §4291. The County Fire Marshal (Cal Fire San Mateo-Santa Cruz Unit) conducts annual LE-100 inspections in coastal mountain communities including La Honda, Pescadero, Loma Mar, Woodside hills, and Emerald Hills. Failure to clear triggers abatement at the owner's expense plus administrative liens.
Large portions of unincorporated San Mateo County (Skyline, La Honda, Pescadero, Kings Mountain, Woodside hills) are in Very High Fire Hazard Severity Zones. PRC §4291 mandates 100-foot defensible space. CalFire and County Fire enforce; WUI building standards apply to new construction.
All fireworks are illegal in unincorporated San Mateo County — including 'Safe and Sane' fireworks. Fines are $1,000 per offense (raised from $100 in 2021). Spectator fines of $500 added in 2023. Parents/property owners liable.
Open burning is banned in unincorporated San Mateo County under BAAQMD Regulation 5. Wood-burning devices cannot be used on Spare the Air Alert days. The county includes extensive fire hazard severity zones (hills, coastal areas).
Wood-burning fire pits in unincorporated San Mateo County are banned on Spare the Air Alert days under BAAQMD. Hillside and fire hazard zone properties face additional restrictions from CAL FIRE and San Mateo County Fire.
Unincorporated San Mateo County allows backyard chickens on residential parcels of at least 2,500 sq ft under the County Zoning Regulations. 2,500 to 7,500 sq ft: up to 6 hens. 7,500+ sq ft: up to 10 hens (up to 12 total fowl per lot). No roosters over 4 months old. Coops must be in the rear yard, under 100 sq ft, under 6 ft tall, clean, and set back at least 35 feet from any dwelling, street line, or neighboring property line.
Unincorporated San Mateo County prohibits intentional feeding of coyotes, deer, and other wildlife. CA Fish & Game Code §251.3 prohibits feeding big game mammals (deer, bear, mountain lion). Coastside areas have active coyote and mountain lion populations.
San Mateo County follows California CDFW regulations banning many exotic species. Local zoning code requires a use permit for exotic animals in residential zones. Dangerous animal designations from any jurisdiction are recognized county-wide.
San Mateo County Title 6 does not ban specific breeds. However, dogs designated 'dangerous' or 'vicious' by any jurisdiction cannot be kept in the county. All dogs must be licensed and vaccinated.
San Mateo County does not have a specific beekeeping ordinance for unincorporated areas. Beekeeping may be permitted as an accessory agricultural or residential use subject to nuisance rules. CDFA hive registration required.
San Mateo County Title 6 requires all dogs to be on a leash or in an approved enclosure when off private property. Electric or invisible fences do not meet enclosure requirements. No voice-control exemption.
Unincorporated San Mateo County requires building permits for carports regardless of size. Zoning Regulations set setback, height, and lot coverage limits. Typically 5-foot side setback, 20-foot front setback, max 15 feet height in residential zones.
Unincorporated San Mateo County permits tiny homes on foundations as ADUs under state law (Gov Code §65852.2). Movable tiny houses (MTH) allowed as JADUs per HCD guidance. Tiny homes on wheels classified as RVs with storage-only use unless on approved site.
Unincorporated San Mateo County allows detached ADUs up to 800 sq ft or 35% of primary up to 1,500 sq ft; attached ADUs up to 800 sq ft or 50% up to 1,500 sq ft. ADUs up to 26 ft tall. 4-ft rear/side setbacks. ADUs under 750 sq ft exempt from impact fees.
Garage conversions to ADUs are permitted in unincorporated San Mateo County per California ADU law. Building permit required. No replacement parking required. Coastal Zone conversions need a Coastal Development Permit.
Small accessory structures (sheds) in unincorporated San Mateo County must comply with zoning setbacks. Sheds under 120 sq ft generally do not require a building permit but must comply with zoning requirements.
Unincorporated San Mateo County does not have a standalone leaf blower ordinance, but use is governed by County Code Chapter 4.88 (Noise Control) exterior dBA standards and the statewide AB 1346 ban on new sales of gas-powered small off-road engines (SORE) effective January 1, 2024. Operation must stay within permitted construction hours: 7 AM to 6 PM weekdays, 9 AM to 5 PM Saturdays, and never on Sundays, Thanksgiving, or Christmas.
Amplified music in unincorporated San Mateo County is regulated by County Code Chapter 4.88 Noise Control, which caps exterior noise at 55-75 dBA daytime and 50-70 dBA nighttime at neighboring residential property lines. Outdoor events with amplified sound require a Special Events Permit from the Sheriff and/or Planning Department, and operators must comply with CEQA noise analysis for new entertainment venues.
San Mateo County Title 6 prohibits animals from habitually barking, meowing, or otherwise disturbing the peace of any citizen. Animal control in unincorporated areas is handled by Peninsula Humane Society & SPCA.
San Mateo County unincorporated areas are governed by noise ordinance Chapter 4.88. Daytime hours are 7 AM–10 PM; nighttime 10 PM–7 AM. Exterior noise limits range from 55–75 dBA daytime and 50–70 dBA nighttime based on duration.
Construction hours in unincorporated San Mateo County are typically set by permit conditions. Chapter 4.88 noise standards apply to construction activity. Common permitted hours are 7 AM–7 PM weekdays and 9 AM–5 PM Saturdays.
Unincorporated San Mateo County enforces California Swimming Pool Safety Act (H&S Code §115920-115929) and CBC Chapter 31B. Minimum 60-inch barrier, self-closing/self-latching gates, plus at least TWO additional drowning prevention features for new pools since 2018.
Unincorporated San Mateo County zoning allows wood, vinyl, masonry, wrought iron, and chain-link fencing subject to zoning-district and Design Review requirements. Barbed wire and razor wire are prohibited in residential districts. Fences in the Coastal Zone require a Coastal Development Permit if they impair public views or scenic corridors. Design Review (DR) district overlays, common in Emerald Hills and coastal neighborhoods, impose additional material and color limits.
Unincorporated San Mateo County requires building permits for retaining walls over 4 feet measured from bottom of footing to top of wall, per California Building Code. Engineered plans required. Steep terrain common on the Peninsula often triggers geotechnical review.
Fence cost sharing between neighbors in unincorporated San Mateo County is governed by California Civil Code §841 (Good Neighbor Fence Act). The county does not mediate fence disputes.
Fences up to 6 feet in unincorporated San Mateo County generally do not require a building permit. Fences over 6 feet or masonry fences of any height require a building permit from Planning & Building.
Unincorporated San Mateo County limits front yard fences to 4 feet, and side/rear yard fences to 6 feet. A Fence Height Exception may allow up to 2 additional feet. Coastal Zone properties cannot apply for height exceptions.
California H&S Code §1597.40-.45 preempts local restrictions on family daycare homes. Small (up to 8 children) and Large (up to 14) family daycares allowed BY RIGHT in all residential zones in unincorporated San Mateo County. State license required through CDSS.
Unincorporated San Mateo County follows California Homemade Food Act (AB 1616) and Microenterprise Home Kitchen Operations (MEHKO, AB 626). Class A and Class B cottage food operations allowed. SMC opted in to MEHKO permitting in 2022 — hot meals permitted from registered home kitchens.
No exterior business signage is permitted for home-based businesses in unincorporated San Mateo County residential zones. Any commercial identification visible from the street violates Home Occupation Permit conditions.
Customer visits to home businesses in unincorporated San Mateo County are restricted to incidental levels. Retail sales, regular appointments, and commercial deliveries creating traffic or parking impacts are prohibited.
Home occupations in unincorporated San Mateo County require a Home Occupation Permit under the County Zoning Ordinance. The business must be secondary to the residential use with no exterior evidence or outside employees.
Unincorporated San Mateo County requires STR operators to carry $1,000,000 minimum commercial general liability insurance under Ordinance Code Chapter 5.152. Certificate of insurance naming the County as additional insured must be submitted with permit application.
Unincorporated San Mateo County caps short-term rental occupancy at 2 persons per bedroom plus 2 additional, with an absolute maximum of 10 guests. STRs in Coastside areas (Montara, Moss Beach, El Granada, Pescadero) require a County STR permit under Ordinance Code Chapter 5.152.
San Mateo County charges 10% TOT on STR stays in unincorporated areas. All STR permit applicants must provide proof of TOT certificate registration before a permit is issued. Annual permit fee is $300.
San Mateo County requires at least 1 on-site parking space for STR properties in the Coastal Zone; 2 spaces if max occupancy exceeds 8. STR guests must comply with all county parking regulations.
San Mateo County requires an annual STR permit ($300) for unincorporated coastal zone properties. STRs limited to R-1/R-3 single or multi-family parcels. ADUs cannot be STRs. Maximum 180 nights/year. Non-coastal unincorporated areas have no STR program.
STR guests in unincorporated San Mateo County must comply with Chapter 4.88 noise standards. Hosts are responsible for guest conduct. The local contact must be within 20 miles and reachable at all times during the rental.
Cannabis retail dispensaries are PROHIBITED in unincorporated San Mateo County. The Board of Supervisors has adopted a ban on all commercial cannabis retail licenses under MAUCRSA. Limited commercial cultivation (mixed-light greenhouse and nursery) is allowed only on parcels designated Agriculture in the General Plan with a County commercial cannabis license. Delivery from licensed operators in other jurisdictions into unincorporated areas is permitted per state law (Bus & Prof Code §26090) and cannot be banned locally.
Unincorporated San Mateo County allows adults 21+ to cultivate up to 6 cannabis plants per residence for personal, non-medical use under County Code Chapter 5.148 (Personal Cultivation). Cultivation must occur inside a private residence or a fully enclosed and secure accessory structure — OUTDOOR personal cultivation is PROHIBITED in unincorporated San Mateo County, going further than state law's baseline. Qualified medical patients may also cultivate indoors. Sale or commercial distribution requires a commercial cannabis license, which the County does NOT issue for retail activities.
Unincorporated San Mateo County does not codify a specific numeric annual cap on garage sales per household, but treats sales as permissible incidental residential use when occasional — typically understood as 2-4 per year. Holding sales with greater frequency or for extended durations can trigger home-business zoning review, require a business license, and constitute an unpermitted retail use of residential property. HOA communities often impose stricter limits (commonly 1-2 per year).
Unincorporated San Mateo County garage sales must stay within reasonable daylight hours, typically 8 AM to 6 PM, and remain within the Chapter 4.88 Noise Control exterior limits at the property line. Friday-Sunday weekend sales are most common. All merchandise, tables, and signs must be removed from public view at the end of each sale day. Leaving items outside overnight can trigger property blight/nuisance enforcement.
Unincorporated San Mateo County does not require a permit for occasional residential garage/yard sales. Sales are treated as incidental residential activity, not commercial operations, so long as they remain occasional and comply with County Code frequency and sign rules. Merchandise must be personal property, not goods purchased for resale — the latter would require a business license and zoning clearance as a home business or retail operation.
The San Mateo County Protected Tree Ordinance (No. 4895) requires replacement planting when a Significant or Heritage Tree is removed under permit. Standard replacement ratios range from 1:1 to 3:1 depending on the DBH and species of the removed tree. Replacement trees must meet minimum size specifications (typically 15-gallon to 24-inch box), be from an approved native/adapted species list, and established for a 2-year maintenance period. When on-site replacement is infeasible, an in-lieu fee is paid to the County Tree Replacement Fund.
The San Mateo County Protected Tree Ordinance (Ordinance No. 4895, adopted October 22, 2024; Code Title 11) requires a permit to remove or significantly prune any tree 12.1+ inches in diameter at breast height (DBH) anywhere in the unincorporated County, and any tree 6+ inches DBH in the Residential Hillside (RH) District. Certain native species (coast live oak, California bay laurel, redwood, Douglas-fir) receive heightened protection regardless of size. An arborist report is typically required, and replacement planting or in-lieu fees apply.
Under the 2024 Protected Tree Ordinance (No. 4895), San Mateo County designates Heritage Trees based on exceptional size, species rarity, historical significance, or ecological value. Heritage status can be conferred on mature coast live oaks, valley oaks, redwoods, and other native specimens. Removal is rarely permitted except for documented safety emergencies, and damage to a Heritage Tree triggers the most severe penalties under the ordinance, with fines up to $25,000 per tree plus restoration and restitution.
Unincorporated San Mateo County does not designate specific food truck vending zones but restricts operations through general zoning and parking rules. Food trucks may not vend from the public right-of-way for extended periods (not a permitted commercial use), must comply with parking time limits on County roads, and cannot operate within 500 feet of a school during school hours per Education Code §49535.5. Private property vending requires property owner written permission and may trigger a use permit.
Mobile food facilities operating in unincorporated San Mateo County must obtain a Mobile Food Facility (MFF) permit from San Mateo County Health Environmental Health Services (EHS), pay the annual permit fee, pass a pre-operational vehicle inspection, secure a commissary agreement with a permitted commercial kitchen, and hold a California Food Handler Card. MFF permits run February 1 through January 31 annually. Contact EHS at (650) 372-6200.
Recology San Mateo County provides residential customers with up to two on-call bulky item pickups per year included in service, with additional pickups available for a fee. Eligible items include furniture, mattresses, appliances (with refrigerant-removal tag for refrigerators/AC units), and e-waste. Construction debris, paint, motor oil, and hazardous materials are NOT eligible and must be taken to the San Mateo County Household Hazardous Waste Program or Shoreway Environmental Center in San Carlos.
California SB 1383 (effective 2022, enforcement 2024) and AB 341 require all residential and commercial generators in unincorporated San Mateo County to separate organic waste, recyclables, and landfill trash. Recology's blue cart accepts paper, cardboard, glass, aluminum, tin, and plastics #1-5. The green organics cart accepts food scraps, food-soiled paper, and yard trimmings. Contamination above 10% can result in skipped carts and eventual fines for repeat offenders.
Residential trash, recycling, and organics collection in unincorporated San Mateo County is provided primarily by Recology San Mateo County under franchise agreements coordinated through the South Bayside Waste Management Authority (RethinkWaste) and SBR (South Bayside Recycling). Weekly curbside service includes three carts: gray for garbage, blue for recycling, and green for organics. Holiday service is delayed by one day the week of the holiday.
Unincorporated San Mateo County residents must place the three carts (gray/blue/green) at the curbside by 6 AM on collection day with lids fully closed, at least 3 feet apart from each other and from vehicles, mailboxes, or utility poles. Carts must be retrieved from the curb within 24 hours after collection. Between pickups, carts must be stored out of sight from the public right-of-way (behind fencing, in side yards, or in garages).
Unincorporated San Mateo County regulates outdoor lighting through zoning standards requiring fully shielded (full-cutoff) fixtures, downward direction of light, and control of glare and light trespass onto neighboring properties. Title 24 Part 6 (California Energy Code §140.7) also caps outdoor lighting power density by zone. Coastal Zone and Scenic Road corridors impose additional lighting restrictions to protect nighttime views and sensitive habitat. Residential properties must not cast light onto neighboring dwellings.
Unincorporated San Mateo County regulates outdoor lighting through Zoning Regulations Chapter 22.5 (Dark Sky) and Building Regulations. Exterior lighting must be shielded, downward-directed, and limited to 0.5 foot-candles at residential property lines. Coastal zone and rural areas (La Honda, Pescadero, Skyline) have stricter dark-sky rules.
Residential height in unincorporated San Mateo County varies by paired S-District — typically 28-36 feet or 2.5 stories, whichever is less. Residential Hillside (RH) zones generally limit height to 28 feet, measured from average natural grade to highest roof point. Chimneys, vents, antennas, and mechanical equipment have limited additional allowance. The Design Review (DR) combining district and the Scenic Road combining district impose additional height and bulk review.
San Mateo County parcels are assigned BOTH a Use District (R-1, R-2, RH, C, M, A, RM) AND a paired Development Standards 'S' District (e.g., S-101, S-17, S-94) that sets specific setbacks, lot coverage, FAR, and height. Typical R-1/S-100-series residential setbacks: 20-25 ft front, 5-10 ft sides, 15-20 ft rear, with increased side setbacks on corner lots. The Design Review (DR) overlay, Coastal Zone, and Resource Management (RM) districts impose additional constraints.
Lot coverage limits in unincorporated San Mateo County range from 25% to 50% depending on paired S-District and zoning. Typical R-1 with S-100-series: 40-45% maximum coverage. Hillside (RH): 25-30% with additional slope-based reductions. Coverage includes the footprint of all buildings and covered structures; impervious surface limits (including driveways and patios) separately apply under the NPDES Stormwater requirements (C.3) for projects creating or replacing 2,500+ sq ft of impervious surface.
Recreational drone flight in unincorporated San Mateo County is governed by FAA rules (49 USC §44809, 14 CFR Part 107 exemption) plus a countywide Park Orders ban: drones are PROHIBITED in all San Mateo County Parks (Huddart, Wunderlich, San Bruno Mountain, Edgewood, Pescadero Creek, Memorial, Sam McDonald, Junipero Serra, Crystal Springs). FAA Part 107 registration required for any drone over 0.55 lbs. SFO, Half Moon Bay Airport, San Carlos Airport, and Hayward Executive are nearby controlled airspaces requiring LAANC authorization.
Commercial drone operations in unincorporated San Mateo County require an FAA Part 107 Remote Pilot Certificate (14 CFR Part 107), LAANC authorization for controlled airspace (most of the Peninsula falls within SFO Class B), and coordination with affected airports (SQL, HAF, PAO, SFO). San Mateo County Parks prohibit commercial drone use; filming permits may be obtainable for specific projects via County Film Commission coordination. Commercial filming in the Coastal Zone may require a Coastal Development Permit.
Unincorporated San Mateo County requires commercial peddlers and solicitors to obtain a Peddler/Solicitor License from the San Mateo County Sheriff's Office, including a fingerprint-based background check and photo ID badge. Licensed solicitors may operate 9 AM to sunset (or 8 PM, whichever is earlier), must display the County-issued badge visibly, and may not solicit at any address with a posted 'No Soliciting' sign. Religious, political, and charitable canvassing are exempt under First Amendment protections.
Many San Mateo County cities (Redwood City, San Carlos, others) maintain 'Do Not Knock' registries that residents can join free of charge, and the County Sheriff requires all licensed solicitors to check the registry and respect posted No Soliciting signs before knocking. Unincorporated areas rely primarily on posted signs — a sign reading 'No Soliciting' or 'No Trespassing' on a home, gate, or driveway is legally sufficient to make subsequent solicitation a citable offense under Penal Code §602 and County Code.
Snow sidewalk clearing is not a regular concern in unincorporated San Mateo County's Mediterranean coastal climate, and the County has no dedicated snow-clearance ordinance. On the rare occasions of snow at Skyline Ridge or upper La Honda/Kings Mountain elevations, Caltrans clears State Routes 35, 84, and 92, while property owners are generally responsible for keeping their own driveways and sidewalks (where they exist) passable. Streets & Highways Code §§5610-5618 gives local agencies general authority over abutting-property sidewalk maintenance.
San Mateo County property maintenance and nuisance provisions apply to garage/yard sales in unincorporated areas: merchandise must be displayed in an organized manner and completely removed from public view at the end of each sale day. Leaving unsold items in the yard, driveway, or curbside between sale days or after the sale ends triggers blight/public nuisance enforcement by County Code Enforcement, with escalating fines for repeat violations.
Unincorporated San Mateo County franchise haulers (Recology San Mateo County, GreenWaste, South San Francisco Scavenger) service different areas. Bins must be stored out of public view except on collection day and retrieved by end of collection day.
Unincorporated San Mateo County requires vacant lot maintenance under Ordinance Code Chapter 4.48 and PRC §4291 (defensible space). Grass/weeds must not exceed 6-12 inches; wildfire zone lots require 100-foot defensible space clearance.
Unincorporated San Mateo County enforces property maintenance through Ordinance Code Chapter 4.90 (Property Maintenance Code) and Chapter 4.48 (nuisances). Blight including peeling paint, broken windows, debris, and abandoned vehicles subject to 10-30 day correction notices.
San Mateo County Planning & Building Department requires submittal of an Erosion and Sediment Control Plan prior to issuance of any demolition, grading, or building permit that involves site disturbance. Standard BMPs include silt fencing, straw wattles, erosion control blankets, stabilized construction entrances, and covered stockpiles. Wet-season work (October 1 - April 30) triggers additional inspection requirements and may be restricted on steep slopes. SWPPP required for sites 1+ acre.
Unincorporated San Mateo County is a permittee under the San Francisco Bay Area Municipal Regional Stormwater Permit (MRP 3.0, Order R2-2022-0018) which imposes NPDES Phase I stormwater requirements. Projects creating/replacing 2,500+ sq ft of impervious surface trigger C.3 post-construction stormwater treatment requirements (LID, biofiltration). Illicit discharges to storm drains are prohibited. Construction sites disturbing 1+ acres require SWPPPs and monthly wet-season inspections.
San Mateo County administers its own certified Local Coastal Program (LCP) and issues Coastal Development Permits (CDPs) for projects in the Coastal Zone, which covers roughly 240 sq miles from Devil's Slide south through Pescadero, Año Nuevo, and the Santa Cruz County line. Projects in the Coastal Zone typically require a CDP from County Planning; certain appealable areas (near the shoreline, in sensitive habitat, or in rural areas) can also be appealed to the California Coastal Commission. ESHA (Environmentally Sensitive Habitat Area) buffers, public access, and view corridors are key LCP policies.
San Mateo County requires a Grading Permit from Planning & Building for projects involving more than 250 cubic yards of cut and/or fill, or any grading on slopes over 20%, or grading within 100 ft of a watercourse. Drainage design must direct runoff away from structures and must not adversely redirect water onto neighboring properties. Retaining walls over 4 feet in height need separate engineering and permits. Pre-site erosion-control and tree-protection inspection may be required.
Unincorporated San Mateo County has significant flood risk in coastal lowlands, creek corridors, and bayfront areas. FEMA flood zones require permits, elevation certificates, and flood insurance for federally-backed loans. Sea level rise is a major threat.
Unincorporated San Mateo County uses expedited solar permitting under California AB 2188 (Solar Rights Act). Residential rooftop systems under 10 kW qualify for same-day online permits through SolarAPP+ or the County Building Division. Fire setbacks per CFC Chapter 11B.
California Civil Code §714 (Solar Rights Act) strongly limits HOA authority to restrict solar panels. HOAs in unincorporated San Mateo County (Emerald Hills, West Menlo Park subdivisions) cannot effectively prohibit solar or impose costs over $1,000 or reduce efficiency over 10%.
San Mateo County Code Chapter 3.04 (Juvenile Curfew Regulations) prohibits minors under 18 from being in public places within unincorporated areas of the County between 11:30 PM and 5:00 AM on weeknights, and between 12:30 AM and 5:00 AM Friday, Saturday, and holiday nights. A daytime truancy curfew applies during school hours. Standard exceptions include minors accompanied by a parent/guardian, traveling to or from work or school activities, or in case of emergency.
San Mateo County Parks are closed from sunset to 8 AM under the County Parks Department Rules & Regulations (Chapter 3.68 County Parks and Recreation Areas — Rules). After-hours presence is an infraction prosecuted as unlawful entry/trespass. Camping is allowed only at designated campgrounds with a reservation (Memorial Park, Sam McDonald Park, Huddart Park group sites). State Parks (Año Nuevo, Butano, Half Moon Bay State Beach) have their own hours and rules under California State Parks authority.
Unincorporated San Mateo County permits residential holiday decorations without permits. Displays must comply with electrical code, not obstruct public rights-of-way, and respect noise ordinance quiet hours (10 PM to 7 AM). Coastal zone properties may have additional restrictions.
Unincorporated San Mateo County permits political signs on private property without permits, consistent with First Amendment protections and Reed v. Gilbert. Zoning Regulations §6408 sets general temporary sign limits. Signs in public rights-of-way and on County property are prohibited.
Unincorporated San Mateo County permits temporary garage sale signs under Zoning Regulations §6408. Signs limited to 4 sq ft, posted only during the sale, and prohibited on utility poles or public rights-of-way. Maximum 2 sales per household per year typical.
Unincorporated San Mateo County does NOT have a rental registration program. Landlords must comply with state habitability laws (Civil Code §1941.1) and the California Building Code. Business license required only for property management companies, not individual landlords.
Unincorporated San Mateo County applies California's statewide just-cause eviction protections under AB 1482 (Civil Code §1946.2). After 12 months of tenancy, landlords must state an at-fault or no-fault reason. No-fault evictions require one month's rent in relocation assistance.
Unincorporated San Mateo County has NO local rent control. State law AB 1482 (Tenant Protection Act, Civil Code §1946.2 and §1947.12) caps annual rent increases at 5% plus CPI (maximum 10%) for qualifying units. Single-family homes owned by non-corporate owners and buildings under 15 years old are exempt.