Why is this Important?


Natural resources are those resources that exist in the environment -water, air, soil, flora, and fauna. While some of these resources, such as the sun, air, and wind, are considered renewable, others, including fossil fuels and minerals, are considered non-renewable because their replenishment rate is vastly slower than the current rate of extraction.

The depletion of natural resources can lead to scarcity and increased costs of goods, and excessive resource extraction can cause loss of species and habitat. Pollution of natural resources, such as our air, water, and soils, impacts the health of humans, animals, and ecosystems. Their careful management and protection are therefore vital to our well-being.


What is a Sustainable State?


In a sustainable state, natural resources are managed efficiently to minimize environmental degradation, prevent scarcity, and to ensure that resources are available for future generations. Water supply and demand are in balance, and adequate infrastructure and storage reduce the risk of shortages. Water quality is high enough to support different uses including recreation and manufacturing, while also ensuring the health of aquatic ecosystems. Waste prevention and diversion help conserve natural resources. Soils are healthy and support agriculture, while good air quality protects public health.


Key Findings

  • In 2015, 90% of monitored days in San Mateo County had “Good” air quality as rated under the U.S. Environmental Protection Agency’s Air Quality Index (AQI). Though the number of “Good” air quality days in San Mateo county was down from 93% in 2012, it had the highest percentage in the nine county Bay Area.
  • Total water usage in San Mateo County in 2012-13 was 81.78 million gallons per day, down slightly from the year prior. Total water use is 15% below levels from 2003-04, despite a population increase of over 41,000 residents during that time.
  • The county receives 91% of its water supply from the San Francisco Public Utilities Commission (SFPUC). SFPUC receives on average 85% of its water from the Hetch Hetchy Reservoir in Yosemite National Park and the remainder from local Bay Area watersheds.
  • Residential consumption accounts for 69% of water usage in the county, with the majority of this usage for single family homes.
  • The largest source of pollution in our waterways is storm water runoff, which carries untreated contaminants like motor oil, animal waste, pesticides, and sometimes sewage directly from our streets to our beaches. In water year 2015 (running from 10/1/2014-9/30/2015), over 1,880,528 gallons of raw or partially-treated sewage spilled in San Mateo County, well above the 151,000 gallons that spilled in water year 2014.
  • In 2015, there were 583,990 pounds of solid waste generated in San Mateo County, up 6% from the year prior. Since 2004, countywide disposal is down 23%.
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Air Quality

The U.S. Environmental Protection Agency’s Air Quality Index (AQI) measures overall air quality in a region on a scale of 0-500: Good = 0-50, Moderate = 51-100, Unhealthy for Sensitive Groups = 101-150, and Unhealthy for All = 151+.

San Mateo County has one air quality monitoring station in Redwood City. Of the key air pollutants measured at this station, only ozone and particulate matter have exceeded state or federal standards in the past decade.

Ground-level ozone is formed when Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOC) mix in the presence of sunlight. The major sources of NOx and VOCs are factories, power plants, and on-road vehicles. Short-term exposure to ozone can irritate the eyes, cause airway constriction, and aggravate existing respiratory diseases. Chronic exposure to ozone can permanently damage lung tissue. Ozone levels in the Bay Area are usually highest during the Summer Spare the Air Season (May through mid-October).

Particulate matter consists of solid or liquid particles in the atmosphere, including smoke, dust, and aerosols. Particulate matter contributes to haze and is also associated with respiratory ailments including asthma. The smallest sized particles, PM 2.5, are the most dangerous as they can penetrate deeply into lung tissue. Particulate matter pollution in the Bay Area is at its highest level during the Winter Spare the Air Season (November 1st through the end of February), and the largest sources of winter particulate matter are wood burning (38%) and on-road vehicles (15%).


Percent of Monitored Days with Good Air Quality, 2006-2015

  • Six air quality pollutants are considered to determine good air quality, set by the U.S. Environmental Protection Agency: ozone (O3), particulate matter (PM10 and PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and lead (Pb).
  • The percentage of monitored days in the Bay Area with good air quality dropped sharply in 2013, but rose significantly in all Bay Area counties in 2015.
  • In 2015, P.M 2.5 reached the “Moderate” range 32 days, although the county had zero days in the category of “Unhealthy for Sensitive Groups” for San Mateo County. Ozone levels reached the moderate range for two monitored days.


  • All nine Bay Area counties increased their percent of monitored air days with “Good” quality from 2014 to 2015.
  • In 2015, San Mateo County came close to the peak of Good Air Quality days (93%) it saw in 2012, and rebounded from an off-year in 2013.
  • Alameda County’s air quality dropped significantly from 2014-2015 by 9%.

Drought & Dirty Air

Eleven consecutive Spare the Air days were issued by the Bay Area Air Quality Management District (BAAQMD) in January of 2015, equivalent to 2014’s record of eleven days. BAAQMD issues Spare the Air day alerts to warn Bay Area residents of poor air quality. The BAAQMD’s main goal in the winter is to curb the burning of firewood, which releases fine particles and soot. These particles can be harmful to children and the elderly, but those with asthma and respiratory problems are at the highest risk. A dry winter contributed to trapped particles in the air, with no source of strong winds and rains to push the pollutants away.


  • While San Mateo County’s emergency department visit rate for asthma is lower than California’s, significant disparities exist within the county by race/ethnicity.

An Unequal Burden

Emergency department visits for asthma are usually a result of poor asthma management, lack of primary care, and exposure to triggers such as air pollution. Many of these triggers”vehicle pollution, mold, rodents, and cockroaches”disproportionately impact low-income families who are more likely to live near freeways or in less expensive rental housing that has not been properly maintained.In San Mateo County, childhood hospitalization rates for asthma (per 10,000 population) were highest in these three zip codes: (For comparison, the state-wide rate is 11.)

  • 94303 (East Palo Alto) 15.0
  • 94061 (Redwood City) 12.5
  • 94025 (Menlo Park) 10.7
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Blue skies over Hillsborough.

Photo courtesy of Jack Gordon.

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Drought Monitor


Source: United States Drought Monitor (http://droughtmonitor.unl.edu)

  • 46% of the state is in exceptional drought, the highest level, as of October 9, 2015.
  • The urban and agricultural areas of California are experiencing the most intense part of the drought.
  • San Mateo County and the rest of the Bay Area are currently in extreme drought conditions, which increases the risk of larger fires.
  • California population, 2014 estimate: 38,802, 500 (US Census Bureau).
  • Population affected by California drought: 37,014,818.

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Water: Supply and Demand

The State Water Resources Control Board releases conservation data at the beginning of every month. We pull data from San Mateo County water agencies and show how each is progressing on their new conservation targets. These conservation targets, or tiers, were established by the Water Board based on prior conservation efforts and overall usage per capita by each agency.


  • The state assigned a conservation standard to each water supplier based on their average residential gallons per capita day (R-GPCD) usage from July-Sept 2014. These conservation standards are used to ensure that the state, on average, reduces its water consumption by 25% compared to 2013 usage. The State Water Board’s compliance period for water suppliers began on June 1st and lasts through February 2016. The Board will track compliance on a cumulative basis following the month of June.
  • Hillsborough has seen the largest percentage of water savings.
  • All water suppliers are either meeting or exceeding their conservation standards heading into the month of June.
  • For more information on SSMC’s methodology for this indicator, please see our appendix.

Water Conservation


  • The county as a whole has reduced water use by 14%, which is short of the 25% reduction target for the state as a whole.
  • Redwood City, Cal Water Mid-Peninsula, and Cal Water Bear Gulch have had the largest total water savings, each saving more than 500 million gallons of water.
  • City of Menlo Park and Town of Hillsborough lead the county in percentage reduction with 26% saved.
  • 10 of the 16 water suppliers with assigned conservation tiers are exceeding their requirements.
  • For more information on SSMC’s methodology for this indicator, please see our appendix.

Water Consumption vs. Population Growth


  • San Mateo County’s Population has grown steadily since 2006; however, total water consumption has decreased by over 14 million gallons per day since its peak in 2000.
  • Since 2011, water consumption has grown slightly overall, but is still decreasing per-capita.
  • County water use in FY 2013-2014 was at 82.96 MGD (Million gallon/day), below the supply assurance of 90.96 MGD.
  • Annual usage has been trending upwards since FY 2010-2011 due to population growth. Officials will need to consider other supply options if population trends continue.

Water Recycling

Water recycling is an important element of water conservation and the practice is increasing in San Mateo County homes and businesses. Though drinking water must be of the highest quality, many other uses for water, including irrigation and commercial processes are suited for reused water. Non-potable recycled water has lower levels of nitrogen and phosphorous, which is a health benefit for the bay. Locally, Redwood City provides recycled water to businesses and residents through purple pipes. Daly City uses recycled water to irrigate the Lake Merced Golf Course, decreasing the demand on the lake itself. Wastewater treatment is a highly regulated process that may produce water suitable for drinking (potable reuse). The Bay Area Water Supply and Conservation Agency (BAWSCA) is considering recycled water recharge for the San Mateo sub-basin.

See our solutions page for information on residential greywater systems.

Water Use by Supply Source


  • 91% of the county’s water is sourced from San Francisco Public Utilities Commission (SFPUC), while the other 9% is sourced locally.
  • SFPUC’s water supply comes from Hetch Hetchy.
  • Burlingame (7.3%) and Redwood City (6.8%) have the highest recycled water usage, while cities like Daly City (4.2%) and Millbrae (1%) also use recycled water.
  • Daly City (44.6%) and San Bruno (54.26%) also rely on groundwater for roughly half of their water supply. North county cities account for nearly all of the county’s groundwater usage; they have a groundwater management plan with SFPUC.

Water Use by Customer Class


  • Approximately 67% of San Mateo County’s water is used for residential purposes, 56% of it used for single-family residential homes.
  • For tips on how to reduce water usage, please visit our resources page.

Lawn Be Gone

Outdoor irrigation can make up more than 50% of residential water use for the average California homeowner. The Bay Area Water Supply and Conservation Agency (BAWSCA) Lawn Be Gone Program provides rebates ranging from $500-$3,000 to approved customers for converting lawns to water-efficient landscapes. To be eligible for this program, an applicant must be a customer of a participating BAWSCA Member Agency. For more information, visit The Bay Area Water Supply and Conservation Agency (BAWSCA) Lawn Be Gone Program. [/smc-box] PhotoContest12.gif

A local San Mateo County home where over 2,000 square feet of water-thirsty lawn was replaced with drought-tolerant California native grasses. Photo courtesy of Jessica Norling.

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Water Quality: Bay and Ocean

Sanitary Sewer Overflows (SSOs) are caused by unintentional discharges of raw sewage into bay and ocean water. This can happen through a variety of causes ranging from blockage and defects to power failure. Heavy rainwater can pour into cracked or clogged sewer pipes, causing untreated sewage to overflow into storm drains and area waterways. San Mateo County, with its aging sewer systems, is at heightened risk of sanitary sewer overflows. San Francisco Baykeeper, a local nonprofit, tracks sanitary sewer overflows and has used the Clean Water Act to file lawsuits against the greatest offenders.


  • Heavy rainwater can pour into cracked or clogged sewer pipes, causing untreated sewage to overflow into storm drains and area waterways. San Mateo County, with its aging sewer systems, is at heightened risk of sanitary sewer overflows.
  • In water year 2015 (running from: 10/1/14-9/30/15), over 1,880,528 gallons of raw or partially-treated sewage spilled in San Mateo County, well above the 151,090 gallons that spilled in water year 2014.
  • Contra Costa County saw the greatest increase in total spill volume in the nine-county Bay Area compared to 2014.


A beach at Half Moon Bay.

Photo courtesy of Shelby Scherer.


Beach Report Card, San Mateo County, 2014-2015

  • The Beach Report Card assesses water quality based on the health risk for beachgoers and assigns letter grades (A being best and F being worst). Beach scores are broken out by Summer Dry Period (April-October) and Wet Weather (sample collected during or within three days of a rainstorm).
  • In wet weather, half of county beaches monitored had water quality that posed a health risk for beachgoers, versus only 10% for the summer dry period.
  • Wet weather results in stormwater runoff, which carries untreated contaminants like motor oil, animal waste, pesticides, and sometimes sewage directly from our streets and wastewater treatment plants to our beaches. Stormwater is the largest source of pollution in our waterways.
  • San Mateo County’s summer dry grades were excellent, with 91% of the 21 locations receiving an A or B grade. Winter dry weather grades were very good, with 81% receiving A or B grades (data not included in the above chart).
  • The County of San Mateo Environmental Health Department monitors 21 ocean and bayside locations on a weekly basis year round.


  • Aquatic Park and Lakeshore Park again top the list of most polluted county beaches. Both beaches are lagoon-based with limited circulation potential and were also impacted by sanitary sewer overflows.

Green Streets and Parking Lots

Green Streets integrate trees and water-absorbing landscapes or other pervious surfaces into streets, sidewalks, and parking lots to filter and dissipate stormwater. Traditional street design funnels stormwater directly into sewer systems that empty into watersheds untreated. This water is often polluted with trash, construction debris, pesticides and other chemicals. When new buildings are constructed or streets/sidewalks are repaired, green streets offer an opportunity to balance development through sustainable designs that mimic natural systems.

Visit the San Mateo Countywide Water Pollution Prevention Program website to learn more about stormwater management.

Brisbane City Hall, Rain Garden.
Photo by Matt Fabry.


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Solid Waste


  • The solid waste reported above includes content that is part of CalRecycle’s recycling program and everything disposed in landfill, including the materials used to temporarily overlay exposed landfills.
  • Tons of waste disposed in San Mateo County increased 6% in 2015. This is partially due to population growth as well as an increase in business related disposal and enhanced recycling programs.
  • 18 millions tons of recyclable material were exported from California by sea in 2014, with an estimated value of $6.9 billion.
  • According to a 2014 study of the composition of solid waste in California, over 17% is paper, at least 16% is food, and approximately 10% is plastic.

  • The per capita disposal rate increased by 5% in San Mateo County and 4.5% for the state of California from 2014 to 2015. CalRecycle suggests that this increase is due to growth in the labor market, real estate market, and construction.
  • Per capita daily countywide disposal has declined 26% from 2006 to 2015.
  • The county recycling rate in 2013 was 50%, higher than the national average of 34.5% (not including green waste used as landfill cover and fuel).


Local Initiative: Reusable Bag Ordinance

Estimates show that Bay Area residents use between 42 and 227 plastic bags per person annually. These bags do not biodegrade, and they clog storm drains, harm wildlife, and pollute local waterways.

Under San Mateo County’s Reusable Bag Ordinance, which went into effect April 22, 2013, retail stores in unincorporated San Mateo County are no longer distributing plastic bags to customers. The Ordinance will not apply to plastic bags used for restaurant take-out, produce, meats, bulk foods, and prescription medicines.

Customers who don’t have a reusable bag will be charged ten cents for a paper bag, with the price increasing to twenty-five cents by January 2015.

As of March 2013, 18 cities in San Mateo County have adopted similar bans. Making the ordinance regional will create consistency for businesses and shoppers.

For more information, visit smchealth.org.


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