Water, Air & Waste

Water, Air & Waste

Water Supply and Demand  Bay and Ocean Water Quality  Drought Monitor  Air Quality  Solid Waste  Food Waste

Sustainability Goals

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.

Water Supply and Demand

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.

Updated June 2017 Water Consumption and Population Growth San Mateo County, 2000-2016
  • 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.
  • Conservation efforts in response to a historic drought are evident in the drastic reduction of water in the past two water years.

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.

  • 90% of the county’s water is sourced from San Francisco Public Utilities Commission (SFPUC), while the other 10% is sourced locally.
  • 85% of SFPUC’s water supply comes from Hetch Hetchy. The remaining 15% is gathered from surface water from the Alameda and Peninsula watersheds.
  • Burlingame (9%) and Redwood City (7.4%) have the highest recycled water usage, while Daly City (2.9%) and the Northcoast CWD (2%) also use recycled water.
  • The 2015-2016 water year saw a decrease in groundwater use by 5.5% compared to the 2013-2014 water year.
  • Only 4 San Mateo County water jurisdictions rely on groundwater to supplement their water supply.
  • Groundwater accounts for half of San Bruno’s water supply, and 23.9% of Daly City’s, 17% of South San Francisco’s, and 0.2% of Coastside CWD.
  • North County accounts for nearly all of the county’s groundwater usage; they have a groundwater management plan with SFPUC.
Updated June 2017Water Users by Agency and Customer Class San Mateo County, 2016Updated June 2017
  • Residential water use decreased slightly to 63% in 2016 compared with 67% in 2014.
  • 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.


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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Bay and Ocean Water Quality

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 2016 (running from: 10/1/15-9/30/16), 1,658,316 gallons of raw or partially-treated sewage spilled in San Mateo County, below the 1,880,528 gallons that spilled in water year 2015.
  • Sonoma County saw the greatest increase in total spill volume in the nine-county Bay Area compared to 2015.
Updated March 2017

  • San Mateo County’s public beaches are priceless conservation areas enjoyed by people of all economic backgrounds. Visitors are drawn to our beaches from throughout the region and across the world.
  • The County of San Mateo Environmental Health Department monitors 22 ocean and bayside locations on a weekly basis year round to gather the data compiled within Heal the Bay’s beach report card.
  • The Beach Report Card assesses water quality based on the health risk for beachgoers and assigns letter grades. Beach scores are divided into the summer dry period (April–October) and wet weather period (data collected during or within three days of a rainstorm).
  • 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 very good, with 87% of the 22 locations receiving an A or B grade, compared to excellent grades in the previous water year with 91% A or B grades. 2015-2016 also saw a decline in beach grades during wet weather periods with 36% A or B grades compared to 52% A or B grades in the prior year.
  • The lowest summer dry period grade was a “D”, received by Pillar Point Beach in San Mateo County.

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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Drought Monitor

Updated March 2017

Source: United States Drought Monitor (

  • Though drought conditions have improved since January 2016, the long-term impacts on groundwater supplies persist.
  • California’s historically arid climate coupled with changes in precipitation due to climate change are likely to make drought conditions more common in the future.
  • Extreme drought continues in parts of Santa Barbara, Venture, and Los Angeles counties.

Drought and 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.

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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 two air quality monitoring stations in Redwood City and the San Carlos Airport. Of the key air pollutants measured at this station, only ozone and particulate matter have exceeded state or federal standards in the past decade.

  • Six air quality pollutants are considered to determine good air quality, set by the U.S. Environmental Protection Agency: ozone (O3), particulate matter (PM10and PM5), 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 2014.
  • In 2016, PM 2.5 reached the “Moderate” range on 58 days, compared with 32 days in 2015. However, the county had zero days in the category of “Unhealthy for Sensitive Groups”.
  • Ozone levels reached the moderate range for 6 monitored days in 2016, compared to 2 days in 2015.

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%).

  • All nine Bay Area counties increased their percent of monitored air days with “Good” quality from 2015 to 2016, except San Mateo County.

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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 2.2% in 2016. This is partially due to population growth as well as an increase in business related disposal and enhanced recycling programs.
  • 18 million 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 1.5% in San Mateo County and 5% for the state of California from 2015 to 2016. 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 19% from 2007 to 2016.
  • 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

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Food Waste

40% of food produced in the US goes to waste, while a significant number of people are food insecure. The opportunity to feed the hungry with excess food is lost, as well as the water and energy used to produce and transport the food.

According the ReFED Report:

  • 16% of food waste is generated on farms
  • 2% is created during food manufacturing
  • 40% is produced by customer facing businesses (grocery stores, restaurants, and institutions)
  • 43% is discarded in homes

Considering just the retail food landscape, 31% or 133 billion pounds of food available to retailers and consumers is wasted, which represents a financial loss of $161 billion (EPA, 2015).

In the US, food is the single largest waste stream in landfills. When food decomposes in a landfill, it generates methane gas that is released into the atmosphere. This methane accounts for approximately 18% of landfill emissions across the US, and landfills are the third largest source of emissions (EPA, 2015).

In 2013 the USDA and EPA launched the Food Waste Challenge and announced the goal to collaborate with businesses and community organizations to reduce food waste 50% by 2030. To prioritize this effort, the EPA produced a Food Recovery Hierarchy that clarifies which waste reduction practices are most effective and sustainable.


Source Reduction and Feeding Hungry People

The USDA has initiated programs to fund source reduction by food producers such as on-farm storage to prevent spoilage of produce that is waiting to go to market, donation procedures for misbranded meat and poultry products, and education programs.

The Ugly Food Movement

Produce that is sold at retailers must appear to look perfect in size, shape, and color. This focus on the appearance and uniformity of food is often at odds with nature. Beginning at the farm, produce that is not fit for consumers is often discarded and tilled back into the soil. This practice is a missed opportunity for composting. Less than perfect produce that makes it off the farm is often sold at a discounted rate to food banks or produce delivery services that specialize in this budding market.

Consumers have an opportunity to prevent food waste by planning meals in advance of shopping, changing food storage habits, and donating unwanted food.

  • Find food storage tips on Make Dirt Not Waste.
  • Learn how to regrow certain types of produce from scraps on Food Revolution.
  • Store winter veggies in a root cellar, with help from the Farmers Almanac.
  • Village Harvest is a nonprofit organization that connects volunteers with those that have an over abundance of fruit trees in their yard or small orchard. Volunteers harvest the fruit and deliver it to local agencies that feed the hungry. The organization also provides education on fruit tree care and harvesting.

Food in Local Landfills

RethinkWaste conducted a food waste study in 2015 to learn how much food waste was mixed in with regular garbage. The results give a snapshot of food waste rates in San Mateo County and are comparable to national rates. The study found that 24% of the waste contributed by residential customers was compostable food waste and the rate was 6% higher for commercial waste. The compostable category includes soiled paper and fiber. The study found unopened soda, food, and beer cans in the trash, which is not unusual.

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Bay Area Water Supply and Conservation Agency’s (BAWSCA). Annual Survey FY 2014-2015.  Retrieved from:

State Water Resources Control, C. (n.d.). SSO Report Form. Retrieved February 19, 2017, from

Griffin, L., & Alamillo, J. (2016, May 24). 2015-16 Beach Report Card. Retrieved February 19, 2017, from

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From the 2017 Indicators Report

Annual per capita greenhouse gas emissions in California have dropped by 14% from a peak in 2001 of 14.0 metric tons per person to 12.0 metric tons per person in 2013.

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‟When one tugs at a single thing in nature, he finds it attached to the rest of the world.”—John Muir