Why is this Important?

[smc-hide] Over the past decade, California residents have experienced two droughts: one from 2007-2009 and another beginning in 2012 through present day. The current California drought is one of the worst since recordkeeping began, and 2013 was the driest year in recorded history.

Rainfall has declined dramatically, causing most of the states major reservoir levels to drop below 50%. The federal government also declared all 58 counties in California as natural disaster areas due to the drought. As a result, Governor Brown issued the first state mandate to cutback urban water usage in April 2015. Water restrictions do vary by water usage per capita in each city; cities with low per-capita usage have lower restrictions.

In California, water is a key natural resource in the environment and affects multiple sectors directly and indirectly. Roughly half of the state’s water is used for environmental purposes”to maintain adequate flows and to protect threatened species. Of the remaining half, 80% is used for irrigation for farmers to support California’s agriculture sector. The rest of the state’s water is used for urban uses, including renewable energy, commercial, and residential uses. The drought has caused many farms to shut down due to a declining amount of irrigated water.

In the energy sector, hydroelectricity production has declined because of low reservoir levels. In response, natural gas usage has increased during the drought, causing an increase in GHG emissions. Other renewable sources of energy, such as solar and wind, have increased during this same time period as well. Although many rural areas of the state have felt the effects of the drought since its inception, many urban areas”such as San Mateo County”are now noticing the drought as water conservation has become stricter through fees, regulations, rebates, and outreach. [/smc-hide]

What is a Sustainable State?

[smc-hide] In a sustainable state, multiple water supplies would be carefully managed: ground water levels, reservoirs currently in use, and identification of newer storage facilities are all possibilities. Additionally, increased recycling, greywater, building and plumbing code updates, green and blue infrastructure, and desalination plant construction are a few additional options available for government agencies.

Agencies must take into account “worst case scenarios,” including the long term implications of climate change, when planning for water security. At home, households can install greywater systems that recycle water, repurpose water for toilets, install water efficient appliances, fix leaks, and remove lawns. The most important factor is to conserve water year round in order to reduce overall water usage. Conservation must be a priority during periods of drought as well as wet periods in order to reduce the risk of a water shortage. [/smc-hide]

Key Findings

  • The entire state of California is in an extreme drought, covering most of the state’s urban areas.
  • California only received between 25 and 50% of its average precipitation in 2013-2015.
  • Because of low precipitation across the state, Sierra snowpack is also at an all time low. Due to low precipitation levels and low snowpack levels, most of California’s major reservoirs are critically low.
[smc-trend-box] [smc-trend name=”Drought Monitor” dir=”down” new=1] [smc-trend name=”Rainfall” dir=”down” new=1] [smc-trend name=”Water: Supply and Demand” dir=”down” new=1 tags=”water_supply_and_demand”] [/smc-trend-box]

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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Percent of Average Precipitation, 2015 Water Year to Date


Source: Western Regional Climate Center. (http://www.wrcc.dri.edu)

  • As the new water year begins (10/01/2015), most of the Bay Area received almost none of its average precipitation.

California State Reservoir Conditions Screen Shot 2015-10-16 at 10.55.14 AM

Data source: Department of Water Resources, California Data Exchange Center


  • Due to low precipitation across the state, California’s major reservoirs are below their historical averages.
  • Lake Shasta, California’s largest reservoir, has declined from 53% in May to 34% in October.
  • All of the reservoirs above have fallen below 50% of capacity.


Dashboard 1-55

  • In 2013, departure from normal precipitation was at its lowest in the past 40 years at -7.3 inches and has risen slightly during the drought to -3.8 inches in 2014.

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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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