Chico 2019 Water Quality Report


Water on a leafWe encourage you to review this annual water quality report, also called your Consumer Confidence Report, as it details any constituents detected in your water supply in 2019 and shows how your water compares to federal and state standards.

If you have any questions, please Contact Us. We are here to assist you.

Your Water System

Water pipeDistrict: Chico
System: Chico
System ID: #410002

Cal Water has provided high-quality water utility services in the Chico area since 1926. To meet the needs of our Chico customers, we use 63 wells to pump an average of 15.9 million gallons of groundwater per day, which is delivered to customers through 373 miles of pipeline, nine storage tanks, and 11 booster pumps.

Our company-wide water quality assurance program includes vigilant monitoring throughout our systems and testing at our state-of-the-art laboratory. Additionally, we proactively maintain and upgrade our facilities to ensure a reliable, high-quality supply.

If you have any questions, suggestions, or concerns, please contact our local Customer Center, either by phone at (530) 893-6300 or through the Contact Us page.


By the end of 2002, Cal Water had submitted to the Division of Drinking Water (DDW) a Drinking Water Source Assessment and Protection Program (DWSAPP) report for each water source in the water system. The DWSAPP report identifies possible sources of contamination to aid in prioritizing cleanup and pollution prevention efforts. All reports are available for viewing or copying at our Customer Center.

The water sources in the Chico District are considered most vulnerable to the following activities associated with contaminants detected in the water supply: sewer collection systems, septic systems, parks, RV parks, agricultural drainage, fertilizer and pesticide application, automobile body and repair shops, utility stations (maintenance areas), railroad yards (maintenance/fueling areas), electrical/electronic manufacturing, chemical/petroleum processing or storage, machine shops, grazing, lumber processing/manufacturing, wood preserving/treating, fleet/truck/bus terminals, known contaminant plumes, and drinking water treatment plants.

The water sources are considered most vulnerable to the following activities, for which no associated contaminant has been detected:

  • Gas stations
  • Metal plating (finishing/fabricating)
  • Junk/scrap/salvage yards
  • Furniture repair/manufacturing
  • Dry cleaners
  • Home manufacturing
  • Dredging
  • High-density housing
  • Storm drain discharge
  • Freeways
  • Railroads
  • Road right-of-ways
  • Chemical/petroleum processing or storage
  • Fleet/truck/bus terminals
  • Machine shops
  • Photo processing/printing
  • Above-ground storage tanks
  • Wells (water supply and agricultural)
  • Automobile body and repair shops
  • Parks
  • Grazing
  • Sewer collection systems
  • Lumber processing/manufacturing
  • Wood/pulp/paper processing and mills
  • boat services/repair/refinishing
  • Airports (maintenance/fueling areas)
  • Irrigated crops
  • Hospitals
  • Farm machinery repair
  • Historic waste dumps/landfills
  • Food processing

A copy of this assessment may be viewed at:
DDW Valley District Office
364 Knollcrest Drive
Redding, CA 96002

We encourage customers to join us in our efforts to prevent water pollution and protect our most precious natural resource.

The Water Quality Lab

Laboratory equipmentWater professionals collect samples from throughout the water system for testing at our state-of-the-art water quality laboratory, which is certified each year through the stringent Environmental Laboratory Accreditation Program (ELAP). Scientists, chemists, and microbiologists test the water for 326 constituents with equipment so sensitive it can detect levels as low as one part per trillion. In order to maintain the ELAP certification, all of our scientists must pass blind-study proficiency tests for every water quality test performed. Water quality test results are entered into our Laboratory Information Management System (LIMS), a sophisticated software program that enables us to react quickly to changes in water quality and analyze water quality trends in order to plan effectively for future needs.

Possible Contaminants

Laboratory equipmentAll drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk.

More information about contaminants and potential health effects can be obtained by calling the United States Environmental Protection Agency (EPA) Safe Drinking Water Hotline at (800) 426-4791.

The sources of drinking water (both tap and bottled) include rivers, lakes, streams, ponds, reservoirs, springs, and wells. As water travels over the surface of the land or through the ground, it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or human activity.

Contaminants that may be present in source water include:

  • Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.
  • Inorganic contaminants, such as salts and metals, which can be naturally occurring or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining, or farming.
  • Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.
  • Organic chemical contaminants, including synthetic and volatile organic chemicals, which are byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff, agricultural application, and septic systems.
  • Radioactive contaminants, which can be naturally occurring or the result of oil and gas production and mining activities.

In order to ensure that tap water is safe to drink, the EPA and DDW prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. FDA regulations establish limits for contaminants in bottled water, which must provide the same protection for public health.

Some people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised people, such as those with cancer undergoing chemotherapy, those who have undergone organ transplants, and those with HIV/AIDS or other immune system disorders; some elderly people; and infants can be particularly at risk from infections. These people should seek advice from their health care providers about drinking water. EPA and Centers for Disease Control and Prevention (CDC) guidelines on appropriate means to lessen the risk of infection by cryptosporidium and other microbial contaminants are available from the Safe Drinking Water Hotline.

About Lead

Laboratory equipmentAs the issue of lead in water continues to be top of mind for many Americans, Cal Water wants to assure you about the quality of your water. We are compliant with health and safety codes mandating use of lead-free materials in water system replacements, repairs, and new installations. We have no known lead service lines in our systems. We test and treat (if necessary) water sources to ensure that the water delivered to customer meters meets all water quality standards and is not corrosive toward plumbing materials.

The water we deliver to your home meets lead standards. However, if present, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing (for example, lead solder used to join copper plumbing, and brass and other lead-containing fixtures).

Cal Water is responsible for providing high-quality drinking water to our customers' meters, but cannot control the variety of materials used in plumbing components. When your water has been sitting for several hours, you can minimize the potential for lead exposure by flushing your tap for 30 seconds to 2 minutes before using water for drinking or cooking.

If you are concerned about lead in your water, you may wish to have your water tested by a certified lab. More information about lead in drinking water can be found on the Safe Drinking Water Hotline or at

Testing for Lead in Schools

The State of California required that all public schools built before 2010 test for lead in their drinking water by July 1, 2019. We are committed to supporting our school districts' efforts to protect students and ensure that the drinking water at their school sites are below lead limits. We worked with all school districts in our service area that serve kindergarten through 12th grade to develop sampling plans, test samples, and conduct follow-up monitoring, if needed, for corrective actions. We have published the total number of schools requesting testing from last year in this year's Water Quality report.

For more information, please see our Testing for Lead in Schools web page. For specific information regarding local school data, see the state web portal.

Lead and Copper Rule

The lead and copper rule requires us to test water inside a representative number of homes that have plumbing most likely to contain lead and/or lead solder to determine the presence of lead and copper or any action level exceedance (AL). An action level is the concentration of a contaminant which, when exceeded, triggers corrective actions before it becomes a health concern. If action levels are exceeded, either at a customer's home or system-wide, we work with the customer to investigate the issue and/or implement corrosion control treatment to reduce lead levels.

Lead Service Line Inventory (LSLI)

Protecting our customers' health and safety is our highest priority. As part of this commitment, we have been working to identify and replace any old customer water service lines and fittings that may contain lead. California Senate Bill (SB) 1398 requires all water utilities in California to develop an inventory of all distribution service line materials, and submit a list of known service lines to the state by 2018. A list of unknown service lines that may contain lead, along with a plan for replacement, is due to the state by July 1, 2020. Known lines are replaced as soon as possible.

More information regarding LSLI and specific data for each water system can be found on the state web site.

Key Definitions

Fish bowlMaximum Contaminant Level (MCL): The highest level of a contaminant that is allowed in drinking water. Primary MCLs protect public health and are set as close to the PHGs (or MCLGs) as are economically and technologically feasible. Secondary MCLs (SMCLs) relate to the odor, taste, and appearance of drinking water.

In Compliance: Does not exceed any applicable MCL, SMCL, or action level, as determined by DDW. For some compounds, compliance is determined by averaging the results for one source over a one-year period.

Regulatory Action Level (AL): The concentration of a contaminant which, if exceeded, triggers treatment or other required action by the water provider.

Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs are set by the EPA.

Maximum Residual Disinfectant Level (MRDL): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants.

Maximum Residual Disinfectant Level Goal (MRDLG): The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs are set by the EPA and do not reflect the benefits of the use of disinfectants to control microbial contaminants.

Non-Detect (ND): The constituent was not detected.

Notification Level (NL) and Response Level (RL): Health-based advisory levels for unregulated contaminants in drinking water. They are used by DDW to provide guidance to drinking water systems.

Primary Drinking Water Standard (PDWS): MCLs and MRDLs for contaminants that affect health, along with their monitoring, reporting, and water treatment requirements.

Public Health Goal (PHG): The level of a contaminant in drinking water below which there is no known or expected risk to health. PHGs are set by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment without regard to cost or available detection and treatment technologies.

Treatment Technique (TT): A required process intended to reduce the level of a contaminant in drinking water.

Table Introduction

Water moleculeCal Water tests your water for more than 140 regulated contaminants and dozens of unregulated contaminants. This table lists only those contaminants that were detected.

In the table, water quality test results are divided into several major sections (as needed): "Primary Drinking Water Standards," "Secondary Drinking Water Standards," "State-Regulated Contaminants with Notification Levels," and "Unregulated Compounds." Primary standards protect public health by limiting the levels of certain constituents in drinking water. Secondary standards are set for substances that don't impact health but could affect the water's taste, odor, or appearance. Some unregulated substances (hardness and sodium, for example) are included for your information. The State allows us to monitor for some contaminants less than once per year because the concentrations of these contaminants do not change frequently. Some of our data, though representative, are more than one year old.

A list of codes found in the "Source" column and their definitions can be found at the bottom of this page.

Water Quality Table

Primary Drinking Water Standards

Microbiological Year Tested Unit MCL PHG (MCLG) In Compliance Distribution System-Wide Source
Highest Monthly
Total coliform
(systems with >40 samples/month) (Total Coliform Rule)
2019 Positive samples 5% (0) Yes 0 EN
Fecal coliform and E. coli 2019 Positive samples 11 (0) Yes 0 FE
Radiological Year Tested Unit MCL PHG (MCLG) In Compliance Groundwater Source
Range Average
Gross alpha 2011-2019 pCi/L 15 (0) Yes ND-4.8 ND ER
Radium 226 2012-2019 pCi/L n/a 0.05 Yes ND-4.0 ND ER
Inorganic Year Tested Unit MCL PHG (MCLG) In Compliance Groundwater Source
Range Average
Fluoride2 2011-2019 ppm 2 1 (4.0) Yes ND-0.11 ND ER, FL
Nitrate as N3 2015-2019 ppm 10 10 (10) Yes ND-9.5 2.0 ER, FR
Lead and Copper Year Tested Unit AL PHG (MCLG) In Compliance Distribution System-Wide Source
90th Percentile Samples > AL
Copper 2017 ppm 1.3 0.3 Yes 0.16 0 of 52 IC, ER, WD
Lead 2017 ppb 15 0.2 Yes ND 0 of 52 IC, IM, ER
Schools that requested lead sampling in 2019: 4
Volatile Organic Contaminants Year Tested Unit MCL PHG (MCLG) In Compliance Groundwater Source
Range Average
1,1-Dichloroethane 2014-2019 ppb 5 3 Yes ND-0.50 ND EX
cis-1,2-Dichloroethylene 2014-2019 ppb 6 13 (70) Yes ND-1.9 ND CF, BB
Tetrachloroethylene (PCE) 2014-2019 ppb 5 0.06 (0) Yes ND-2.0 ND FD
Disinfection Byproducts Year Tested Unit MCL PHG (MCLG) In Compliance Distribution System-Wide Source
Range Highest Annual Average
Haloacetic acids 2019 ppb 60 n/a Yes ND ND DI
Total trihalomethanes 2019 ppb 80 n/a Yes ND-3.2 1.4 DI
Disinfectants Year Tested Unit MRDL MRDLG In Compliance Distribution System-Wide Source
Range Average
Chlorine 2019 ppm 4 4 Yes 0.28-0.87 0.57 DS

Secondary Drinking Water Standards

Contaminants Year Tested Unit SMCL PHG (MCLG) In Compliance Groundwater Source
Range Average
Chloride 2011-2019 ppm 500 n/a Yes 1.7-60 11 RU, SW
Color 2011-2019 UNITS 15 n/a Yes ND-5.0 ND OM
Specific conductance 2011-2019 US 1600 n/a Yes 210-660 307 SW, IO
Manganese 2011-2019 ppb 50 n/a Yes ND-29 ND RU
Odor 2011-2019 T.O.N. 3 n/a Yes ND-1.0 ND OM
Sulfate 2011-2019 ppm 500 n/a Yes 1.3-16 5.8 RU, IW
Total dissolved solids 2011-2019 ppm 1000 n/a Yes 160-430 214 RU
Turbidity 2011-2019 NTU 5 n/a Yes ND-0.44 0.14 SO

State Regulated Contaminants with Notification Levels

Contaminants Year Tested Unit NL PHG (MCLG) In Compliance Groundwater Source
Range Average
Hexavalent chromium4 2011-2019 ppb n/a 0.02 Yes ND-7.4 2.1 UR
Manganese 2011-2019 ppb 500 n/a Yes ND-29 ND RU
Perfluorooctanoic acid (PFOA)5,4 2019 ppt 5.1 n/a Yes ND-12 ND UR
Perfluorooctanesulfonic acid (PFOS)6,7 2019 ppt 6.5 n/a Yes ND-84 3.7 UR

Unregulated Contaminant Monitoring Rule UCMR

Contaminants Year Tested Unit MCL PHG (MCLG) In Compliance Groundwater Source
Range Average
Strontium 2015 ppb n/a n/a Yes 140 140 UR

Unregulated Compounds

Contaminants Year Tested Unit MCL PHG (MCLG) In Compliance Groundwater Source
Range Average
Alkalinity (total) 2011-2019 ppm n/a n/a Yes 95-270 131 UR
Calcium 2011-2019 ppm n/a n/a Yes 16-58 25 UR
Hardness (total) 2011-2019 ppm n/a n/a Yes 81-290 128 UR
Potassium 2011-2019 ppm n/a n/a Yes ND-3.8 0.58 UR
Magnesium 2011-2019 ppm n/a n/a Yes 10-36 16 UR
Sodium 2011-2019 ppm n/a n/a Yes 8.3-38 15 UR
Perfluorobutanesulfonic acid (PFBS) 2019 ppt n/a n/a Yes ND-9.0 ND UR
Perfuoroheptanoic acid (PFHpA) 2019 ppt n/a n/a Yes ND-6.0 ND UR
Perfluorohexanoic acid (PFHxA) 2019 ppt n/a n/a Yes ND-10 ND UR
Perfluorhexanesulfonic acid (PFHxS) 2019 ppt n/a n/a Yes ND-30 4.0 UR

1 The MCL for fecal coliform and E. coli is exceeded when a routine sample and a repeat sample are total coliform positive, and one of these is also E. coli positive.

2 Chico has 55 active groundwater wells. One of these wells had a single detection of 0.11 ppm of fluoride in 2017. Fluoride is not added to the water supply in Chico.

3 The average nitrate level was 2.0 ppm, with a maximum level at a single well of 9.5 ppm. We are closely monitoring the nitrate levels. Nitrate in drinking water at levels above 10 ppm is a health risk for infants of less than six months of age. Such nitrate levels in drinking water can interfere with the capacity of the infant’s blood to carry oxygen, resulting in a serious illness; symptoms include shortness of breath and blueness of the skin. Nitrate levels above 10 ppm may also affect the ability of the blood to carry oxygen in other individuals, such as pregnant women and those with certain specific enzyme deficiencies. If you are caring for an infant or you are pregnant, you should seek advice from your health care provider.

4 The previous MCL of 0.010 mg/L (10 ppb) for hexavalent chromium was withdrawn on September 11, 2017, and there is currently no MCL in effect.

5 In 2019, Cal Water tested all Chico wells for PFOS and PFOA. There is no MCL or SMCL for PFOS; however, there is an established NL and RL. In August 2019, DDW lowered the NL to 5.1 ppt for PFOA, with a combined RL of 70 ppt for PFOS and PFOA. 70 ppt is also EPA’s lifetime health advisory level (HAL).

6 In 2019, Cal Water tested all Chico wells for PFOS and PFOA. There is no MCL or SMCL for PFOS; however, there is an established NL and RL. In August 2019, DDW lowered the NL to 6.5 ppt for PFOS, with a combined RL of 70 ppt for PFOS and PFOA. 70 ppt is also EPA’s lifetime health advisory level (HAL). One of the wells tested over the RL at 84 ppt, but on multiple repeat tests, never rose above 12 ppt and the 84 ppt is considered to be an anomaly.

7 NLs are non-regulatory, health-based advisory levels established for constituents that may be candidates for MCLs in the future. The HAL is the level below which concentrations are not expected to result in adverse health effects over a lifetime of exposure; it was set to reflect a margin of protection for even the most sensitive populations. Studies indicate that long-term exposure to PFOS and PFOA over certain levels could have adverse health effects, including developmental effects to fetuses during pregnancy or infants; cancer; or liver, immunity, thyroid, and other effects. Cal Water is working closely with DDW and EPA to conduct extensive monitoring and identify the best available treatment technology for PFOS and PFOA.

Substance Sources

ASInternal corrosion of AC water mains
BBMajor biodegradation byproduct of TCE and PCE groundwater contamination
BDBiodegradation byproduct of TCE and PCE groundwater contamination
BHResidue of banned herbicide
BIResidue of banned insecticide
BNBanned nematocide that may still be present in soils due to runoff/leaching from former use on soybeans, cotton, vineyards, tomatoes, and tree fruit
BRResidue of banned insecticide and rodenticide
BTBanned nematocide that may still be present in soils due to runoff and leaching from grain and fruit crops
CFDischarge from industrial chemical factories
CPDischarge from chemical plants and other industrial activities
DCDischarge from industrial and agricultural chemical factories and dry cleaning facilities
DIByproduct of drinking water disinfection
DKDecay of natural and manmade deposits
DSDrinking water disinfectant added for treatment
EFDischarge from electroplating factories, leather tanneries, wood preservation, chemical synthesis, refractory production, and textile manufacturing facilities
ENNaturally present in the environment
ERErosion of natural deposits
EXExtraction and degreasing solvent; used in manufacture of pharmaceuticals, stone, clay and glass products; fumigant
FDDischarge from factories, dry cleaners, and auto shops (metal degreaser)
FEHuman and animal waste
FIFire retardants; ceramics; electronics; solder
FLWater additive that promotes strong teeth; discharge from fertilizer and aluminum factories
FMPrimary component of some fumigants
FRRunoff and leaching from fertilizer use; leaching from septic tanks and sewage
FSFuel solvent
FWManufacture of food wrappings
GPInternal corrosion of galvanized pipes; discharge from electroplating and industrial chemical factories and metal refineries; runoff from waste batteries and paint
HBRunoff/leaching from herbicide used on beans, peppers, corn, peanuts, rice, and ornamental grasses
HDRunoff from herbicide use for terrestrial and aquatic weeds; defoliant
HEHerbicide runoff
HPBreakdown of heptachlor
HRRunoff from herbicide used on row crops
HSRunoff from herbicide used on soybeans, vegetables, and fruits
HTRunoff from herbicide use for terrestrial and aquatic weeds
IADischarge from industrial and agricultural chemical factories; leaching from hazardous waste sites; used as cleaning and maintenance solvent, paint and varnish remover, and cleaning and degreasing agent; byproduct of production of other compounds and pesticides
ICInternal corrosion of household plumbing systems
IDIndustrial discharges
IFDischarge from industrial factories; degreasing solvent; propellant and refrigerant
ILRunoff/leaching from insecticide used on cattle, lumber, and gardens
IMDischarge from industrial manufacturers
INRunoff/leaching from insecticide used on cotton and cattle
IOSubstances that form ions when in water
ITRunoff/leaching from insecticide used on field crops, fruits, and ornamentals, especially apples, potatoes, and tomatoes
IVRunoff/leaching from insecticide used on fruits, vegetables, alfalfa, and livestock
IWIndustrial waste
LARunoff from landfills; discharge of waste chemicals
LELeaking underground storage tanks
MADischarge from metal refineries and agricultural chemical factories; byproduct of chlorination reactions in wastewater
MDDischarge from metal-degreasing sites and other factories
MFDischarge from metal factories
MRDischarge from metal refineries, coal-burning factories, and electrical, aerospace, and defense industries
MSDischarge from metal degreasing sites and other factories; dry cleaning solvent; refrigerant
MUMunicipal and industrial waste discharges
OCRunoff from orchards; glass and electronics production waste
ODDischarges of oil-drilling waste and from metal refineries
OMNaturally occurring organic materials
ORLeaching from ore-processing sites; discharge from electronics, glass, and drug factories
PCDischarge from petroleum and chemical factories
PDDischarge from plastics, dyes, and nylon factories; leaching from gas storage tanks and landfills
PGDischarge from petroleum, glass, and metal refineries; discharge from mines and chemical manufacturers; runoff from livestock lots (feed additive)
PHInherent characteristic of water
PIDischarge from pharmaceutical and chemical factories; insecticide
PRInorganic chemical used in solid rocket propellant, fireworks, explosives, flares, matches, and a variety of industries; usually gets into drinking water as a result of environmental contamination from historic aerospace or other industrial operations that used or use, store, or dispose of perchlorate and its salts
PTDischarge from petroleum refineries
PVLeaching from PVC piping; discharge from plastics factories; biodegradation byproduct of TCE and PCE groundwater contamination
RBDischarge from rubber and chemical factories; inert ingredient in pesticides
RCRunoff from herbicide used on row crops, range land, lawns, and aquatic weeds
RFDischarge from refineries and factories; runoff from landfills and cropland
RIRunoff/leaching from rice herbicide
RURunoff/leaching from natural deposits
RPDischarge from rubber and plastic factories; leaching from landfills
RRRunoff from herbicide used on row crops and along railroad and highway rights-of-way
RSResidue from some surface water treatment processes
RTRunoff/leaching from nematocide used on croplands
RWRunoff from herbicide used on rights-of-way, and crops and landscape maintenance
SFLeaching of soil fumigant used on rice, alfalfa, and grape vineyards
SMDischarge from steel/metal, plastic, and fertilizer factories
SOSoil runoff
SPDischarge from steel and pulp mills and chrome plating
SWSeawater influence
TCDischarge from industrial and agricultural chemical factories; solvent used in production of TCE, pesticides, varnish, and lacquers
TXDischarge from textile-finishing factories
UNUnderground gas tank leaks
VAVarious natural and manmade sources
WDLeaching from wood preservatives
WIEmissions from waste incineration and other combustion
WPDischarge from wood preserving factories, cotton, and other insecticidal/herbicidal uses
WSLeaching from linings of water storage tanks and distribution mains
URUnregulated constituents with no source listed and that do not have standardized "source of substance" language

Thank You

Hands catching waterA full-color, printable version of this report in PDF format is also available.

If you have any questions about your water quality table, please Contact Us.