Chino Hills Water Quality

Chino Hills Water Quality Report


The city of chino hills drinking water supply is a blend of surface water (rivers, lakes, streams) and groundwater (wells). surface water is imported from Northern California by the Metropolitan Water District (MWD) of Southern California via the State Water Project aqueduct and is treated at the Agua de Lejos Water Treatment Plant located in Upland. Groundwater supplies are extracted via local wells operated by the city of chino or by the Chino Basin Desalter Authority (cDA). In 2017, treated groundwater represented approximately 75% of your drinking water supply, while the remaining 25% was produced by the Agua de Lejos Water Treatment Plant.

source water assessments were conducted in 2001, 2007 and 2017 to determine the contamination vulnerabilities of the city of chino’s active wells. You may request a summary of the assessments by contacting the state Water Resources Control Board Division of Drinking Water (sWRcB-DDW) District Engineer at (909) 383-4328.


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

Contaminants that may be present in source water include:

Pesticides and herbicides, which may come from a variety of sources such as agriculture, urban stormwater runoff, and residential uses.

Microbial contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations, and wildlife.

Radioactive contaminants, which can be naturally occurring or be the result of oil and gas production or mining activities.

Inorganic contaminants, such as salts and metals, which can be naturally occurring or result from urban storm runoff, industrial or domestic wastewater discharges, oil and gas production, mining and farming.

Organic chemical contaminants, including synthetic and volatile organic chemicals, which are by-products of industrial processes and petroleum production, and can also come from gasoline stations, urban stormwater runoff, agricultural application, and septic systems


Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised people, such as those with cancer who are undergoing chemotherapy, persons who have had organ transplants, people with HIV/AIDS or other immune system disorders, some elderly persons and infants can be particularly at risk from infections. These people should seek advice about drinking water from their health care providers.

The USEPA and the federal Centers for Disease Control
guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from USEPA’s Safe Drinking Water Hotline at (800) 426-4791 between 10 a.m. and 4 p.m. Eastern Time (7 a.m. to 1 p.m. in California)- source: 2017 Rowland Water consumer confidence report.

Click here to find out the water quality of other cities in Southern California


In 1979, the County of San Bernardino initiated the development of the Chino Hills Specific Plan – the document that would plan for the eventual development of 18,000 acres – 26 square miles – located in Chino Hills.  The area had been protected from haphazard development because the land was not flat enough to build inexpensively.  It was clear, however, that development pressures were moving toward Chino Hills.  The innovative Specific Plan was the first in the State of California to be designed for an unincorporated area.  A Citizen’s Advisory Committee and County officials worked in cooperation with 150 property owners to develop the Plan.  The Southwest Hills Environmental and Planning Association (SHEPA) also participated in the public land use discussions during that time.  The Specific Plan called for clustered residential development concentrated in village cores, decreasing in density away from the core to protect as much open space as possible.  Commercial development was slated along the Highway 71 corridor.  By 1982, when the Specific Plan was approved, there were approximately 4,000 homes and 12,000 residents in Chino Hills.

Chino Hills has always been a special place in Southern California. It is a place that is close in miles to large metropolitan cities and yet far in spirit. Virtually unchanged for hundreds of years, the rolling hills were home to a few ranches and homesteaders. A handful of property owners appreciated the beauty of the hills. The majority of the residents were red tail hawks, mule ear deer, ground squirrels, mountain lions, cottontail rabbits, and coyotes.