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How Your Water Quality is Measured

Technician at one of NID’s water treatment plants ensuring our water meets all standards and regulations.

NID has been delivering water from the mountain top to your tap for 100 years, and we take this responsibility very seriously. In fact, our water consistently meets and exceeds State and Federally mandated water quality standards. Our water originates as snowmelt in 70,000 acres of high elevation watershed near the Yuba River, Bear River, and Deer Creek headwaters. The water is stored in 29 reservoirs before moving through one of six treatment plants and hundreds of miles of canal and pipe. Annually we deliver three billion gallons of high-quality drinking water and enough water to irrigate 30,000 acres of agricultural land.

NID is vigilant in meeting the challenges of new regulations, source water protection, water conservation, and community outreach and education. As we proceed through the year with our Plan for Water, these challenges are at the forefront of our discussions.

So What is Water Quality?

Water quality is a measure of the suitability of water for a particular use. This quality is based on selected physical, chemical, and biological characteristics. Water quality properties measured include alkalinity, biological oxygen demand, water color, dissolved oxygen, electrical conductance, water hardness, nitrogen, pH, phosphorus, and turbidity.

There are numerous state standards in effect in California per the Clean Water Act. In addition to the Environmental Protection Agency, California has a State Water Resources Control Board and nine Regional Water Quality Control Boards. Together they provide comprehensive protection for California's waters.

Why is Water Quality Important?

Water quality in the U.S. is considered among the safest in the world. However, contamination may still occur. Sewage, naturally occurring chemicals and minerals, fertilizers, pesticides, and manufacturing processes are all possible sources of contamination. The malfunctioning of an on-site wastewater treatment system or improperly maintained pipes may also contaminate the water.

Contaminated water can lead to health issues. Contaminants may cause gastrointestinal illness, reproductive problems, and neurological disorders. People with weakened immune systems, infants, young children, pregnant women, and the elderly may be especially at risk.

Sources of drinking water require appropriate treatment to remove disease-causing contaminants. The EPA sets standards and regulations for the presence and acceptable levels of contaminants in public drinking water to protect consumers. E. coli, Salmonella, Cryptosporidium, lead, and chemical byproducts are included. You can learn more about diseases and contaminants on the Centers for Disease Control and Prevention (CDC) website. You can also get more information about contaminants and potential health effects by calling the U.S. EPA's Safe Drinking Water Hotline at (800) 424-4791.

How Does NID Monitor Water Quality?

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NID performs weekly water quality testing. This strict sampling schedule ensures that your drinking water continues to meet State and Federal requirements. We also perform effective operation and maintenance of our drinking water distribution system, including annual flushing of water mains and rotation of stored supplies to keep water fresh and limit the growth of organisms.

The State does recommend monitoring certain substances less than once per year because the concentrations of these substances do not change frequently. You can view the Test Results of our Annual Water Quality Report on our website.

Water Quality Parameters

NID's water quality testing is based on a series of levels and goals, including:

  • Regulatory Action Level: The concentration of a contaminant that, if exceeded, triggers treatment or other requirements that a water system must follow.
  • Maximum Contaminant Level (MCL): The highest level of a contaminant allowed in drinking water. Primary MCLs are set as close to PHGs, or MCLGs, as is economically and technologically feasible. Secondary MCLs (SMLCs) are set to protect drinking water's odor, taste, and appearance.
  • Maximum Contaminant Level Goal (MCLG): The level of a contaminant in drinking water below which there is no known or expected health risk. The U.S. EPA sets MCLGs.
  • Maximum Residual Disinfectant Level (MRDL): The highest level of a disinfectant allowed in drinking water. There is convincing evidence that the addition of a disinfectant is necessary to control microbial contaminants.
  • Maximum Residual Disinfectant Level Goal (MRDLG): The level of disinfectant in drinking water below which there is no known or expected health risk. MRDLGs do not reflect the benefits of the use of disinfectants to control microbial contaminants.
  • Nephelometric Turbidity Units (NTU):  Measurement of the clarity of water. Turbidity is monitored because it is a good indicator of the effectiveness of our filtration system. Turbidity above 5 NTU is just noticeable to the average person.
  • Primary Drinking Water Standard (PDWS): MCLs and MRDLs for contaminants that affect health and their monitoring and reporting requirements and water treatment requirements.

Public Health Goal (PHG): The level of a contaminant in drinking water below which there is no known or expected health risk. The California EPA sets PHGs.

Delivering Safe, High-Quality Water to Your Tap

NID is committed to providing the best-quality drinking water possible, and we are ever vigilant in ensuring the safety of the water flowing from your tap. As we pledge water quality, we seek public participation. Our Board of Directors encourages you to participate in our water systems issues and become involved in our 50-year Plan for Water. Visit our Meetings & Events Calendar for Board Meeting dates and times and links to join via Zoom. After all, well-informed customers are our best allies!

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