National Pollutant Discharge Elimination System (NPDES)

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Water purveyors regularly discharge drinking water into storm drains or other conveyances that drain to surface waters. Planned discharges are part of a water purveyor's essential operations to comply with the federal Safe Drinking Water Act and the California Health and Safety Code for providing reliable and safe drinking water. Surface water discharges also occur from pipe breaks, system failures, and emergencies.

Section 402 of the Clean Water Act requires that a discharge of any pollutant or combination of pollutants to surface waters that are deemed waters of the United States be regulated by a National Pollutant Discharge Elimination System (NPDES) permit. To provide coverage to discharges by water purveyors to waters of the United States in compliance with Clean Water Act section 402, the State Water Board adopted the Statewide General NPDES Permit for Drinking Water System Discharges to Waters of the United States on November 18, 2014. To get coverage under the permit, a water purveyor (community drinking water system or wholesaler) must submit an application to the State Water Board no later than September 1, 2015. Alternatively, if a water purveyor does not need coverage under the permit, it must submit a notice of non-applicability to the State Water Board also by September 1, 2015.

It is the intention of the State Water Board to regulate all mandatory low-threat-type discharges from community water systems statewide with consistent regulation. This means that with the transition from Regional Water Board permits to the statewide permit, the Regional Water Boards will no longer be regulating the mandatory low-threat-type discharges from drinking water systems that meet the criteria of the statewide permit. The new statewide permit provides coverage for unplanned and emergency discharges in addition to discharges from supply wells and distribution systems. The statewide permit also grants a regulatory exemption to water purveyors for compliance with federal water quality criteria (the California Toxic Rule), and requires minimal monitoring and reporting.

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