Napa Sanitation District Code & NPDES Permit

Napa Sanitation District Code

The Napa Sanitation District Code regulates the use of public and private sewers and drains within the District. This includes the installation and connection of building sewers, the installation of sewer laterals, and public sewer main extensions. The Code also provides the fee structure for the installation and connection of sanitary sewers, regulates the discharge of waters and wastes into the public sewer system and provides penalties for the violations of any of these provisions.


National Pollutant Discharge Elimination System (NPDES) Permit

Napa Sanitation District has a permit to discharge treated wastewater under the National Pollutant Discharge Elimination System (NPDES). This system, established under the federal Clean Water Act, regulates point source dischargers (wastewater treatment plants, factories) as well as non-point sources (stormwater).

The District’s NPDES permit consists of waste discharge requirements specifying the amount of wastewater that can be discharged, sampling frequency, and the types of testing and monitoring that must be done by the District, and also sets limits of pollutant concentrations. The current NPDES permit was issued to the District jointly by the U.S. EPA and the San Francisco Bay Regional Water Quality Control Board (RWQCB) in February 2011. The District’s NPDES permit must be renewed every five years.

Under its NPDES permit, the District is allowed to discharge treated wastewater to the Napa River during the wet season, November 1 through April 30. NSD provides full secondary treatment of wastewater whenever discharging to the river. From May 1 through October 31, the dry season, discharge to the river is prohibited, and wastewater is either stored in the treatment ponds at the treatment plant, or treated to produce recycled water. The recycled water  is used for irrigation by golf courses, business parks, pastureland and vineyards.