Brief History of NPDES Program
The National Pollutant Discharge Elimination System (NPDES) originally began as part of the 1972 Clean Water Act. The U.S. Environmental Protection Agency (USEPA) initially targeted point-source pollution (industrial plants, sewage plants) with sampling, monitoring, water treatment, improved material handling, better manufacturing technology, etc. This portion of the NPDES program has been very effective at improving water quality for lakes and streams in urban areas. However, as more data was gathered, it was learned that most pollution comes from nonpoint sources where it is difficult to identify the source and responsible party. Nonpoint pollution sources include: soil erosion, aerially-deposited particles, roadside trash, leaves and sticks, automotive fluids from leaking vehicles, products of incomplete combustion, food processing wastes, and transportation spills of chemicals and other pollutants. The Clean Water Act was amended in 1987 to include provisions for reducing nonpoint pollution sources. The NPDES permit system is managed by the Tennessee Department of Environment and Conservation (TDEC), with federal oversight maintained by USEPA.
The Storm Water Phase I Rule (1990) requires that large and medium-sized cities/counties must obtain a NPDES permit for municipal separate storm sewer systems (MS4s). These NPDES permits are renewable for a period of 5 years. A stormwater management program must be developed to reduce stormwater pollution, with several elements for which demonstrable progress must be achieved each year. The original NPDES permit
for the City of Knoxville was approved on July 1, 1996 by TDEC for a period of 5 years. It is currently in the process of being reissued by TDEC.
Example of NPDES Activities
NPDES activities are reported annually to TDEC as required by the NPDES permit. NPDES activities are grouped into the following five programs:
Residential and Commercial
Illicit Discharges and Improper Disposal
Industrial and Related Facilities
Construction Site Runoff
The Stormwater Engineering Division maintains stormwater monitoring stations in the following watersheds: First Creek, Second Creek, Loves Creek, and two on Fourth Creek. The locations are shown in the NPDES Annual Reports that are submitted to TDEC. In addition to continuous wet-weather sampling at five locations, dry-weather samples are obtained and tested periodically at other locations in order to locate illegal discharges.
See the Knoxville BMP Manual
for a more thorough discussion of stormwater pollution and best management practices (BMPs). The BMP Manual contains an overview of stormwater pollution in Chapters 2 through 4, along with detailed BMP descriptions and applications. In addition, Chapter 8 contains many other weblinks to state and federal agencies of concern to stormwater drainage and stormwater quality designers.
The Stormwater Engineering Division investigates illegal discharges into the stormwater drainage systems and natural streams; call the Water Quality Hotline (215-4147; anonymous calls are accepted) to report spills and leaks during business hours. Emergency calls are typically handled by calling 911 for the City of Knoxville emergency hazmat team.
NPDES Links from the U.S. Environmental Protection Agency
Tennessee Department of Conservation (TDEC)