Final Arizona ADEQ Industrial Stormwater MSGP Storm Water Rule

The Arizona Department of Environmental Quality (ADEQ) has finalized its multisector industrial stormwater discharge general permit, known officially as the AZPDES Multi-Sector General Permit, or MSGP 2010. This permit replaces the existing industrial stormwater permit, which expired in 2005. This permit is nearly identical to the draft permit released for public comment in February 2010.

[Review a summary of the draft ADEQ Industrial Stormwater Permit]

All facilities that require permit coverage are required to submit a permit application (Notice of Intent, or NOI) to ADEQ; an NOI needs to be submitted even for facilities that were previously covered by the old permit.

Some key changes in the new permit compared to the previous permit are the additional of sector-specific requirements for each of 30 different sectors.

Click on a sector below to review proposed sector specific requirements:

Arizona DEQ SWPPP Requirements for Sector A - Timber Products
Arizona DEQ SWPPP Requirements for Sector B - Paper and Allied Products Manufacturing
Arizona DEQ SWPPP Requirements for Sector C - Chemical and Allied Products Manufacturing
Arizona DEQ SWPPP Requirements for Sector D - Asphalt Paving and Roofing Materials and Lubricant Manufacturing
Arizona DEQ SWPPP Requirements for Sector E - Glass, Clay, Cement, Concrete, and Gypsum Products
Arizona DEQ SWPPP Requirements for Sector F - Primary Metals
Arizona DEQ SWPPP Requirements for Sector G - Metal Mining
Arizona DEQ SWPPP Requirements for Sector H - Coal Mining
Arizona DEQ SWPPP Requirements for Sector I - Oil and Gas Extraction and Refining
Arizona DEQ SWPPP Requirements for Sector J - Mineral Mining
Arizona DEQ SWPPP Requirements for Sector K - Hazardous Waste Treatment, Storage, or Disposal Facilities
Arizona DEQ SWPPP Requirements for Sector L - Landfills, Land Application Sites, and Open Dumps
Arizona DEQ SWPPP Requirements for Sector M - Automobile Salvage Yards
Arizona DEQ SWPPP Requirements for Sector N - Scrap Recycling and Waste Recycling Facilities
Arizona DEQ SWPPP Requirements for Sector O - Steam Electric Generating Facilities
Arizona DEQ SWPPP Requirements for Sector P - Land Transportation and Warehousing
Arizona DEQ SWPPP Requirements for Sector Q - Water Transportation
Arizona DEQ SWPPP Requirements for Sector R - Ship and Boat Building and Repair Yards
Arizona DEQ SWPPP Requirements for Sector S - Air Transportation Facilities
Arizona DEQ SWPPP Requirements for Sector T - Treatment Works
Arizona DEQ SWPPP Requirements for Sector U - Food and Kindred Product
Arizona DEQ SWPPP Requirements for Sector V - Textile Mills, Apparel, and Other Fabric Products
Arizona DEQ SWPPP Requirements for Sector W - Furniture and Fixtures
Arizona DEQ SWPPP Requirements for Sector X - Printing and Publishing
Arizona DEQ SWPPP Requirements for Sector Y - Rubber, Miscellaneous Plastic Products, and Miscellaneous Manufacturing Industries
Arizona DEQ SWPPP Requirements for Sector Z - Leather Tanning and Finishing
Arizona DEQ SWPPP Requirements for Sector AA - Fabricated Metal Products
Arizona DEQ SWPPP Requirements for Sector AB - Transportation Equipment, Industrial and Commercial Machinery
Arizona DEQ SWPPP Requirements for Sector AC - Electronic and Electrical Equipment and Components

[Read more about ADEQ stormwater monitoring requirements and industrial stormwater benchmarks]

Caltha LLP provides expert consulting services to public and private sector clients in Arizona to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.

For further information contact Caltha LLP at

info@calthacompany.com or Caltha LLP Website

Arizona DEQ Stormwater Monitoring and Industrial Storm Water Benchmarks

In December 2010, the Arizona Department of Environmental Quality (ADEQ) issued the Multi-Sector General Permit (MSGP) for industrial stormwater discharges. The revised permit included significant changes to stormwater discharge requirements for permitted sites, which are now divided into 29 industrial sectors. One of the most significant changes was the requirement for sampling stormwater and reporting results to ADEQ. The monitoring requirement begins immediately after permit coverage begins. ADEQ has defined monitoring seasons in the permit:
Summer wet season: June 1 – October 31
Winter wet season: November 1 – May 31
The frequency for stormwater sampling in the permit is at least twice each wet season (summer and winter) from each monitoring location.

All sites permitted under the MSGP (with some limited exceptions) will have to collect stormwater samples and have samples analyzed for their sector-specific benchmark parameters. If one or more benchmarks are exceeded, sites will be required to upgrade their pollution prevention measures and will need to do further stormwater monitoring.

Some stormwater benchmarks that apply to several sectors include:

Ammonia 2.14 mg/L
Biochemical Oxygen Demand (BOD) 30 mg/L
Chemical Oxygen Demand (COD) 120 mg/L
pH 6.0 – 9.0 s.u.
Total Aluminum 0.75 mg/ L
Total Arsenic 0.15 mg/L
Total Cyanide 0.022 mg/ L
Total Iron 1.0 mg/L
Total Magnesium 0.064 mg/L
Total Mercury 0.0014 mg/L
Total Selenium 0.005 mg/L
Total Suspended Solids (TSS) 100 mg/L


Since the 1980s, the U.S. Environmental Protection Agency (EPA) has collected industry-sector data on stormwater discharge. The linked presentation provides a comparison of these historic industrial stormwater results to the many of the ADEQ stormwater benchmark concentrations. The results are discussed in context of which stormwater benchmark parameters have a higher potential for exceedance of benchmark values. This presentation also discusses which of the industrial sectors have a higher potential for exceedance of their specific benchmark values.

Note: Arizona uses the same benchmark concentrations used by EPA and many other States; although the this linked presentation was specific to Minnesota, the analysis and conclusions apply to Arizona.
Link to presentation slides:

Industrial Stormwater Benchmarks – Comparison of New Minnesota Benchmark Concentrations To Historic Industry-specific Testing Results
Caltha LLP provides expert consulting services to public and private sector clients in Arizona to address Stormwater Permitting & Regulatory Support, Stormwater Pollution Prevention Plans (SWPPP), Stormwater Monitoring and Stormwater Training.


For further information contact Caltha LLP at
info@calthacompany.com or Caltha LLP Website