Step 3: Assess for pollutants, sources of contaminated stormwater

How do I assess for pollutants at my facility?

All facilities requiring permit coverage must assess for industrial activities and materials, and consider the potential pollutants that can come from these activities and materials

Step 3a: Review significant materials

Here’s a general list of significant materials that can cause contaminated stormwater runoff:


  • Fuels, solvents, coolants, lubricants and cleaners
  • Raw, intermediate, and final products
  • Metallic materials
  • Chemicals
  • Wastes and scrap materials
  • Hazardous materials/wastes
  • Processing or production operations
  • Machining fluids
  • Dust or residuals
  • Fueling stations
  • Above-ground tanks for liquid storage

Step 3b: Review industrial activities

Here’s a general list of industrial activities that can cause contaminated stormwater runoff:


  • Outdoor storage activities
  • Outside manufacturing areas
  • Vehicle & equipment washing, maintenance and storage areas
  • Loading and unloading operations
  • Fueling of vehicles and equipment
  • Other substance transfer areas
  • Outdoor manufacturing or processing activities
  • Significant dust or particulate generating activities
  • Onsite waste disposal practices
  • Outside storage areas for raw materials, by-products, and finished products
  • Grinding, cutting, degreasing, buffing, and brazing
  • Industrial waste management areas (landfills, waste piles, treatment plants, disposal areas)

Step 3c: Review the pollutants of concern by sector

Based on the MPCA’s Multi-Sector General Permit, below is a list of pollutants to monitor for, listed by sector. If you have more than one sector at your facility, you will have to monitor for all of the pollutants within each sector and/or sub-sector. Note: the information below is for the ENTIRE sector.


Sector Description

Pollutants to Monitor
(list represents entire sector)

Sector A

Timber products

Arsenic, Chromium, COD,  Copper, Pentachlorophenol, pH, TSS, Zinc

Sector B

Paper and Allied Products Manufacturing


Sector C

Chemical and Allied Products Manufacturing

Aluminum, CBOD5, Fluoride,  Iron, Lead, Phosphorus, TSS, Zinc

Sector D

Asphalt Paving and Roofing Materials Manufactures and Lubricant Manufacturers

pH, Oil & Grease, TSS

Sector E

Glass, Clay, Cement, Concrete, and Gypsum Product Manufacturing

Aluminum, Iron, pH, TSS

Sector F

Primary Metals

Aluminum, Copper, Iron, TSS, Zinc

Sector G

Metal Mining (Ore Mining and Dressing)

Antimony, Arsenic, Cadmium, COD, Copper, Hardness, Iron, Lead, Nickel, Nitrate + Nitrite, pH, Selenium, Silver, Zinc, TSS

Sector H

Coal Mines and Coal Mining-Related Facilities

Aluminum,  pH, Iron, TSS

Sector I

Oil and Gas Extraction and Refining

Ammonia,  Lead, Nickel, Nitrate + Nitrite, Nitrogen, pH, TSS,  Zinc

Sector J

Mineral Mining and Dressing


Sector K

Hazardous Waste Treatment Storage or Disposal Facilities

Alpha Terpineol, Aniline, Arsenic, Ammonia, Benzoic Acid, Cadmium, CBOD5, Chromium, COD, Cyanide, Lead, Naphthalene, pH, Phenol,  p-Cresol, Pyridine, Selenium, Silver, Total Cadmium, TSS, Zinc

Sector L

Landfills and Land Application Sites

Alpha Terpineol, Ammonia, , Benzoic Acid, CBOD5,  Iron, P cresol, pH, Phenol, TSS, Zinc

Sector M

Automobile Salvage Yards

Aluminum, Benzene, Ethylbenzene, Iron, Lead, Toluene, TSS, Xylene

Sector N

Scrap Recycling and Waste Recycling Facilities

Aluminum, COD, Copper, Iron, Lead,  pH, TSS, Zinc

Sector O

Steam Electric Generating Facilities

Iron, pH, TSS

Sector P

Land Transportation and Warehousing


Sector Q

Water Transportation

TSS, Aluminum, Lead, Zinc, Iron

Sector R

Ship and Boat Building and Repair Yards


Sector S

Air Transportation

BOD, CBOD5, Ammonia, TSS, pH

Sector T

Treatment Works


Sector U

Food and Kindred Products

TSS, CBOD5, COD, Ammonia, Total Nitrogen, Nitrate + Nitrite, Nitrogen, Phosphorus

Sector V

Textile Mills, Apparel, and Other Fabric Products Manufacturing


Sector W

Furniture and Fixtures


Sector X

Printing and Publishing

TSS, Silver

Sector Y

Rubber, Miscellaneous Plastic Products, and Miscellaneous Manufacturing Industries

Lead, TSS, Zinc

Sector Z

Leather Tanning and Finishing

CBOD5, Chromium, TSS

Sector AA

Fabricated Metal Products

Aluminum, Iron, Zinc, TSS

Sector AB

Transportation Equipment, Industrial and Commercial Machinery


Sector AC

Electronic and Electrical Equipment and Components, Photographic and Optical Goods

TSS, Copper, Lead

KEY: CBOD5=Five-Day Carbonaceous, Biochemical Oxygen Demand, BOD=Biological Oxygen Demand, TSS=Total Suspended Solids

Step 3d: Implement a Mercury Minimization Plan, if required

Any time mercury sources or devices are found to be exposed to stormwater, a Mercury Minimization Plan shall be developed that describes how mercury sources will be managed at the site to eliminate exposure to precipitation and stormwater runoff. The mercury sources and devices shall be removed from stormwater exposure and managed in accordance with Minn. R. 7045, Hazardous Waste, and any additional applicable state and federal rules.


Go to Step 4