PURPOSE: This rule sets forth the requirements and process of application for permits for storm water discharges and the terms and conditions for the permits.

PUBLISHER’S NOTE: The secretary of state has determined that publication of the entire text of the material that is incorporated by reference as a portion of this rule would be unduly cumbersome or expensive. This material as incorporated by reference in this rule shall be maintained by the agency at its headquarters and shall be made available to the public for inspection and copying at no more than the actual cost of reproduction. This note applies only to the reference material. The entire text of the rule is printed here.

1. (1) Storm Water Permits—General.

   1. (A) All persons who operate, use, or maintain existing storm water point sources or who disturb land that would result in a storm water point source shall apply to the department for the permits required by the Missouri Clean Water Law and these regulations. A permit must be obtained before beginning any new construction related to the above activities. The department issues these permits in order to enforce the Missouri Clean Water Law and regulations and administer the state operating permit program.

   2. (B) Nothing shall prevent the department from taking action, including the requirement for issuance of any permits under the Missouri Clean Water Law and regulations, if any of the operations exempted should cause pollution of waters of the state or otherwise violate the Missouri Clean Water Law or these regulations. The following are exempt from storm water permit regulations:

      1. 1. Areas located on plant lands separate from the plant’s

industrial activities, such as office buildings and accompanying parking lots, as long as the drainage from the excluded areas is not mixed with storm water drained from permitted areas;

1. 2. De minimis discharges as defined by the department in

general permits or by the Clean Water Commission;

1. 3. Recycling collection points which are covered in a

manner which prevents contact with storm water, including run on;

1. 4. Farmlands, domestic gardens, or lands used for sludge

management where domestic sludge is beneficially reused and which are not physically located in the confines of the facility producing the sludge;

1. 5. Agricultural storm water discharges and irrigation

return flows;

1. 6. Sites that disturb less than one (1) acre of total land

area which are not part of a common plan or sale. Land disturbance activity on an individual residential building lot is not considered as part of the overall subdivision unless the activity is by the developer to improve the lot for sale;

1. 7. Linear, strip, or ribbon construction or maintenance

operations meeting one (1) of the following criteria:

1. A. Grading of existing dirt or gravel roads which does

not increase the runoff coefficient and the addition of an impermeable surface over an existing dirt or gravel road;

1. B. Cleaning or routine maintenance of roadside ditches,

sewers, waterlines, pipelines, utility lines, or similar facilities;

1. C. Trenches two (2) feet in width or less; or
2. D. Emergency repair or replacement of existing facilities

as long as best management practices are employed during the emergency repair;

1. 8. Mowing, brush hog clearing, tree cutting, or similar

activities which do not grade, dig, excavate, or otherwise remove or kill the surface growth and root system of the ground cover;

1. 9. Landfills which have received Missouri Department

of Natural Resources approval to close and which are in compliance with any post-closure monitoring, management requirements, and deed restrictions, unless the department determines the facility is a significant discharger of storm water related pollutants;

1. 10. Facilities built to control the release of only storm water

are not subject to the construction permitting requirement of 10 CSR 20-6.010(4), provided that the storm water does not come in contact with process waste, process wastewater, or significant materials, and the storm water is not a significant contributor of pollutants;

1. 11. Phase II municipal separate storm sewer systems (MS4)

may request a waiver from the department in accordance with 40 CFR part 122.32(c), December 8, 1999, as published by the Environmental Protection Agency (EPA) Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, are incorporated by reference. This rule does not incorporate any subsequent amendments or addition;

1. 12. A regulated MS4 may share the responsibility under the

following:

1. A. A MS4 may develop an agreement with another

entity to assist with satisfying the National Pollutant Discharge Elimination System (NPDES) permit obligations or with implementing a minimum control measure if—

1. (I) The other entity currently implements the control

measure;

1. (II) The particular control measure, or component

thereof, is at least as stringent as the corresponding permit requirement; and

1. (III) A MS4 that relies on another entity to satisfy

some of the permit obligations specifies the condition of the agreement, including a description of the obligations implemented by the other entity. The permitted MS4 remains ultimately responsible for compliance with the permit obligations if the other entity fails to implement the control measure (or component thereof);

1. B. In some cases, the department may recognize,

either in an individual permit or in a general permit, that another governmental entity is responsible under a permit for implementing one (1) or more of the minimum control measures for a MS4. Where the department recognizes these dual responsibilities, the department may not require the MS4 to include such minimum control measure(s) in their program. The MS4 permit may be modified to include the requirement to implement a minimum control measure if the other entity fails to implement it; and

1. 13. The director may waive the otherwise applicable

requirements in a general permit for a storm water discharge from construction activities that disturb less than five (5) acres, but more than one (1) acre, where—

1. A. The value of the rainfall erosivity factor R in the

Revised Universal Soil Loss Equation is less than five (5) during the period of construction activity. The rainfall erosivity factor is determined in accordance with Chapter 2 of Agriculture Handbook Number 703, Predicting Universal Soil Loss Equation (RUSLE), pages 21–64, dated January 1997, which is incorporated in this rule by reference. Copies may be obtained from EPA’s Water Resource Center, Mail Code RC4100, 401 M Street SW, Washington, DC 20460. An operator must certify to the director that the construction activity will take place during a period when the value of the rainfall erosivity factor is less than five (5); or

1. B. A total maximum daily load (TMDL) approved or

established by the department or by the EPA that addresses the pollutant(s) of concern without the need for storm water controls; and

1. C. Waste load allocations are not needed on non-im-

paired waters to protect water quality based on consideration of existing in-stream concentrations, expected growth in pollutant contributions from all sources, and a margin of safety. For the purpose of paragraph (1)(B)13. and subparagraph (1) (B)13.C. of this rule, the pollutant(s) of concern include sediment or a parameter that addresses sediment (such as total suspended solids, turbidity, or siltation) and any other pollutant that has been identified as a cause or a potential cause of impairment of any water body that will receive a discharge from the construction activity. The operator must certify to the department that the construction activity will take place, and that storm water discharges will occur, within the drainage area addressed by the TMDL or by an equivalent analysis.

1. (C) No Exposure Certification. A storm water permit under this rule may be excluded for industrial activities that do not expose materials to storm water. No exposure exists if the industrial materials and activities are protected from rain, snow, snowmelt, and/or runoff and the operator meets the requirements under paragraph (C)1. and subparagraph (C)2.C. of this subsection.

   1. 1. Industrial materials and activities protected by storm

resistant shelter. No exposure means that all industrial materials and activities are protected by a storm resistant shelter to prevent exposure to rain, snow, snowmelt, and/or runoff. Industrial materials or activities include, but are not limited to, material handling equipment or activities, industrial machinery, raw materials, intermediate products, by-products, final products, or waste products. Material handling activities include the storage, loading and unloading, transportation, or conveyance of any raw material, intermediate product, final product, or waste product. To qualify a permit exclusion under this paragraph, the operator of the discharge must:

1. A. Provide a storm resistant shelter to protect industrial

materials and activities from exposure to rain, snow, snowmelt, and runoff;

1. B. Complete and sign a certification that storm water

is not contaminated by exposure to industrial materials and activities from the entire facility;

1. C. Re-submit the signed certification to the department

once every five (5) years;

1. D. Allow the department to inspect the facility to deter-

mine compliance with the no-exposure conditions;

1. E. Make the no-exposure inspection reports available to

the public upon request; and

1. F. For facilities that discharge through a MS4, submit a

copy of the certification of no-exposure to the MS4 operator, as well as allow inspection and public reporting of the inspection findings by the MS4 operator.

1. 2. Industrial materials and activities not requiring storm

resistant shelter. An industrial site may qualify for this exclusion without a storm resistant shelter if—

1. A. Drums, barrels, tanks, and similar containers are

tightly sealed, provided those containers are not deteriorated and do not leak. Sealed means banded or otherwise secured and without operational taps or valves;

1. B. Adequately maintained vehicles are used in material

handling; and

1. C. All industrial materials consist of final products, other

than products that would be mobilized by storm water.

1. (D) Definitions.

   1. 1. Best management practices (BMPs). Schedules of

activities, prohibitions of practices, maintenance procedures, and other management practices to prevent or reduce the pollution of waters of the state. BMPs also include treatment requirements, operating procedures, and practices to control plant site runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.

1. 2. BMPs for land disturbance. A schedule of activities,

practices, or procedures that reduces the amount of soil available for transport or a device that reduces the amount of suspended solids in runoff before discharge to waters of the state. Types of BMPs for storm water control include but are not limited to—

1. A. State-approved standard specifications and permit

programs;

1. B. Employee training in erosion control, material

handling and storage, and housekeeping of maintenance areas;

1. C. Site preparation such as grading, surface roughening,

topsoiling, tree preservation and protection, and temporary construction entrances;

1. D. Surface stabilization such as temporary seeding,

permanent seeding, mulching, sodding, ground cover including vines and shrubs, riprap, and geotextile fabric. Mulches may be hay, straw, fiber mats, netting, wood cellulose, corn or tobacco stalks, bark, corn cobs, wood chips, or other suitable material which is reasonably clean and free of noxious weeds and deleterious materials. Grasses used for temporary seeding shall be a quick-growing species such as rye grass, Italian rye grass, or cereal grasses suitable to the area and which will not compete with the grasses sown later for permanent cover;

1. E. Runoff control measures such as temporary diversion

dikes or berms, permanent diversion dikes or berms, rightof-way or perimeter diversion devices, and retention and detention basins. Sediment traps and barriers, sediment basins, sediment (silt) fence, and staked straw bale barriers;

1. F. Runoff conveyance measures such as grass-lined

channels, riprap, and paved channels, temporary slope drains, paved flumes, or chutes. Slope drains may be constructed of pipe, fiber mats, rubble, Portland cement concrete, bituminous concrete, plastic sheets, or other materials that adequately will control erosion;

1. G. Inlet and outlet protection;
2. H. Streambank protection such as a vegetative greenbelt

between the land disturbance and the watercourse. Also, structural protection which stabilizes the stream channel;

1. I. A critical path method analysis or a schedule for

performing erosion control measures; and

1. J. Other proven methods for controlling runoff and

sedimentation.

1. 3. Copetitioner. A person with apportioned legal, financial,

and administrative responsibility based on land area under its control for filing Part 1 and Part 2 of a state operating permit for the discharge of storm water from municipal separate storm sewer systems. A copetitioner becomes a copermittee once the permit is issued.

1. 4. Copermittee. A permittee to a state operating permit

that is responsible only for permit conditions relating to the discharge for which it is owner or operator, or both.

1. 5. De minimis water contaminant source. A water

contaminant source, point source, or wastewater treatment facility that is determined by the department to pose a negligible potential impact on waters of the state, even in the event of the malfunction of wastewater treatment controls or material handling procedures.

1. 6. Field screening point. A specific location which during

monitoring will provide representative information to indicate the presence of illicit connections or illegal dumping and quality of water within a municipal separate storm sewer system.

1. 7. Illicit discharge. Any discharge to a municipal separate

storm sewer that is not composed entirely of storm water, except discharges pursuant to a state operating permit, other than storm water discharge permits and discharges from fire fighting activities.

1. 8. Incorporated place (in Missouri, a municipality). A city,

town, or village that is incorporated under the laws of Missouri.

1. 9. Landfill. Location where waste materials are deposited

on or buried within the soil or subsoil. Included are open dumps and landfills built or operated, or both, prior to the passage of the Missouri Solid Waste Management Law as well as those built or operated, or both, since.

1. 10. Large municipal separate storm sewer system. This

term is defined in 40 CFR part 122.26(b)(4), promulgated as of November 2, 2020, and hereby incorporated by reference in this rule, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004. This rule does not incorporate any subsequent amendments or additions.

1. 11. MS4 means a municipal separate storm sewer system.
2. 12. Major structural controls. Man-made retention basins,

detention basins, major infiltration devices, or other structures designed and operated for the purpose of containing storm water discharges from an area greater than or equal to fifty (50) acres.

1. 13. Medium municipal separate storm sewer system. This

term is defined in 40 CFR part 122.26(b)(7), promulgated as of November 2, 2020, and hereby incorporated by reference in this rule, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004. This rule does not incorporate any subsequent amendments or additions.

1. 14. Municipal separate storm sewer means a conveyance

or system of conveyances including roads and highways with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, paved or unpaved channels, or storm drains designated and utilized for routing of storm water which—

1. A. Does not include any waters of the state as defined in

section 644.016, RSMo;

1. B. Is owned and operated by the state, city, town, village,

county, district, association, or other public body created by or pursuant to the laws of Missouri having jurisdiction over disposal of sewage, industrial waste, storm water, or other liquid wastes;

1. C. Is not a part or portion of a combined sewer system;
2. D. Is not a part of a publicly owned treatment works as

defined in 40 CFR 122.2; and

1. E. Sewers that are defined as large or medium or

small municipal separate storm sewer systems pursuant to paragraphs 10., 13., and 27. of this section, or designated under subsection (1)(B) of this rule.

1. 15. Operator. The owner, or an agent of the owner, of a

separate storm sewer with responsibility for operating and maintaining the effectiveness of the system.

1. 16. Outfall. A point source as defined by 10 CSR 20-2.010 at

the point where a municipal separate storm sewer discharges and does not include open conveyances connecting two (2) municipal separate storm sewers, pipes, tunnels, or other conveyances which connect segments of waters of the state and are used to convey waters of the state.

1. 17. Overburden. Any material of any nature consolidated

or unconsolidated that overlays a mineral deposit excluding topsoil or similar naturally occurring surface materials that are not disturbed by mining operations.

1. 18. Owner. A person who owns and controls the use,

operation, and maintenance of a separate storm sewer.

1. 19. Process wastewater. Any water which, during

manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, by-product, or waste product.

1. 20. Receiving waters. Waters of the state as defined in this

rule.

1. 21. Recycling facilities. Locations where metals, paper,

tires, glass, organic materials, used oils, spent solvents, or other materials are collected for reuse, reprocessing, or resale.

1. 22. Regulated MS4 means—

   1. A. A MS4 which serves a population of one thousand

(1,000) or more within an urban area with a population of fifty thousand (50,000) or more people as determined by the latest decennial census by the Bureau of the Census, or any MS4 located outside of an urban area with a population of fifty thousand (50,000) or more people as determined by the latest decennial census by the Bureau of the Census serving a jurisdiction with a population of at least ten thousand (10,000) and a population density of one thousand (1,000) people per square mile or greater; or

1. B. A MS4 which is designated by the department when it

is determined that the discharges from the MS4 have caused or have the potential to cause an adverse impact on water quality. An application shall be submitted within one hundred eighty (180) days of the designation by the department.

1. 23. Runoff coefficient. The fraction of total rainfall that will

appear at a conveyance as runoff.

1. 24. Significant contributor of pollutants. A person who

discharges or causes the discharge of pollutants in storm water which can cause water quality standards of the waters of the state to be violated.

1. 25. Significant material or activity associated with

industrial activity.

1. A. For the categories of industries identified in

subsections (2)(A)–(C) of this rule, the term includes, but is not limited to, storm water discharged from industrial plant yards, immediate access roads and rail lines used or traveled by carriers of raw materials, manufactured products, waste material, or by-products used or created by the facility.

1. B. Significant materials include, but are not limited to,

raw materials; fuels; materials such as solvents, detergents, and plastic pellets; finished materials such as metallic products; raw materials used in food processing or production; hazardous substances designated under Section 101(14) of the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA); any chemical the facility is required to report pursuant to Section 313 of Title III of Superfund Amendments & Reauthorization Act of 1986 (SARA); fertilizers; pesticides; and waste products such as ashes, slag, and sludge that have the potential to be released with storm water discharges.

1. C. Material received in drums, totes, or other secure

containers or packages which prevent contact with storm water, including run on, are exempted from the significant materials classification until the container has been opened for any reason. If the container is moved into a building or other protected area prior to opening, it will not become a significant material.

1. D. Empty containers which have been properly triple

rinsed are not significant materials.

1. 26. Construction activity means—

   1. A. Construction activities including clearing, grading,

and excavating that result in land disturbance of equal to or greater than one (1) acre. Construction activity also includes the disturbance of less than one (1) acre of total land area that is part of a larger common plan of development or sale if the larger common plan will ultimately disturb equal to or greater than one (1) acre. Construction activity does not include routine maintenance that is performed to maintain the original line and grade, hydraulic capacity, or original purpose of the facility; or

1. B. Any other construction activity designated by

the department, based on the potential for contribution to a violation of a water quality standard or for significant contribution of pollutants to waters of the United States.

1. 27. Small municipal separate storm sewer system means—

   1. A. Owned or operated by the United States, a state,

city, town, borough, county, parish, district, association, or other public body (created by or pursuant to state law) having jurisdiction over disposal of sewage, industrial wastes, storm water, or other wastes, including special districts under state law such as a sewer district, flood control district, or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal organization, or a designated and approved management agency under Section 208 of the Clean Water Act (CWA) that discharges to water of the United States;

1. B. Not defined as large or medium municipal separate

storm sewer systems pursuant to paragraphs 10. and 13. of this subsection; and

1. C. This term includes systems similar to separate storm

sewer systems in municipalities, such as systems at military bases, large hospital or prison complexes, and highways and other thoroughfares. The term does not include separate storm sewers in very discrete areas, such as around individual buildings.

1. 28. Storm water means storm water runoff, snowmelt

runoff and surface runoff, and drainage.

1. 29. Storm water discharge associated with industrial

activity means the discharge from any conveyance which is used for collecting and conveying storm water and which is directly related to manufacturing, processing, or raw material storage areas at an industrial plant.

1. (2) Storm water discharge associated with industrial activity. The discharge from any conveyance which is used for collecting and conveying storm water which is not under a permit issued under 10 CSR 20-6.010 and which is directly related to manufacturing, processing, or raw materials storage areas at an industrial plant.

   1. (A) For the listed industries identified in subsection (2)(B) of this rule, the term includes but is not limited to storm water discharges from industrial plant yards; immediate access roads and rail lines used or traveled by carriers of raw materials, manufactured products, waste material, or by-products used or created by the facility; material handling sites; sites used for the application or disposal of process wastewaters; sites used for the storage and maintenance of material handling equipment; sites used for residual treatment, storage, or disposal; shipping and receiving areas; manufacturing buildings; storage areas (including tank farms) for raw materials and intermediate and finished products unless material is in closed cars or trailers and the loading/unloading operation does not expose material to storm water or otherwise pose risk of storm water contamination and areas where industrial activity has taken place in the past and where significant materials remain and are exposed to storm water.

   2. (B) Industries subject to this requirement include—

      1. 1. Facilities classified with the following primary standard

industry classification (SIC) are considered to be included in this paragraph: 10, Metal Mining; 12, Coal Mining; 13, Oil and Gas Extraction; 14, Nonmetallic Minerals; 24, Lumber and Wood Products; 26, Paper and Allied Products; 28, Chemical and Allied Products; 29, Petroleum Refining; 311, Leather Tanning and Finishing; 32, Stone, Clay, Glass, Concrete; 33, Primary Metal Industries; 3441, Fabricated Structural Metal; 373, Ship and Boat Building and Repair; 5171, Petroleum Bulk Stations and Terminals; and industries regulated under section 644.052.4, RSMo, except for those SICs addressed in paragraph (2)(B)4. of this rule;

1. 2. Facilities classified with the following primary SIC are

considered to be included in this paragraph: 40, Railroad; 41, Local, Suburban Transit, etc.; 42, Motor Freight Transportation and Warehousing; 43, United States Postal Service; 44, Water Transportation; 45, Air Transportation. Only those portions of the facility listed under this paragraph that are either involved in vehicle maintenance (including vehicle rehabilitation, mechanical repairs, painting, fueling, and lubrication), equipment cleaning operations, airport deicing operations, or which are otherwise identified under paragraph (2)(B)1., 3., or 4. of this rule are associated with industrial activity;

1. 3. Facilities which meet the following definitions are

considered to be included in this subsection:

1. A. Hazardous waste treatment, storage, or disposal

facilities, including those that are operating under interim status or a permit under Subtitle C of the Resource Conservation and Recovery Act (RCRA). Hazardous waste generator sites which are exempt from interim status or permitting because they accumulate wastes on-site less than ninety (90) days are not included;

1. B. Landfills, land application sites, and open dumps

that receive or have received any industrial wastes (waste that is received from any of the facilities described under this paragraph) including those that are subject to regulation under Subtitle D of RCRA;

1. C. Facilities involved in the recycling of materials

including metal scrap yards, battery re-claimers, salvage yards, and automobile junk yards, including those with an SIC classification of 5015 and 5093;

1. D. Steam electric power generating facilities, including

coal handling sites;

1. E. Treatment works treating domestic sewage, or any

other sewage sludge or wastewater treatment device or system, used in the storage treatment, recycling, and reclamation of municipal or domestic sewage, including land dedicated to the disposal of sewage sludge that is located within the confines of the facility, with a design flow of 1.0 million gallons per day (mgd) or more or required to have an approved pretreatment program under 10 CSR 20-6.100; and

1. F. Industrial facilities that are federally, state, or

municipally owned or operated; and

1. 4. Facilities classified with the following primary SIC are

considered to be included in this paragraph: 20, Food and Kindered Products; 21, Tobacco Products; 22, Textile Mill Products; 23, Apparel and Other Finished Products; 2434, Wood Kitchen Cabinets; 25, Furniture and Fixtures; 265, Paperboard Containers and Boxes; 267, Converted Paper and Paperboard Products; 27, Printing, Publishing, and Allied Industries; 283, Drugs; 285, Paints, Varnishes, Lacquers, and Enamels; 30, Rubber and Miscellaneous Plastics; 31, Leather and Leather Products (except for 311); 323, Glass Products; 34, Fabricated Metal Products (except for 3441); 35, Industrial and Commercial Machinery; 36, Electronic and Other Electrical Equipment; 37, Transportation Equipment (except for 373); 38, Measuring, Analyzing, and Controlling Instruments; 39, Miscellaneous Manufacturing Industries; 4221–25, Public Warehousing and Storage, only if any of the following activities and materials listed are exposed to storm water: discharges from industrial plant yards; material handling sites; sites used for the application or disposal of any water which, during manufacturing or processing, comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, by-product, or waste product; sites used for the storage and maintenance of material handling equipment; sites used for residual treatment, storage, or disposal; shipping and receiving areas; manufacturing buildings; storage areas (including tank farms) for raw materials and intermediate and finished products; and areas where industrial activity has taken place in the past and significant materials remain and are exposed to storm water. (C) Application Requirements for Storm Water Discharges Associated With Industrial Activity.

1. 1. Individual application. Dischargers of storm water as-

sociated with industrial activity shall apply for an individual permit or seek coverage under a promulgated storm water general permit. Facilities that are required to obtain an individual permit, or any discharge of storm water which the director is evaluating for designation under this paragraph and is not a municipal separate storm sewer, shall submit a state operating permit application in accordance with the following requirements:

1. A. A site plan map showing topography or indicating

the outline of drainage areas served by the outfall(s) covered in the application if a topographic map is unavailable of the facility including facility property line, each of its drainage and discharge structures, the drainage area of each storm water outfall, paved areas and buildings within the drainage area of each storm water outfall that drain to a storm water outfall, and those that do not drain to a storm water outfall, each past or present area used for outdoor storage or disposal of significant materials, each existing structural control measure to reduce pollutants in storm water runoff, materials loading and access areas, areas where pesticides, herbicides, soil conditioners and fertilizers are applied, each of its hazardous waste treatment, storage, or disposal facilities (including each area not required to have an RCRA permit which is used for accumulating hazardous waste under 10 CSR 25-5.262; each well where fluids from the facility are injected underground; springs and sink holes and other surface water bodies which receive storm water discharges from the facility;

1. B. An estimate of the area of impervious surfaces

(including paved areas and building roofs) and the total area drained by each outfall, if known, and a narrative description of the following: significant materials that in the three (3) years prior to the submittal of this application have been treated, stored, or disposed in a manner to allow exposure to storm water; method of treatment, storage, or disposal of materials; materials management practices employed in the three (3) years prior to the submittal of this application to minimize contact by these materials with storm water runoff; materials loading and access areas; outdoor vehicle maintenance and cleaning areas; the location, manner, and frequency in which pesticides, herbicides, soil conditioners, and fertilizers are applied; the location and a description of existing structural and nonstructural control measures to reduce pollutants in storm water runoff; and a description of the treatment the storm water receives, including the ultimate disposal of any solid or fluid waste other than by discharge;

1. C. A certification that all outfalls that should contain

storm water discharges associated with industrial activity have been tested or evaluated for the presence of nonstorm water discharges which are not covered by a state operating permit. Tests for nonstorm water discharges may include smoke tests and dye tests as well as other appropriate tests or analysis. The certification shall include a description of the method used, the date of any testing and the on-site drainage points that directly were observed during a test;

1. D. Existing information regarding significant leaks or

spills of toxic or hazardous pollutants at the facility that have taken place within the three (3) years prior to the submittal of this application;

1. E. Quantitative data based on samples collected during

storm events from all outfalls containing a storm water discharge associated with industrial activity shall be submitted. When an applicant has two (2) or more outfalls that are similar in nature, an individual outfall can be designated as representative and samples only collected from the representative outfall. Quantitative data will be submitted for the following parameters:

1. (I) Any pollutant limited in an effluent guideline to

which the facility is subject;

1. (II) Any pollutant listed in the facility’s state operating

permit for its process wastewater (if the facility is operating under an existing state operating permit);

1. (III) Oil and grease, pH, biochemical oxygen demands

(BOD5), chemical oxygen demands (COD), total suspended solids (TSS), conductivity, total phosphorus, total Kjeldahl nitrogen, and nitrate plus nitrite nitrogen;

1. (IV) Any information on the discharge required by the

appropriate application form;

1. (V) Flow measurements or estimates of the flow rate,

the total amount of discharge for the storm event(s) sampled, and the method of flow measurement or estimation; and

1. (VI) The date and duration (in hours) of the storm

event(s) sampled, rainfall measurements of the storm event which generated the sampled runoff, and the duration between the storm event sampled and the end of the previous measurable (greater than one-tenth inch (0.1") rainfall) storm event (in hours), at least one-tenth inch (0.1") of rainfall per storm water event are required to be considered a valid storm water event. The reporting rainfall station, if possible, should be within one (1) mile of the sampled outfall and shall be capable of providing rainfall measurements in at least tenths of an inch;

1. F. Sampling and flow measurements or estimates shall

be made to assess both the initial discharge loading and the total loading through the outfall during the measured rainfall event. A grab sample shall be taken within the first sixty (60) minutes of discharge. Sampling shall continue at the frequency of at least one (1) sample each sixty- (60-) minute period. Sampling should continue for three (3) hours or until discharge ceases, whichever is first. A sample aliquot representing the initial discharge shall be analyzed separate from the event composite sample. The composite sample shall include an aliquot from the initial discharge sample. The composite sample should be flow-weighted using approved procedures. Samples shall be collected, preserved, and analyzed according to 40 CFR Part 136 or other methods approved by the department. When analysis is required, grab samples must be used for pH, temperature, cyanide, total phenols, residual chlorine, oil and grease, fecal coliform, and fecal streptococcus;

1. G. Applicants shall provide other information the direc-

tor reasonably may require to determine whether to issue a permit; and

1. H. Within one (1) year after commencement of dis-

charge, operators of new sources or new discharges which are composed in part or entirely of storm water must include estimates for the pollutants or parameters listed in subparagraph (2)(C)1.E. of this rule, unless this data has already been reported under the monitoring requirements of the state operating permit for the discharge.

1. 2. The operator of an existing or new discharge composed

entirely of storm water from an oil or gas exploration, production, processing or treatment operation, or transmission facility is not required to submit a permit application in accordance with paragraph (2)(C)1. of this rule, unless the facility—

1. A. Has a discharge which is contaminated by contact

with, or that has come into contact with, any overburden, raw materials, intermediate products, finished product, by-product, or waste products located on the site of the operation;

1. B. Has had a discharge of storm water resulting in the

discharge of a reportable quantity for which notification is or was required at any time since November 16, 1987;

1. C. Contributes to a violation of a water quality standard.
2. 3. The operator of an existing or new discharge composed

entirely of storm water from a mining operation is not required to submit a permit application unless the discharge has come into contact with any overburden, raw material, intermediate products, finished product, by-product, or waste products located on the site of the operations.

1. (3) Land Disturbance and Construction Activity.

   1. (A) The owner/operator of an existing or new storm water discharge from a land disturbance or construction activity shall provide—

      1. 1. The location (including a map);
      2. 2. The total area of the site and the area of the site that is

expected to undergo excavation during the life of the permit;

1. 3. The name of the receiving water; and
2. 4. Applicable requirements under 40 CFR part 122.21(f),

April 1, 1983, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, are incorporated by reference. This rule does not incorporate any subsequent amendments or additions.

1. (B) Land Disturbance and Construction Activity. Storm water permits shall be the responsibility of the owner/operator of the site. The owner/operator is responsible to see that all contractors comply with the requirements of the permit.

   1. 1. A land disturbance permit must be obtained before the

date construction operations begin.

1. 2. Land disturbance permits must be applied for and issued

electronically unless a waiver is obtained from the department.

1. (4) Application requirements for large, medium municipal separate storm sewer discharges.

   1. (A) All Phase I large and medium MS4s were determined in accordance with the 1990 census. Application requirements for new Phase I large and medium MS4s based on the 1990 census were in accordance with 40 CFR 122.26(d), November 16, 1990, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, are incorporated by reference. This rule does not incorporate any subsequent amendments or additions.

   2. (B) Reapplication minimum requirements for large and medium MS4s are as follows:

      1. 1. Name and mailing address of the permittee(s) that op-

erate the MS4;

1. 2. Names and titles of the primary administrative and tech-

nical contacts for the municipal permittee(s);

1. 3. Minimum application requirements as established in

40 CFR 122.21(f), April 1, 1983, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, are incorporated by reference. This rule does not incorporate any subsequent amendments or additions;

1. 4. Any proposed changes or improvements to the storm-

water management program, including monitoring activities for the upcoming five- (5-) year term of the permit unless the proposed changes have already been submitted in the most recent annual report; and

1. 5. If applicable, any changes in co-applicants/co-permit-

tees.

1. (5) Application Requirements for Phase II MS4s.

   1. (A) General Permit Option. Applicants seeking coverage under a general permit for small MS4 discharges shall submit the department’s most recent version of application forms K or L, unless approved for an alternate form, and must develop and submit descriptions of storm water management programs designed to reduce pollutants in storm water runoff to protect water quality of receiving waters. The application must include program descriptions for at least the following six (6) minimum control measures:

      1. 1. Public education and outreach on storm water impacts.

The public education program should inform individuals and households about impacts of storm water discharges on water bodies and steps which can be taken to reduce or prevent storm water pollution;

1. 2. Public involvement/participation process. A program

must be developed which at a minimum complies with state and local public notice requirements;

1. 3. Illicit discharge detection and elimination. Discharges

to MS4s of wastewater other than those consisting entirely of storm water are considered “illicit discharges” except for discharges permitted under other state operating permits or directly from fire fighting activities. A program to detect and eliminate such discharges must be developed;

1. 4. Construction site storm water runoff control. A program

to control discharges of storm water and sediment from construction sites and activities must be developed. The program must be designed to protect receiving waters from sediment and other pollutants such as petroleum products, solid wastes, fertilizers, pesticides, and other construction related chemicals;

1. 5. Post-construction storm water management in new

development and redevelopment. A program must be developed to address storm water runoff from new development and redevelopment projects that result in land disturbance of greater than or equal to one (1) acre, including projects less than one (1) acre that are part of a larger common plan of development or sale, and discharge into the MS4; and

1. 6. Pollution prevention/good housekeeping for municipal

operations. A program must be developed which addresses pollution prevention and good housekeeping from municipal operations. The program must include a training component and have the ultimate goal of preventing or reducing impacts from storm water runoff from all municipal operations including those not currently required to be permitted as storm water associated with industrial activities.

1. A. Implementation and enforcement of these six (6)

minimum measures will be a requirement of the general permit when issued. Guidance on the content of these programs is available in the “EPA Phase II Storm Water Regulations” dated December 8, 1999.

1. (B) Site-Specific Option. Applicants who do not wish to be covered under a general permit for small MS4 discharges can apply for a site-specific permit by submitting the most recent version of form K or L and by submitting program descriptions of the six (6) minimum measures as outlined in paragraphs (5)(A)1.–6. Additional information regarding issues to be addressed in the site-specific permit shall accompany the application. Implementation and enforcement of the six

1. (6) minimum measures will be one of the requirements of any issued permit.

   1. (C) Copermittee Option.

      1. 1. The department encourages cooperation between

potential small MS4 applicants when addressing application requirements and in the development, implementation, and enforcement of the six (6) minimum measures under issued permits. Applicants within one (1) urban area, or within a common watershed, or in an area served in common by one (1) service provider should consider applying as coapplicants to share the financial and administrative responsibilities of the application process and to become co-permittees under an issued permit.

1. 2. Applications from copermittees shall include the

requirements of either subsection (5)(A) or (B) and in addition shall contain information designating responsibilities of each coapplicant in regard to development, implementation, and enforcement of the six (6) minimum measures.

1. (D) Operating permits for small MS4s will contain the minimum requirements as established in 40 CFR part 122.34, November 2, 2020, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington DC, 20004, and incorporated by reference. This rule does not incorporate any subsequent amendments or additions.

1. (6) Permit Requirements.

   1. (A) The director may issue a general permit for storm water discharges in accordance with the following:

      1. 1. The general permit shall be written to cover a category

of discharges described in the permit except those covered by individual permits within a geographic area. The area shall correspond to existing geographic or political boundaries, such as—

1. A. Designated planning areas under Sections 208 and

303 of the federal Clean Water Act;

1. B. City, county, or state political boundaries or special

sewer districts chartered by the state;

1. C. State highway systems; and
2. D. Any other appropriate division or combination of

boundaries;

1. 2. The general permit shall be written to regulate a

category of point sources if the sources all—

1. A. Involve the same or substantially similar types of

operations;

1. B. Discharge the same types of wastes;
2. C. Require the same operating conditions;
3. D. Require the same or similar monitoring; and
4. E. In the opinion of the director, are more appropriately

controlled under a general permit than under individual permits;

1. 3. General permits may be issued, modified, revoked,

and reissued or terminated in accordance with applicable requirements of this rule and the permit. To be included under a general permit, a permittee must submit an application on forms supplied by the department;

1. 4. The director may require any person authorized by a

general permit to apply for and obtain an individual operating permit. Any interested person may petition the director to require a permittee to apply for an individual permit. Cases where an individual operating permit may be required include, but are not limited to, the following:

1. A. Effluent limitation guidelines are promulgated for

point sources covered by a general state operating permit;

1. B. The discharge(s) is a significant contributor of

pollutants. In making this determination, the director may consider the following factors:

1. (I) The location of the discharge with respect to waters

of the state;

1. (II) The size of the discharge;
2. (III) The quantity and nature of the pollutants

discharged to waters of the state; and

1. (IV) Other relevant factors;
2. C. The discharge(s) is a significant contributor of

pollution which impairs the beneficial uses of the receiving stream;

1. D. The discharger is not in compliance with the

conditions of the general operating permit; or

1. E. A water quality management plan containing

requirements applicable to point sources is approved;

1. 5. Any owner or operator authorized by a general permit

may request to be excluded from the coverage of the general permit by applying for an individual permit. The owner or operator shall submit an application with reasons supporting the request to the director. The request shall be granted by issuing an individual permit if the reasons cited by the owner or operator are adequate to support the request.

1. A. When an individual operating permit is issued

to an owner or operator otherwise subject to a general operating permit, the applicability of the general permit to the individual operating permittee is automatically terminated on the effective date of the individual permit.

1. B. A source excluded from a general permit solely

because it already has an individual permit may request that the individual permit be revoked and that it be issued a general permit. Upon revocation of the individual permit and issuance of the general permit to the permittee, the general permit shall apply to the source. The source shall be included under the general permit only if it meets all the requirements for coverage under the general permit;

1. 6. Petitions may be submitted to the director requesting

the development of a general permit for a group of facilities or activities meeting the criteria listed in paragraph (2)(B)1.

1. A. Information required in a petition must include—

   1. (I) A full description of the group including names,

addresses, and locations and the industrial activities conducted by group members;

1. (II) Any significant materials stored, used, loaded,

unloaded, treated, or disposed outdoors at these facilities;

1. (III) The existence and permit status of any other

wastewater discharges from the group;

1. (IV) Analytical data which exists for any group

members’ storm water runoff;

1. (V) A summary of the history of spills, leaks, and

complaints relating to significant materials used, stored, treated, or disposed of on these facilities; and

1. (VI) Management practices used to prevent or

minimize materials contacting storm water.

1. B. Within ninety (90) days of receipt of the petition, the

director shall notify the applicant that—

1. (I) A general permit will be developed;
2. (II) A general permit will not be developed and reason;

or

1. (III) Further information is re quired to make a

decision; and

1. C. If the director has indicated that a general permit

will be developed for specific facilities/activities, application for general permit as indicated in 10 CSR 20-6.010(13) may be submitted in lieu of an individual industrial storm water runoff permit application;

1. 7. General permits shall have conditions to meet any

applicable technology or water quality based standard;

1. 8. A general permit will be issued to cover the geographi-

cal area of any city, county, state, or federal government agency or other utility with approval of the department that performs or contracts for land disturbance activities. The general permit will be issued for all activities that are conducted within the geographic area under contract by, or performed by, the entity. The applicant will need only to secure one (1) general permit for all activities that occur during the life of the permit.

1. (B) Site-specific industrial permits issued pursuant to this rule shall contain the following:

   1. 1. Identification of the permit holder; and
   2. 2. Effluent limitation if necessary to protect waters of the

state. The limitation shall be based on one (1) or more of the following:

1. A. The application and information filed by the permit-

tee;

1. B. Effluent guidelines promulgated by the department or

Environmental Protection Agency for the facility;

1. C. Best professional judgment of the permit writer;
2. D. A water quality determination made by the depart-

ment; or

1. E. BMP requirements that are proposed in city-wide

management programs;

1. 3. Monitoring and reporting requirements; and
2. 4. A schedule of compliance and interim limitations allow-

ing up to three (3) years from permit issuance to gain compliance with the effluent limitation.

1. (7) Qualifying Local Programs.

   1. (A) Regulated municipal separate storm sewer systems (MS4s) may request department approval to implement a qualifying local program. A qualifying local program is a formal recognition that a regulated MS4 has a departmentapproved local sediment and erosion control program that meets or exceeds the requirements listed in 10 CSR 20-6.200(7)

2. (B) for construction and land disturbance activities occurring within the regulated MS4’s jurisdiction. While a regulated MS4 has an approved qualifying local program, construction and land disturbance activities in its jurisdiction for which the regulated MS4 has issued a land disturbance or equivalent permit do not require an NPDES operating permit from the department.

   1. (B) Qualifying local programs are for storm water discharges associated with land disturbance activities only, which includes clearing, grubbing, excavating, grading, and other activities that result in the destruction of the root zone and have potential to cause negative impacts to receiving waterbodies. Each approved qualifying local program shall include reviewing site plans, inspecting construction sites, and taking enforcement action against owners or operators of sites that are polluting the waters of the state within its jurisdiction.

      1. 1. Qualifying local programs are only applicable to

regulated MS4s, as defined in paragraph (1)(D)22. of this rule, including large, medium, or small MS4s, as defined in paragraphs (1)(D)10., 13., and 27., respectively, of this rule.

1. 2. At a minimum, a qualifying local program shall

include—

1. A. Requirements for construction site operators to

implement appropriate erosion and sediment control best management practices that meet or exceed applicable state requirements;

1. B. Requirements for construction site operators to

control waste such as discarded building materials, concrete truck washout, chemicals, litter, and sanitary waste at the construction site that may cause negative impacts to water quality;

1. C. Requirements for construction site operators to

develop and implement a storm water pollution prevention plan. A storm water pollution prevention plan includes site descriptions, descriptions of appropriate control measures to protect water quality, copies of approved state, tribal, or local requirements, maintenance procedures, inspection procedures, and identification of non-storm water discharges; and

1. D. Requirements to submit a site plan for review that

incorporates considerations of potential water quality impacts.

1. 3. Regulated MS4s seeking to become recognized as having

a qualifying local program may apply by sending a letter to the department requesting formal recognition pursuant to this subsection.

1. 4. The department will review each request to become

recognized as a qualifying local program submitted by a regulated MS4.

1. A. The department will review the regulated MS4’s land

disturbance program and compliance history to determine eligibility and to ensure that the program meets or exceeds state requirements outlined in the Missouri land disturbance permit and the MS4 permit.

1. B. If the department concurs that the regulated MS4

is eligible to have a qualifying local program and that its land disturbance program meets or exceeds applicable state requirements, then the department will incorporate the local requirements specific to that regulated MS4’s qualifying local program into its permit. If covered by a site-specific permit, the department will modify its MS4 permit if necessary. If under a general two-step permit, the MS4 shall modify and public notice its storm water management plan for thirty (30) days to incorporate the local requirements specific to that regulated MS4’s qualifying local program.

1. C. For site-specific MS4 permits, the regulated MS4 must

submit a modified storm water management plan within thirty (30) days of the MS4 permit modification. For general two-step permits, the regulated MS4 must submit the modified storm water management plan after the public notice is complete.

1. D. After the department receives and approves the

modified storm water management plan, the department will send official correspondence to the regulated MS4 indicating that the department has approved its qualifying local program.

1. 5. A regulated MS4 may end its qualifying local program

at its discretion upon written notice to the department. The qualifying local program shall remain effective for at least ninety (90) days after the date the written notice is sent to the department, ending on a date determined by the regulated MS4. This provides time for the regulated MS4 to notify all affected construction site permit holders of the need to obtain a Missouri state operating permit for land disturbance.

1. 6. The department may revoke any qualifying local pro-

gram designation if the regulated MS4 does not comply with this rule or the program requirements as established. The department’s revocation may be appealed to the Missouri Clean Water Commission by the regulated MS4 or by any adversely affected party within thirty (30) days of the date of revocation. The appeal shall be filed with the Administrative Hearing Commission, 131 W. High St., PO Box 1557, Jefferson City, MO 65101 and shall be a contested case and be conducted pursuant to section 644.066, RSMo. The filing of an appeal shall stay the department’s revocation. If the revocation is not appealed, or upon the final disposition of an appeal in which the revocation is sustained, the qualifying local program shall remain effective for ninety (90) days after the department’s revocation or final disposition of the appeal, whichever occurs later. This provides time for the regulated MS4 to notify all affected construction site permit holders of the need to obtain a Missouri state operating permit for land disturbance.

1. (8) Silvicultural Activities.

   1. (A) The department does not require storm water permitting for silviculture activities conducted in accordance with 33 U.S. Code 1342(l)(3), January 2014, as published by the U.S. Government Publishing Office, available at https://bookstore. gpo.gov/ or for mail orders print and fill out order form online and mail to U.S. Government Publishing Office, PO Box 979050, St. Louis, MO 63197-9000.

AUTHORITY: sections 644.026 and 644.036, RSMo 2016.* Original rule filed July 15, 1991, effective Oct. 1, 1992. Amended: Filed Sept. 14, 2001, effective May 30, 2002. Amended: Filed Feb. 3, 2009, effective Oct. 30, 2009. Amended: Filed June 13, 2018, effective Feb. 28, 2019. Amended: Filed June 30, 2022, effective Feb. 28, 2023. Amended: Filed July 15, 2025, effective Feb. 28, 2026. *Original authority: 644.026, RSMo 1972, amended 1973, 1987, 1993, 1995, 2000, 2012, 2014, and 644.036, RSMo 1972, amended 1973, 2000, 2002, 2006, 2009, 2011.