10 CSR 20-6.200
Storm Water Regulations
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) Storm Water Permits—General.
(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 depart
ment issues these permits in order to enforce the Missouri
Clean Water Law and regulations and administer the state
operating permit program.
(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. 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;
2. De minimis discharges as defined by the department in
general permits or by the Clean Water Commission;
3. Recycling collection points which are covered in a
manner which prevents contact with storm water, including
run on;
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;
5. Agricultural storm water discharges and irrigation
return flows;
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;
7. Linear, strip, or ribbon construction or maintenance
operations meeting one (1) of the following criteria:
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;
B. Cleaning or routine maintenance of roadside ditches,
sewers, waterlines, pipelines, utility lines, or similar facilities;
C. Trenches two (2) feet in width or less; or
D. Emergency repair or replacement of existing facilities
as long as best management practices are employed during the
emergency repair;
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;
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;
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;
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;
12. A regulated MS4 may share the responsibility under the
following:
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—
(I) The other entity currently implements the control
measure;
(II) The particular control measure, or component
thereof, is at least as stringent as the corresponding permit
requirement; and
(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);
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
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—
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
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
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 pol
lutant 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 sedi
ment or a parameter that addresses sediment (such as total
suspended solids, turbidity, or siltation) and any other pollut
ant 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.
(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 in
dustrial materials and activities are protected from rain, snow,
snowmelt, and/or runoff and the operator meets the require
ments under paragraph (C)1. and subparagraph (C)2.C. of this
subsection.
1. Industrial materials and activities protected by storm
resistant shelter. No exposure means that all industrial mate
rials 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 ma
chinery, 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:
A. Provide a storm resistant shelter to protect industrial
materials and activities from exposure to rain, snow, snowmelt,
and runoff;
B. Complete and sign a certification that storm water
is not contaminated by exposure to industrial materials and
activities from the entire facility;
C. Re-submit the signed certification to the department
once every five (5) years;
D. Allow the department to inspect the facility to deter
mine compliance with the no-exposure conditions;
E. Make the no-exposure inspection reports available to
the public upon request; and
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.
2. Industrial materials and activities not requiring storm
resistant shelter. An industrial site may qualify for this exclu
sion without a storm resistant shelter if—
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;
B. Adequately maintained vehicles are used in material
handling; and
C. All industrial materials consist of final products, other
than products that would be mobilized by storm water.
(D) Definitions.
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.
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—
A. State-approved standard specifications and permit
programs;
B. Employee training in erosion control, material
handling and storage, and housekeeping of maintenance
areas;
C. Site preparation such as grading, surface roughening,
topsoiling, tree preservation and protection, and temporary
construction entrances;
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;
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;
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;
G. Inlet and outlet protection;
H. Streambank protection such as a vegetative greenbelt
between the land disturbance and the watercourse. Also,
structural protection which stabilizes the stream channel;
I. A critical path method analysis or a schedule for
performing erosion control measures; and
J. Other proven methods for controlling runoff and
sedimentation.
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.
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.
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.
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.
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.
8. Incorporated place (in Missouri, a municipality). A city,
town, or village that is incorporated under the laws of Missouri.
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.
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.
11. MS4 means a municipal separate storm sewer system.
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.
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.
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—
A. Does not include any waters of the state as defined in
section 644.016, RSMo;
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;
C. Is not a part or portion of a combined sewer system;
D. Is not a part of a publicly owned treatment works as
defined in 40 CFR 122.2; and
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.
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.
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.
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.
18. Owner. A person who owns and controls the use,
operation, and maintenance of a separate storm sewer.
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.
20. Receiving waters. Waters of the state as defined in this
rule.
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.
22. Regulated MS4 means—
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
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.
23. Runoff coefficient. The fraction of total rainfall that will
appear at a conveyance as runoff.
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.
25. Significant material or activity associated with
industrial activity.
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.
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.
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.
D. Empty containers which have been properly triple
rinsed are not significant materials.
26. Construction activity means—
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
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.
27. Small municipal separate storm sewer system means—
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;
B. Not defined as large or medium municipal separate
storm sewer systems pursuant to paragraphs 10. and 13. of this
subsection; and
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.
28. Storm water means storm water runoff, snowmelt
runoff and surface runoff, and drainage.
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.
(2) Storm water discharge associated with industrial activity.
The discharge from any conveyance which is used for collect
ing 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.
(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, man
ufactured products, waste material, or by-products used or cre
ated 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 contam
ination and areas where industrial activity has taken place in
the past and where significant materials remain and are ex
posed to storm water.
(B) Industries subject to this requirement include—
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;
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;
3. Facilities which meet the following definitions are
considered to be included in this subsection:
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;
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;
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;
D. Steam electric power generating facilities, including
coal handling sites;
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
F. Industrial facilities that are federally, state, or
municipally owned or operated; and
4. Facilities classified with the following primary SIC are
considered to be included in this paragraph: 20, Food and Kin
dered Products; 21, Tobacco Products; 22, Textile Mill Products;
23, Apparel and Other Finished Products; 2434, Wood Kitchen
Cabinets; 25, Furniture and Fixtures; 265, Paperboard Contain
ers 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 Mis
cellaneous 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 In
dustries; 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-prod
uct, or waste product; sites used for the storage and mainte
nance 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 As
sociated With Industrial Activity.
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 gen
eral 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 require
ments:
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 dispos
al 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 haz
ardous waste treatment, storage, or disposal facilities (includ
ing 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 under
ground; springs and sink holes and other surface water bod
ies which receive storm water discharges from the facility;
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;
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;
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;
E. Quantitative data based on samples collected during
storm events from all outfalls containing a storm water dis
charge 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 repre
sentative and samples only collected from the representative
outfall. Quantitative data will be submitted for the following
parameters:
(I) Any pollutant limited in an effluent guideline to
which the facility is subject;
(II) Any pollutant listed in the facility’s state operating
permit for its process wastewater (if the facility is operating un
der an existing state operating permit);
(III) Oil and grease, pH, biochemical oxygen demands
(BOD5), chemical oxygen demands (COD), total suspended sol
ids (TSS), conductivity, total phosphorus, total Kjeldahl nitro
gen, and nitrate plus nitrite nitrogen;
(IV) Any information on the discharge required by the
appropriate application form;
(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
(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 measur
able (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;
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. Sam
pling should continue for three (3) hours or until discharge ceas
es, 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;
G. Applicants shall provide other information the direc
tor reasonably may require to determine whether to issue a
permit; and
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 esti
mates 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 per
mit for the discharge.
2. The operator of an existing or new discharge composed
entirely of storm water from an oil or gas exploration, produc
tion, 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—
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;
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;
C. Contributes to a violation of a water quality standard.
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 lo
cated on the site of the operations.
(3) Land Disturbance and Construction Activity.
(A) The owner/operator of an existing or new storm water
discharge from a land disturbance or construction activity
shall provide—
1. The location (including a map);
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;
3. The name of the receiving water; and
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.
(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. A land disturbance permit must be obtained before the
date construction operations begin.
2. Land disturbance permits must be applied for and issued
electronically unless a waiver is obtained from the department.
(4) Application requirements for large, medium municipal sep
arate storm sewer discharges.
(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.
(B) Reapplication minimum requirements for large and me
dium MS4s are as follows:
1. Name and mailing address of the permittee(s) that op
erate the MS4;
2. Names and titles of the primary administrative and tech
nical contacts for the municipal permittee(s);
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;
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
5. If applicable, any changes in co-applicants/co-permit
tees.
(5) Application Requirements for Phase II MS4s.
(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. 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;
2. Public involvement/participation process. A program
must be developed which at a minimum complies with state
and local public notice requirements;
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;
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;
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
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.
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.
(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
(6) minimum measures will be one of the requirements of any
issued permit.
(C) Copermittee Option.
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.
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.
(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.
(6) Permit Requirements.
(A) The director may issue a general permit for storm water
discharges in accordance with the following:
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—
A. Designated planning areas under Sections 208 and
303 of the federal Clean Water Act;
B. City, county, or state political boundaries or special
sewer districts chartered by the state;
C. State highway systems; and
D. Any other appropriate division or combination of
boundaries;
2. The general permit shall be written to regulate a
category of point sources if the sources all—
A. Involve the same or substantially similar types of
operations;
B. Discharge the same types of wastes;
C. Require the same operating conditions;
D. Require the same or similar monitoring; and
E. In the opinion of the director, are more appropriately
controlled under a general permit than under individual
permits;
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;
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:
A. Effluent limitation guidelines are promulgated for
point sources covered by a general state operating permit;
B. The discharge(s) is a significant contributor of
pollutants. In making this determination, the director may
consider the following factors:
(I) The location of the discharge with respect to waters
of the state;
(II) The size of the discharge;
(III) The quantity and nature of the pollutants
discharged to waters of the state; and
(IV) Other relevant factors;
C. The discharge(s) is a significant contributor of
pollution which impairs the beneficial uses of the receiving
stream;
D. The discharger is not in compliance with the
conditions of the general operating permit; or
E. A water quality management plan containing
requirements applicable to point sources is approved;
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.
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.
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;
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.
A. Information required in a petition must include—
(I) A full description of the group including names,
addresses, and locations and the industrial activities conducted
by group members;
(II) Any significant materials stored, used, loaded,
unloaded, treated, or disposed outdoors at these facilities;
(III) The existence and permit status of any other
wastewater discharges from the group;
(IV) Analytical data which exists for any group
members’ storm water runoff;
(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
(VI) Management practices used to prevent or
minimize materials contacting storm water.
B. Within ninety (90) days of receipt of the petition, the
director shall notify the applicant that—
(I) A general permit will be developed;
(II) A general permit will not be developed and reason;
or
(III) Further information is required to make a
decision; and
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;
7. General permits shall have conditions to meet any
applicable technology or water quality based standard;
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.
(B) Site-specific industrial permits issued pursuant to this rule
shall contain the following:
1. Identification of the permit holder; and
2. Effluent limitation if necessary to protect waters of the
state. The limitation shall be based on one (1) or more of the
following:
A. The application and information filed by the permit
tee;
B. Effluent guidelines promulgated by the department or
Environmental Protection Agency for the facility;
C. Best professional judgment of the permit writer;
D. A water quality determination made by the depart
ment; or
E. BMP requirements that are proposed in city-wide
management programs;
3. Monitoring and reporting requirements; and
4. A schedule of compliance and interim limitations allow
ing up to three (3) years from permit issuance to gain compli
ance with the effluent limitation.
(7) Qualifying Local Programs.
(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)
(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.
(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. 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.
2. At a minimum, a qualifying local program shall
include—
A. Requirements for construction site operators to
implement appropriate erosion and sediment control best
management practices that meet or exceed applicable state
requirements;
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;
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
D. Requirements to submit a site plan for review that
incorporates considerations of potential water quality impacts.
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.
4. The department will review each request to become
recognized as a qualifying local program submitted by a
regulated MS4.
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.
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.
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.
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.
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.
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 de
partment’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 Com
mission, 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 revoca
tion 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 con
struction site permit holders of the need to obtain a Missouri
state operating permit for land disturbance.
(8) Silvicultural Activities.
(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, ef
fective 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.