PURPOSE: This rule sets forth the definitions of terms used in the Missouri Clean Water Law and Missouri Concentrated Animal Feeding Operation Law (640.700-640.760, RSMo) and all regulations passed pursuant to it, specifically 10 CSR 20.

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) “Abandoned well,” as defined in section 256.603, RSMo.
2. (2) “Agrichemical,” any fertilizer licensed by the Missouri Fertilizer Control Program or any pesticide but does not include anhydrous ammonia fertilizer material.

3. (3) “Agrichemical facility,” as defined by section 644.016, RSMo, any site, with the exception of chemical production facilities, where bulk pesticides or fertilizers, excluding anhydrous ammonia fertilizer, are—

   1. (A) Stored and combined in non-mobile containers, dedicated containers, or storage basins; or
   2. (B) Stored or being mixed, applied, repackaged, or transferred between containers or storage basins.
4. (4) “Application,” the application form supplied by the department, the filing fee, if applicable, and other supporting documents if requested.
5. (5) “Appurtenances,” valves, pumps, fittings, pipes, hoses, plumbing, or metering devices connected to sewers, basins, tanks, storage vessels, treatment units, and discharge or delivery structures, or used for transferring products or wastes.
6. (6) “Aquaculture facility,” as defined by section 644.016, RSMo, a hatchery, fish farm, or other facility used for the production of aquatic animals that is required to have a permit pursuant to the federal Clean Water Act, as amended, 33 U.S.C. Section 1251, et seq.
7. (7) “Aquifer,” as defined by section 640.403, RSMo, for the purposes of these rules, does not include water in the vadose zone, or sandy or gravelly alluvial soils in or on the floodplains of intermittent streams.
8. (8) “Best management practices (BMPs),” schedules of activities, prohibitions of practices, maintenance procedures, and other management practices to prevent pollution and protect the environment. BMPs also include treatment requirements, operating procedures, and practices to control facility runoff, spillage or leaks, sludge or waste disposal, or drainage from raw material storage.
9. (9) “Biosolids,” the solid, semisolid, or liquid residue from treatment works treating domestic sewage and then further treated physically, biologically, and/or chemically. Commonly called sewage sludge, biosolids are treated to reduce pathogens and vector attraction. Materials like grit, screenings, and incinerator ash are excluded.
10. (10) “Blending,” the practice of diverting wet-weather flows around any treatment unit and recombining those flows within the treatment facility, while providing primary and secondary or biological treatment up to the available capacity, consistent with all applicable effluent limits and conditions. See bypass, section (14) of this rule.
11. (11) “Bulk fertilizer,” any liquid or dry fertilizer which is transported or stored in undivided quantities of greater than five hundred (500) gallons measure or five thousand (5,000) pounds net dry weight respectively.
12. (12) “Bulk pesticide,” any registered pesticide which is transported or stored in an individual container in undivided quantities greater than fifty-six (56) gallons liquid measure or one hundred (100) pounds dry weight respectively.
13. (13) “Bulk repackaging,” the transfer of a registered pesticide from one (1) container to another in an unaltered state in preparation for sale to or distribution for use by another person.
14. (14) “Bypass,” as defined by 40 CFR part 122 subpart C, October 22, 2015, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, is incorporated by reference. This rule does not incorporate any subsequent amendments or additions. Blending is not a bypass.
15. (15) “Catastrophic storm,” a precipitation event of twenty-four- (24-) hour duration or less that exceeds the twenty-five- (25-) year, twenty-four- (24-) hour storm event. This does not amend the definition of “chronic weather event” in 10 CSR 20-6.300.
16. (16) “Chronic storm event,” unless otherwise defined in a rule, a precipitation event with a duration of more than twenty-four
17. (24) hours that exceeds the one-in-ten- (1-in-10-) year return frequency. This does not amend the definition of “chronic weather event” in 10 CSR 20-6.300.
18. (17) “Clean Water Act,” the Clean Water Act (formerly referred to as the Federal Water Pollution Control Act or Federal Water Pollution Control Act Amendments of 1972) (P.L. 92- 500) as amended in 1977 (P.L. 95-217), 1978 (P.L. 95-576), 1980 (P.L. 96-483), and in 1981 (P.L. 97-117), 33 U.S.C. 1251 et seq, as published by the Office of the Law Revision Counsel, U.S. House of Representatives, H2-308 Ford House Office Building, Washington, DC 20515, are incorporated by reference. This rule does not incorporate any subsequent amendments or additions.
19. (18) “Collection system,” a network of pipes or similar conduits, pump stations, air release valves, and all other structures, devices and appurtenances for collecting and conveying wastewater to wastewater treatment facilities. Service lines and service connections are typically excluded.
20. (19) “Commingled offsite industrial wastewater or wastewater residuals open storage basin or open storage vessel,” an open earthen basin or open storage vessel (as defined in section 644.016, RSMo) in which process wastes from other operating location(s) are brought in, stored, and mixed prior to land application.
21. (20) “Commission,” as defined by section 644.016, RSMo, the Clean Water Commission of the state of Missouri created in section 644.021, RSMo.
22. (21) “Common promotional plan,” a plan, undertaken by one (1) or more persons, to offer individual lots or residential housing units within a residential housing development for sale or lease; where land or residential housing units are offered for sale or lease by a person or group of persons acting in concert, and the land is contiguous or is known, designated, or advertised as a common unit or by a common name or similar names, the land is presumed, without regard to the number of lots or residential housing units covered by each individual offering, as being offered for sale or lease as part of a common promotional plan. State and county roads are not considered property boundaries.
23. (22) “Composite sample,” a combination of individual samples collected over a designated period of time.
24. (23) “Conference, conciliation, and persuasion,” as defined by section 644.016, RSMo, a process of verbal or written communications consisting of meetings, reports, correspondence, or telephone conferences between authorized representatives of the department and the alleged violator. The process shall, at a minimum, consist of one (1) offer to meet with the alleged violator tendered by the department. During any such meeting, the department and the alleged violator shall negotiate in good faith to eliminate the alleged violation and shall attempt to agree upon a plan to achieve compliance.
25. (24) “Construction,” any activities including but not limited to the erection, installation, or significant modification of any dwelling, structure, building, sewer system, water contaminant source, or point source. Construction commences with any preparatory activity including but not limited to trenching, excavation for any building in a subdivision, or for a wastewater treatment facility, demolition of existing wastewater treatment facility structures or change in the wastewater treatment facility operation necessary to allow modification, but not to include interior remodeling of singlefamily residences or commercial buildings which will not result in a substantial change in wastewater volume, nature, or strength of the discharge therefrom.
26. (25) “Continuing authority” is a company, business, entity, or person(s) that is the owner of, operator of, or area-wide management authority for a water contaminant source, point source, or treatment facility, or sewer collection system that will ensure compliance with the permit requirements.
27. (26) “Daily maximum,” an effluent limitation that specifies the total mass or average concentration of pollutants that may be discharged in a calendar day.
28. (27) “Dedicated agrichemical container,” a container effectively designed and constructed to hold a specific agrichemical and to be reused, repackaged, or refilled.
29. (28) “Department,” as defined by section 644.016, RSMo, the Department of Natural Resources.
30. (29) “Developer,” any person or group of persons who directly or indirectly sells or leases or offers to sell or lease any lots, residential housing units, or recreational camping sites, but not to include any licensed broker or licensed salesman who is not a shareholder, director, officer, or employee of a developer and who has no legal or equitable interest in the land.
31. (30) “Director,” as defined by section 644.016, RSMo, the director of the Department of Natural Resources.
32. (31) “Discharge,” as defined by section 644.016, RSMo, the causing or permitting of one (1) or more water contaminants to enter the waters of the state.
33. (32) “Domestic wastewater,” wastewater (i.e., human sewage) originating primarily from the sanitary conveniences of residences, commercial buildings, factories, and institutions, including any water which may have infiltrated the sewers. Domestic wastewater excludes stormwater, animal waste, industrial process wastewater, industrial process wastewater treatment residuals, and other similar industrial residuals.
34. (33) “Earthen basin,” a basin to hold liquids, solids, semi-solids, or a combination thereof constructed by excavation and/ or forming structure, bottom, and berms made of earthen materials. Earthen basins are designed and constructed to prevent ground and surface water contamination and may be storage basins, equalization basins, or lagoons.
35. (34) “Effluent,” any wastewater or other substance flowing out of or released from a point source, water contaminant source, or wastewater treatment facility.
36. (35) “Effluent control regulations,” as defined by section 644.016, RSMo, limitations on the discharge of water contaminants.
37. (36) “Effluent limitation segment,” any segment of water where the water quality meets and will continue to meet water quality standards or where the water quality will meet water quality standards after the application of effluent limitation guidelines.
38. (37) “Electrical feed,” an electrical supply or device that supplies power to equipment through a transmission line.
39. (38) “Engineer,” as defined by section 327.011, RSMo.
40. (39) “Environmental Protection Agency (EPA),” the United States Environmental Protection Agency.
41. (40) “Fertilizer,” as defined by section 266.291(4), RSMo.
42. (41) “Freeboard,” the vertical distance from the liquid water surface to the overflow point, spillway, emergency overflow, pipe, or top of the berm or tank, whichever is lowest.
43. (42) “General permit,” as defined by section 644.016, RSMo, a permit written with a standard group of conditions and with applicability intended for a designated category of water contaminant sources that have the same or similar operations, discharges, and geographical locations, and that require the same or similar monitoring, and that would be more appropriately controlled pursuant to a general permit rather than pursuant to a site-specific permit.
44. (43) “General permit template,” as defined by section 644.016, RSMo, a draft general permit that is being developed through a public participation process.
45. (44) “Grab sample,” any individual sample collected without compositing or adding other samples.
46. (45) “Human sewage,” as defined by section 644.016, RSMo, human excreta and wastewater, including bath and toilet waste, residential laundry waste, residential kitchen waste, and other similar waste from household or establishment appurtenances.
47. (46) “Innovative technology,” new and generally unproven technology in the type or method of its application that bench testing or theory suggests has environmental, efficiency, and cost benefits beyond standard technologies.
48. (47) “Lagoon,” an earthen basin or lined basin used for biological treatment of wastewater, usually designed for biochemical oxygen demand (BOD) removal and settling of solids. Lagoons can be designed as flow-through, controlled discharge, no-discharge systems, or for storage.
49. (48) “Lake,” a naturally or artificially impounded body of water. For the purposes of these rules, lakes include constructed reservoirs. This does not include ponds which were built as stormwater diversions for agricultural needs.
50. (49) “Losing streams,” a stream which distributes thirty percent (30%) or more of its flow during low flow conditions through natural processes. Losing streams are identified in the digital geospatial dataset ‘LOSING_STREAM’ developed by the Missouri Department of Natural Resources, Missouri Geological Survey; additional streams may be determined to be losing by the department.
51. (50) “Lot,” any portion, piece, division, unit, or undivided interest in real estate, if the interest includes the right to the exclusive use of a specific portion of real estate, whether for a specific term or in perpetuity.
52. (51) “Minor violation,” as defined by section 644.016, RSMo, a violation which possesses a small potential to harm the environment or human health or cause pollution, was not knowingly committed, and is not defined by the United States Environmental Protection Agency as other than minor.
53. (52) “Missouri Clean Water Law,” as defined by sections 644.006 through 644.141, RSMo.
54. (53) “Mobile container,” a container designed and used for transporting agrichemicals that meet the United States Department of Transportation standards for the product being transported.
55. (54) “Monthly average,” the total mass or concentration of all daily discharges sampled during a calendar month divided by the number of daily discharges sampled or measured during that month.
56. (55) “Municipality,” an incorporated city, town, or village (including an intermunicipal agency of two (2) or more of the foregoing entities).
57. (56) “National Pollutant Discharge Elimination System (NPDES),” as defined in the Clean Water Act. See Clean Water Act, section

58. (17) of this rule.

    1. (A) NPDES permit. Any permit issued by either the EPA or the state of Missouri under authorization by EPA which fulfills the NPDES requirements as set forth in the Clean Water Act.
    2. (B) NPDES application. Any application on a form supplied by the department, submitted for an NPDES permit.

59. (57) “New discharger,” any building, structure, facility or installation—

    1. (A) Which on October 18, 1972, has never discharged pollutants;
    2. (B) Which has never received a finally effective NPDES permit;
    3. (C) From which there is or may be a new or additional discharge of pollutants; and
    4. (D) Which does not fall within the definition of new source.
60. (58) “New source,” as defined by 40 CFR part 122 subpart A, June 29, 2015, 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.
61. (59) “No-discharge,” a facility designed, constructed, and operated to hold or irrigate, or otherwise dispose without discharge to surface or subsurface waters of the state, all process wastes and associated stormwater flows except for discharges that are caused by catastrophic and chronic storm events; any basin is sealed in accordance with 10 CSR 20-8, Minimum Design Standards; and no subsurface releases exist in violation of 10 CSR 20-7.015, Effluent Regulations, or section 577.155, RSMo.
62. (60) “Non-mobile container,” a stationary container designed to be incapable of movement once installed; not defined as mobile.
63. (61) “Occupied residence or dwelling” means a residential dwelling which has been inhabited at least fifty percent (50%) of the previous year. Residences or dwellings for which construction began after the associated permit application was submitted, or neighbor notice was conducted, are excluded.
64. (62) “Open storage basin,” as defined by section 644.016, RSMo, an open earthen basin (nonconcrete) with a capacity of two and one-half million gallons (2.5 MG) or larger that stores industrial process wastewater or industrial process wastewater residuals for disposal or land application.
65. (63) “Open storage vessel,” as defined by section 644.016, RSMo, any metal, plastic, or polymer lined basin with a capacity of two and one-half million gallons (2.5 MG) or larger that stores industrial process wastewater or industrial process wastewater residuals for disposal or land application.
66. (64) “Operating location,” as defined by section 644.016, RSMo, all contiguous lands owned, operated, or controlled by one
67. (1) or more persons jointly or as tenants in common, except land application sites are not required to be contiguous. State and country roads (excluding interstates) are not considered property boundaries for the purposes of this rule.

68. (65) “Operation and maintenance,” activities to assure the dependable and economical function of wastewater and stormwater systems.

    1. (A) Maintenance. Preservation of functional integrity and efficiency of equipment and structures. The proper keeping of all aspects of a collection system and wastewater treatment facility and appurtenances thereto, that pertain to safety, in a state of repair and working order as necessary to comply with the Missouri Clean Water Law and any permit issued thereunder and to protect public health and safety. This includes preventive maintenance, corrective maintenance, and replacement of equipment as needed.
    2. (B) Operation. Control of the unit processes and equipment which make up the wastewater treatment facility. This includes financial and personnel management, records, laboratory control, process control, safety, and emergency operation planning.
69. (66) “Operational area,” an area(s) at an agrichemical facility where agrichemicals are transferred, loaded, unloaded, mixed, repackaged, refilled, or where agrichemicals are cleaned, washed, or rinsed from containers or equipment that is used in application, handling, storage, or transportation.
70. (67) “Operational containment area,” any structure or system effectively designed and constructed to intercept and contain discharges, including container or equipment wash water, rinsates and precipitation, and to prevent escape, runoff, or leaking from the operational area.
71. (68) “Pasture,” a field for raising, housing, stabling, feeding, or maintaining livestock or other animals upon which grass, crops, or other vegetation is sustained over fifty percent (50%) of the area within the normal growing season.
72. (69) “Permit by rule,” as defined by section 644.016, RSMo, a permit granted by rule, not by a paper certificate, and conditioned by the permit holder’s compliance with commission rules.
73. (70) “Person,” as defined by section 644.016, RSMo, any individual, partnership, copartnership, firm, company, public or private corporation, association, joint stock company, trust, estate, political subdivision, or any agency, board, department, or bureau of the state or federal government, or any other legal entity whatever which is recognized by law as the subject of rights and duties.
74. (71) “Pesticide,” as defined by section 281.020(25), RSMo.
75. (72) “Point source,” as defined by section 644.016, RSMo, any discernible, confined, and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged. Point source does not include agricultural storm water discharges and return flows from irrigated agriculture.
76. (73) “Pollutant,” as defined by 40 CFR part 122 subpart A, June 29, 2015, as published by the EPA Docket Center, EPA West, 1301 Constitution Avenue NW, Washington, DC 20004, is incorporated by reference. This rule does not incorporate any subsequent amendments or additions.
77. (74) “Pollution,” as defined by section 644.016, RSMo, such contamination or other alteration of the physical, chemical, or biological properties of any waters of the state, including change in temperature, taste, color, turbidity, or odor of the waters, or such discharge of any liquid, gaseous, solid, radioactive, or other substance into any waters of the state as will or is reasonably certain to create a nuisance or render such waters harmful, detrimental, or injurious to public health, safety, or welfare, or to domestic, industrial, agricultural, recreational, or other legitimate beneficial uses, or to wild animals, birds, fish or other aquatic life.
78. (75) “Pretreatment regulations,” as defined by section 644.016, RSMo, limitations on the introduction of pollutants or water contaminants into publicly owned treatment works or facilities which the commission determines are not susceptible to treatment by such works or facilities or which would interfere with their operation, except that wastes as determined compatible for treatment pursuant to any federal water pollution control act or guidelines shall be limited or treated pursuant to this chapter only as required by such act or guidelines.
79. (76) “Primary containment,” the storage of an agrichemical in either its original container or other suitable container, including dedicated containers, effectively designed and constructed to contain the product that may be stored there.
80. (77) “Process waste(s),” for the purposes of 10 CSR 20, any process wastewater or process wastewater treatment residuals.
81. (78) “Process wastewater,” any wastewater originating from sanitary conveniences, or 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, byproduct, or waste product, including direct discharges from a land application field, but not agricultural stormwater as exempted in 644.059, RSMo. This does not include stormwater unless explicitly defined as wastewater in rule.
82. (79) “Process wastewater treatment residuals,” sludges, biosolids, or other residuals originating from sanitary conveniences, or generated during manufacturing or processing, or results from the production or use of any raw material, intermediate product, finished product, by-product, or waste product.
83. (80) “Public building,” a building routinely open to use by the public for public purposes.
84. (81) “Publicly owned treatment works (POTW),” wastewater treatment facility and collection system which conveys wastewater to the POTW owned by the state, a municipality, a political subdivision, or a sewer district defined by Chapters 644, 249, and 250, RSMo.
85. (82) “Pump and haul,” a no-discharge system which temporarily holds wastewater and wastewater treatment residuals until it is pumped down and the materials hauled to a permitted wastewater treatment facility or to an out-of-state location.
86. (83) “Regional administrator,” regional administrator of the Environmental Protection Agency’s regional office for the region in which the state of Missouri is located.
87. (84) “Release,” to discharge directly or indirectly to waters of the state, or to place, cause, or permit to be placed, any water contaminant in any location where it is reasonably certain to enter waters of the state. For agrichemical facilities, this includes any spill, leak, deposit, dumping, or emptying of an agrichemical, process wastewater, or collected precipitation from a secondary containment area or operational containment area. Release does not include the lawful transfer, loading, unloading, repackaging, refilling, distribution, use, or application of an agrichemical, agrichemical process wastewater, or related collected precipitation.

88. (85) “Residence,” any structure, dwelling, unit, or shelter which is intended or used for human habitation as a permanent, vacation, or recreational home or building. They may be detached or part of one (1) or more attached units.

    1. (A) “Multiple-family,” residential housing units that share the same structure, dwelling, unit, shelter, or common wall with or without a common social area that includes the right to the exclusive use of a specific portion of real estate, whether for a specific term or in perpetuity; they may include but are not limited to duplexes, condominiums, townhouses, apartments, hotels, motels, hospitals, dormitories, boarding schools, group homes, barracks, etc.
    2. (B) “Single-family,” an individual structure, dwelling, unit, or shelter constructed for the purpose of human habitation, with one (1) or more rooms occupied or intended for occupancy by one (1) family for cooking, sanitary, and sleeping purposes that includes the right to the exclusive use of a specific portion of real estate, whether for a specific term or in perpetuity; they do not include multiple-family residences.
89. (86) “Residential housing development,” as defined by section 644.016, RSMo, any land which is divided or proposed to be divided into three (3) or more lots, whether contiguous or not, for the purpose of sale or lease as part of a common promotional plan for residential housing.
90. (87) “Rinsate,” any water containing contaminant that has been washed off or rinsed from containers, application equipment, handling or storage areas, or transportation equipment, including but not limited to industrial chemicals, agrichemicals, or concrete.
91. (88) “Satellite collection system,” a collection system owned or operated by one person which conveys wastewater to a treatment works treating domestic sewage owned or operated by another entity.
92. (89) “Saturated soil,” a soil in which voids are filled with water. Saturation does not require flow. For the purposes of land application, soils shall be considered saturated if standing water is present or the pressure of a person standing on the soil causes the release of free water.
93. (90) “Secondary containment,” any structure effectively designed and constructed to contain one (1) or more primary storage containers to collect any leaks or spills in the event of loss of integrity or primary container failure.
94. (91) “Separate storm sewer,” conveyance or systems of conveyances primarily used for conducting and conveying storm water runoff and located in an area designated by the department as a separate storm sewer due to its size, its location, the quantity and nature of pollutants reaching the waters of the state, and other relevant factors.
95. (92) “Septage,” domestic wastewater sewage sludge that is removed from septic tanks or similar treatment works, including domestic wastewater treatment works serving up to one hundred fifty (150) persons.
96. (93) “Service area population,” the population to be served by a wastewater treatment facility.
97. (94) “Service connection,” the connection point of the service line and the sanitary sewer system which is operated and maintained by one (1) of the continuing authorities listed in 10 CSR 20-6.010(3)(B).
98. (95) “Seven- (7-) day Q10 stream flow,” the lowest average flow that occurs for seven (7) consecutive days that has a probable recurrence interval of once every ten (10) years.
99. (96) “Sewer extension,” sewer systems which are added to existing sewers and wastewater treatment facilities.
100. (97) “Sewer system,” as defined by section 644.016, RSMo, pipelines or conduits, pumping stations, and force mains, and all other structures, devices, appurtenances and facilities used for collecting or conducting wastes to an ultimate point for treatment or handling.
101. (98) “Single family residence wastewater treatment facility,” any method or system for the treatment of domestic wastewater from a single-family residence.
102. (99) “Site-specific permit,” as defined by section 644.016, RSMo, a permit written for discharges emitted from a single water contaminant source and containing specific conditions, monitoring requirements and effluent limits to control such discharges.
103. (100) “Sludge,” precipitated solid, semisolid, or liquid residue matter produced by the treatment of wastewater or sewage from any treatment facilities.
104. (101) “Small rural community,” a community of less than ten thousand (10,000) population and not located in whole or in part, in an area of St. Louis County or City encircled by Interstate Route 270, or in an area of Jackson, Clay, or Platte Counties encircled by State Route 150 and 291 and Interstate Routes 29 and 635.
105. (102) “Soil scientist,” as defined by section 701.040.1.(2)(e), RSMo.
106. (103) “Stormwater,” storm water runoff, snow melt runoff, and surface runoff and drainage as a result of precipitation events.
107. (104) “Stream,” a defined watercourse that carries water which flows either continuously or intermittently and which is not entirely confined or located completely upon land owned, leased, or otherwise controlled by one (1) person.
108. (105) “Test hole,” a hole which has been drilled, bored, augered, or otherwise excavated in the exploration for mineral commodities or for obtaining geologic data. Test holes that penetrate only the residuum or unconsolidated materials and which do not enter a geologic unit, are deemed to be an aquifer, exempt from this definition.
109. (106) “Treatment facilities,” as defined by section 644.016, RSMo, any method, process, or equipment which removes, reduces, or renders less obnoxious water contaminants released from any source. Treatment facilities may include storage, treatment devices, and land application fields.
110. (107) “Treatment works treating domestic sewage,” any wastewater treatment devices, systems, or facilities, regardless of ownership, used in the treatment, storage, recycling, reclamation, and land application of principally domestic wastewater, which may include up to forty-nine percent (49%) non-domestic wastewater flows.
111. (108) “Twenty-five- (25-) year, twenty-four- (24-) hour rainfall,” the wettest precipitation event for a twenty-four- (24-) hour period with a probable recurrence interval of once in twenty-five
112. (25) years based on at least thirty (30) years of record from nationally recognized, credible data sources, with preference for more recent and localized data.
113. (109) “User charge,” a charge levied on users of a wastewater treatment facility for the user’s share of the costs of operation, maintenance, and replacement of the collection system and wastewater treatment facility.
114. (110) “Waste load allocation,” the amount of pollutants each discharger is allowed by the department to release into a given stream after the department has determined the total amount of pollutants that may be discharged into that stream without endangering its water quality.
115. (111) “Wastewater,” water or other liquids which carry or contain pollutants or water contaminants from any source.
116. (112) “Water contaminant,” as defined by section 644.016, RSMo, any particulate matter or solid matter or liquid or any gas or vapor or any combination thereof, or any temperature change which is in or enters any waters of the state either directly or indirectly by surface runoff, by sewer, by subsurface seepage or otherwise, which causes or would cause pollution upon entering waters of the state, or which violates or exceeds any of the standards, regulations or limitations set forth in sections 644.006 to 644.141, RSMo, or any federal water pollution control act, or is included in the definition of pollutant in such federal act.
117. (113) “Water contaminant source,” as defined by section 644.016, RSMo, the point or points of discharge from a single tract of property on which is located any installation, operation, or condition which includes any point source defined in sections 644.006 to 644.141, RSMo, and nonpoint source pursuant to any federal water pollution control act, which causes or permits a water contaminant therefrom to enter waters of the state either directly or indirectly.
118. (114) “Waters of the state,” as defined by section 644.016(31), RSMo.
119. (115) “Water quality limited segment,” a segment where water quality does not meet and/or is not expected to meet applicable water quality standards even after the application of effluent limitations.
120. (116) “Weekly average,” the total mass or concentration of all daily discharges sampled during any calendar week divided by the number of daily discharges sampled or measured during that week.

AUTHORITY: section 644.026, RSMo 2016.* Original rule filed June 6, 1974, effective June 16, 1974. Rescinded: Filed Oct. 12, 1979, effective July 10, 1980. Readopted: Filed Feb. 4, 1980, effective July 11, 1980. Amended: Filed Nov. 10, 1982, effective May 12, 1983. Amended: Filed Oct. 13, 1983, effective May 15, 1984. Amended: Filed July 15, 1991, effective Jan. 13, 1992. Amended: Filed Sept. 2, 1993, effective May 9, 1994. Amended: Filed Nov. 14, 1995, effective July 30, 1996. Amended: Filed April 24, 2018, effective Jan. 30, 2019. Amended: Filed July 14, 2025, effective Feb. 28, 2026. *Original authority: 644.026, RSMo 1972, amended 1973, 1987, 1993, 1995, 2000, 2012, 2014.