Effluent Regulations

PURPOSE: This rule sets forth the limits for various pollutants which are discharged to the various waters of the state. The two previous rules 10 CSR 20-6.050 and 10 CSR 20-7.010 have been rescinded and this rule combines certain aspects of both rules and modifies the format of the effluent regulations. This rule also complies with the latest changes to the Federal Clean Water Act, P.L. 97-117 (1981). 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) Designations of Waters of the State. (A) Definitions. 1. Acute Toxicity Test—a test used to determine the concentration of an effluent that causes an adverse effect (usually death) in a group of test organisms during a shortterm exposure. 2. Allowable Effluent Concentration—the concentration of a toxicant or the parameter toxicity in the receiving water after mixing, sometimes referred to as the receiving water concentration or the in-stream waste concentration. 3. Chronic Toxicity Test—a short-term test, usually ninetysix (96) hours or longer in duration, in which sublethal effects such as reduced growth or reproduction rates are measured in addition to lethality. 4. Nutrient Credits are reductions that can be generated and used to achieve compliance with nutrient target reduction levels or other nutrient limitations, as follows: A. For point sources, a reduction in discharges of nutrients in pounds that is greater than the reduction required by law or permit conditions or aggregate assessment for facilities under common ownership or operational control; or B. For nonpoint sources with established load allocations, an actual reduction in discharge of nutrients in pounds that is greater than the reduction necessitated by the load allocation; or C. For other nonpoint sources, an actual reduction in discharges of nutrients, for example a nonpoint source installing best management practices. 5. Representative Sample—a small quantity whose characteristics represent the nature and volume of the whole as described in 40 CFR Part 122.48, September 26, 1984, as published by the Office of the Federal Register, National Archives and Records Administration, 700 Pennsylvania Avenue, Washington, DC 20408, which is hereby incorporated by reference and does not include later amendments or additions. 6. Toxic Unit—a measure of effluent toxicity generally expressed as acute toxicity unit or chronic toxicity unit. The larger the toxicity unit, the greater the toxicity. 7. Toxic Unit-Acute—one-hundred (100) times the reciprocal of the effluent concentration that causes fifty percent (50%) of the organisms to die in an acute toxicity test. 8. Toxic Unit-Chronic—one hundred (100) divided by either the highest effluent concentration that causes no observable effect on the test organisms or the inhibition concentration (IC25) causing a twenty-five percent (25%) or more reduction in the reproduction or growth of the test organisms in a chronic toxicity test. (B) For the purpose of this rule, the waters of the state are divided into the following categories: 1. The Missouri and Mississippi Rivers (section (2) of this rule); 2. Lakes and reservoirs, including natural lakes and any impoundments created by the construction of a dam across any waterway or watershed. An impoundment designed for or used as a disposal site for tailings or sediment from a mine or mill shall be considered a wastewater treatment device and not a lake or reservoir. Releases to lakes and reservoirs include discharges into streams one-half (1/2) stream mile (.80 km) before the stream enters the lake as measured to its conservation pool (section (3) of this rule); 3. A losing stream is a stream which distributes thirty percent (30%) or more of its flow through natural processes such as through permeable geologic materials into a bedrock aquifer within two (2) miles flow distance downstream of an existing or proposed discharge. Flow measurements to determine percentage of water loss must be corrected to approximate the seven- (7-) day Q10 stream flow. If a stream bed or drainage way has an intermittent flow or a flow insufficient to measure in accordance with this rule, it may be determined to be a losing stream on the basis of channel development, valley configuration, vegetation development, dye tracing studies, bedrock characteristics, geographical data, and other geological factors. Only discharges which in the opinion of the Missouri Department of Natural Resources (department) reach the losing section and which occur within two (2) miles upstream of the losing section of the stream shall be considered releases to a losing stream. Losing streams are defined in 10 CSR 20-2.010(40). Other streams may be determined to be losing by the department (section (4) of this rule); 4. Metropolitan no-discharge streams. These streams and the limitations on discharging to them are listed in Table F of