Missouri Code of State Regulations › Title 10 - DEPARTMENT OF NATURAL RESOURCES › Division 20 - Clean Water Commission › Chapter 7 - Water Quality › Section 10 CSR 20-7.015 - Effluent Regulations

Current through Register Vol. 49, No. 14, July 15, 2024
PURPOSE: This amendment modifies the definition of
				  losing streams for consistency with
				  10 CSR
				  20-7.031, directly incorporates language regarding
				  permitting activities related to losing streams previously located in
				  10 CSR
				  20-7.031, incorporates requirements for water reuse
				  discharges, and adds statewide nutrient reduction requirements for point
				  sources that typically discharge nutrients and have design flows greater than
				  1,000,000 gallons per day; these total phosphorus nutrient reductions are
				  neither water quality based effluent limits nor technology based effluent
				  limits.
(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 short-term
				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 ninety-six (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
				Resister, 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.