Oklahoma Administrative Code › Title 785 - Oklahoma Water Resources Board › Chapter 46 - Implementation of Oklahoma's Water Quality Standards › Subchapter 15 - Use Support Assessment Protocols › Section 785:46-15-10 - Nutrients

Current through Vol. 41, No. 20, July 1, 2024
(a)
General.
OAC
										785:45-3-2(c)
										prohibits water quality degradation by nutrients which will interfere with the attainment or maintenance of
										any existing or designated beneficial use. OAC
										785:46-13-3(a)(1)
										requires maintenance of any existing or designated beneficial use. This Section provides a framework which
										shall be used in assessing threats or impairments to beneficial uses and waterbodies and watersheds caused by
										nutrients, and the consequences of such assessments.
(b)
Determining whether a stream is nutrient-threatened.
The dichotomous process stated in this
										subsection shall be used in the determination of whether a stream is nutrient-threatened.
(1) The stream order shall be identified. If the stream order is 1, 2 or 3,
										then proceed to paragraph (2). If the stream order is not 1, 2 or 3, then proceed to paragraph (9).
(2) The stream slope shall be identified. If the stream slope is greater
										than or equal to 17 feet per mile, then proceed to paragraph (3). If the stream slope is less than 17 feet
										per mile, then proceed to paragraph (4).
(3) Subject to the
										application of the foregoing paragraphs of this subsection, if phosphorus concentrations in the stream are
										greater than 0.24 mg/L or if nitrite plus nitrate concentrations in the stream are greater than 4.95 mg/L,
										then proceed to paragraph (5). If such nutrient concentrations are less than the levels specified in this
										paragraph, then the stream is not threatened by nutrients.
(4)
										Subject to the application of the foregoing paragraphs of this subsection, if phosphorus concentrations in
										the stream are greater than 0.15 mg/L or if nitrite plus nitrate concentrations in the stream are greater
										than 2.4 mg/L, then proceed to paragraph (5). If such nutrient concentrations are less than the levels
										specified in this paragraph, then the stream is not threatened by nutrients.
(5) Subject to the application of the foregoing paragraphs of this
										subsection, if the percentage of canopy shading is greater than or equal to 80%, then the stream is not
										threatened by nutrients. If the percentage of canopy shading is less than 80%, then proceed to paragraph
										(6).
(6) Subject to the application of the foregoing paragraphs
										of this subsection, if the stream's turbidity is organic, then proceed to paragraph (7). If the stream's
										turbidity is inorganic, then proceed to paragraph (8).
(7)
										Subject to the application of the foregoing paragraphs of this subsection, if turbidity measured at seasonal
										base flow conditions is less than 20 NTU, then the stream is not threatened by nutrients. If turbidity
										measured at seasonal base flow conditions is 20 or more NTU, then the stream is threatened by
										nutrients.
(8) Subject to the application of the foregoing
										paragraphs of this subsection, if turbidity measured at seasonal base flow conditions is less than 20 NTU,
										then the stream is threatened by nutrients. If turbidity measured at seasonal base flow conditions is 20 or
										more NTU, then the stream is not threatened by nutrients.
(9)
										Subject to the application of the foregoing paragraphs of this subsection, if the stream slope is greater
										than or equal to 17 feet per mile, then proceed to paragraph (10). If the stream slope is less than 17 feet
										per mile, then proceed to paragraph (11).
(10) Subject to the
										application of the foregoing paragraphs of this subsection, if phosphorus concentrations in the stream are
										greater than 1.00 mg/L, or if nitrite plus nitrate concentrations in the stream are greater than 4.65 mg/L,
										then proceed to paragraph (12). If such nutrient concentrations are less than the levels specified in this
										paragraph, then the stream is not threatened by nutrients.
(11)
										Subject to the application of the foregoing paragraphs of this subsection, if phosphorus concentrations in
										the stream are greater than 0.36 mg/L, or if nitrite plus nitrate concentrations in the stream are greater
										than 5.0 mg/L, then proceed to paragraph (12). If such nutrient concentrations are less than the levels
										specified in this paragraph, then the stream is not threatened by nutrients.
(12) Subject to the application of the foregoing paragraphs of this
										subsection, if the stream's inorganic turbidity measured at seasonal base flow conditions is greater than or
										equal to 20 NTU, then the stream is not threatened by nutrients. If the stream's inorganic turbidity measured
										at seasonal base flow conditions is less than 20 NTU, then the stream is threatened.