Oklahoma Administrative Code › Title 252 - Department of Environmental Quality › Chapter 740 - Implementation of Oklahoma's Water Quality Standards › Subchapter 15 - Use Support Assessment Protocols › Section 252:740-15-10 - Nutrients

Current through Vol. 41, No. 20, July 1, 2024
(a)
General.
OAC
				252:730-3-2(c)
				prohibits water quality degradation by nutrients which will interfere with the
				attainment or maintenance of any existing or designated beneficial use. OAC
				252:740-13-3(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.