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Oklahoma Administrative Code (Last Updated: March 11, 2021) |
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TITLE 785. Oklahoma Water Resources Board |
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Chapter 46. Implementation of Oklahoma's Water Quality Standards |
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Subchapter 15. Use Support Assessment Protocols |
SECTION 785:46-15-3. Data requirements
Latest version.
- (a) General. In order to determine whether a given beneficial use of a waterbody is supported, scientific data from the waterbody shall be used as prescribed in this Section. Data shall be collected and analyzed in a manner consistent with testing procedures provided in 785:45-1-4 or practices that are institutionally recognized and appropriate for the parameter of concern and documented in accordance with 785:46-15-3(g). All existing data available for a waterbody shall be used in the analysis, subject to the spatial, temporal and other requirements of this Section.(b) Spatial coverage.(1) General for streams. The spatial extent of assessment of use support in terms of stream miles shall be determined after taking into account existing data, spatial distribution of monitoring sites, sources of pollution and influence of tributaries. Major hydrological features, such as the confluence of a major tributary or a dam, may limit the spatial extent of an assessment based on one station.(2) Non-wadable streams. Unless it is demonstrated to the contrary, a single monitoring site shall be considered representative of no more than 25 stream miles for non-wadable streams.(3) Wadable streams. Unless it is demonstrated to the contrary, a single monitoring site shall be considered representative of no more than 10 stream miles for wadable streams.(4) Lakes. The spatial extent of assessment of use support in terms of lake surface acres shall be estimated based on the spatial distribution of monitoring sites having the requisite number of samples, sources of pollution, influence of tributaries and best professional judgment. Arms or portions of lake may be treated separately from the main body of a lake. Unless it is demonstrated to the contrary, a single site shall be considered representative of an entire lake or an arm of no more than two hundred and fifty surface acres in size.(5) Spatial limitation for sampling sites. For purposes of this Subchapter, observations, samples, and other data shall not be taken within any regulatory mixing zone.(c) Temporal coverage.(1) General. Observations, samples or other data collected for purposes of assessing use support shall be taken to avoid temporal bias, and seasonality shall be represented in the sampling scheme.(2) Streams. Data no older than five years old shall be utilized in assessing use support for a stream unless(A) the data available from the preceding five year period is insufficient to satisfy the requirements of 785:46-15-3(d) or other more specific minimum requirements provided in this Subchapter, in which case data older than five years old may be utilized, or(B) the provisions of 785:46-15-4(b)(3) or 785:46-15-4(c)(3) apply.(3) Lakes. Data no older than ten years old shall be utilized in assessing use support for a lake unless(A) the data available from the preceding ten year period is insufficient to satisfy the requirements of 785:46-15-3(d) or other more specific minimum requirements provided in this Subchapter, in which case data older than ten years old may be utilized, or(B) the provisions of 785:46-15-4(b)(3) or 785:46-15-4(c)(3) apply.(d) Minimum number of samples.(1) Except when (f) of this Section applies, or unless otherwise noted in subchapter 785:46-15 for a particular parameter, a minimum number of samples shall be required to assess beneficial use support.(A) For streams and rivers, a minimum of 10 samples shall be required.(B) For lakes greater than 250 surface acres, a minimum of 20 samples shall be required.(C) For lakes 250 surface acres or smaller, a minimum of 10 samples shall be required.(D) For toxicants for the protection of the Fish and Wildlife Propagation and Public and Private Water beneficial uses, a minimum of 5 samples shall be required.(2) In order to satisfy the minimum sample requirements of this sub-section, samples may be aggregated consistent with the spatial and temporal requirements prescribed in (b), (c), and (d) of this Section.(3) The prescribed minimum samples shall not be necessary if the available samples already assure exceedance of the applicable percentage for beneficial use assessment.(4) If a mathematical calculation including, but not limited to, a mean, median, or quartile, is required for assessment, a minimum of ten samples shall be required, regardless of the parameter type.(5) Additional samples for the calculation of temperature, pH and hardness dependent acute and chronic criteria shall be collected as required by OAC 785:46-5-8.(e) Application of PQL.(1) Criteria above PQL.(A) If sample values are below the PQL for a parameter whose criterion is above the PQL, appropriate nonparametric statistical measures shall be used to determine the reporting value.(B) For waterbodies identified as impaired on the current 303(d) List or 305(b) Report, if sample values are nondetectable for a parameter whose criterion is above the PQL, then such value shall be deemed to be one-half (1/2) of the parameter PQL.(C) All sample values that are above the PQL shall be the reported values.(2) Criteria equal to or below PQL.(A) If sample values are below the PQL for a criterion which is less than one-half (1/2) of the PQL, then the values shall be deemed to be zero (0) until the first test result above the PQL appears. After that time, sample values which are below the PQL shall be deemed to be equal to the criterion value until four (4) subsequent contiguous samples are shown to be below the PQL. Any subsequent sample values which are nondetectable may be treated as zero (0) until the next test result appears above the PQL.(B) For those parameters whose criteria are at least two (2) orders of magnitude below the PQL, evidence considered with respect to assessment of use support shall include fish tissue analysis, biological community analysis, biological thresholds wherever available, or other holistic indicators which are appropriate for the beneficial use in question.(C) If sample values are below the PQL for a criterion which is greater than or equal to one-half (1/2) of the PQL but less than the PQL, then the values shall be deemed to be one-half (1/2) of the criterion value until the first test result above the PQL appears. After that time, sample values which are below the PQL shall be deemed to be equal to the criterion value until four (4) subsequent contiguous samples are shown to be below the PQL. Any subsequent sample values which are nondetectable may be treated as equal to one-half (1/2) of the criterion value until the next test result appears above the PQL.(D) For waterbodies identified as impaired on the current 303(d) List or 305(b) Report, if sample values are nondetectable for a parameter whose criterion is below the PQL, then such value shall be deemed to be one-half (1/2) of the criterion value.(E) All sample values that are above the PQL shall be the reported values.(f) Magnitude of criteria exceedance.(1) General. The magnitude of exceedance, as well as frequency of exceedances, shall be used in determining beneficial use support. Samples shall be taken only during conditions when criteria apply.(2) Toxicants. If two or more concentrations of toxicants exceed criteria or screening levels to protect human health or aquatic life by two orders of magnitude or more, the associated beneficial use shall be deemed to be not supported.(3) Dissolved oxygen. If more than two concentrations of DO in a stream are observed to be below 2 mg/L in any given year, the Fish and Wildlife Propagation beneficial use shall be deemed to be not supported.(4) Other parameters. The magnitude and frequency of exceedances to be used for determining beneficial use support for parameters other than toxicants and DO shall be as prescribed in the rules elsewhere in this Subchapter.(g) Quality assurance. On and after July 1, 2002, data collected for purposes of use support assessment shall be collected using documented programmatic quality assurance and quality control methods substantially in accordance with those required by "EPA Requirements for Quality Assurance Project Plans", EPA publication no. EPA/240/B-01/003 (March 2001). The sampling and testing methods used shall protect the integrity of the sample and provide detailed documentation of analysis.