Wisconsin Administrative Code › Department of Natural Resources › NR 100-199 - Environmental Protection - General › Chapter NR 102 - Water Quality Standards For Wisconsin Surface Waters › Subchapter III - Waterbody Assessments and Reporting › Section NR 102.52 - Assessment protocols

Current through June 24, 2024
(1) GENERAL. The department's protocols for
				  assessing waterbodies shall be consistent with the state's water quality
				  standards and federal regulations and be based on relevant scientific
				  information. The department's protocols may include components such as minimum
				  data requirements, sampling methods, quality control, statistical analysis of
				  data, allowable frequency of exceedance of criteria or thresholds, and use of
				  professional judgment.
Note:
When assessing waterbodies, the
					 department uses its guidance for waterbody assessments titled "Wisconsin
					 Consolidated Assessment and Listing Methodology," or WisCALM. Although a
					 description of the state's assessment methodology is required to be submitted
					 to U.S. EPA, U.S. EPA does not approve or disapprove the state's assessment
					 methodology under section 303 (d) of the Clean Water Act.
(2) SAMPLE VARIABILITY AND CONFIDENCE
				  INTERVALS.
(a) For assessment determinations,
				  the department may determine that multiple samples are necessary to account for
				  variability inherent in the waterbody, sampling results, or other conditions.
				  The department may evaluate attainment of criteria or thresholds, using
				  assessment methodology that accounts for both the central tendency of the data,
				  such as the mean or median, and the variability of the samples.
(b) The department may apply a confidence
				  interval approach to determine the number of samples needed and to increase
				  certainty in the attainment decision. For metrics expressed as a mean or
				  percentile of a group of samples, the department may use the two-sided 80
				  percent confidence interval of the mean or percentile for assessment. Other
				  methods of calculating a confidence interval may be applied as appropriate for
				  a specific metric, data type, or statistical goal. Once the confidence interval
				  is determined under this paragraph, it is then compared to the criterion or
				  threshold as specified in par. (c).
(c) When applying an approach under par. (b),
				  the department shall compare the confidence interval to the applicable
				  criterion or threshold using one of the following evaluation criteria:
1. If the entire confidence interval is
				  attaining the criterion or threshold, no further samples are needed to make the
				  attainment determination.
2. If the
				  entire confidence interval is not attaining the criterion or threshold, no
				  further samples are needed to make the non-attainment determination.
3. If the criterion or threshold is within
				  the confidence interval, the assessment will be deferred until more data can be
				  collected with the goal of narrowing the interval to determine whether subd. 1.
				  or 2. applies. After further data collection, if the criterion or threshold
				  continues to be within the confidence interval, the attainment determination
				  shall be made by directly comparing the sample mean or percentile to the
				  criterion or threshold.