Current through Register Vol. XLI, No. 45, November 8, 2024
Section 47-2B-3 - Benthic Macroinvertebrate Assessment Methodology3.1. The Department will assess the biological integrity of wadeable streams using WVSCI (WV Stream Condition Index), an index of biotic integrity for benthic macroinvertebrates (Benthic IBI) developed for use in West Virginia's wadeable streams. 3.1.a. The Department will use appropriately collected and processed biological samples that meet quality assurance/quality control and comparability protocols set forth in the Department's Watershed Assessment Section's Standard Operating Procedures Manual.3.1.b. The attainment threshold for the Benthic IBI is 72, which is based on the 5th percentile of reference samples. The impairment threshold is 61, which reflects the threshold at which the Department is confident an impairment is present.3.2. Initial Biological Integrity Assessment - Collection and evaluation of benthic macroinvertebrate data. In most circumstances, at least two samples collected within five years are required to make an attainment determination for a previously unclassified stream segment. 3.2.a. For stream segments with a Benthic IBI value equal to or greater than 72,a single sample may be used to determine attainment with the biological integrity criterion. A stream segment with multiple samples at a single location shall be considered to be in attainment if the most recent 2 samples have an average value equal to or greater than 72.3.2.b. For stream segments with multiple sample stations, assessment decisions will be based on the preponderance of the Benthic IBI values from recent samples from those stations or, if an obvious reason for data disagreement amongst sample stations exists, the Secretary may subdivide the stream segment into smaller assessment units.3.2.c. For stream segments with a Benthic IBI value less than 50, a single sample may be used to determine non-attainment with the biological integrity criterion.3.2.d. In all other circumstances, at least one additional Benthic IBI sample is required to determine compliance with the biological integrity criterion. 3.3. Collection and evaluation of additional biological data where the initial Benthic IBI value is between 50 and 72. 3.3.a. The Department will prioritize the collection of additional biological data from streams that have an initial Benthic IBI value between 50 and 72.3.3.b. The Department will determine biological integrity criterion compliance by averaging the score of both samples, or in cases where more than two samples exists, by averaging the score of the two most recent samples.3.3.c. Stream segments with average scores less than the impairment threshold will be classified as impaired for the biological integrity criterion. Stream segments with average scores equal to or greater than the attainment threshold will be classified as meeting the biological integrity criterion.3.3.d. Where the average Benthic IBI value is between 61 and 72, the stream segment will neither be categorized as in attainment nor impaired but will be considered as having insufficient data until additional information is collected or supplied that allows a determination to be made based on the thresholds set forth above in 3.1.b.3.4. Fish Index of Biological Integrity - Reserved.