62-303.430. Biological Impairment

(1) All Biological Health Assessments used to list a water on the Verified List shall be conducted and interpreted in accordance with Chapter 62-160, F.A.C., including Department-approved Standard Operating Procedures and Department documents that are incorporated by reference in Chapter 62-160, F.A.C., for the SCI, LVI, and Shannon-Weaver Diversity Index.

(2) If the water met the requirements for placement on the Planning List based on Biological Health Assessment results, the water shall be determined to be biologically impaired if any of the following conditions occur, given a minimum sample size of two temporally independent bioassessments:

(a) The average score of all the SCIs is below 40, or either of the two most recent temporally independent SCI scores is less than 35. If there are only two SCIs and the difference between the two scores is greater than 20 points, then an additional SCI shall be required and the average of all three scores shall be used.

(b) The average score of all the temporally independent LVIs is below 43 for a lake segment.  If there are only two LVIs for a lake segment and the difference between the two scores is greater than 20 points, then an additional LVI shall be required and the average of all three scores shall be used.

(c) The historic maximum SCI value, as defined in subsection 62-303.330(4), F.A.C., is above 64 and the average of the two most recent temporally independent SCI scores is 20 or more points below the historic maximum value.

(d) The historic maximum value LVI, as defined in subsection 62-303.330(4), F.A.C., is above 78 and the average of the two most recent temporally independent LVI scores is 20 or more points below the historic maximum value.

(e) The average score of at least two temporally independent Shannon-Weaver Diversity Indices is less than 75 percent of the average score from an appropriate control site, pursuant to subsection 62-302.530(10), F.A.C.

(3) If the water was listed on the Planning List based on BioRecon data, two or more temporally independent SCIs shall be conducted. If the water segment was listed on the Planning List based on other information specified in subsection 62-303.330(6), F.A.C., indicating biological impairment, two or more temporally independent Biological Health Assessments appropriate for the waterbody type shall be conducted in the waterbody segment to verify whether the water is impaired. If available, the Department shall consider other scientifically credible biological assessment methods in predominantly marine waters to verify that the water is biologically impaired. Results from these biological assessments shall be evaluated in accordance with subsection 62-303.430(2), F.A.C., as applicable.

(4) If a waterbody was listed on the Planning List based on failure of the Shannon-Weaver Diversity Index under subsection 62-302.530(10), F.A.C., a minimum of two Biological Health Assessments shall be conducted in accordance with the methodology in Rule 62-303.330, F.A.C., to verify whether the water is impaired. If an SCI or LVI is not applicable for the waterbody type, then the Biological Health Assessment shall be the Shannon-Weaver Diversity Index or other scientifically credible method.

(5) Following verification that a waterbody is biologically impaired, a waterbody shall be included on the Verified List for biological impairment if:

(a) There are water quality data reasonably demonstrating the particular pollutant(s) causing the impairment and the concentration of the pollutant(s); and,

(b) One of the following demonstrations is made:

1. If there is a numeric criterion for the specified pollutant(s) in Chapter 62-302, F.A.C., but the criterion is met, an identification of the specific factors that reasonably demonstrate why the numeric criterion is not adequate to protect water quality and how the specific pollutant is causing the impairment, or

2. If there is not a numeric criterion for the specified pollutant(s) in Chapter 62-302, F.A.C., an identification of the specific factors that reasonably demonstrate how the particular pollutant(s) are associated with the observed biological effect. If the numeric interpretation of the narrative nutrient criterion in paragraph 62-302.531(2)(c), F.A.C., is exceeded, then nutrients shall be identified as the causative pollutant unless a stressor identification study links the adverse biological effects to causal factor(s) other than nutrients.

(6) If a waterbody is verified as biologically impaired, but a causative pollutant has not been identified, the waterbody shall be included on the Study List.

Rulemaking Authority 403.061, 403.067 FS. Law Implemented 403.062, 403.067 FS. History–New 6-10-02, Amended 12-11-06, 7-2-12, 2-17-16