62-303.450. Assessments of Numeric Interpretation of Narrative Nutrient Criteria  


Effective on Wednesday, February 17, 2016
  • 1(1) A stream or estuary without applicable numeric criteria in subsection 1262-302.531(2), 13F.A.C., shall be placed on the Verified List for impairment due to nutrients if 27it exceeds the chlorophyll 31a 32thresholds in subsection 3562-303.351(4), 36F.A.C., or subsection 3962-303.353(2), 40F.A.C., more than once in any consecutive three year period, and there are sufficient data from the last 7.5 years to meet the data sufficiency requirements of subsections 6862-303.350(2)-69(6), F.A.C. If there are insufficient data, additional data shall be collected as needed to meet the requirements. Once these additional data are collected, the Department shall determine if there is sufficient information to develop a site-specific chlorophyll 107a 108threshold that better reflects conditions beyond which an imbalance in flora or fauna occurs in the water segment. If there is sufficient information, the Department shall re-evaluate the data using the site-specific thresholds. If there is insufficient information, the Department shall re-evaluate the data using the thresholds provided in subsections 15862-303.351(4) 159and 16062-303.353(2), 161F.A.C., for streams and estuaries and verify impairment if there is more than one exceedance in any consecutive three year period. In any case, the Department shall limit its analysis to the use of data collected during the last 7.5 years. If alternative thresholds are used for the analysis, the Department shall provide the thresholds for the record and document how the alternative threshold better represents conditions beyond which an imbalance in flora or fauna is expected to occur.

    240(2) If the waterbody was listed on either the Planning or Study List for nutrient enrichment based on other information indicating an imbalance in flora or fauna, as provided in paragraphs or subsection 27362-303.350(1), 27462-303.351(3), 27562-303.352(1)(b) 276or 27762-303.353(3), 278F.A.C., the Department shall verify the imbalance before placing the water on the Verified List for impairment due to nutrients and shall provide documentation supporting the imbalance in flora or fauna.

    309(3) If the waterbody was listed on the Planning List based on paragraphs or subsections 32462-303.351(1), 32562-303.352(1)(a) 326and (d), 32862-303.353(1) 329and (5), or 33262-303.354(1), 333F.A.C., the Department shall place the waterbody on the Verified List for exceedances of the narrative nutrient criteria in paragraph 35362-302.530(47)(b), 354F.A.C., if the applicable numeric interpretation of the narrative nutrient criterion is exceeded based on the last 7.5 years of data. 

    375(4) If a lake was listed on the Planning List based on subsection 38862-303.352(2), 389F.A.C., and there are still insufficient data to determine the long-term geometric mean color or alkalinity, the Department shall place the lake on the Verified List for exceedances of the narrative nutrient criterion in paragraph 42462-302.530(47)(b), 425F.A.C., if the annual geometric mean chlorophyll 432a 433exceeds the applicable criterion for a colored lake in sub-subparagraph 44362-302.531(2)(b)1.b., 444F.A.C., more than once in a three year period in the last 7.5 years.

    458(5) If the waterbody was listed on the Study List for an adverse trend in nutrient response variables pursuant to paragraph 47962-303.390(2)(a), 480F.A.C., the Department shall analyze the potential risk of nonattainment of the narrative nutrient criteria in paragraph 49762-302.530(47)(b), 498F.A.C. This analysis shall take into consideration the current concentrations of nutrient response variables, the slope of the trend, and the potential sources of nutrients (natural and anthropogenic). If there is a reasonable expectation that the waterbody will become impaired within 5 years, the Department shall place the waterbody on the Verified List to develop a TMDL that establishes a numeric interpretation pursuant to paragraph 56362-302.531(2)(a), 564F.A.C.

    565(6) The thresholds for impairment due to nutrients in paragraph 57562-302.531(2)(c) 576and subsections 57862-303.351(4) 579and 58062-303.353(2), 581F.A.C., are not required to be used during development of wasteload allocations or TMDLs where a site-specific interpretation of the narrative nutrient criterion in paragraph 60662-302.530(47)(b), 607F.A.C., is established.

    610(7) When assessing waters for nutrient impairment, the Department shall evaluate whether the data were collected under extreme climatic conditions, such as floods, droughts, and hurricanes. If the needed supporting information is provided to the Department, the Department shall also evaluate whether the data were collected under conditions that are representative of the type of waterbody used to derive the applicable criteria, and whether the samples are biased towards specific non-representative flow conditions. When assessing estuary specific numeric interpretations of the narrative nutrient criterion in Rule 69662-302.532, 697F.A.C., the Department shall also evaluate whether the current ambient monitoring network is representative of the network that was the basis for the numeric interpretation of the narrative nutrient criterion in Rule 72962-302.532, 730F.A.C. The Department will consider this information when developing the final Verified List and shall not list waters as impaired based solely on extreme climatic conditions, non-representative data, or changes in the monitoring network.

    764Rulemaking Authority 766403.061, 767403.067 FS. 769Law Implemented 771403.062, 772403.067 FS. 774History–New 6-10-02, Amended 12-11-06, 7-2-12, 8-1-13, 2-17-16.

     

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