62-303.420. Aquatic Life-Based Water Quality Criteria Assessment

(1) The Department shall reexamine the data used in Rule 62-303.320, F.A.C., to determine whether water quality criteria are met.

(a) If values exceeding the criteria are not due to pollutant discharges or reflect natural background conditions, including seasonal or other natural variations, the water shall not be listed on the Verified List. In such cases, the Department shall note for the record why the water was not listed and provide the basis for its determination that the exceedances were not due to pollutant discharges.

(b) If the Department has information suggesting that the values not meeting the dissolved oxygen (DO) criterion are due to natural background conditions, it is the Department’s intent to support that conclusion through the use of Biological Health Assessment procedures referenced in Rule 62-303.330, F.A.C. The waterbody or segment shall not be included on the Verified List for DO if two or more temporally independent Biological Health Assessments indicate the waterbody supports the protection and maintenance of a healthy, well-balanced population of fish and wildlife. The Biological Health Assessments shall be conducted either in the same waterbody segment, or for streams, in the contiguous waterbody segment downstream of the segment where the water quality samples were taken. These Biological Health Assessments shall be conducted on the same day or after the water quality samples were collected.

(2) If the water was listed on the Planning List and there were insufficient data from the most recent five years of the Planning List assessment to meet the data distribution requirements of subsection 62-303.320(4), F.A.C., and to meet a minimum sample size for verification of twenty samples, additional data will be collected as needed to provide a minimum sample size of twenty. Once these additional data are collected, the Department shall re-evaluate the data using the approach outlined in subsection 62-303.320(1), F.A.C., but using Table 3, and place waters on the Verified List when 10% or more of the samples do not meet the applicable criteria, with a minimum of a 90% confidence level using a binomial distribution. The Department shall limit the analysis to data collected during the last 7.5 years. For sample sizes greater than 500, the Department shall calculate the number of samples not meeting the criterion that are needed for the given sample size using the binomial distribution.

Table 3: Verified List

Minimum number of samples not meeting an applicable water quality criterion needed to put a water on the Verified List with at least 90% confidence.
Sample sizes		Are listed if they have at least this # of samples that do not meet a criterion		Sample sizes		Are listed if they have at least this # of samples that do not meet a criterion
From	To			From	To
20	25	5		254	262	33
26	32	6		263	270	34
33	40	7		271	279	35
41	47	8		280	288	36
48	55	9		289	297	37
56	63	10		298	306	38
64	71	11		307	315	39
72	79	12		316	324	40
80	88	13		325	333	41
89	96	14		334	343	42
97	104	15		344	352	43
105	113	16		353	361	44
114	121	17		362	370	45
122	130	18		371	379	46
131	138	19		380	388	47
139	147	20		389	397	48
148	156	21		398	406	49
157	164	22		407	415	50
165	173	23		416	424	51
174	182	24		425	434	52
183	191	25		435	443	53
192	199	26		444	452	54
200	208	27		453	461	55
209	217	28		462	470	56
218	226	29		471	479	57
227	235	30		480	489	58
236	244	31		490	498	59
245	253	32		499	500	60

(3) If the waterbody was placed on the Planning List based on worst case values used to represent multiple samples taken during a four day period, the Department shall evaluate whether the worst case value should be excluded from the analysis pursuant to subsections (4) and (5). If the worst case value should not be used, the Department shall then re-evaluate the data following the methodology in subsection 62-303.420(2), F.A.C., using the more representative worst case value or, if all valid values are below acutely toxic levels, the median value.

(4) If the waterbody was listed on the Planning List based on samples that do not meet water quality criteria for metals, the metals data shall be excluded if it is determined that the quality assurance requirements of subsection 62-303.320(10), F.A.C., were not met or that the sample was not collected and analyzed using clean techniques, if the use of clean techniques is appropriate. The Department shall re-evaluate the remaining valid data using the methodology in subsection 62-303.420(2), F.A.C., excluding any data that cannot be validated.

(5) Values that exceed possible physical or chemical measurement constraints (pH greater than 14, for example) or that represent data transcription errors, outliers the Department determines are not valid measures of water quality, water quality criteria exceedances due solely to violations of specific effluent limitations contained in state permits authorizing discharges to surface waters, water quality criteria exceedances within permitted mixing zones for those parameters for which the mixing zones are in effect, and water quality data collected during extended drought or following contaminant spills, discharges due to upsets or bypasses from permitted facilities, or rainfall in excess of the 25-year, 24-hour storm, shall be excluded from the assessment carried out under this rule. However, the Department shall note for the record that the data were excluded and explain why they were excluded.

(6) Once the additional data review is completed pursuant to subsections (1) through (5), the Department shall re-evaluate the data and shall include waters on the Verified List that meet the criteria in subsection 62-303.420(2) or paragraph 62-303.320(7)(b), F.A.C.

(7) Notwithstanding the requirements of subsection (2), water segments shall also be included on the Verified List if, based on representative data collected and analyzed in accordance with Chapter 62-160, F.A.C.:

(a) For parameters other than bacteriological water quality criteria, there are less than twenty samples, but there are five or more samples that do not meet an applicable water quality criterion based on data from at least five temporally independent sampling events, or

(b) Scientifically credible and compelling information regarding the magnitude, frequency, or duration of samples that do not meet an applicable water quality criterion provides overwhelming evidence of impairment. Any determinations to list waters based on this provision shall be documented, and the documentation shall include the basis for the decision.

(c) For any water chemistry data used to list waters under paragraph 62-303.420(7)(b), F.A.C., the Department shall include in the administrative record all of the applicable data quality assessment elements listed in Table 2 of the Department’s Guidance Document “Data Quality Assessment Elements for Identification of Impaired Surface Waters” (DEP EAS 01-01, April 2001), which was incorporated by reference in subsection 62-303.320(9), F.A.C.

(8) For lakes, the daily average DO level shall be calculated as the average of measurements collected in the upper two meters of the water column at the same location on the same day. For all other fresh waters, the daily average freshwater DO level shall be calculated as the average of all measurements collected in the water column at the same location and on the same day. If any individual DO measurement is greater than 100 percent saturation, 100 percent shall be substituted for that value for the purpose of calculating daily averages.

(9) The daily average freshwater DO criteria shall be assessed preferentially using daily average values calculated from full days of diel monitoring data. A full day of diel data shall consist of 24 hours of measurements collected at a regular time interval of no longer than one hour. If diel monitoring data are not available, instantaneous samples may be used to assess the DO criterion by comparing the instantaneous value with a time-of-day-specific translation of the daily average criterion. To determine the time-of-day-specific translation of the daily average criterion, the time (T) at which the DO sample was taken (in minutes past midnight) is entered into the appropriate equation below for the applicable region and waterbody type. The actual DO measurement collected at a given time is assessed against the calculated time-of-day-specific translation for that time, and if the instantaneous DO is greater than or equal to the calculated value, the daily average DO criterion is achieved.

 

RegionEquations for Time-of-Day-Specific Translation of the Daily Average DO Criterion

Streams

Northeast + Big Bend1.1844 x 10-13 • T5 – 4.1432 x 10-10 • T4 + 4.7729 x 10-7 • T3 – 1.9692 x 10-4• T2 + 0.02314 • T + 31.24

Peninsula + Everglades1.9888 x 10-13 • T5 – 6.8941 x 10-10 • T4 + 7.8373 x 10-7 • T3 – 3.1598 x 10-4• T2 + 0.03551 • T + 33.43

Panhandle West9.0851 x 10-14 • T5 – 2.9941 x 10-10 • T4 + 3.1560 x 10-7 • T3 – 1.0851 x 10-4• T2 + 0.006285 • T + 65.61

Lakes

Northeast + Big Bend1.4578 x 10-13 • T5 – 5.5607 x 10-10 • T4 + 7.0683 x 10-7 • T3 – 3.1879 x 10-4• T2 + 0.02817 • T + 34.19

Peninsula + Everglades1.3709 x 10-13 • T5 – 5.0496 x 10-10 • T4 + 6.1352 x 10-7 • T3 - 2.5817 x 10-4• T2 + 0.01960 • T + 37.14

Panhandle West7.1190 x 10-14 • T5 – 2.6420 x 10-10 • T4 + 3.2247 x 10-7 • T3 – 1.3607 x 10-4• T2 + 0.01071 • T + 66.35

 

If multiple instantaneous DO samples are available in a day, the time-of-day-specific translation of the daily average criterion will be calculated for each individual sample. Achievement of the daily average DO  criterion will be assessed by comparing the average of the actual DO measurements collected at each time against the average of the calculated time-of-day-specific translations for each time. If the average of the measured DO values is greater than or equal to the average of the time-of-day- specific translations of the criteria, the daily average DO criterion is achieved. An average of multiple daily values calculated in this manner will be considered as a single sample for assessment purposes.

(10) For predominantly marine waters, the Department shall evaluate the daily average DO criterion using Table 3 set forth in subsection 62-303.420(1), F.A.C., above, and shall also evaluate whether the seven-day and 30-day average criteria have been achieved during the verified period. A water segment shall be placed on the Verified List for DO impairment if the number of samples below the daily average DO criterion is greater than or equal to the number listed in Table 3 for the given sample size, or if there is more than one weekly average value below the weekly average DO criterion in any twelve week period of the verified period or more than one monthly average value below the monthly average DO criterion in any calendar year of the verified period. Prior to placing a waterbody on the Verified List, the Department shall identify the causative pollutant(s) responsible for the exceedances of the DO criteria. Before assessing the weekly and monthly average DO criterion, the DO data shall be evaluated pursuant to subsections 62-303.420(3) and (5), F.A.C.

(a) If any individual DO measurement is greater than 100 percent saturation, 100 percent shall be substituted for that value for the purpose of calculating daily, weekly and monthly averages.

(b) Where DO values are collected at multiple depths at a given station and time, the average of the values shall be used to represent the measurements unless any of the individual DO values are less than 2 mg/l, in which case the lower 25th percentile of the measured values shall be used.

(c) For assessment purposes, the seven-day average DO percent saturation shall be calculated as a weekly average using a minimum of three full days of diel data collected within a week, or a minimum of ten grab samples collected over at least three days within a week, with each sample measured at least four hours apart.

(d) For assessment purposes, the 30-day average DO percent saturation shall be calculated as a monthly average using a minimum of three full days of diel data, with each diel sampling conducted in different weeks of the month, or grab samples collected from a minimum of ten different days of the month.

(e) A full day of diel data shall consist of 24 hours of measurements collected at a regular time interval of no longer than one hour.

(11) For assessment of the DO criteria for the portions of the Suwannee, Withlacoochee (North), and Santa Fe Rivers utilized by the Gulf Sturgeon, and in the portions of the Santa Fe and New Rivers utilized by the Oval Pigtoe Mussel, waters will be placed on the Verified List when more than 50 percent of the measurements are below the applicable median or more than 10 percent of the daily average values are below the applicable 10th percentile values, specified in Appendix I of the “Technical Support Document: Derivation of Dissolved Oxygen Criteria to Protect Aquatic Life in Florida’s Fresh and Marine Waters,” (http://www.flrules.org/Gateway/reference.asp?No=Ref-02972) which was incorporated by reference in subsection 62-303.320(5), F.A.C, at a minimum of a 90 percent confidence level using the binomial distribution.

(12) For the assessment of the DO criteria, any DO data collected as a concentration in mg/L shall be converted to percent saturation using the temperature and salinity measured at the same location within fifteen minutes of the DO measurement.  Percent DO saturation shall be calculated using the method in Section 5.4 of the “Technical Support Document: Derivation of Dissolved Oxygen Criteria to Protect Aquatic Life in Florida’s Fresh and Marine Waters,” (http://www.flrules.org/Gateway/reference.asp?No=Ref-02971) which was incorporated by reference in subsection 62-303.320(11), F.A.C.

(13) A water segment shall be placed on the Verified List for DO impairment if there has been a statistically significant decreasing trend in DO levels or an increasing trend in the range of daily DO fluctuations over the verified period at the 95 percent confidence level using a one-sided Seasonal Kendall test for trend, as described in Helsel, D.R. and R.M. Hirsch, 2002, Statistical Methods in Water Resources, USGS, pages 338 through 340 (http://www.flrules.org/Gateway/reference.asp?No=Ref-02973), which were incorporated by reference in subsection 62-303.320(14) F.A.C., after controlling for or removing the effects of confounding variables, such as climatic and hydrologic cycles, quality assurance issues, and changes in analytical methods. Water segments shall not be placed on the Verified List for DO impairment until the Department has identified a pollutant causing the decrease or if the decrease in DO levels was authorized under Rules 62-302.300 and 62-4.242, F.A.C.

(14) For assessment of the 30-day average total ammonia criterion, the monthly average total ammonia shall be calculated for a station using a minimum of four samples collected within the month. A water segment shall be placed on the Verified List for total ammonia impairment if a station within the segment has more than one monthly average value above the 30-day average criterion in any calendar year of the verified period.

Rulemaking Authority 403.061, 403.067 FS. Law Implemented 403.021(11), 403.062, 403.067 FS. History–New 6-10-02, Amended 12-11-06, 7-2-12, 8-1-13, 2-17-16.