PC_WQBEL_Final_12-16-2019.pdf

Water Quality Based Effluent Limitation for the Plant City Water Reclamation Facility

Prepared for:

City of Plant City 1500 W. Victoria Street Plant City, FL 33563

Prepared by:

Janicki Environmental, Inc.

Frydenborg EcoLogic

December 16, 2019

WQBEL for the City of Plant City Water Reclamation Facility

December 16, 2019 i

FOREWORD

This project was conducted under an Agreement with the City of Plant City. The Agreement includes the following: Request for Proposal # 16-91897-01.

December 16, 2019 ii

ACKNOWLEDGMENTS

This project was completed with the assistance from a number of key individuals and firms:

City of Plant City Lynn Spivey

David Buyens Steve Saffels

Patrick Murphy Mike Darrow Lyudmila Gassaway Zoé Chaiser

Frydenborg Ecologic – Biological sampling and analysis

VHB – Field logistics and sampling

Benchmark EnviroAnalytical – Laboratory analysis

Atkins – Bathymetric survey

Hillsborough County Parks and Recreation – Site access

December 16, 2019 iii

TABLE OF CONTENTS

FOREWORD ................................................................................................................................................... i

ACKNOWLEDGMENTS ................................................................................................................................. ii

TABLE OF CONTENTS .................................................................................................................................. iii

LIST OF FIGURES .......................................................................................................................................... v

LIST OF TABLES ........................................................................................................................................... vii

BACKGROUND

Description of Problem

Description of the Plant City WRF

Applicable Regulatory Criteria

Water Quality Based Effluent Limitations

Description of Remaining Sections of this Report

CHARACTERIZATION OF EAST CANAL-ITCHEPACKESASSA SYSTEM

Physical Setting

Hydrology

Stream Flow

Rainfall

Land Use

Biological Communities

Stream Habitat Assessment

Rapid Periphyton Survey

Linear Vegetation Survey

BioRecon……

Stream Condition Index

Summary

Recent Water Quality Conditions

CONCEPTUAL MODEL OF POTENTIAL EFFECT OF PLANT CITY WRF ON EAST CANAL/

ITCHEPACKESASSA SYSTEM

Analytical Approaches

Objectives

Empirical Stressor-Response Approach

Box model/Mass Balance Approach

Mechanistic Modeling Approach

Model Selection

December 16, 2019 iv

Description of QUAL2Kw

Data Needs…

Model Set-up

Model Set-up - Temporal Aspect

Hydrologic and Nutrient Loads

Model Calibration

Calibration Results

ANALYTICAL RESULTS

Empirical Model Approach

Box Model/Mass Balance Approach

Mechanistic Model Approach

Comparison of Outputs from the Two Model Scenarios – Baseline and Proposed

Chlorophyll a

Total Phosphorus

Ortho-Phosphate

Total Nitrogen

Nitrate-Nitrite

Total Kjeldahl Nitrogen

Dissolved Organic Carbon

Total Organic Carbon

Dissolved Oxygen

Periphyton…

Assessment Criteria

CONCLUSIONS

WQBEL RECOMMENDATION

REFERENCES

Appendix 1 Streams Exception Demonstration

Appendix 2 Biological Field Methods

Appendix 3 Field WQ Data

Appendix 4 Stream Cross-Sections

Appendix 5 Flow Regressions

Appendix 6 Monthly Box Model

Appendix 7 QUAL2Kw Model Inputs

Appendix 8 Calibration Statistics

December 16, 2019 v

LIST OF FIGURES

Figure 1. Aerial view of the City of Plant City Water Reclamation Facility Figure 2. Plant City WRF D-002 outfall to East Canal Figure 3. Map of WBIDs downstream of the outfall of the Plant City WRF Figure 4. Location of the City of Plant City Water Reclamation Facility Figure 5. Location of the East Canal drainage Basin Figure 6. Location of flow monitoring sites Figure 7. Time series plots of recent flow data collected during this project Figure 8. Plots of monthly rainfall during the monitoring period (top panel) and summarized by calendar month for the period of record (bottom panel) Figure 9. Map showing the approximate boundary of the McIntosh Park Enhanced Stormwater Treatment Wetland Project Figure 10. Location of Biological Sampling Locations Figure 11. Box plots of periphyton chlorophyll a results (artificial substrates). The periphyton rack from the East Canal test site was stolen during the second sampling. Note that all values are lower than periphyton chlorophyll a from selected FDEP minimally disturbed control sites in Florida (see Table 7) Figure 12. Box plots of LVS % Florida Exotic Plant Pest Council (FLEPPC) results at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge. N = 4. Passing score for streams (not ditches) is 25% and lower Figure 13. Box plots of LVS Coefficient of Conservatism results at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge. N = 4. Passing score for streams (not ditches) is 2.5 and higher Figure14. Box plots of BioRecon results from two temporally independent samplings at sites located upstream and downstream from the Plant City WRF discharge. Passing score for streams (not ditches) is 4 or higher Figure 15. Location of Water Quality Sampling Locations Figure 16. Photograph of Itchepackesassa Creek sampling site (WQ-4) on 11MAY17 Figure 17. Time series plots the specific conductance data from the 4 project sampling sites – March 2017-March 2018 Figure 18. Time series plots the TP concentration data from the 4 project sampling sites – March 2017-March 2018 Figure 19. Time series plots the orthophosphate concentration data from the 4 project sampling sites

– March 2017-March 2018 Figure 20. Time series plots the TN concentration data from the 4 project sampling sites – March 2017-March 2018 Figure 21. Time series plots the TKN concentration data from the 4 project sampling sites – March 2017-March 2018 Figure 22. Time series plots the NO3+NO2 concentration data from the 4 project sampling sites – March 2017-March 2018 Figure 23. Time series plots the NH3 concentration data from the 4 project sampling sites – March 2017-March 2018 Figure 24. Time series plots the chlorophyll a concentration data from the 4 project sampling sites – March 2017-March 2018

December 16, 2019 vi

Figure 25. Time series plots the DO percent saturation data from the 4 project sampling sites – March 2017-March 2018 Figure 26. Conceptual model of critical inter-relationships that influence the effects of the Plant City

WRF

Figure 27. Relationship between chlorophyll and TN concentrations as defined by a linear regression Figure 28. Locations of bathymetric transects used to develop model segment (reach) dimensions Figure 29. Location of model reaches extending from Knights Griffin Rd. upstream of the outfall to just above Blackwater Creek downstream Figure 30. Daily hydrologic loads (m3/day) from the three major sources Figure 31. Daily TN loads from the three major sources Figure 32. Daily TP loads from the three major sources Figure 33. Comparison of predicted and observed depth in model reaches 3 and 5 Figure 34. Comparison of predicted and observed temperature in model reaches 3 and 5 Figure 35. Comparison of predicted and observed specific conductance in model reaches 3 and 5 Figure 36. Comparison of predicted and observed stream flow in model reaches 3 and 5 Figure 37. Comparison of predicted and observed pH in model reaches 3 and 5 Figure 38. Comparison of predicted and observed DO in model reaches 3 and 5 Figure 39. Comparison of predicted and observed TN in model reaches 3 and 5 Figure 40. Comparison of predicted and observed NO3-NO2 in model reaches 3 and 5 Figure 41. Comparison of predicted and observed TKN in model reaches 3 and 5 Figure 42. Comparison of predicted and observed TP in model reaches 3 and 5 Figure 43. Comparison of predicted and observed ortho P in model reaches 3 and 5 Figure 44. Comparison of predicted and observed chlorophyll a in model reaches 3 and 5 Figure 45. Comparison of predicted and observed TOC in model reaches 3 and 5 Figure 46. Comparison of predicted and observed DOC in model reaches 3 and 5 Figure 47. Relationships between chlorophyll a and TN (upper) and TP (lower) loads in Reach 3 Figure 48. Relationships between chlorophyll a and TN (upper) and TP (lower) loads in Reach 5 Figure 49. Annual mass balances of water (fluxes=m3/year), TN (mass=kg, fluxes=kg/year), and TP (mass=kg, fluxes=kg/year) Figure 50. Comparison of the mean monthly chlorophyll a concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 51. Comparison of the mean monthly TP concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 52. Comparison of the mean monthly Ortho-phosphate concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 53. Comparison of the mean monthly TN concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 54. Comparison of the mean monthly NO3-NO2 concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 55. Comparison of the mean monthly TKN concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 56. Comparison of the mean monthly DOC concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 57. Comparison of the mean monthly TOC concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios Figure 58. Comparison of the mean monthly DO concentrations in each model reach from the Baseline and Proposed Plant Discharge Limit model scenarios

December 16, 2019 vii

Figure 1-1. A 1938 aerial photograph of East Canal at Knights Griffin Road, clearly showing the artificial channelization Figure 1-2. 1968 aerial photo of East Canal at Knights Griffin Road, showing that maintaining the artificial channelization for flood control continues to routinely occur Figure 1-3. Current aerial photo of East Canal at Knights Griffin Road demonstrating the continued artificial channelization of the system. Red dashed lines indicate locations of maintenance activities conducted by Hillsborough County Figure 4-1. Locations of bathymetric transects used to develop model segment (reach) dimensions Figure 4-2. Bathymetric transects used to develop model segment (reach) dimensions

LIST OF TABLES

Table 1. Effluent Limitations for TN and TP for the Plant City WRF Table 2. Nutrient Impaired WBIDs downstream of the Plant City WRF outfall (D-002) Table 3. Summary of biological sampling efforts Table 4. Average habitat assessment scores for the East Canal Control site, the East Canal test site, and Itchepackesassa Creek site at Audubon Road Table 5. Rapid Periphyton Survey results Table 6. Periphyton chlorophyll a and Ash-Free-Dry-Weight results from artificial substrates Table 7. FDEP periphyton chlorophyll a data (glass slides) from selected minimally disturbed control sites in Florida Table 8. Linear Vegetation Survey (LVS) data. Itchepackesassa Creek at Audubon Road had no aquatic vegetation present (passing the LVS) Table 9. BioRecon results from two temporally independent samplings at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge.

Passing score for streams (not ditches) is 4 or higher Table 10. Stream Condition Index (SCI) scores for Itchepackesassa at Audubon Road, the far-field test site Table 11. Table of field and laboratory parameters Table 12. Model reach dimensions. *Depths are based on observed values Table 13. Mean replacement time (days) in each reach from the Baseline and Proposed model scenarios Table 14. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for chlorophyll a. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 15. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for TP. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 16. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for ortho P. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 17. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for TN. Differences are Baseline – Proposed (positive differences indicate declines in concentration)

December 16, 2019 viii

Table 18. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for NO3-NO2. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 19. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for TKN. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 20. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for DOC. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 21. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for TOC. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 22. Summary statistics of the model outputs for the Baseline and Proposed Plant Discharge Limit for DO. Differences are Baseline – Proposed (positive differences indicate declines in concentration) Table 23. Results from the Baseline and Proposed scenarios compared to applicable criteria for TN, TP and DO (% saturation) for the portion of Itchepackesassa Creek covered by Reaches 4, 5, and 6 Table 24. Percent of daily mean DO saturation values not meeting the freshwater stream criterion by reach Table 25. Monthly Median DO percent saturation values by reach Table 26. Ambient dissolved organic carbon concentrations (mg/L) Table 27. Loading estimates from the TBEP loading model and the discharge from the Plant City WRF, accounting for the increase in the discharge from the WRF Table 28. Recommended WQBEL limits for TN, TP, and CBOD for the Plant City Water Reclamation Facility (FL0026557) Table 1-2. Selected habitat measures for the study areas, including the control site (upstream of the discharge in East Canal), the test site (downstream of the discharge in East Canal), and the far-field test site (Itchepackesassa Creek at Audubon Road) Table 3-1. Field data collected at water quality sites from March 2017 - February 2018 Table 7-1. Table of field and laboratory parameters Table 7-2. Table of model rates and constants identifiers

December 16, 2019 1

BACKGROUND

Description of Problem The City of Plant City operates the Plant City Water Reclamation Facility (Plant City WRF) under permit number FL0026557 under Chapter 403, Florida Statutes covering a period from January 15, 2016 – January 14, 2021. At the time of issuance, the Florida Department of Environmental Protection issued an Administrative Order (AO-002SWD15) establishing a compliance schedule under Section 403.088(2)(f), Florida Statues. The order calls for the City to, among other things, develop a Level II Water Quality Based Effluent Limitation (WQBEL) to authorize an increase in the permitted discharge to East Canal that was requested by the City of Plant City. The WQBEL shall provide reasonable assurance that the receiving waters continue to meet the applicable numeric nutrient criteria for total nitrogen (TN) and total phosphorus (TP).

Description of the Plant City WRF The Plant City WRF is a 10.0 MGD annual average daily flow Type 1 activated sludge domestic wastewater treatment plant with chlorine disinfection (Figure 1). Treated effluent is either disposed via an existing discharge to East Canal after dechlorination and reaeration. The plant also supplies reclaimed water to a public access reuse system serving the city and surrounding area and an industrial reuse system. The permitted capacity is set at 8.0 MGD until such time as the City develops the master reuse service area.

Figure 1. Aerial view of the City of Plant City Water Reclamation Facility.

Applicable Regulatory Criteria Under the Plant City WRF Domestic Wastewater Permit, the facility must meet several different but related nutrient effluent limits. Effluent discharged by the plant must meet certain criteria, December 16, 2019 2 established by Florida Statute (403.086, F.S.), as an advance wastewater treatment facility with a surface water discharge as shown in Table 1.

Table 1. Effluent Limitations for TN and TP for the Plant City WRF.

Temporal Basis TN (mg/L)

TP

(mg/L)

Annual Average 3.0 1.0 Monthly Average 3.75 1.25 Weekly Average 4.5 1.5 Single Sample 6.0 2.0

The discharge must also be in accordance with the “Final Order Adopting Water Quality Based Effluent Limits (WQBEL) for Point Source Discharges to the Tampa Bay Watershed” adopted in 2010 by FDEP. The annual total load is calculated as a 12-month rolling total based on the current month plus the previous 11-month’s load not to exceed 21.0 tons TN /year. The discharge is also limited to 10.5 tons TN/year on a 5-year rolling average calculated as the current month plus the previous 59 months divided by 5.

The Plant City WRF discharges through outfall D-002 to East Canal (WBID 1518) (Figure 2). East Canal is a Class III freshwater stream located in the West Central Nutrient Watershed Region. Nutrient criteria for these waterbodies are found in subparagraph 62-302.531(2)(c)(2) F.A.C, with TN and TP criteria of 1.64 mg/L annual geometric mean (AGM) and 0.49 mg/L AGM, respectively. Neither should be exceeded more than once in a three-year period.

Information provided in Appendix 1 provides the necessary documentation to demonstrate that East Canal meets the stream exclusion for managed conveyances under paragraph 62-302.200(36)(b), F.A.C., and as such, the numeric nutrient standard for streams does not apply.

The canal will be assessed via the narrative nutrient criterion.”

East Canal was last assessed by the FDEP Assessment Section in 2016 using data collected from January 1, 2007 to June 30, 2014. The WBID was delisted for two previous impairments, one for dissolved oxygen and the other for nutrients (chlorophyll a).

Any proposed changes to the permitted discharges from the Plant City WRF will also need to take into account any downstream impairments and TMDLs as the effluent passes through 11 waterbodies on its way to Hillsborough Bay (Figure 3). They include (from upstream to downstream) East Canal, Itchepackesassa Creek, Blackwater Creek, multiple segments of the Hillsborough River, and finally McKay Bay. The figure is accompanied by a table (Table 2) of

Figure 2. Plant City WRF D-002 outfall to East Canal.

December 16, 2019 3 downstream impairments associated with nutrients, i.e., nutrients, chlorophyll a, and dissolved oxygen. The Hillsborough Reservoir (1443H) is the only downstream WBID impaired for a nutrient impairment, TP.

Figure 3. Map of WBIDs downstream of the outfall of the Plant City WRF.

Water Quality Based Effluent Limitations The Water Quality Based Effluent Limitation (WQBEL) process, pursuant to Chapter 62- 650, F.A.C., is the mechanism for determining the levels of nutrients in a point source discharge (i.e., effluent nutrient limits) that will comply with the narrative criterion in paragraph 62-302.530(47)(b), F.A.C. The derivation of a Level II nutrient WQBEL is a site-specific interpretation of the NNC and is based on the highest permitted flows and the associated nutrient loads from a discharge. To serve as the interpretation of the narrative nutrient criteria, the WQBEL must provide nutrient limits for the discharge, and calculate the total allowable load that would maintain the designated use of the waterbody. Further, if downstream waters are anticipated to be

Table 2. Nutrient Impaired WBIDs downstream of the Plant City WRF outfall (D-002).

WBID Waterbody Waterbody Type

Waterbody Class Parameter

1443H Hillsborough Reservoir Lake 1 Nutrients (Total Phosphorus)

December 16, 2019 4 potentially affected by the discharge of nutrients from an upstream facility, the potential impact must also be assessed, regardless of distance.

The Plant City WRF permit was renewed on January 15, 2016, with an Administrative Order (AO) that required a Level II WQBEL study with interim discharge limitations for flow.

A WQBEL is recognized as the applicable interpretation of the narrative nutrient criteria if:

A. The documentation for the WQBEL includes a site-specific numeric interpretation of the narrative criterion at paragraph 62-302.530(47)(b), F.A.C., for the waterbody;

B. The WQBEL is established pursuant to the Level II Process contained at Rule 62-650.500, F.A.C.; and

C. The public notice for the WQBEL specifically states that the Level II WQBEL includes a site-specific interpretation of the narrative for the receiving waterbody.

Because NPDES dischargers must demonstrate reasonable assurance that they comply with all applicable water quality standards, a Level II WQBEL is a scientifically and legally defensible method to establish appropriate nutrient targets and assure compliance. This WQBEL study assessed the feasibility of expanding the discharge volume while fully protecting designated uses.

In addition, if higher flows or higher levels of TN and/or TP are demonstrated to be protective of East Canal and downstream waters, then the Plant City WRF would be able to discharge at the protective flows or nutrient levels as needed. This study examined a range of potential effluent characteristics (concentrations and flow, including flows higher than those currently observed) and those scenario outcomes are presented in the modeling chapter below.

When the results of this WQBEL study is approved by FDEP, the AO and permit will be revised and the permit will incorporate the effluent limitations shown to be acceptable.

FDEP’s Map Direct showed that there are no other NPDES surface water discharges upstream of the Plant City WRF or in Itchepackesassa Creek upstream of the confluence with East Canal. In summary, this Level II WQBEL Study assures compliance with any active TMDLs and provides reasonable assurance that the proposed Plant City WRF capacity increases will be associated with effluent limits that comply with water quality standards.

Description of Remaining Sections of this Report The remaining sections of this report include:

• Characterization of East Canal-Itchepackesassa System

• Conceptual Model of Potential Effect of the Plant City WRF on East Canal/ Itchepackesassa

System

• Analytical Approach

• Analytical Results

• Conclusions and Recommendations

December 16, 2019 5

CHARACTERIZATION OF EAST CANAL-ITCHEPACKESASSA SYSTEM

Physical Setting The location of the Plant City WRF, the D-002 outfall, East Canal, Itchepackesassa Creek and Blackwater Creek are shown on Figure 4. The Plant City WRF is located just south of I-4 in Plant City and the discharge is located north of I-4 at the intersection of Knights-Griffin Rd and East Canal. The East Canal combines with Itchepackesassa Creek before entering Blackwater Creek to the Hillsborough River and ultimately Hillsborough Bay.

Figure 4. Location of the City of Plant City Water Reclamation Facility.

December 16, 2019 6

Hydrology East Canal directs excess stormwater runoff away from Plant City. The stormwater is diverted from East Canal into the McIntosh Park Enhanced Stormwater Treatment Wetland Project by a diversion dam located approximately 1000m south of Knights Griffin Road. The treated stormwater is then discharged back into East Canal 600m downstream of the diversion dam. The diversion dam is set at an elevation to prevent upstream flooding by allowing excessive high flows to bypass the treatment system. The outfall of the Plant City WRF enters East Canal an additional 500m downstream of the discharge from the wetland treatment system. Approximately 3,500m further downstream is the confluence between East Canal and Itchepackesassa Creek. The Itchepackesassa Creek flow about another 4.5KM to Blackwater Creek. The location of the East Canal drainage basin is shown in Figure 5.

Figure 5. Location of the East Canal drainage Basin

December 16, 2019 7

Stream Flow Stream flow measurements were made monthly during the monitoring year at the sites shown in Figure 6. Time-series plots of flow from all sites are shown in Figure 7 from upstream (WQ-1, top panel) to downstream (WQ-5, bottom panel). The daily data of the Plant City WRF discharge to East Canal was provided by City staff.

Figure 6. Location of flow monitoring sites.

December 16, 2019 8

Figure 7. Time series plots of recent flow data collected during this project.

December 16, 2019 9

Rainfall Rainfall information was downloaded from the National Weather Service for Plant City. Plots of the monthly rainfall data for the monitoring period (March 2017 – March 2018) are shown in Figure 8.

For comparison, calendar month summaries for the period of record are also shown. Rainfall for the monitoring period exhibited the same temporal pattern as the historical record. Rainfall in June was the highest on record, and the area experienced two tropical systems, Emily in July and Irma in September. Regardless, rainfall in 2017 at 56.7 in. was only slightly higher than the mean annual rainfall over the last 20-year 54.7 in.

Figure 8. Plots of monthly rainfall during the monitoring period (top panel) and summarized by calendar month for the period of record (bottom panel).

December 16, 2019 10

Land Use Land uses upstream of the discharge point range from rural/agriculture to urban. Stormwater runoff is treated through the McIntosh Park Enhanced Stormwater Treatment Wetland Project funded by a number of agencies completed in 2009 (Figure 9). Stormwater is diverted from East Canal and routed through series of wetlands and settling ponds, treated with alum, routed through another series of ponds and discharged to back to East Canal. During the monitoring period of this project, discharges from the treatment wetland was limited to March and April of 2017, and the rainy season, June to October, leaving the discharge from the Plant City WRF as the only source of water in East Canal during the remaining months.

Figure 9. Map showing the approximate boundary of the McIntosh Park Enhanced Stormwater Treatment Wetland Project.

December 16, 2019 11

Biological Communities An assessment of the biological communities was conducted twice during the monitoring period at the three locations depicted in Figure 10.

Figure 10. Location of Biological Sampling Locations.

December 16, 2019 12

Four sampling events (which comprised two temporally independent samplings) were conducted on 2/13/2017, 3/13/2017, 11/6/2017, and 12/4/2017. Sampling consisted of: Physical/chemical characterization (FDEP SOP FT 3001); Habitat Assessment (HA) (FDEP SOP FT 3010); Stream Condition Index (SCI) at Itchepackesassa Creek and BioRecon at the two East Canal sites (FDEP SOP SCI 1000 and BRN 1000); Rapid Periphyton Survey (RPS) (FDEP SOP FS 7230); Linear Vegetation Survey (LVS) (FDEP SOP FS 7320); and Periphyton rack deployment and retrieval for chlorophyll a and ash-free-dry-weight (FDEP SOP FS 2110). A summary of the parameters sampled follows:

• Physical/chemical characterization (FDEP SOP FT 3001);

• Habitat Assessment (HA) (FDEP SOP FT 3010);

• Stream Condition Index (SCI) at Itchepackesassa Creek and BioRecon at the two East

Canal sites (FDEP SOP SCI 1000, BRN 1000);

• Rapid Periphyton Survey (RPS) (FDEP SOP FS 7230);

• Linear Vegetation Survey (LVS) (FDEP SOP FS 7320); and

• Periphyton rack deployment and retrieval for chlorophyll a (FDEP SOP FS 2110).

Biological sampling dates were established in accordance with the hydrologic requirements as specified in DEP SOP SCI 1000. One complete sampling event (consisting of a deployment and retrieval of periphyton racks, one faunal sampling, and two RPS, LVS, and Habitat Assessments) occurred during February/March 2017, and another was conducted during November/December 2017 (Table 3). The second set of sampling tasks was delayed until November to achieve proper antecedent hydrologic conditions necessary for biological sampling (FDEP, 2012). This was due to extreme flooding associated with Hurricane Irma (which was followed by usually high precipitation during the fall period). Data

Table 3. Summary of biological sampling efforts.

Parameters

February-March 2017 November-December 2017

East Canal Control and Test sites

Itchepackesassa Creek at Audubon

Road

East Canal Control and Test sites

Itchepackesassa Creek at Audubon

Road RPS Twice Twice Twice Twice LVS Twice Twice Twice Twice HA Twice Twice Twice Twice SCI NA Once NA Once BioRecon Once NA Once NA Physical/Chemical Twice Twice Twice Twice Periphyton Rack (deployment and retrieval – 2 visits)

Once Once Once Once

These data were interpreted according to the NNC Implementation Document (FDEP, 2013). This means that the ditch sites were compared qualitatively (control to test sites) and the downstream

December 16, 2019 13 protection site was assessed according to the floral, faunal, and nutrient evidentiary thresholds.

Biological sampling locations are shown in Figure 9.

Stream Habitat Assessment The FDEP Stream Habitat Assessment consists of scoring eight parameters based on field measurements and observations, including substrate diversity, substrate availability, water velocity, habitat smothering, bank stability, degree of artificial channelization, riparian zone buffer width and riparian zone vegetation quality. Mean habitat scores were 30.3 points (poor) upstream of the Plant City discharge, 47.3 points (poor) downstream of the discharge, and 102 points (sub-optimal) at the Itchepackesassa far-field site (Table 4).

Table 4. Average habitat assessment scores for the East Canal Control site, the East Canal test site, and Itchepackesassa Creek site at Audubon Road.

Location Mean East Canal Upstream 30.3 East Canal Downstream 47.3 Itchepackesassa Creek 102

Rapid Periphyton Survey The Rapid Periphyton Survey (RPS) achieved the expected floral evidentiary threshold for streams (< 25% coverage of rank 4-6) at all sites during all 4 RPS samplings associated with the study, which included two (2) temporally independent samplings (conducted > 3 months apart) (Table 5).

Therefore, the RPS evidentiary threshold requirement in Rule 62-302.531, F.A.C., was achieved both upstream and downstream of the Plant City WRF (an indication of no nutrient-induced imbalances). The RPS evidentiary threshold was also achieved at the far-field test site (Itchepackesassa Creek at Audubon Road), which is one floral indicator of downstream protection.

Table 5. Rapid Periphyton Survey results.

Station Date RPS (% 4-6) Pass?

East Up 2/13/2017 11 Yes East Down 2/13/2017 0 Yes Itch Audubon 2/13/2017 0 Yes East Up 3/13/2017 0 Yes East Down 3/13/2017 0 Yes Itch Audubon 3/13/2017 0 Yes East Up 11/6/2017 0 Yes East Down 11/6/2017 0 Yes Itch Audubon 11/6/2017 0 Yes East Up 12/4/2017 0 Yes East Down 12/4/2017 0 Yes Itch Audubon 12/4/2017 0 Yes

Periphyton rack artificial substrate (glass slides) results are found in Table 6 and Figure 11. All chlorophyll a results were lower than the range of periphyton chlorophyll a values collected by

December 16, 2019 14

FDEP from glass slides at several minimally disturbed control or references sites in Florida (Table 6).

This indicates that the existing responses to nutrient concentrations downstream of the Plant City discharge are acceptable, as the periphyton biomass was lower than many control sites in Florida.

Note that the East Canal test site periphyton rack was stolen during the second sampling event.

Table 6. Periphyton chlorophyll a and Ash-Free-Dry-Weight results from artificial substrates.

Station Date Periphyton Chlorophyll (mg/m2)

Periphyton AFDW (mg/m2)

East Up 3/13/2017 3.98 213 East Down 3/13/2017 12.2 506 Itch Audubon 3/13/2017 12.2 1000 East Up 12/4/2017 7.3 1660 East Down 12/4/2017 Stolen Stolen Itch Audubon 12/4/2017 2.85 327

Figure 11. Box plots of periphyton chlorophyll a results (artificial substrates). The periphyton rack from the East Canal test site was stolen during the second sampling. Note that all values are lower than periphyton chlorophyll a from selected FDEP minimally disturbed control sites in Florida (see Table 7).

Table 7. FDEP periphyton chlorophyll a data (glass slides) from selected minimally disturbed control sites in Florida.

Waterbody Periphyton Chlorophyll

(mg/m2) Citation

Upper Suwannee Control (above White Springs) 28.1 (FDEP, 1995) Upper Suwannee Control (above Gold Kist) 43.8 (FDEP, 2001) Camp Branch Control (above Bonifay) 25.2 (FDEP, 1993a) Troublesome Creek Control (Polk County) 19.3 (FDEP, 1993b) Withlacoochee River Control (Hamilton County) 32.5 (FDEP, 1997) Econfina Creek Reference Site (Bay County) 20.4 (mean) (FDEP, 1992)

December 16, 2019 15

Linear Vegetation Survey The Linear Vegetation data are presented in Table 8 and Figures 12 and 13. Because there were no aquatic plants present, the Itchepackesassa Creek at Audubon Road passed the LVS all 4 times it was sampled, demonstrating compliance with paragraph 62-302.531(2)(c), F.A.C. For graphical purposes, Itchepackesassa Creek was assigned a FLEPPC score of zero and a Coefficient of.

Conservatism (C of C) score of 5. The East Canal control site failed the LVS all four times it was sampled. The East Canal test site failed the LVS twice and passed the LVS twice (for one temporally independent passing score and one temporally independent failing score). The passing LVS results occurred after ditch maintenance, which consisted of herbicide spraying of invasive exotic aquatic and riparian zone vegetation. Because the narrative nutrient criterion is in effect at East Canal, the test site LVS results were compared with the control site LVS results. There were slight improvements in both LVS components at the test site, indicating there were no imbalances in aquatic flora attributable to nutrients in the discharge.

Table 8. Linear Vegetation Survey (LVS) data. Itchepackesassa Creek at Audubon Road had no aquatic vegetation present (passing the LVS).

Station Date LVS (C of C)

LVS

(% FLEPPC) Pass LVS?

East Up 2/13/2017 1.2 65.5 No East Down 2/13/2017 1.7 46.2 No Itch Audubon 2/13/2017 NA NA Yes East Up 3/13/2017 0.84 72.7 No East Down 3/13/2017 1.3 53.1 No Itch Audubon 3/13/2017 NA NA Yes East Up 11/6/2017 2.5 28.6 No East Down 11/6/2017 2.9 16.7 Yes Itch Audubon 11/6/2017 NA NA Yes East Up 12/4/2017 1.8 45 No East Down 12/4/2017 2.7 23.1 Yes

Figure 12. Box plots of LVS % Florida Exotic Plant Pest Council (FLEPPC) results at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge. N = 4. Passing score for streams (not ditches) is 25% and lower.

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Figure 13. Box plots of LVS Coefficient of Conservatism results at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge. N = 4. Passing score for streams (not ditches) is

2.5 and higher.

BioRecon BioRecon was conducted upstream and downstream from the Plant City discharge to evaluate potential differences in the invertebrate community that may be associated with the discharge (Table 9, Figure 14). Although the stream BioRecon thresholds are not applicable to ditches, the test site exceeded the threshold once (with a BioRecon score of 4.6) and was below the threshold once (with a BioRecon score of 3.3). The test site results were higher than the control site results, where the BioRecon scores were 0.53 and 0.69 during two temporally independent sampling events. The observation that the BioRecon scores were higher at the test site, when compared with the control site is likely due to the substantially higher water velocity at the test site (increasing from 0.0 m/sec to an average of 0.12 m/sec), which was attributable to the Plant City WRF discharge. The improvements in BioRecon scores at the test site also indicate that there were no imbalances in fauna from nutrients in the discharge.

Table 9. BioRecon results from two temporally independent samplings at sites located upstream (control site) and downstream (test site) from the Plant City WRF discharge.

Passing score for streams (not ditches) is 4 or higher.

Station Date BioRecon Score BioRecon Interpretation East Up 3/13/2017 0.53 Fail East Down 3/13/2017 4.6 Pass East Up 12/4/2017 0.69 Fail East Down 12/4/2017 3.3 Fail

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Figure14. Box plots of BioRecon results from two temporally independent samplings at sites located upstream and downstream from the Plant City WRF discharge. Passing score for streams (not ditches) is 4 or higher.

Stream Condition Index During the 2017 WQBEL study, the Stream Condition Index averaged 59 (n=2) at Itchepackesassa Creek, the far-field site established to assess downstream protection (Table 10). Neither of the most recent two scores was less than 35. Therefore, achievement of the streams faunal measurements required in Chapter 62-302.531, F.A.C., indicated that fauna was healthy at the far-field test site, demonstrating downstream protection for this metric in Itchepackesassa Creek.

Table 10. Stream Condition Index (SCI) scores for Itchepackesassa at Audubon Road, the far-field test site.

Station Date SCI Score SCI Interpretation Itchepackesassa at Audubon 3/13/2017 58 Pass Itchepackesassa at Audubon 12/4/2017 60 Pass Mean 59 Pass

Summary Because East Canal meets the stream exclusion as a managed conveyance as demonstrated in Appendix1, the flora and fauna inhabiting the test site (downstream of the Plant City WRF) were compared with flora and fauna at the control site (upstream of the discharge). The RPS indicated low algal abundance at both the East Canal control and test sites, which is one aspect of demonstrating no imbalances in flora. The LVS results indicated a somewhat better quality vascular plant community at the test site compared with the control, which is additional evidence demonstrating no floral imbalances associated with the discharge. Finally, water column chlorophyll a was much lower at the East Canal test site and at the Itchepackesassa far-field test site, compared to their respective upstream control sites. This is site-specific evidence that the Plant City WRF does not cause or contribute to phytoplanktonic floral imbalances, but instead, reduces the existing phytoplankton biomass. These three individual types of floral measures (RPS, LVS, and chlorophyll a) clearly demonstrated there were no floral imbalances attributable to nutrients in the Plant City WRF discharge.

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Similarly, the improvements in the BioRecon scores between the control and test sites demonstrate no faunal imbalances attributable to the Plant City WRF discharge.

As further evidence that East Canal attains the narrative nutrient criteria, an analysis of dissolved oxygen in the canal (reaches 1, 2, and 3) attain the dissolved oxygen criteria for freshwater streams (Table 24).

The Itchepackesassa Creek far-field site (which met the definition of a “stream”) achieved the streams evidentiary thresholds for the RPS, LVS, chlorophyll a, and SCI during two temporally independent samplings, demonstrating healthy flora and fauna, in compliance with NNC (Chapter 62-302.531, F.A.C.). This demonstrates that downstream communities were protected.

Recent Water Quality Conditions To aid the development of the WQBEL, water quality data were collected monthly from March 2017 through March 2018. Field data and sample collection was followed FDEP SOP-001/01 with samples analyzed by a NELAC certified laboratory. Field and laboratory parameters were collected at 4 sites listed below and shown in Figure 15:

• WQ-1 – East Canal downstream of the McIntosh Stormwater Treatment system and upstream WRF outfall

• WQ-3 – East Canal downstream of the WRF outfall and upstream of the confluence of East Canal and the Itchepackesassa Creek. This site was moved downstream due to access issues with the proposed Plan of Study site.

• WQ-4 – Itchepackesassa Creek upstream of the confluence with East Canal

• WQ-5 – Itchepackesassa Creek downstream of the confluence with East Canal and upstream of Blackwater Creek

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Figure 15. Location of Water Quality Sampling Locations.

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The field and laboratory parameters collected are listed in Table 11. Time-series plots of key parameters, specific conductance, TP, TN, TKN, NO3+NO2, NH3, chlorophyll a, and DO percent saturation are shown for each station from which data are available in Figures 17 to 25. It should be noted that little or no flow on several dates during the monitoring period precluded collection of water quality samples (Figure 16).

Table 11. Table of field and laboratory parameters.

Field Parameters Laboratory Parameters

Temperature (°C) pH (SU) Specific Conductance (µmhos/cm) Dissolved Oxygen (mg/L) Dissolved Oxygen (µg/L) Flow (cfs) Depth (feet)

Ammonia (mg/L) Total Kjeldahl Nitrogen (mg/L) Nitrate (mg/L) Nitrate-Nitrite as N (mg/L) Orthophosphate as P (mg/L) Total Phosphorus as P (mg/L) Chlorophyll a (µg/L) Ammonium as NH4 (mg/L) Total Suspended Solids (mg/L) Volatile Suspended Solids (mg/L) Nitrite (mg/L) Carbonaceous BOD (mg/L) Total Organic Carbon (mg/L) Dissolved Organic Carbon (mg/L)

Figure 16. Photograph of Itchepackesassa Creek sampling site (WQ-4) on 11MAY17.

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With respect to specific conductance (Figure 17), there is a rather distinct seasonal pattern in that values are depressed during the rainy season. Sites inline with East Canal, WQ-1, WQ-3, WQ-5, all have similar patterns where the Itchepackesassa site, WQ-4 has generally lower values.

Total phosphorus (TP) (Figure 18) exhibits the same seasonal pattern with higher concentrations during the rainy season. The project site is located in the West Central Nutrient region known for the presence of high concentrations of phosphorus in the soils just below the surface. This is expressed as higher than normal concentrations of phosphorus leached out during the rainy season.

Orrthophosphate (Figure 19) follows a similar temporal pattern as TP.

Total nitrogen (TN) (Figure 20) is slightly higher in the wet season, though the increase isn’t as obvious as for TP. The site in Itchepackesassa has generally higher values than those in East Canal possibly due to increase in the breakdown of detritus deposited after the rainy season. It should also be noted that the 5-year mean average daily mean of the PC WRF is 1.152 mg/L which marked lower then many of the samples collected as part of this project, particulary those collected in Itchepackesassa Creek (WQ-4) and downstream of the confluence between East Canal and Itchepackesassa (WQ-5).

Organic nitrogen, measured in the form of total Kjeldahl nitorgen (TKN) (Figure 21), exhibits similar patterns as TN above. This is expected since most inorganic forms of nitrogen are used up by available plankton communities. It was the dominant fraction of nitrogen until November.

Inorganic nitrogen, includes nitrate-nitrite (Figure 22) and ammonia (Figure 23). Nitrate-nitrite becomes the dominant fraction of nitrogen in the latter part of the year in Itchepackesassa at WQ-4 and at WQ-5. Ammonia remains relatively low throughout the monitoring period.

Water column chlorophyll a (Figure 24) also exhibits a season pattern with higher values in the wet season. This is not unexpected as phytoplankton is known to proliferate with increase temperatures and available sunlight of the summer season. Of note are the relatively consistent lower chlorophyll a values at station WQ-3, downstream of the PC WRF outfall.

Dissolved oxygen (Figure 25) values expressed as percent saturation values are lowest downstream of the wetland system (WQ-1) as can be expected. In other sites, the percent saturation results are rarely < 50% saturation. The criteria for freshwater streams in the Peninsular Region in 38% saturation.

The ambient water quality data generally show seasonal patterns related to rainfall variability. As a result the relative effect of the discharges from the Plant City WRF was most notable during the dry months. The spatial patterns in water quality also reflected the influence of flows from Itchepackesassa Creek particularly at WQ-5.

The limiting nutrient for each of the sites was also determined using the mean N:P ratio of the samples. Each of the sites had N:P ratios less than 4. The FDEP has determined that N:P ratios less than 10 were N limited. As such, all of these sites are nitrogen limited.

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Figure 17. Time series plots the specific conductance data from the 4 project sampling sites – March 2017- March 2018.

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Figure 18. Time series plots the TP concentration data from the 4 project sampling sites – March 2017-

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Figure 19. Time series plots the orthophosphate concentration data from the 4 project sampling sites – March 2017-March 2018.

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Figure 20. Time series plots the TN concentration data from the 4 project sampling sites – March 2017-

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Figure 21. Time series plots the TKN concentration data from the 4 project sampling sites – March 2017-

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Figure 22. Time series plots the NO3+NO2 concentration data from the 4 project sampling sites – March 2017-March 2018.

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Figure 23. Time series plots the NH3 concentration data from the 4 project sampling sites – March 2017-

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Figure 24. Time series plots the chlorophyll a concentration data from the 4 project sampling sites – March 2017-March 2018.

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Figure 25. Time series plots the DO percent saturation data from the 4 project sampling sites – March 2017-March 2018.

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CONCEPTUAL MODEL OF POTENTIAL EFFECT OF PLANT CITY WRF ON

EAST CANAL/ ITCHEPACKESASSA SYSTEM

Understanding of the manner by which the discharge from the Plant City WRF can influence the East Canal system provides the context that can lead to meaningful and defensible conclusions and recommendations. The inter-relationships of the watershed and stream channel characteristics along with the hydrology and water quality of the East Canal/Itchepackesassa System have both direct and indirect effects on how the discharges from the Plant City WRF influence the downstream areas. Figure 26 presents a simple flow diagram that depicts these inter-relationships.

The information/data that have been provided by field collection of the physio-chemical and biological data along with the predictive modeling of the water quality responses to changes in WRF discharges are necessary to draw defensible conclusions regarding those responses. The following sections describe the analytical approach to the quantitative methods of data analysis and predictive modeling and the results obtained by the implementation of this approach.

Figure 26. Conceptual model of critical inter-relationships that influence the effects of the Plant City WRF.

East Canal Downstream

Water Quality

Watershed Hydrologic

Loading

East Canal Downstream Residence Time

WRF

Hydrologic

Loading

Watershed Nutrient Loading

WRF

Nutrient Loading

Rainfall

Watershed Characteristics

Itchepackasassa Downstream

Water Quality

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Analytical Approaches The following provides a discussion of the approaches used to assess the relationships between water quality and changes in loadings, particularly those from the WRF.

Objectives Three analytical approaches were applied to assess the potential influence of variation in the loadings from the Plant City WRF on water quality within East Canal and Itchepackesassa Creek:

• Empirical stressor-response analysis,

• Simple box model, and

• Mechanistic modeling.

Specifically, the objective is to provide a predictive tool that quantifies the relationships between water quality responses and changes in loadings, particularly those from the WRF.

Empirical Stressor-Response Approach Linear regression is a parametric statistical technique that is used to explore the relationship between two or more variables. In univariate ordinary linear regression, the relationship between the dependent variable (y-axis) and independent variable (x-axis) is developed. This is done by fitting a straight line through the set of points such that the sum of squared residuals of the model is as small as possible. That is to say, the vertical distances between the individual points and the fitted line are minimized. Ordinary linear regression is a well-established method.

In linear regression, it is assumed that the data are independent samples from the population. For example, if the objective is to define the relationship between chlorophyll a concentrations and nutrient loading, the data should come from samples that are representative of the spatial and temporal variability of the system. Another important assumption of linear regression is that the error term of the model is normally distributed, with constant variance. Often times, one or more of the variables exhibits a non-linear relationship with the other variables. While there are non-linear regression techniques that can be employed, one approach often taken is to transform the data. Often times ordinary linear regressions can be developed using transformed data and these models will satisfy the assumptions of linear regression.

Diagnostic statistics and plots are commonly used to determine if the regression model meets the assumptions of linear regression. The most commonly used statistics are the statistical significance of the model coefficients and the coefficient of determination (r2). The statistical significance of the model coefficients tests whether the slope and intercept of the model are significantly different from zero.