PBSD Clam Bay Committee Agenda 01/09/2020 PELICAN BAY SERVICES DIVISION
Municipal Service Taxing and Benefit Unit
NOTICE OF PUBLIC MEETING JANUARY 9, 2020
THE CLAM BAY COMMITTEE OF THE PELICAN BAY SERVICES DIVISION WILL
MEET AT 1:30 PM ON THURSDAY, JANUARY 9 AT THE PELICAN BAY SERVICES
DIVISION, 3RD FLOOR OF THE SUNTRUST BUILDING, SUITE 302, LOCATED AT 801
LAUREL OAK DRIVE, NAPLES, FLORIDA 34108.
AGENDA
1. Roll call
2. Agenda approval
3. Approval of 11/14/19 meeting minutes
4. Audience comments
5. Clam Bay
a. 2019 Monitoring Report*
b. Canoe trail marker 6 signage
c. Scaevola treatment proposal
d. Tidal gauge at marker 26
e. Update on County boater safety signage
6. Clam Pass
a. 2019 Physical and Tidal Monitoring Report*
b. December tidal ratio report
c. Video of H&M report
d. Timeline for dredging-related activities
7. Water Quality
a. Copper results
b. Second and third water quality report
c. 2019 Annual Water Quality Report
d. FDEP Water Quality findings
8. Next meeting: March 12 or 13, 2020
9. Adjournment
*Reports are available on PBSD's website. Copies may be requested.
ANY PERSON WISHING TO SPEAK ON AN AGENDA ITEM WILL RECEIVE UP TO THREE (3) MINUTES PER ITEM TO
ADDRESS THE BOARD.THE BOARD WILL SOLICIT PUBLIC COMMENTS ON SUBJECTS NOT ON THIS AGENDA AND ANY
PERSON WISHING TO SPEAK WILL RECEIVE UP TO THREE(3)MINUTES. THE BOARD ENCOURAGES YOU TO SUBMIT
YOUR COMMENTS IN WRITING IN ADVANCE OF THE MEETING. ANY PERSON WHO DECIDES TO APPEAL A DECISION
OF THIS BOARD WILL NEED A RECORD OF THE PROCEEDING PERTAINING THERETO,AND THEREFORE MAY NEED
TO ENSURE THAT A VERBATIM RECORD IS MADE,WHICH INCLUDES THE TESTIMONY AND EVIDENCE UPON WHICH
THE APPEAL IS TO BE BASED.IF YOU ARE A PERSON WITH A DISABILITY WHO NEEDS AN ACCOMMODATION IN ORDER
TO PARTICIPATE IN THIS MEETING YOU ARE ENTITLED TO THE PROVISION OF CERTAIN ASSISTANCE.
01/02/2020 10:26 AM
PELICAN BAY SERVICES DIVISION
CLAM BAY COMMITTEE MEETING
NOVEMBER 14,2019
The Clam Bay Committee of the Pelican Bay Services Division met on Thursday, November 14
at 1:30 p.m. at the SunTrust Bank Building, 801 Laurel Oak Drive, Suite 302, Naples, Florida
34108. In attendance were:
Clam Bay Committee Denise McLaughlin
Susan O'Brien, Chairman Rick Swider
Pelican Bay Services Division Staff Lisa Jacob, Project Manager
Neil Dorrill, Administrator (absent) Mary McCaughtry, Ops. Analyst (absent)
Chad Coleman, Operations Manager Barbara Shea, Recording Secretary
Also Present Jeremy Sterk, Earth Tech
Tim Hall, Turrell, Hall & Associates Scott Streckenbein, PBSD Board
APPROVED AGENDA (AS AMENDED)
1. Roll call
2. Agenda approval
3. Approval of 09/10/19 meeting minutes
4. Audience comments
5. Clam Pass
a. October tidal ratio report
b. October aerial photo
c. Video of H&M report
d. Timeline for dredging-related activities
6. Water Quality
a. Copper results
b. Second and third water quality reports
7. Clam Bay
a. Update on monitoring
b. Canoe trail markers 10 and 12
c. Scaevola treatment
d. Update on County boater safety zone signage
8. Clam Bay Expenses
a. Consulting expenses in FY19
b. $150,000 in Fund 111
9. Annual reports
a. Clam Bay: due December 20, 2019
b. Bathymetric and Tidal Analysis: due December 20, 2019
c. Water Quality: due March 15, 2020
9.5 Review of dredging article (add-on)
1
Pelican Bay Services Division Clam Bay Committee Meeting
November 14,2019
9.6 Sunshine Law(add-on)
10. Next meeting: December 10 or 12, 2019 or January 7 or 9, 2020
11. Adjournment
ROLL CALL
All members were present and a quorum was established
AGENDA APPROVAL
Ms. McLaughlin motioned, Ms. O'Brien seconded to approve the agenda as
amended with the addition of agenda items #9.5 and #9.6. The motion carried
unanimously.
APPROVAL OF 09/10/19 MEETING MINUTES
Ms.McLaughlin motioned,Ms.O'Brien seconded to approve the 09/10/19 meeting
minutes as amended. The motion carried unanimously.
AUDIENCE COMMENTS
None
CLAM PASS
OCTOBER TIDAL RATIO REPORT
Ms. O'Brien reported that the October tidal ratios look excellent. She noted that markers
26 and 32 levels are at their lowest of the year,and that these tidal ratios will continue to be closely
monitored.
OCTOBER AERIAL PHOTO
Ms. O'Brien reported that October Clam Pass aerial photos were provided to the committee
via e-mail and that the pass continues to look very good. Mr. Swider requested that Dr. Dabees
provide a few comments on the aerial photos provided to us each month. Ms. Jacob commented
that Dr. Dabees reported that in October, the capacity has never looked better.
VIDEO OF H&M REPORT
Ms. O'Brien commented that staff will be working with Dr. Dabees to produce a video
presentation of his report on his 2019 review of the management of the Clam Pass Inlet. Ms.
McLaughlin suggested that members of the Mangrove Action Group could serve as audience
members for the video.
TIMELINE FOR DREDGING-RELATED ACTIVITIES
Ms. O'Brien commented that she has suggested 13 dredging process steps, which were
provided to staff for review, editing, and possible re-ordering. Ms. Jacob commented that she is
in the process of completing a timeline for dredging-related activities. Mr. Swider suggested that
this process is a management function, not a PBSD Board function. He commented that he does
not see the value in this exercise, and it should not be a priority at this time. Staff resources are
limited. He also suggested there are so many variables which contribute to the need to dredge,
that we control none of these, and that a dredge event will always be an emergency event.
2
Pelican Bay Services Division Clam Bay Committee Meeting
November 14, 2019
Ms. Mary Johnson commented on past maintenance dredge events, and that recent
emergency dredges may be "used against" PBSD management. She suggested that the PBSD
needs a better relationship with the County Procurement Dept. Ms. McLaughlin suggested that
Dr. Dabees,in general, does not favor maintenance dredging. Our environmental consultants,Mr.
Tim Hall and Mr. Jeremy Sterk, commented that maintenance dredging is needed from time to
time. Ms. Jacob commented on the time needed for approvals from the TDC and BCC to obtain
tourist development tax dollars to fund a dredging event. Mr. Hall recommended that the PBSD
pre-qualify dredging contractors, to help shorten the timeline of the pre-dredging steps. He noted
that the Clam Bay management plan spells out the criteria to trigger a dredge, and there is a
subsequent small window of viability to complete the dredge. Ms. O'Brien and Ms. McLaughlin
commented in favor of this idea and suggested that Mr. Callahan and Procurement staff be
contacted to pursue this suggestion.
Mr. Streckenbein commented that he will attend a meeting on Nov.18, organized by
Deputy County Manager Nick Casalanguida, to hear Dr. Dabees' presentation of his 2019 review
of the management of the Clam Pass Inlet. Invitees include Commissioner Solis, Mr.
Casalanguida,Mr. Bodo(PBF Board Chair),Mr. Hoppensteadt,and Mr.Dorrill. Mr. Streckenbein
commented that the goal of the meeting is to (1) educate Commissioner Solis on why emergency
dredges occurred in the past and may be needed in the future, and (2) provide information on the
conditions which produce the need for an emergency dredge in order to deal with possible negative
publicity. Ms. Mary Johnson expressed concern that no additional PBSD Board members were
invited to this meeting.
WATER QUALITY
COPPER RESULTS
Ms. O'Brien commented that the Clam Bay copper results look fabulous.
SECOND AND THIRD WATER QUALITY REPORTS
Mr. Hall commented that Dr. Tomasko's 2nd and 3rd quarter combined Clam Bay Nutrient
Report was received this morning. He highlighted, (1) phosphorus continues to be problematic,
41 out of 47 data points exceeded acceptable levels,(2)nitrogen levels are O.K. and have improved
since last year, and(3)there are no conductivity results in the July samples; he will follow up with
the County Lab on the reason for this. Ms. O'Brien commented that the first quarter berm nutrients
did not exceed acceptable levels, whereas the second and third quarter data show higher levels of
nutrients.
Ms. O'Brien commented that the County Lab now provides our nutrient level reports on a
quarterly basis. In order to get in sync with their quarterly reporting, she suggested that the 2019
annual report include 11 months of data, and then next year's report would include 12 months.
Mr. Hall commented that he will review his purchase order with Ms. Jacob to determine if this
would be possible.
Mr. Swider suggested that PBSD staff should internally maintain nutrient data. Currently
Turrell, Hall &Associates maintains the data, and enters the data into the state's database.
Ms. McLaughlin questioned what the source of the phosphorus in Clam Bay could be. Mr.
Hall suggested that the high levels of phosphorus existing within the Clam Bay system,continually
gets put back into solution, and never leaves the system. Mr. Mumm commented that phosphorus
is naturally occurring in our soil and continuously leaches out into the Clam Bay System.
3
Pelican Bay Services Division Clam Bay Committee Meeting
November 14,2019
CLAM BAY
UPDATE ON MONITORING
Mr. Sterk reported that he completed the gopher tortoise survey and the coastal dunes
survey. He noted an apparent 12% decline in the gopher tortoise population.
CANOE TRAIL MARKERS 10 AND 12
Mr. Sterk reported that canoe trail markers 6, 10, and 12 have been replaced. He noted that
one tidal gauge is currently not working; a battery replacement is necessary.
SCAEVOLA TREATMENT
Ms. O'Brien commented that Mr. Sterk will work on developing a proposal for a future
scaevola removal project, to be included in a future PBSD budget.
UPDATE ON COUNTY BOATER SAFETY ZONE SIGNAGE
Mr. Sterk reported that he will contact the County Coastal Zone Dept. to obtain an update
on the County boater safety zone signage planned for Clam Bay. Ms. O'Brien suggested that Ms.
Jacob contact the Coastal Zone Dept. for additional information on this subject.
CLAM BAY EXPENSES
CONSULTING EXPENSES IN FY19
Ms. O'Brien commented that the PBSD spent $120,000 for Clam Bay environmental
consulting services in FY19. She noted that an Earth Tech purchase order for water management
work was charged to the Clam Bay cost center, and suggested that in the future, only Clam Bay
related expenses should be charged to this cost center.
$150,000 IN FUND 111
Ms. O'Brien commented that the County contributes$150,000 annually towards Clam Bay
environmental expenses.
ANNUAL REPORTS DUE: CLAM BAY, BATHYMETRIC AND TIDAL ANALYSIS,
WATER QUALITY
No discussion
INVASIVE EXOTICS ON CONDO PROPERTY ALONG THE BERM
Ms. McLaughlin commented on invasive exotics on private condo properties along the
berm, and she suggested that their association managers may not be aware that they are required
to remove these exotics. Ms. O'Brien suggested that this issue be brought up to and discussed by
the full PBSD Board. She suggested that the PBSD needs to communicate with condo boards to
remind them of their responsibility to remove exotics on their property. Mr. Hall commented that
he believes the PBF covenants include required invasive exotic removal on condo property, and
that the PBF has the ability to enforce these covenants. Ms. Jacob suggested that we follow up on
this issue with Ms. Lisa Warren, PBF Covenants Director.
REVIEW OF DREDGING ARTICLE (ADD-ON)
Ms. McLaughlin provided her draft PB Post article entitled "Five Year Review of Clam
Pass Inlet Management including Dredging Program,"which was added to the record.Ms. O'Brien
4
Pelican Bay Services Division Clam Bay Committee Meeting
November 14, 2019
provided Ms. McLaughlin with her edits to the article, and Ms. McLaughlin welcomed any
additional edits.
SUNSHINE LAW (ADD-ON)
Ms. McLaughlin commented that she requested staff provide documentation showing that
County Attorney Klatzkow has stated that public funds collected cannot be used for the benefit of
private property. Ms. Shea commented that she has requested this documentation from Assistant
County Attorney Colleen Greene. Ms. O'Brien commented that the PBSD Board has traditionally
used the one-way communication as an informational tool, resulting from the lack of key
documents being provided by staff to the board.
NEXT MEETING:
By consensus,the committee agreed that the next meeting of the committee would be held
on Jan. 9, 2020 at 1:30 p.m.
ADJOURNMENT
The meeting was adjourned at 2:59 p.m. I
Susan O'Brien, Chairman
Minutes approved 1 1 as presented OR 1 1 as amended ON I 1 date
5
1/3/2020 ClamPass-TIDE I humistonandmoore Agenda item#6b
Page 1 of 2
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HENGUMISTON INEERS& MOORE
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https://www.humistonandmoore.com/clampass-tide 1/3
1/3/2020 ClamPass-TIDE I humistonandmoore Agenda item#6b
Page 2 of 2
eestoril:o ¢3eaclies as /Uatural Coastal Systems "
HUMISTON & MOORE
ENGINEERS Home About H&M Services Projects Contact Careers Client Login
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'Consulting Coastal Engineers
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Definitions:
Mean Tide Ratio:ratio of tide amplitude of gages over the tide amplitude from the Gulf of Mexico,averaged over a month.This
ratio is representative of the pass's effectiveness in flushing water from the bay. The lower the ratio, the less efficient is
flushing,indicating material accumualting in the pass.
Mean Low Tide Lag: time difference between low tide in the Gulf of Mexico and at the gage's locations, averaged over a
month in minutes.The time lag is also represenattive of the pass's effectiveness in flushing water from the bay.The higher the
lag the less efficient is flushing,indicating material accumulating in the pass.
Background
Clam Pass is a small wave dominated inlet on the southwest coast of Florida that provides a tidal connection to 500 acres of the
wetland preserve of Clam Bay Natural Resource Protection Area(NRPA).This preserve includes several interconnected bays
surrounded by extensive areas of mangrove wetlands. The preserve is a pristine environmental resource that is collectively
known as Clam Bay.Clam Pass has gone through periods of inlet migration as well as closure,because the relatively small tidal
prism for Clam Bay provides critical balance between tidal energy and littoral process at the inlet channel.
Humiston & Moore Engineers provides professional engineering services to Pelican Bay Services Division of Collier County,
Florida for Clam Pass and Clam Bay. Humiston & Moore Engineers provided engineering services to assist Turrell Hall &
Associate in the development of the Clam Bay NRPA management plan of 1998 and the updated plan of 2014. The engineering
services included the development of design criteria for the inlet stability and conditions for maintenance dredging to maintain
hydraulic efficiency and avoid potential inlet closure including. The implementation of the NRPA management plan includes
various monitoring to maintain the health of the eco system. In addition to the ecological and biological monitoring of the bay
system and its function as a protected environmental resource, the monitoring program includes hydraulic and physical
monitoring of the inlet and bay system to monitor the stability of the pass and assess maintenance requirements.Monitoring of
the hydraulic and physical conditions of the Clam Bay system continues according to the updated NRPA management plan. The
hydraulic monitoring includes continuous water level and tidal data collection at 4 locations within the bay system.
https://www.humistonandmoore.com/clampass-tide 2/3
Agenda item#7a
Page 1 of 1
Clam Bay Copper ug/L
Collection Date CB1 CB2 CB3 CB4 CB5 CB6 CB7 CB8 CB9 Report Date
6/22/2016 0.862 0.700 0.700 0.700 1.640 2.100 0.700 3.520 1.510 9/8/2016
7/20/2016 0.924 5.330 5.110 5.660 2.470 3.960 4.950 5.710 10.500 9/12/2016
7/20/2016 0.924 6.160 4.700 1.690 2.470 1.830 1.980 1.870 8.360 9/21/2016
8/25/2016 2.000 1.850 1.680 1.470 1.240 1.520 2.250 1.280 8.060 10/4/2016
9/20/2016 1.690 2.280 1.280 1.760 0.751 0.700 0.700 1.030 0.700 11/22/2016
10/12/2016 2.760 2.200 2.130 1.190 2.900 1.860 1.060 0.954 1.310 12/7/2016
11/9/2016 2.340 3.390 2.300 2.250 1.630 1.500 1.180 2.030 1.300 1/16/2017
12/6/2016 2.330 2.930 5.100 2.450 2.390 1.780 1.270 1.880 1.720 3/14/2017
1/19/2017 2.570 3.560 2.110 1.990 0.818 0.800 0.961 1.110 2.020 4/4/2017
2/23/2017 2.510 3.350 1.600 1.120 0.851 0.848 1.500 2.570 2.600 4/24/2017
3/21/2017 7.970 4.080 1.710 1.120 0.894 0.846 1.080 1.090 0.957 6/1/2017
4/18/2017 6.480 8.160 1.620 1.240 0.800 0.956 1.280 1.010 1.100 6/14/2017
5/24/2017 2.840 4.060 4.990 0.800 0.800 0.959 0.800 0.920 0.946 7/6/2017
6/21/2017 3.840 4.240 3.850 0.906 1.200 1.140 1.260 1.110 0.760 8/8/2017
7/13/2017 4.700 2.950 3.800 4.080 2.500 2.440 2.370 2.380 2.210 8/29/2017
8/14/2017 4.290 3.810 3.220 2.650 1.400 1.220 1.470 1.020 0.700 10/10/2017
10/4/2017 2.680 1.270 0.600 0.800 12.600 1.610 0.600 0.600 1/22/2018
11/28/2017 0.700 0.722 2.540 0.700 0.700 0.700 0.700 0.700 0.700 1/22/2018
12/12/2017 1.780 2.250 1.890 0.700 1.210 1.210 1.300 0.728 0.911 3/26/2018
1/8/2018 0.420 1.510 1.690 1.590 0.800 0.809 0.800 0.800 2.400 4/27/2018
2/6/2018 3.400 3.980 2.130 2.420 0.829 1.640 3.920 0.800 0.800 4/30/2018
3/22/2018 5.450 4.890 3.670 2.370 1.010 1.040 1.750 1.010 1.320 5/11/2018
4/4/2018 2.370 3.190 2.380 1.970 1.690 0.848 1.280 1.250 5.160 6/11/2018
5/8/2018 5.490 4.880 2.360 1.090 0.800 1.050 1.270 1.570 1.640 7/2/2018
6/6/2018 3.120 3.320 2.670 0.800 0.800 0.853 0.828 1.080 1.220 7/18/2018
7/17/2018 1.400 1.440 1.600 1.600 2.270 1.600 1.600 1.600 1.600 8/21/2018
8/15/2018 1.500 1.410 1.400 1.400 1.600 1.600 1.600 1.650 1.600 10/8/2018
9/13/2018 1.720 1.960 1.200 1.200 1.400 1.400 1.400 1.600 1.400 10/9/2018
10/15/2018 3.190 4.800 4.400 4.030 1.400 1.400 1.960 1.400 1.400 12/21/2018
11/14/2018 1.750 1.900 1.960 1.600 1.600 1.600 1.600 1.600 1.600 2/28/2019
12/12/2018 4.480 2.790 2.400 1.820 1.600 1.600 1.600 1.600 1.600 2/28/2019
1/14/2019 3.150 2.740 2.100 1.880 1.600 1.600 1.600 1.600 1.600 5/3/2019
2/25/2019 3.420 2.470 2.000 1.940 1.600 1.600 1.600 1.600 1.600 5/3/2019
3/25/2019 1.830 3.090 1.600 2.730 1.600 1.600 1.600 1.600 1.600 5/14/2019
4/11/2019 2.310 2.530 1.720 1.910 1.600 1.600 1.600 1.600 1.600 8/8/2019
5/9/2019 2.290 3.160 2.030 2.720 1.600 1.600 1.600 1.600 1.600 8/8/2019
6/25/2019 3.030 2.460 1.720 1.600 1.600 1.600 1.600 1.400 1.450 8/8/2019
7/24/2019 2.660 2.020 1.770 1.600 1.400 1.400 1.400 1.400 1.660 10/1/2019
8/8/2019 2.760 1.710 2.100 2.090 1.400 1.400 1.400 1.400 1.400 10/1/2019
9/5/2019 2.030 1.410 1.400 1.400 1.400 1.400 1.400 1.400 1.400 10/1/2019
Agenda item#7b
r ESA 4350 West Cypress Street Page 1 8tv7w.esassoc.com
Suite 950
Tampa,FL 33607
813.207.7200 phone
813.207.7201 fax
memorandum
date November 11, 2019
to Tim Hall, Turrell, Hall and Associates, Inc.
from David Tomasko, Ph.D.
Emily Keenan, M.S.
subject Quarter 2 and 3: Clam Bay NNC SSAC evaluation
Background
The United States Environmental Protection Agency and the Florida Department of
Environmental Protection Agency (FDEP) adopted site specific alternative nutrient criteria
(SSAC) for Clam Bay, as listed in Florida Administrative Code (FAC) 62-302.531. The SSAC
were derived based upon a nutrient: salinity relationship from the Estero Bay Wetlands, a
reference waterbody for water quality, as established by FDEP in prior TMDLs. The SSAC for
Clam Bay is considered in the context of specific conductance, which is directly related to salinity.
The reason for this is that nutrient concentrations vary with the amount of freshwater influence,
even in watersheds with no human impacts. The Clam Bay NNC criteria are constructed in such
a manner that changes in nutrient concentrations that are likely due to variation in rainfall alone
are identified, so that the focus can remain on changes in nutrient concentrations due to sewage
spill
Based on prior work that showed that phytoplankton growth in Clam Bay was likely stimulated
by both Total Nitrogen (TN) and Total Phosphorous (TP), both TN and TP are used to determine
the degree of nutrient enrichment of Clam Bay's waters. As outlined in FAC 62-302.531, water
quality status is determined on an annual basis, preferably within a calendar year. Within a
calendar year, each individual TN and TP value collected within the waterbody is compared to
the nutrient: conductivity 90th percentile prediction limit (Figure 1), and an annual percent
exceedance is calculated to determine the magnitude of exceedances per year. To be consistent
with the method currently implemented by FDEP to identify impaired water bodies, if 13 percent
or more of the TN or TP values in a calendar year exceed the 90th percentile prediction limit
(after being normalized for conductivity) the duration of exceedance is then determined. Based
on the duration of exceedance (one year or greater than one year), the outcome designation is
assigned. If fewer than 13 percent of the values exceed the 90th percent prediction limit, then
the outcome is "0". If the magnitude (i.e., 13 percent) and duration (i.e., less than 1 year) of the
exceedances are deemed small, the outcome is "1". If the magnitude or duration of the
exceedances is large, then the outcome is "2". If both the magnitude and duration of the
Agenda item#7b
Page 2 of 7
exceedances are large, then the outcome is "3". The management response for Clam Bay would
be determined based on the outcomes assigned to both the TN and TP evaluations for the
magnitude and duration of exceedance (Figure 2).
The water quality status of Clam Bay would be assigned a green, yellow, or red designation
annually based on the magnitude and duration of exceedances of the 90th percent prediction
limit. The color designation is then used to determine what level(s) of management actions are
appropriate.
Annual management response actions are based on the response to nutrient concentrations of
phytoplankton and dissolved oxygen (DO) as well as impacts on water clarity (Figure 3). If the
outcome of the TN and TP evaluation is green, then no management actions are required.
However, if the outcomes are yellow or red then further evaluation of the effect of elevated
nutrient concentrations on both phytoplankton biomass and DO concentrations need to be
reviewed. If there is no relationship between nutrients and chlorophyll-a or DO, then no
management actions are required. If there is a signification relationship, then the impact of
chlorophyll-a on the water clarity (Secchi disk depth) would be evaluated. If there is no
relationship between chlorophyll-a and water clarity, then no management actions are required.
If there is a significant relationship between chlorophyll-a concentrations and water clarity, an
outcome designation of "yellow" (indicative of small magnitude or duration of exceedances)
identifies that management actions should be taken to identify the potential causes and
responses for the elevated nutrient levels. It the outcome designation is "red" (indicative of a
large magnitude or duration of exceedances), management actions should be taken to
implement recommended response tactics to reduce nutrient concentrations. In this manner, the
"health" of Clam Bay is to be assessed annually.
Do?13%of all TN&/orTP
values from a calendar year _
No exceed the 90%prediction limit
from the reference WBID?
Outcome0 Yes
>13% Magnitude of ?15%
exceedance
Duration of Duration of
exceedance exceedance
l year >1 year l year =1 year
Outcome 1 Outcome 2 Outcome 2 Outcome 3
Figure 1. Clam Bay water quality flow chart.
2
Agenda item#7b
Page 3 of 7
Total Phosphorus
Total Nitrogen Outcome 0 Outcome 1 Outcome 2 Outcome 3
Outcome 0
Outcome 1
Outcome 2
Outcome 3
Figure 2. Management response matrix using outcomes from both TN and TP
evaluation.
Response Yellow or Red
evaluation
Hold the
line
Evaluatephytoplankton/ significant
dissolved oxygen (p<0.05)
Not significant response to nutrient
(p,0.05) concentrations
Evaluate water clarity
Not significant response to chlorophyll-a
(p>0.05)
Significant(p<0.05)
Small difference or
Identify potential causes short duration
Identify potential
and implement
recommended response Large difference or causes and
long duration responses
Figure 3. Management response actions in response to various outcomes.
3
Agenda item#7b
Page 4 of 7
Data Analysis
The analysis conducted below was used to assess the water quality status of Clam Bay during
the months of February 2019 to July 2019. Since, the SSAC developed for Clam Bay is to be
evaluated on an annual time step, this analysis provides insight into current water quality
conditions within the Bay, but it does not substitute for the more comprehensive annual
assessment required. Clam Bay surface water quality data were provided by Turrell, Hall and
Associates, Inc. for comparison with the FDEP adopted SSAC established for Clam Bay and
found within FAC. 62-302-532 -1-j. The NNC SSAC states the following;
"No more than 10 percent of the individual Total Phosphorus
(TP) or Total Nitrogen (TN) measurements shall exceed the
respective TP Upper Limit or TN Upper Limit."
The TP and TN upper limits are calculated using equations 1 and 2:
Equation 1 : TP Upper Limit (mg/L)= e(-1.06256-o.0000328465*Conductivity(ps))
Equation 2: TN Upper Limit (mg/L)= 2.3601 — 0.0000268325*Conductivity(pS)
The dataset was supplemented with in situ water quality data (e.g., temperature, dissolved
oxygen, pH, conductivity, and salinity) retrieved from the chain of custody forms for each
sampling event. The corresponding TN or TP Upper Limit was calculated for each Clam Bay
estuarine water quality station and sampling date in which conductivity was available using
Equations 1 and 2. TN and TP concentrations were compared to the derived upper limit
thresholds to ascertain if elevated concentrations were identified (Appendix A). It is important
to note that while TN and TP measurements were collected at each of the 9 sampling
locations, corresponding conductivity data are not available at 7 of the locations in July 2019
due to equipment failure. As such, a comparison between the discrete measurement and
calculated TN or TP Upper Limit cannot be performed for all data.
Results
The period of time covered in this memo is from February 2019 to July 2019 which
encompasses two quarterly periods (Quarter 2 and Quarter 3). Additional data, from
November 2018 to January 2019, are included here as well. During the time period of
February 2019 to July 2019, there were six TN measurement from the open waters of Clam
Bay) which exceeded their Upper Limits for NNC criteria. In the prior annual report, a total of
fifteen (15) ambient water quality values for TN exceeded the respective TN Upper Limit. In the
prior quarterly report, there were four exceedances of the TN Upper Limit. These results
suggest that at least in terms of nitrogen, it does not appear that the open waters of Clam Bay
are overly problematic, as their frequency of exceeding the TN criteria is lower than during the
last annual report.
In contrast, 41 of the 47 TP measurements (87 percent) from the open waters of Clam Bay
exceeded their respective Upper Limits. This frequency of occurrence exceeds the 13 percent
threshold shown in Figure 1, which means that for this time period the open waters of Clam
4
Agenda item#7b
Page 5 of 7
Bay continue to have phosphorus concentrations that exceed the established criteria. The
exceedances occurred throughout all areas of Clam Bay and all sampling events In the prior
annual report, 67 of 108 samples exceeded NNC criteria for TP, which indicates that elevated
TP concentrations have been prevalent for an extended period of time. Based on the results
from this time period, and if the frequency of exceedance seen here was to be maintained over
the course of a calendar year, Clam Bay would likely be determined to be impaired for TP.
The TN and TP exceedances are illustrated in Tables 1 and 2. The TP exceedances during the
second and third quarter are numerous, and are consistent with the widespread elevated
concentrations noted in the 2018 annual report. Since July 2018, TP concentrations have
been elevated throughout the entire Clam Bay system. This widespread pattern of
exceedances had been previously suggested to be related to tree defoliation and excessive
rainfall and runoff associated with Hurricane Irma. For example, after Hurricane Charley hit
Southwest Florida in 2004, widespread defoliation of vegetation brought about impacts to
water quality throughout both Charlotte Harbor and the Peace River watershed (Tomasko et al.
2006). However, the persistence of TP exceedances more than a year after the passage of
Hurricane Irma is not consistent with the shorter-term impacts that were recorded after the
passage of Hurricane Charley (Tomasko et al. 2006).
Table 1. Observed TN Exceedances (marked with an "X") at the ambient Clam Bay
surface water sample sites over the period of November 2018 to July 2019. Table
extended to show 12 months of data required for an annual assessment. "-" indicates
sampling dates without corresponding conductivity data. Boxes with neither an X or a
dash are in compliance with existing criteria.
Sampling event
Station Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
1 -
2
.
3 X -
4
5 X
•
6 X X -
7 X X•8 X
9 X X -
5
Agenda item#7b
Page 6 of 7
Table 2. Observed TP Exceedances (marked with an "X") at the ambient Clam Bay
surface water sample sites over the period of November 2018 to July 2019. Table
extended to show 12 months of data required for an annual assessment. "-" indicates
sampling dates without corresponding conductivity data. Boxes with neither an X or a
dash are in compliance with existing criteria.
Sampling event
Station Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct
1 X X X X X X X -
2 X X X X X X X X -
3 X X X X X X X -
4 X X X X X X X X
5 X X X X X X X
6 X X X X X X X -
7 X X X X X X X -
8 X X X X X X X X -
9 X X X X X X X X -
In addition, water quality data from six of the Clam Bay Outfall monitoring stations were
compared to the proposed downstream protective values (DPV) for Clam Bay (PBS&J 2011).
Outfall TN and TP concentrations were compared to the median and 90th percentile DPV
values to determine if elevated concentrations were identified (Appendix B).
The median and 90th percentile DPVs for TN are 1.31 and 1.80 mg/L, respectively (PBS&J
2011). The median and 90th percentile DPVs for TP are 0.10 and 0.25 mg/L, respectively. For
TN, 61 and 15 percent of the values exceeded the median and 90th percentile DPV criteria,
respectively, during the months of February 2019 through July 2019 (Table 3). It should be
noted that a "median" value represents a value where 50 percent of samples would be
expected to be in exceedance. Similarly, it would be expected by chance alone that 10
percent of values would exceed the 90th percentile DPV, vs. the 15 percent of TN values found
here. For nitrogen, the findings reported here are not far out of line for expectations set out in
the "hold the line" approach used to develop NNC criteria for Clam Bay. In contrast, while only
64 percent of TP values exceeded the median DPV criterion (which is expected to be
exceeded 50 percent of the time), 30 percent of values exceeded the 90th percentile DPV
criterion, which is expected to be exceeded only 10 percent of the time.
Table 3. Percentage of TN or TP concentrations from outfall stations which exceeded
the median or 90th percentile DPV values for stormwater runoff.
DPV Total Nitrogen Total Phosphorus
Median 90th Percentile Median 90th Percentile
Percent of values below 39 85 36 70
Percent of values above 61 15 64 30
6
Agenda item#7b
Page 7 of 7
Discussion
It should be noted that because this data analysis is not based on a full calendar year of data,
it is only an indicator of the potential for the Clam Bay system to be determined to be out of
compliance with its established water quality criteria (FAC 62-302.531). However, quarterly
status reports can be useful as an early warning system to alert the County of situations where
water quality might be significantly out of compliance with established criteria.
As was previously noted in the 2018 Annual Report, the findings displayed here suggest
phosphorus concentrations in the open waters of Clam Bay are potentially problematic. Within
the Quarters 2 and 3 of 2019, 87 percent of TP values exceeded a threshold value meant to
"hold the line" on nutrient concentrations in the Clam Bay system. Additionally, elevated
nutrient concentrations at outfall sampling locations identified that during this quarter, 30
percent of TP values from sampled outfall locations exceeded a criterion that is expected to be
exceeded 10 percent of the time. These results suggest that the watershed may be
contributing elevated concentrations of TP in runoff to Clam Bay. These findings suggest that
elevated TP concentrations in Clam Bay could be due to activities in the watershed, as well as
from "internal" sources such as mangrove decomposition and/or roosting birds.
In contrast to previous reporting periods, concentrations of nitrogen are slightly elevated at the
outfall locations, as exceedance rates for the median DPV concentration are greater than what
is to be expected. Despite the elevated TN concentrations in the outfalls, a concurrent impact
on nitrogen in Clam Bay was not observed.
Taken as a whole, the water quality data collected between the months of February 2019 and
July of 2019 suggest that the open waters of Clam Bay have more phosphorus than would be
expected, as 87 percent of samples exceeded the criteria spelled out for Clam Bay in the State
of Florida's Impaired Waters Rule (FAC 62-302.531). For nitrogen, no such concern currently
exists.
7
Agenda item#7d
Page 1 of 1
FDEP Water Quality Findings
Clam Bay WBID 3278Q1
June 25, 2019
Parameter Assessment Status Notes
Antimony Insufficient data
Arsenic Not impaired
Cadmium Not impaired
Copper Impaired Medium priority for TMDL*
Dissolved oxygen Impaired Study list
Enterococci Not impaired
Fecal coliform Potentially impaired Planning list
Fluoride Insufficient data
Iron Not impaired
Lead Not impaired
Mercury(in fish) Impaired TMDL* complete
Nickel Not impaired
Chlorophyll a Not impaired
Total nitrogen Not impaired
Total phosphorus Potentially impaired Planning list
pH Not impaired
Silver Not impaired
Turbidity Not impaired
Zinc Not impaired
*Total Maximum Daily Limit: a plan for restoring impaired waters that identifies the maximum
amount of a pollutant that a body of water can receive while still meeting water quality
standards.
n.b.The difference between a study list and a planning list needs to be determined.
Clam Pass Dredging
Total Volume of Sand (CY)
Pre dredge Post dredge
3/8/18 5/10/18 11/6/18 5/2/19 11/22/19
A 3110 A 144 A 3684 A 2223 A 2271
B 3321 B 53 B 1372 B 1813 B 1702
C 2086 C 242 C 2052 C 2075 C 2241
T 8517 T 439 T 7108 T 6111 T 6214
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FDEP Water Quality Findings
Clam Bay WBID 3278Q1-June 25, 2019
Parameter Assessment Status Notes
Antimony Insufficient data
Arsenic Not impaired •
Cadmium Not impaired
Copper Impaired Medium priority for TMDL*
Dissolved oxygen Impaired Study list
Enterococci Not impaired
Fecal coliform Potentially impaired Planning list
Fluoride Insufficient data
Iron Not impaired
Lead Not impaired
Mercury(in fish) Impaired TMDL* complete
Nickel Not impaired
Chlorophyll a (Trend) Not impaired
Chlorophyll a Insufficient data
Total nitrogen (Trend) Not impaired
Total nitrogen Insufficient data
Total phosphorus(Trend) Potentially impaired Planning list
Total phosphorus Insufficient data
pH Not impaired
Silver Not impaired
Turbidity Not impaired
Zinc Not impaired
*Total Maximum Daily Limit: a plan for restoring impaired waters that identifies the maximum amount
of a pollutant that a body of water can receive while still meeting water quality standards.
n.b.The difference between a study list and a planning list needs to be determined.