MSTBU Clam Bay Agenda 10/19/2021PELICAN BAY SERVICES DIVISION
Municipal Service Taxing and Benefit Unit
NOTICE OF PUBLIC MEETING
OCTOBER 19, 2021
THE CLAM BAY COMMITTEE OF THE PELICAN BAY SERVICES DIVISION WILL
MEET AT 9:00 AM ON TUESDAY, OCTOBER 19 AT THE SUNTRUST BANK
BUILDING, 801 LAUREL OAK DRIVE, SUITE 102, NAPLES, FLORIDA 34108,
AGENDA
1. Roll call
L Agenda approval
3. Approval of 07/13/2021 meeting minutes
4. Audience comments
5. Water Quality
a. Report for January -June 2021
b. Total phosphorus results for 2020 and 2021
c. Six-month and annual reports
d. Appendices for TP and TN data
e. Upland pond data for water management
f. Record keeping
6. Clam Pass
a. Timeline for dredging
b. Quantity of sand to be removed
7. Clam Bay
a. Mangrove monitoring
b. Stressed mangroves
c. Scaevola removal
d. Osprey nest
e. Canoe trail marker 8
8. Next meeting
9. Adjournment
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,
10/13/2021 11:26 AM
PELICAN BAY SERVICES DIVISION
CLAM BAY COMMITTEE MEETING
JULY 13, 2021
The Clam Bay Committee of the Pelican Bay Services Division met on Tuesday, July 13 at 2:00
p.m. at the Community Center, 8960 Hammock Oak Dr., Naples, Florida 34108. In attendance
were:
Clam Bay Committee
Susan O'Brien, Chairman
Denise McLaughlin
Pelican Bay Services Division Staff
Neil Dorrill, Administrator
Chad Coleman, Operations Manager
Darren Duprey, Assoc. Project Manager (absent)
A►so Present
Mohamed Dabees, Humiston & Moore
Michael Fogg, PBSD Board
Michael Rodburg (absent)
Rick Swider
Karin Flerrmann, Ops. Analyst
Lisa Jacob, Project Manager
Barbara Shea, Admin. Assistant
Jeremy Sterlc, Earth Tech
APPROVED AGENDA (AS PRESENTED)
1. Roll call
2. Agenda approval
3. Approval of 06/01/2021 meeting minutes
4. Audience comments
5. Beach Renourishment
a. Data from Engineering report
bI Data provided by Humiston &Moore
c. Public -private beach boundary line
d. Recommendation on amount of sand
6. Clam Pass
aI Tidal ratio results for June
b. Bathymetric survey
c. Data provided by Humiston & Moore
d. Timeline for maintenance work
e. Approval of construction drawings
Water Quality
a. Consultant for water quality records and reports
8. Next meeting
9. Adjournment
ROLL CALL
Mr. Rodburg was absent and a quorum was established
Pelican Bay Services Division Clam Bay Committee Meeting
July 13, 2021
Ms. McLaughlin motioned, Mr. Swider seconded to approve the agenda as
nresented. The motion carried unanimouslv.
Ms. McLaughlin motioned, Mr. Swider seconded to approve the 06/Ol/2021
meetine minutes as presented. The motion carried unanimously
AUDIENCE COMMENTS
None
BEACH RENOURISHMENT
Dr. Dabees, Environmental Consultant with Humiston & Moore, commented on the 2021
Truck Haul Renourishment Design Summary by Reach (revised 06/22/2021), included in the
agenda packet. For Pelican Bay sections R-30.8 to R-37 the volume to fill the permitted template
is 49,400 cy, and the revised design is 52,400 cy. He noted that there has been a discussion with
the County to increase the County's renourishment responsibility from 'A mile south of Vanderbilt
Beach to '/2 mile. Mr. Fogg noted that he will continue this discussion with County Coastal Zone
Management staff, Mr. Hoppensteadt, and Mr. Dorrill. At this time, no change in responsibility
has been agreed upon. Requesting that the County taper the sand from 30.8 to about 1000 feet
south was suggested.
Dr. Dabees commented that the state DEP has concluded that PB beaches at R-31 and
southward are not critically eroded, and therefore, not eligible for state funding. He noted that if
the PBSD Board chose to renourish areas between R-30.8 and R-37 that this would be considered
"advanced renourishment." Dr. Dabees discussed the advantages and disadvantages of three
options for the committee to consider: (1) alternative 1: placing approximately 50,000 cy of sand
from R-30.8 to R-37 with an approximate cost of $2 million, (2) alternative 2: placing
approximately 20,000 cy of sand from R-34.5 to R-36.5 (Marker 36 beach) with an approximate
cost of $800,000, and (3) alternative 3: no participation in the County's FY2021 renourishment
project.
Dr. Dabees suggested that we request that our participation in the County's renourishment
contract be included as an "option" on the contract (with fairly wide parameters), so that the PBSD
could have flexibility on the amount and/or location of the placement of sand on our PB beaches.
This would allow us to make a final decision on the amount and location later on in 2021, in the
event that storms change our beach widths over the next several months. The committee agreed,
and suggested that Dr. Dabees pursue this.
Ms. O'Brien commented that the community feels that current PB beach widths near R-36
are inadequate. Ms. McLaughlin commented that the Marker 36 beach is heavily used, and
suggested that at a minimum we should choose alternative #2. Mr. Dorrill commented that he
expects our Clam Pass hydraulic dredge project to be completed in early December, which will
likely result in the placement of approximately 13,000 cubic yards of sand onto South Beach.
Mr. Fogg commented that the PBF will contribute funds for this beach renourishment
project. Ms. O'Brien suggested that Mr. Fogg and/or staff confirm the amount of their
contribution.
Pelican Bay Services Division Clam Bay Committee Meeting
July 13, 2021
Mr. Dorrill recommended "option 2" as it meets community concerns and makes the most
fiscal sense.
Ms. McLaughlin motioned, Ms. O'Brien seconded that we recommend
alternative #2 as structured here (Humiston & Moore Figure 2b alternative #2
Fill Limits for Vanderbilt and PB Beach included in the agenda packet) to the
PBSD Board at an estimated cost of $800,000 out of budgeted funds and that we
focus the benefit in front of Marker 36, with approximately 20,000 cubic yards of
sand. The motion carried unanimously.
Ms.
O'Brien suggested that
staff confirm that the
County's beach
renourishment will
include the
beach area in front of the
beachfront Bay Colony
Beach Club and
homes.
CLAM PASS
Mr. Dorrill reported that we have obtained approval from the TDC and the BCC for one of
two project options, (1) excavation and regrading of Clam Pass, or (2) a full hydraulic dredge of
Clam Pass subsequent to turtle nesting season. We have a marine contractor in place for this work.
Dr. Dabees commented that the construction plans for the project were included in this agenda
packet and tomorrow's board agenda packet, so that these plans can be approved by the board.
WATER QUALITY
CONSULTANT FOR WATER QUALITY RECORDS AND REPORTS
Ms. Jacob commented that there are no remaining budgeted funds in the FY2021 PBSD
budget for water quality reports for the remainder of FY2021. The water quality data will continue
to be collected by the County. Ms. O'Brien commented on the importance of the ESA
(Environmental Science Assoc.) semi-annual water quality reports. She also commented on the
importance of Tim Hall's involvement, as a water quality subcontractor, as Turrell Hall & Assoc.
has maintained our water quality data for the past 20 years. This was agreed upon by the committee
at the last committee meeting. Mr. Dorrill suggested that a budget amendment to provide funding
for a FY2021 semi-annual water quality report be discussed by the board at tomorrow's board
meeting.
OSPREY PLATFORM
Mr. Dorrill commented that a new osprey platform has been fabricated, and will be
installed by Mr. Sterk, Environmental Consultant with Earth Tech, as soon as a County vehicle -
on -the -beach permit has been received.
SCAEVOLA REMOVAL
Mr. Dorrill reported that Bay Colony has a great deal of scaevola which is adjacent to
scaevola in Clam Bay, that the PBSD is planning to remove. A discussion with Bay Colony
representatives about their plans to remove scaevola is needed.
ADJOURNMENT
The meetine was adjourned at 3:37
Pelican Bay Services Division Clam Bay Committee Meeting
July 13, 2021
Susan O'Brien, Chairman
Minutes approved [] as presenas amended ON ( 1 date
Agenda item #5a
Page 1 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
® Stantec
Clam Bay Water Quality Analysis
— Technical Memorandum
Analysis of Bi-Annual Water Quality
Monitoring Data for Clam Bay,
January through June 2021,for
Evaluation of Compliance with
Numeric Nutrient Criteria
September 9, 2021
Prepared for:
Lisa Jacobs
Collier County Pelican Bay Se vices
Division
801 Laurel Oak Drive, Suite 302
Naples, FL 34108
Prepared by:
Stantec Consulting Services Inc.
6920 Professional Parkway East
Sarasota, FL 34240
Agenda item #5a
Page 2 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Table of Contents
EXECUTIVE SUMMARY.........................................................................................................1.1
1.0 BACKGROUND...........................................................................................................1.1
2.0
CLAM BAY NUTRIENT STATUS................................................................................2.2
2.1
DATA ANALYSIS — NUTRIENT STATUS AND DEVELOPMENT OF SITE
SPECIFIC ALTERNATIVE CRITERIA (SSAC).............................................................2.2
2.2
RESULTS — NUTRIENT STATUS................................................................................2.3
2.3
CLAM BAY RESULTS — DISSOLVED OXYGEN........................................................2.10
2A
CLAM BAY RESULTS — COMPARISON OF NUTRIENTS TO DISSOVVED
OXYGEN SATURATION AND CHLOROPHYLL —A CONCENTRATIONS, .... p
............. 2.11
2.5
CLAM BAY RESULTS — COPPER.............................................................................2.12
3.0
STORMWATER
POND
WATER QUALITY DATA.....................................................3.12
3.1
STORMWATER
POND
RESULTS—TP
.....................................................................3.13
3.2
STORMWATER
POND
RESULTS —
TN....................................................................3.15
3.3
STORMWATER
POND
RESULTS —
DO...........................................................4........3.17
3.4
STORMWATER
POND
RESULTS —
COPPER... .....................................................
drv3ml9
4.0 CLAM BAY BERM WATER QUALITY DATA............................................................4.21
4.1 NUTRIENT RESULTS —BERM DATA............................................................ I ....... ..A.21
4.2 DISSOLVED OXYGEN RESULTS — BERM DATA.....................................................4.24
4.3 COPPER RESULTS — BERM DATA..........................................................................4.24
5.0 CONCLUSIONS AND RECOMMENDATIONS .........
APPENDICES
......5.25
APPENDIX A —ESA 2021 ANNUAL REPORT (2020) ON CLAM BAY NUMERIC NUTRIENT
CRITERIA
APPENDIX B —WATER QUALITY RESULTS IN CLAM BAY
APPENDIX C —WATER QUALITY SAMPLE LOCATIONS AND BASINS
Agenda item #5a
Page 3 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Background
Executive Summary
Water quality monitoring data from samples collected monthly from Clam Bay, between January 2021
and June 2021, were analyzed and evaluated to determine whether the different regions of Clam Bay are
currently in compliance with previously established Numeric Nutrient Criteria (NNC) and established
criteria for copper. Twenty-eight (28) of 52 Total Phosphorus (TP) values exceeded established criteria in
Clam Bay during the first six months of 2021 but no Total Nitrogen (TN) concentration exceedances
occurred during this time period. Data presented here are compared to data analyzed by others as
presented in reports submitted for previous years dating back to 2015. These results are similar to those
observed in previous years. Sample results also indicate that Clam Bay is in compliance with percent
dissolved oxygen (DO) saturation for saltwater sites as well as for copper concentrations found in
saltwater sites.
Water quality data, including TN, TP, percent DO saturation and copper were also measured and
compared for numerous samples, collected monthly at berm outfall sites that discharge to Clam Bay. In
addition, quarterly samples were collected in February and May at approximately 31 locations in
stormwater ponds that ultimately discharged to the bay.
The results from the previous 6 months were compared to data available in previous memos dating back
to March 2015. Previous reports have suggested that long term impacts from Hurricane Irma, which
occurred in September 2017, may have had longer term impacts than originally expected, particularly
related to tidal channel restoration activities conducted in 2018 as a result of the storm. Observations
made in 2020 indicated a reduction in TP exceedances of NNC, although observations made in January
through June 2021 showed an increase in exceedances compared to the previous six months. It is
unknown whether high levels of nutrients can still be attributed to Hurricane Irma four years after the
storm event.
A comparison of nutrient concentrations to percent DO saturation and to chlorophyll -a in Clam Bay do not
ndicate that there is any significant relationship between the parameters.
Overall, it appears that nutrient and copper levels are still high in stormwater ponds, possibly bound in
sediments that may be resuspended to release nutrients and copper during storm events.
Recommendations to address these high nutrient levels, which also appear to be causing algal blooms,
as well as high levels of copper in stormwater ponds, include the following options: consideration of
dredging sediments in stormwater ponds; planting wetland vegetation in ponds to be periodically
harvested to remove nutrients and possibly copper; use of alum to treat phosphorus (not generally
recommended upstream of sensitive waters); use of media filters to remove copper from outfall water; or
constructed treatment of wetlands to address the overall water quality improvement of the system.
Aeration of stormwater ponds can also reduce TN concentrations, reducing the growth of algae, although
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1.1
Agenda item #5a
Page 4 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Background
aeration would
not treat TP or
copper.
All
of these options depend on the
availability of funds and most
options require
some uplands
in which
to
implement the listed options.
The most probable cause of high levels of TN, TP and Copper are historic uses of fertilizers and
algicides. Nutrients and metals can become bound in the sediments of stormwater ponds and re-released
when sediments are disturbed, such as after a storm event. Resuspension of sediments can cause new
eleases of contaminants for many years after contaminant inputs cease.
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Agenda item #5a
Page 5 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Background
1.0 BACKGROUND
The overall purpose of this report is to summarize the status of water quality with respect to set criteria for
Clam Bay as measured for Total Nitrogen (TN), Total Phosphorus (TP), percent dissolved oxygen (DO)
saturation, and copper concentrations. Water quality for these and other parameters not discussed here
were measured monthly, between January 2021 and June 2021, at nine locations throughout Clam Bay.
Similar water quality parameters were measured monthly for five locations along a berm that discharges
to Clam Bay. In addition, the above listed and other water quality parameters were measured during
February and May 2021 for approximately 31 locations in stormwater ponds that discharge to Clam Bay.
This report summarizes water quality exceedances for sites located in Clam Bay as well as high levels of
TN, TP and copper at berm and stormwater pond sites that may contribute to the degradation of water
quality in Clam Bay.
One of the reasons for the creation of the Pelican Bay Services Division (PBSD) Municipal Services
Taxing & Benefit Unit (MSTBU) was for the purpose of maintenance of conservation preserve areas and
the PBSD is solely responsible for advising Collier County (County) on dredging and maintaining Clam
Pass for the purpose of enhancing the health of the affected mangrove forest. It should be noted that
mangroves in the region were severely adversely impacted by Hurricane Irma in September 2017 and
restoration activities to clear waterways and conduct other restoration activities were undertaken in 2018.
These activities appear to have affected water quality in subsequent years based on previous reports
submitted by others, although it is does not seem likely that impacts and activities associated with
Hurricane Irma are still affecting water quality four years later. Tropical Storm Sally and Hurricane Eta
passed through the region in September and November 2020, respectively, and may have had an
influence on water quality in the wake of these more recent storms.
As described in detail in the ESA 2020 Annual Report, dated March 24, 2021 (Appendix A), the U.S.
Environmental Protection Agency adopted nutrient concentration criteria for Clam Bay, which was also
reviewed and approved by the Florida Department of Environmental Protection (FDEP). Clam Bay has
been assigned Numeric Nutrient Criteria (NNC) that are termed Site -Specific Alternative Criteria (SSAC)
as listed in Chapter 62-302,501 of the Florida Administrative Code (F.A.C). The criteria developed for
both TN and TP depend upon salinity/conductivity based on the finding that nutrient concentrations in
saltwater systems, including estuaries and tidal rivers, such as Clam Bay, vary with rainfall, runoff and
tidal influence.
The SSAC relates to findings at referenced sites with little or no human influence where nutrient
concentrations decrease as salinity increases, reflecting the combination of terrestrial nutrient runoff
sources from adjacent lands with relatively low nutrient concentrations in offshore waters. As a result,
nutrient concentrations even in pristine locations may pass or fail nutrient criteria targets depending on
rainfall, tidal stage, location, and possibly prevailing winds depending on the depth of the water column. In
addition to considering salinity/conductivity of waters when evaluating whether nutrients meet NNC, the
i
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Agenda Item #5a
Page 6 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
evaluation process also considers the frequency with which nutrient concentrations exceed NNC values
and the amount of time over which exceedances have occurred in order to determine management
responses. Small exceedances over short periods of time would result in a different response than higher
exceedances and/or exceedances that occur over longer periods of time.
The process of management responses previously used to evaluate nutrient results, and to plan for
management responses, related to the degree and length of exceedances between 2015-2020, is
discussed in more detail and is graphically depicted in the ESA 2020 Annual Report (Appendix A).
These management criteria are not discussed here because this report does not cover a complete year of
data and because algal concentrations do not appear to be related to nutrient concentrations in Clam Bay
as discussed below).
2.0 CLAM BAY NUTRIENT STATUS
2.1 DATA ANALYSIS -NUTRIENT STATUS AND DEVELOPMENT OF SITE
SPECIFIC ALTERNATIVE CRITERIA (SSAC)
The analysis conducted below was used to assess the water quality status of Clam Bay, with respect to
nutrients from the months of January through June 2021. Samples were collected monthly at each of the
nine sampling stations within Clam Bay itself. Additional water quality samples collected at stormwater
ponds and at the berm outfall are also discussed separately below. Maps of all sampling sites showing
water quality observations in Clam Bay are presented in Appendix B and maps of all sample locations
are presented in Appendix C, along with the stormwater basins upstream of Clam Bay. A total of 52
water quality samples were collected within Clam Bay itself for the analysis period covered in this report.
In comparison, 29 samples were collected monthly for five sites in the berm outfall sample locations and
61 samples were collected at 31 sites in the months of February and May in the stormwater pond sample
locations. Water quality monitoring results from Clam Bay and its watershed were provided by Collier
County. Water quality samples were collected by County staff. County staff submitted some analytes
submitted to Pace Laboratories for lab analysis.
FDEP adopted Site Specific Alternative Criteria (SSAC) for Clam Bay, as listed in 62-302.532, F.A.C.
Prior research conducted in Clam Bay had determined that both TN and TP need to be considered in
evaluating nutrient conditions in Bay waters as well as for predicting the amount of phytoplankton that
may result from higher nutrient levels. Chapter 62-302.531, F.A.C. states that waterbody nutrient status
shall be determined on an annual basis, preferably for a calendar year; however, this report only covers
samples collected for the first six months of 2021. A subsequent report to be compiled in early 2022
will complete the evaluation of nutrient status results for calendar year 2021.
The SSAC for Clam Bay is written as follows:
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Agenda item #5a
Page 7 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
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 equations below are used to determine the upper limits of TP and TN concentrations noted above for
Clam Bay, as shown in Equations 1 and 2, respectively:
Equation 1: TP Upper Limit (mg/L) = e(-1.06256-0.0000a2a465•conducev¢y/usq)
Equation 2: TN Upper Limit (mg/L) = 2.3601— 0.0000268325*Conductivity (pS)
TN and TP concentrations were compared to the calculated upper limit thresholds to determine if TP or
TN concentrations exceeded the designated upper limits as determined from the equations above for
samples collected between January and June 2021. Information obtained from field data forms was used
to aid in calculation of exceedances where appropriate (e.g., conductivity readings).
The values of TN and TP collected throughout an entire year (only 6 months of data are presented here
per the scope of this assignment) are compared to the Upper Limits (formally known as the "9011
Percentile Protection Limit") calculated as in the equations above using salinity/conductivity of the sample
location. These upper limits are numbers that FDEP has determined are upper limits of concentrations
that cannot be exceeded in order to protect the biological integrity of Clam Bay.
2.2 RESULTS - NUTRIENT STATUS
Throughout the analysis period discussed in this report (January through June 2021), no TN
measurements exceeded the calculated TN upper limit. Comparatively, 28 TP samples (52 percent of
total samples) exceeded the calculated upper limit criteria, although only 2 of the 28 samples exceeded
the criteria by more than 5 percent. These results indicate that TN does not exceed NNC thresholds for
Clam Bay. However, TP values collected for the first 6 months of 2021 do exceed NNC thresholds (28 of
52 samples, or 54%), well in excess than the allowable 10% exceedance rate to the point where Clam
Bay would be determined to be impaired for TP, if these data represented an entire year of data as
specified by 62-302.531, F.A.C. Given that the TP exceedance rate was lower in 2020 than in previous
years, and is lower comparable to the first half of 2021, it seems unlikely that the cause is still residual
effects of impacts and restoration efforts from Hurricane Irma as was often cited in the ESA 2020 Annual
Report (Appendix A). The data presented here are for an incomplete year and it is expected that the final
eport to be presented in early 2022 will provide a complete overall evaluation for a full year of 2021 data
collected for Clam Bay.
While it is beyond the scope of this report to evaluate data collected in previous years, in order to be
consistent with previous years' reporting format, Tables 1 and 2 presented below are replicated from the
ESA 2021 report and provide a visual summary of NNC exceedances for TP and TN , respectively, from
March 2015 through June 2020, with January through June 2021 samples added to the end of each table,
It should be noted that data collected prior to January 2021 were analyzed by previous authors and have
not been re -analyzed for this report.
ral
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ggenda Item #5a
Page 8 of 30
CLAM BAY WATER QUALITY ANALYSIS - TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
Table 1. Representation of frequency of impairment for TP for different site and date
combinations. Green represents samples in compliance with criteria. Red cells indicate
exceedance of criteria. Red cells with an "X" represent values that are within 5 % of criteria
concentrations, suggesting lack of compliance should be interpreted with caution, due to
analytical precision. Clear cells represent a lack of data.
Sampling Station
Event (yr-
month) 1 2
3
4
5
6
7
8
9
15-Mar
15-Mar
15-Apr
Ell
— -
15-May
15-Jun
15-J u l
15-Aug
15-Sep
15-Oct
15-Nov
rr
15-Dec
16-Jan
16-Feb
16-Mar
16-Apr
16-May
16-Jun
16-Jul
16-Aug
16-Sep
IL
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Agenda item #5a
Page 9 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
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Agenda item #5a
Page 10 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
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Agenda item #5a
Page 11 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
Table 2. Representation of frequency of impairment for TN for different site and date
combinations. Green represents samples in compliance with criteria. Red cells indicate
exceedance of criteria. Red cells with an "X" represent values that are within 5 % of criteria
concentrations, suggesting lack of compliance should be interpreted with caution, due to
analytical precision. Clear cells represent a lack of data.
Sampling Station
Event
1
2
3
4
5
6
7
8
9
15-Mar
15-Mar
15-Apr
15-May
15-Jun
15-Jul
15-Aug
15-Sep
15-Oct
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Agenda item #5a
Page 12 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
Sampling Station
Event
1
2
3
4
5 6
7
8
9
15-Nov
15-Dec
-
16-Jan
16-Feb
16-Mar
16-Apr
16-May
16-Jun
16-Jul
16-Aug
16-Sep
—
_, -.
16-Oct
-
16-Nov
16-Dec
17-Jan
— —
17-Fe b
17-Mar
17-Apr
17-May
17-Jun
17-Jul
17-Aug
17-Sep
17-Oct
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Agenda item #5a
Page 13 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
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Agenda Item #5a
Page 14 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
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2.3 CLAM BAY RESULTS -DISSOLVED OXYGEN
Dissolved oxygen (DO) saturation percentages, calculated using temperature and DO concentrations, as
related to minimum criteria are also presented below. As used in previous reports (including Appendix
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Agenda item #5a
Page 15 of 30
CLAM BAY WATER QUALITY ANALYSIS - TECHNICAL MEMORANDUM
Clam Bay Nutrient Status
A), a standard of 42% saturation percent is used to determine whether the samples are meeting criteria
for Class 11 waters. Overall, 6% of samples fell slightly below the 42% saturation criteria (Table 3).
Table 3 -Dissolved oxygen saturation values (%) at sites Clam Bay 1 to 9. Highlighted values fall
below the established standard criteria for Class II waters (42 % saturation) as used in previous
reports analyzing this data.
Station
Date
1
2
3
4
5
6
7
8
9
21-Jan
60A
61.0
57.8
58.2
80.1
86.9
98A
90.9
50.3
21Jan
84.8
61.4
80A
76.8
83.7
84.0
82.6
84.9
76.9
21-Feb
83.2
60.9
76.2
79.3
87.0
89.1
91.9
80.0
81.5
21-Mar
45.9
40.1
51.8
74
81.1
83.1
77.9
71.4
70.8
21-Apr
65.0
40.0
32.8
63.1
76.3
90.3
96.7
93.7
67.9
21-May
60.1
43.9
62.5
83.1
94.5
84.2
91.1
81A
67.1
21-Jun
81.3
33.7
66.7
53.6
74.6
85.8
77.9
92.9
72.9
2.4 CLAM BAY RESULTS -COMPARISON OF NUTRIENTS TO
DISSOVLED OXYGEN SATURATION AND CHLOROPHYLL -A
CONCENTRATIONS
The following is a summary of correlation coefficient (r2) data analyzed to determine whether relationships
exist between nutrients and DO percent saturation of chlorophyll -a concentrations in Clam Bay. Please
note that an rz value should generally be approximately 0.7 or higher to indicate a relationship between
the two analyzed factors.
• There is no correlation between TN and DO (rz = -0.41)
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Agenda item #5a
Page 16 of 30
CLAM BAY WATER QUALITY ANALYSIS - TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
• There is no correlation between TP and DO (r2 = -0.32)
• There is no distinguishable correlation between TN and Chlorophyll -a (rz = 0.55); knowledge of
the depth of sample collection compared to depth at the site would assist in further interpreting
these results as chlorophyll -a may be stratified near the upper portion of the water column to
collect the most sunlight.
• There is no correlation between TP and Chlorophyll -a (rz = 0.35)
2.5 CLAM BAY RESULTS -COPPER
The water quality standard for copper in marine waters is 3.7 Ng/L, although the impaired waters rule
allow for a certain number of exceedances before a waterbody is considered to be out of compliance with
this standard. Table 4 below indicates the copper data collected for the Clam Bay sites for the first 6
months of 2021. Based on information presented in Table 3 of Chapter 52-303 and the number of
samples collected, at least 9 samples would need to exceed the water quality criteria for the waterbody to
be listed as verified impaired for the January to June 2021 sample period. Because only 5 samples
exceeded the 3.7 Ng/L threshold, Clam Bay would not be considered impaired based on results of
samples collected in the first 6 months of 2021.
Table
4 -Copper
values at sites Clam
Bay 1 to 9
(vg/L).
Values highlighted
in yellow exceed the
3.7 ug
Cu
/ L copper criteria for Class
II waters.
Station
Jan
Feb
Mar
Air
Mav
Jun
Mean
Median
N
# > 3.7
3.7
1
2.9
3.5
2,43
3,89
6,58
3,04
3.72
3,27
12
2
17
2
2.89
2.13
6.38
3,85
5.3
2,79
3,89
3,37
12
3
25
3
2,35
3,05
2,24
3.02
3,69
2,18
2,76
2,685
12
0
0
4
1,95
1,82
1.2
2,12
1.2
1,75
1.67
1.785
12
0
0
5
1.2
1.2
1.2
1.53
1.2
1,67
1,33
1.2
12
0
0
6
1.2
1.2
1.2
1.81
2,05
1,47
1,49
1.335
12
0
0
7
1.2
1.2
1.2
2 .11
2,57
2,03
1,72
1,615
12
0
0
8
1.51
1.32
1.2
3A
2,54
1,65
1,89
1,58
12
0
0
9
1.23
1.2
1.2
2,03
1,34
1,73
1,46
1,285
12
0
0
3.0 STORMWATER POND WATER QUALITY DATA
As described in detail in the ESA 2020 Annual Report (Appendix A), while Stormwater ponds and other
upstream sources of pollutants may not be assigned their own upper limits for nutrients and other
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Agenda item #5a
Page 17 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
pollutants, these features may be assigned Downstream Protection Values (DPV). To briefly summarize,
the outfall nutrient and copper concentrations are generally expected to be higher than found in the bay
iItself; however, there is an upper limit to how much higher these concentrations can be before they are
expected to have an adverse impact on water quality in the bay. DPVs were set for berm outfall sites
(Section 4.0) but are also used for the stormwater pond sites in this section for comparison purposes.
There are two DPV values for each parameter (TN and TP), one of which would be expected to be
exceeded 50 percent of the time (50'h percentile) and one of which would be expected to be exceeded
only 10 percent of the time (901h percentile). Therefore, while water quality upstream of the bay cannot be
evaluated based on SSAC set for the bay itself, these DPV numbers can indicate whether the water
discharging from stormwater ponds may be expected to have an adverse impact on the bay. This
evaluation primarily applies to water outfalling from the berm samples sites discussed in Section 4.0
below. DPVs for berm outfall sites for TP have been proposed as 0,10 mg/L and 0,25 mg/L for the 501,
and 90th percentiles, respectively (Table 5), DPVs for TN have been proposed as 1,31 mg/L for the 501h
percentile and 1.80 mg/L for the 90'h percentile, respectively (Table 6).
Stormwater Pond TP and TN results are compared to their respective proposed DPV values (PBS&J
2011 — see Appendix A). Values exceeding the 501h percentile are highlighted in red below. Data from
January to June 2021 is shown in each table. DPVs for TP have been proposed as 0.10 mg/L and 0.25
mg/L for the 501h and 90'h percentiles, respectively (Table 5), DPVs for TN have been proposed as 1,31
mg/L for the 500, percentile and 1.80 mg/L for the 90'h percentile, respectively (Table 6).
3.1 STORMWATER POND RESULTS - TP
Table 5 —Stormwater Pond TP concentration results compared to DPVs. Values exceeding the 50'h
percentile (0.10 mg/L) are highlighted in in red below.
Location
Date
Result mt;/L
1-5_REGISTRY_S
21-Feb
1-6_Heron
21-Feb
0,039
1-4
CRAYTON
21-Feb
0,058
2-1_RIDGEWD_PK
21-Feb
0,056
2-2
GEORGE N
21-Feb
2-6_LUGANO
21-Feb
0,072
3-1
LAUREL OAK
21-Feb
3-5_INTERLOCHEN
21-Feb
5-1—HAMMOCK—OAK
21-Feb
5-2
L AMBIANCE
21-Feb
5-5_BREAKWATR_S
21-Feb
0,092
5-7
B COLONY EN
21-Feb
0,059
5-8
B COLONY WN
21-Feb
0.077
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Agenda item #5a
Page 18 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date Result ms/L
RC_MAIN
21-Feb
21-Feb
0.098
5-10_VIZCAYA
2-4_CLUB_4
0.093
2-3
GEORGE W
E21Feb
3-9_CLUB_9
3-4_PELICAN_9
4-2_BAY_2
0.034
4-4
BAY 4
21-Feb
4-7_PELICAN_6
21-Feb
0.086
4-10 PELICAN 3
21-Feb
1-3_MJ
D
21-Feb
0.095
2-5
CLUB 7
21-Feb
0.08
3-6_VALENCIA
21-Feb
4-8_COCO_BAY
21-Feb
4-6
CRESCENT
21-Feb
0.086
6-2
REMINGTON
21-Feb
2-2
GEORGE N
21-Feb
1-6_Heron
21-May
0.047
1-4
CRAYTON
21-May
0.063
1-3_MJD
21-May
0.056
1-5
REGISTRY S
21-May
2-1
RIDGEWD_PK
21-May
2-2_GEORGE_N
21-May
0.097
2-3
GEORGE W
21-May
0.094
2-4_CLUB_4
21-May
21-May
0.09
2-5_CLUB_7
RC_MAIN
21-1vlay
21-May
0.035
2-6—LUGANO
3-1_LAU
REL_OAK
21-1vlay
3-6_VALENCIA
21-May
3-5_INTERLOCHEN
21-1vlay
3-4_13ELICAN_9
21-May
3-81P
EUCAN_1
21-May
0.095
3-9_CLUB_9
21-May
4-2_13AY_2
21-May
0.022
4-413AY4
21-May
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Agenda item #5a
Page 19 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date
Result me/L
4-6_CRESCENT
21-May
0.062
4-7_PELICAN_6
21-May
0.043
4-8_COCO_BAY
21-May
4-10_PELICAN_3
21-May
5-1 HAMMOCK_OAK
21-May
0.067
5-2 L AMBIANCE
21-May
0.099
5-5_BREAKWATR_S
21-May
0.053
5-7_B_COLONY_EN
21-May
0.04
5-8_B_COLONY WN
21-May
0.045
5-10_VIZCAYA
21-May
0.083
6-2_11EMI11GTO14
21-May
3.2 STORMWATER POND RESULTS - TN
Table 6 —Stormwater Pond TN concentration results compared to DPVs. Values exceeding
the 50th percentile 11.31 m9yL) are highlighted in in red below.
Location
Date
Result ms/L
1-5_REGISTRY_S
21-Feb
1-6—Heron
21-Feb
1-4 CRAYTON
21-Feb
2-1 RIDGEWD_PK
21-Feb
On
2-2_GEORGE_N
21-Feb
2-6_LUGANO
21-Feb
3-1 LAUREL OAK
21-Feb
3-5 INTERLOCHEN
21-Feb
5-1_HAM MOCK_OAK
21-Feb
0.63
5-2 L AMBIANCE
21-Feb
0.683
5-5_BREAKWATR_S
21-Feb
0.75
5-7 B COLONY EN
21-Feb
0.823
5-8_B_COLO NY_W N
21-Feb
0.873
RC_MAI N
21-Feb
6
5-10_VIZCAYA
21-Feb
0,683
2-4 CLUB 4
21-Feb
2-3 GEORGE W
21-Feb
3-9 CLUB 9
21-Feb
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F�genda Item #5a
Page 20 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date Result mg/L
3-4_PELICAN_9
b
4-2_BAY_2
b
4-4
BAY 4
b
221-Feb
4-7_PELICAN_6
4-10_PELICAN_3
21-Feb
1-3_MJ
D
21-Feb
1.069
2-5_CLUB_7
21-Feb
3-6
VALENCIA
21-Feb
21-Feb
0.863
4-8_COCO_BAY
4-6
CRESCENT
21-Feb
0.761
6-2_REM
I NGTO N
21-Feb
0.546
2-2_GEORGE_N
21-Feb
1-6_Heron
21-May
1-4_CRAYTON
21-May
1-3_MJD
21-May
1.023
1-5
REGISTRY S
21-May
0.917
2-1
RIDGEWD_PK
21-May
1.111
2-2—GEORGE.N
21-May
2-3_GEORGE_W
21-May
21-May
2-4—CLUB-4
2-5_CLU
B_7
21-May
1.004
RC —MAIN
21-May
2-6_LUGANO
21-May
0.572
3-1_LAUREL_OAK
21-May
0.8
3-6.VALENCIA
21-May
0.83
3-5_INTERLOCHEN
21-May
0.843
3-4—PELICAN.9
21-May
3-8—PELICAN-1
21-May
3-9_CLU
B_9
21-May
4-2_13AY-2
21-May
0.486
4-4-13AY_4
21-May
4-6
CRESCENT
21-May
0.974
4-7_13ELICAN_6
21-May
4-8_COCO_BAY
21-May
1.13
4-10_PELICAN.3
21-May
5-1_HAMMOCK_OAK
21-May
0.709
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Agenda Item #5a
Page 21 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
stormwater Pond Water Quality Data
Location
Date
Result mg/L
5-2_L_AM BIAN CE
21-May
1,041
5-5_BREAKWATR_S
21-May
0,682
5-7_B_COLONY_EN
21-May
0,922
5-8_B_COLONY—W N
21-May
1,241
5-10_VIZCAYA
21-May
6-2_RE M I NGTO N
21-May
3.3 STORMWATER POND RESULTS - DO
Table 7 below indicates DO percent saturation measurements for stormwater ponds upstream of Clam
Bay. High levels of DO saturation (e.g., above 90-100%) are likely indicative of algal blooms occurring in
the ponds, which in turn is indicative of high nutrient levels in the ponds. Overall, the majority of the
sample locations on the two sampling dates had high enough DO percent saturation to suggest the
presence of algal blooms in the stormwater ponds.
Table 7 —Dissolved
oxygen saturation in
stormwater ponds
for data available between January
and June
2021 (February and May 2021).
Location
Date
Result % DO SAT
1-6 Heron
21-Feb
93.1
1-4 CRAYTON
21-Feb
94.6
1-3 MJD
21-Feb
124.3
1-5 REGISTRY S
21-Feb
79,9
2-1_RIDGEWD_PK
21-Feb
83
2-2 GEORGE N
21-Feb
941
2-3_GEORGE_W
21-Feb
123.2
2-4 CLUB 4
21-Feb
77.1
2-5_CLU B_7
21-Feb
71.7
RC MAIN
21-Feb
93.7
2-6_LUGANO
21-Feb
118A
3-1 LAUREL OAK
21-Feb
103.8
3-6 VALENCIA
21-Feb
86,8
3-5_INTERLOCHEN
21-Feb
53A
3-4 PELICAN 9
21-Feb
74A
3-8_PELICAN_1
21-Feb
100.9
3-9 CLUB 9
21-Feb
71
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Agenda item #5a
Page 22 of 30
CLAM BAY WATER QUALITY ANALYSIS -TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date
Result % DO SAT
4-2
BAY 2
21-Feb
95.7
4-4-BAY-4
21-Feb
83.8
4-6_CRESCENT
21-Feb
106A
4-7-PELICAN-6
21-Feb
102.7
4-8
COCO BAY
21-Feb
112.9
4-10_PELICAN_3
21-Feb
BEA
5-1
HAMMOCK OAK
21-Feb
81.5
5-2_L_AM
BIAN CE
21-Feb
102.3
5-5
BREAKWATR S
21-Feb
97,4
5-7_B_COLONY_EN
21-Feb
105
5-8_B_COLONY_W
N
21-Feb
117.3
5-10_VIZCAYA
21-Feb
117.2
6-2
REMINGTON
21-Feb
50.3
RC -MAIN
-SITE
21-Feb
94A
1-6-Heron
21-May
113.5
1-4_CRAYTON
21-May
100.5
1-3_MJD
21-May
100
1-5_REGISTRY_S
21-May
24.2
2-1_RI
DG E W D_P K
21-May
85.8
2-2_GEORGE_N
21-May
118.5
2-3_GEORGE_W
21-May
80.2
2-4_CLU
B_4
21-May
66.8
2-5
CLUB, 7
21-May
86.9
RC -MAIN
21-May
85.1
2-6_LUGANO
21-May
110.2
3-1
LAUREL_OAK
21-May
108.4
3-6_VALENCIA
21-May
97.2
3-5
INTERLOCHEN
21-May
65A
3-4-PELICAN-9
21-May
119.1
3-8_
PELICAN .... 1
21-May
99.6
3-9-CLUB-9
21-May
93.2
4-2_BAY_2
21-May
99.5
4-4
BAY 4
21-May
171.3
4-6-CRESCENT
21-May
103.6
4-7_PELICAN_6
21-May
103.8
4-8
COCO BAY
21-May
93.1
J
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Agenda item #5a
Page 23 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date
Result % DO SAT
4-10_PELICAN_3
21-May
103
5-1 HAMMOCK OAK
21-May
84.2
5-2_L_AM BIAN CE
21-May
97.4
5-5_BREAKWATR_5
21-May
89.9
5-7_B_COLONY_EN
21-May
117.7
5-8_B_COLONY_W N
21-May
136
5-10_VIZCAYA
21-May
135.5
6-2 REMINGTON
21-May
44.7
3.4 STORMWATER POND RESULTS -COPPER
Stormwater ponds do not actually have assigned water quality criteria as they are not natural
waterbodies; however, knowledge of copper levels in the ponds can inform the potential for each pond to
contribute to copper levels in Clam Bay downstream.
Water quality criteria for copper in freshwater requires knowledge of hardness of the water and is
calculated'to determine the hardness -normalized copper criteria as follows:
Copper Standard (pg/L) = e(o.eanepnH}i.vozf
H =hardness in units of CaCOaIL; a =the base of the natural logarithm (approximately 2.718281)
Copper water quality data was collected quarterly in the stormwater ponds, in February and May, 2021..
at astormwater ponds do not have set upper limit criteria, the numeric criteria for state waters may
be used to determine where copper levels are high and may affect downstream Clam Bay. Also,
hardness data, which is required to determine the hardness -normalized copper criteria in freshwater, was
only collected in February; therefore, only data for February 2021 copper levels in the stormwater ponds
are presented in Table 8 below. Of the 30 samples represented, 77% would be considered to have high
copper concentrations given the hardness associated with each sample.
Table 8 —Copper levels in stormwater ponds upstream of Clam Bay. Cells highlighted in yellow
indicate copper levels that exceed freshwater water quality criteria based on the calculation above
(which criteria should be noted apply to freshwater but do not actually apply to stormwater
ponds). Highlighted cells are intended to indicate where copper levels in stormwater ponds are
considered relatively high compared to copper levels in Clam Bay and and may contribute to
increased copper levels in Clam Bay.
Location
Date
Cu L
1-6 Heron
Feb-21
38.8
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Agenda item #5a
Page 24 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Stormwater Pond Water Quality Data
Location
Date
Cu L
1-4 CRAYTON
Feb-21
42.8
1-3 MJD
Feb-21
24.1
1-5_REGISTRY_S
Feb-21
15
2-1_RIDGEWD_PK
Feb-21
14.7
2-2_GEORGE_N
Feb-21
40.5
2-3 GEORGE W
Feb-21
21.4
2-4_CLUB _4
Feb-21
34.3
2-5 CLUB 7
Feb-21
40.1
RC MAIN
Feb-21
4.12
2-6_LUGANO
Feb-21
5.83
3-1 LAUREL OAK
Feb-21
52
3-6 VALENCIA
Feb-21
138
3-5_INTERLOCHEN
Feb-21
848
3-4 PELICAN 9
Feb-21
25.3
3-8_PERLICAN_1
Feb-21
25.6
3-9—CLUB-9
Feb-21
65A
4-2_BAY _2
Feb-21
55.8
4-4_BAY_4
Feb-21
15
4-6_CRESCENT
Feb-21
43.6
4-7_PELICAN_6
Feb-21
20.4
4-8 COCO BAY
Feb-21
65
4-10 PELICAN 3
Feb-21
78.8
5-1 HAMMOCK OAK
Feb-21
26.4
5-2 L AMBIANCE
Feb-21
65.8
5-5_BREAKWATR_S
Feb-21
27.2
5-7 B COLONY EN
Feb-21
8.38
5-8_B_COLONY_WN
Feb-21
3.66
5-10_VIZCAYA
Feb-21
17.4
6-2 REMINGTON
Feb-21
2.05
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Pyenda item #5a
Page 25 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Clam Bay Berm Water Quality Data
4.0 CLAM BAY BERM WATER QUALITY DATA
4.1 NUTRIENT RESULTS -BERM DATA
As discussed in Section 3.0 above, while features such as stormwater ponds and other holding areas do
not have regulatory water quality standards , DPVs may be set for these features as a way to measure
whether discharges from the features are likely to have an adverse impact on receiving waters that do
have established water quality criteria. Table 9 below indicates the percentage of total samples collected
from the berm discharge outfall sites that exceed the 50th/median or 90th percentile DPV values during the
January to June 2021 sampling period, which Table 10 represents exceedances by site and date from
2015 through June 2021. While TN and TP discharging from berm outfall sites exceed the 50th percentile
DPV values at approximately the same rate, TP exceedances at the 90th percentile level occur more often
for TP than for TN, as reflected by the high number of TP exceedances in the bay itself compared to no
TN exceedances indicated in Clam Bay between January and June 2021. Relatively few TN exceedances
were indicated in prior years compared to frequent exceedances of TP concentration in the bay since
2015 (Tables 2 and 3); this is consistent with previous years' observations. As stated above, DPVs for
berm outfall sites for TP have been proposed as 0.10 mg/L and 0.25 mg/L for the 50th and 90th
percentiles, respectively (Table 5). DPVs for TN have been proposed as 1.31 mg/L for the 50th percentile
and 1.80 mg/L for the 90th percentile, respectively (Table 6).
Table 9. Percentage of TN or TP concentrations from berm outfall stations which exceeded the
median or 90th percentile DPV values between Januaryand June 2021.
Total Nitrogen
Total Phosphorus
Median
901h Percentile
Median
901h Percentile
Exceedance Rate (%)
48
6
51
16
Table 10. Representation of frequency of impairment for median TP DPV (0.10 mglL) for different
outfall site and date combinations. Green represents samples in below with median DPV value.
Red cells indicate exceedance of median DPV value. Grav cells represent a lack of data.
Date I Glenview I N-41 Pipe I N-Berm I N-Boardwalk I P-I1 1 PB-13 � St.
-1
bjv:122561active1225600152105_report_delivldata_2020_reporticlam_bay_water_quality—jan-jun_2021_20210910_final_drafLdocx 4.21
Agenda Item #5a
Page 26 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Clam Bay Berm Water Quality Data
bjv:122561aclive1225600152105_report_delivldala_2020_reporllclam_bay_water_qualityjanjun_2021_20210910_fnal_drafl.docx 4.22
Agenda item #5a
Page 27 of 30
CLAM BAY WATER QUALITY ANALYSIS - TECHNICAL MEMORANDUM
Clam Bay Berm Water Quality Data
bjv:@2561active1225600152105_report_delivldala_2020_repomclam_bay_water_qualityjan.jun 2021_20210g10_final_ mft.docx 4.23
Agenda item #5a
Page 28 of 30
CLAM BAY WATER QUALITY ANALYSIS —TECHNICAL MEMORANDUM
Clam Bay Berm Water Quality Data
Note: nanoevent that multiple outfall samples were taken within a given month at a specify location, cell color
indicates worsefindings.
4.2 DISSOLVED OXYGEN RESULTS -BERM DATA
Dissolved oxygen (DO) saturation data collected for berm outfall stations is presented here to provide an
overview of where DO levels might be low; however, there are no specific water quality standards for DO
n waters behind the berm. Given the overall high levels of DO in Clam Bay, as presented in Table 3
above, it does not appear that low DO percent saturation levels at the outfall stations, as shown in Table
11, are affecting Clam Bay.
Table 11. Percent DO saturation results for berm outfall stations from January through June 2021.
Date
Glenview
PB-11
St Lucia
PBA3
N Boardwalk
N Berm
January-21
27.5
63.9
52.5
53.7
81.4
February-21
12.4
22.6
22.6
57.2
March-21
19A
81.7
77.4
50.3
April-21
9.7
56.6
38.3
56.6
24A
50.7
May-21
9.7
81.1
26.0
7.7
12.9
35.4
June-21
Note: In
an event that multiple outfall
samples were taken within a given month at a
specify
location, cell color
indicates
worsefindings.
4.3 COPPER RESULTS -BERM DATA
As stated above, calculation of copper water quality criteria in freshwater must also consider hardness of
the waterbody the sample was collected from. With regard to the Clam Bay berm outfall stations data,
copper concentrations and hardness are only available for January, February and March and are
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Agenda item #5a
Page 29 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Conclusions and Recommendations
presented in Table 11 below. Hardness data could not be found for April, May and June and therefore
copper data for these months are not included here. Overall, 53 percent of the samples exceeded
calculated freshwater water quality standards for copper at the berm outfall stations discharging into Clam
Bay from January through March 2021.
Table 11. Copper concentrations in berm outfall stations from January to March 2021. Copper
levels exceeding freshwater copper water quality standards (as calculated per the equation in
Section 3.4 above) are highlighted in yellow.
Location
Date
Cu L
Glenview
1/13/2021
13
PB-11
1/13/2021
32.1
ST_LUCIA
1/13/2021
11.6
N_BERM
1/13/2021
20.2
N—BOARDWALK
1/13/2021
26.9
GLENVIEW
2/23/2021
9.61
ST_LUCIA
2/23/2021
5.85
N_BERM
2/23/2021
21.9
N_BOARDWALK
2/23/2021
10.3
Glenview
3/25/2021
16
PB-11
3/25/2021
23.5
N_BERM
3/25/2021
213
N BOARDWALK
3/25/2021
60.2
5.0 CONCLUSIONS AND RECOMMENDATIONS
Water quality collected from Clam Bay between January 2021 and June 2021 were analyzed to
determine whether the different regions of Clam Bay are currently in compliance with previously
established Numeric Nutrient Criteria (NNC) and established criteria for copper. Results indicate that 28.
of 52 Total Phosphorus (TP) values have exceeded established criteria in Clam Bay during the first six
months of 2021 and no Total Nitrogen (TN) concentration exceedances occurred during this time period.
Data presented here are compared to data analyzed by others as presented in reports submitted for
previous years dating back to 2015. These results are similar to those observed in previous years.
Samples also indicate that Clam Bay is currently in compliance with percent dissolved oxygen (DO)
saturation for saltwater sites as well as for copper concentrations found in saltwater sites.
A comparison of nutrient concentrations to percent DO saturation and to chlorophyll -a in Clam Bay do not
indicate that there is any significant relationship between the parameters.
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Agenda item #5a
Page 30 of 30
CLAM BAY WATER QUALITY ANALYSIS — TECHNICAL MEMORANDUM
Conclusions and Recommendations
Overall, it appears that nutrient and copper levels are still high in stormwater ponds, possibly bound in
sediments that may be resuspended to release nutrients and copper during storm events.
Recommendations to address these high nutrient and copper levels, which also appear to be causing
algal blooms, include consideration of dredging stormwater ponds, planting wetland vegetation in ponds
to be periodically harvested to remove nutrients and possibly copper, use of alum to treat phosphorus
not generally recommended upstream of sensitive waters), use of media filters to remove copper from
outfall water, or constructed treatment wetlands. Aeration of stormwater ponds can also reduce TN
concentrations, reducing the growth of algae, though aeration would not treat TP or copper. All of these
options depend on the availability of funds and most options require some uplands in which to implement
the listed options.
The most probable cause of high levels of TN, TP and Copper are historic uses of fertilizers and
algicides. Nutrients and metals can become bound in the sediments of stormwater ponds and re-released
when sediments are disturbed, such as after a storm event. Resuspension of sediments can cause new
releases of contaminants for many years after contaminant inputs cease. The collection depth of samples
should also be recorded because this can affect results; generally samples should be collected from the
middle of the water column for greatest accuracy.
J
biv:122561active1225600152105_report_delivldata_2020_reporllclam_bay_water_quality-janjun_2021_20210910_Flnal_draftdocx 5.26
Agenda item #5a-1
Page 1 of 1
Clam Bay Copper ug/L
Collection Date
CBl
CB2
CB3
CB4
CB5
CB6
CB7
CB8
C89
Report Date
6/22/2016
0.862
0.700
0,700
0.700
1.640
2100
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
1/22/2019
12/12/2017
1.780
2.250
1,890
0,700
L210
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
L720
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
L600
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
10/21/2019
1.870
2.120
1.950
1.450
1.430
1.600
1.600
1.600
1.600
1/13/2020
11/19/2019
1.400
1.600
1.600
1.600
1.600
1.600
1,600
1.600
1.600
1/13/2020
12/16/2019
3.030
3.940
2.310
1.810
1.600
1.600
1.600
1.600
1.600
1/13/2020
1/16/2020
5.090
2.710
2.000
1.670
1.600
1.600
1.600
1.600
1.600
4/14/2020
2/12/2020
2.430
3.580
4.270
2.160
1.600
1.600
2.690
1.600
1.600
4/14/2020
3/2/2020
3.170
4,260
2,080
1.600
1.600
1.600
2.870
1.600
0.200
4/14/2020
4/22/2020
3.040
2.090
1.700
2.000
1.200
1,200
1,450
1,210
1.200
7/29/2020
5/28/2020
2.530
1.870
1.410
1.590
1,200
L200
1.200
1.200
1.200
7/29/2020
6/11/2020
2.640
2,640
2.140
2.350
1.050
1.050
1.050
1.050
1.050
7/29/2020
7/27/2020
3.220
2.290
1.410
1.200
1.200
1.200
1.200
1,200
1.200
10/12/2020
8/26/2020
1.350
1.840
1,200
1.200
1.200
1.200
1.270
1.200
1.200
10/12/2020
9/8/2020
2.010
2.080
1.910
1.630
1.200
2.000
1.310
1.200
1.500
10/12/2020
10/7/2020
2.120
1.670
1.150
1.270
1.050
1,050
1,050
1.050
1,050
2/7/2021
11/23/2020
1.530
1.540
1.470
1.200
1.200
1.050
1.100
1.050
1.240
2/7/2021
12/8/2020
3.700
5.820
6.340
4.890
3.140
3,990
4,420
2.940
3,580
2/7/2021
1/4/2021
2.900
2.890
2,350
1,950
1.200
1.200
1.200
1.510
1.230
4/30/2021
2/4/2021
3.500
3.050
2.130
1.820
1.200
1.200
1.200
1,320
1.200
4/30/2021
3/17/2021
2.430
6,380
2.240
1,200
1.200
1.20D
1.200
1.200
1.200
4/30/2021
4/1/2021
3,890
3.850
3.020
2120
1.530
1.810
2.110
3.100
2.030
7/15/2021
5/18/2021
6.580
5.300
3.690
1.200
1.200
2.050
2,570
2,540
1,340
7/15/2021
6/14/2021
3.040
2.790
2.180
1,750
1.670
1.470
2.030
1.650
1.730
7/15/2021
7/27/2021
2,050
2,350
1,650
1.540
1.090
1.200
1.940
1.050
1.200
10/11/2021
8/23/2021
2.500
1.890
1.400
1,350
1,180
1,050
1.170
1.050
1.050
10/11/2021
9/14/2021
2.380
1,410
1.270
0.976
1.050
1.050
Lose
1.050
1.050
10/11/2021
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Agenda item #7c
Panty 1 of I
PHASE 1
oaY
PHASE 2
PHASE 3
r
Agenda item #7c
Page 3 of 3
On Jun m, 2021, at 1:50 PI, Jacobusa<Lisa vbbmcoiliercountvfl.gove
wrote: '
llear Clam Bay Committee:
Here are the bid taU resulfs for Requests for Quotes for
Phase I Scaevola Eradication & Beach Dune Repiantings; and
2021 Clam Pass Maintenance
ICE .� wu. •• .� - �♦i'wi♦
'i 1M
11
_1 iiil• ,
RMA ♦�u-�
i�: �It
Owl
IM
A Purchase Order ui tUe amount of $G8,400 was issued to Earth Tech
Environmental.
The Foundation will reimbUrse PBSD $12,700 for work being done on
Foundation property.