CLAM PASS ANNUAL RESTORATION & MANAGEMENT PLAN TIDAL ANALYSIS ELEMENT REPORT NO. 13

Transcription

1 CLAM PASS ANNUAL RESTORATION & MANAGEMENT PLAN TIDAL ANALYSIS ELEMENT REPORT NO. 13 Submitted to: Pelican Bay Services Division Prepared by: Humiston & Moore Engineers H&M File No November 2012 Main Office : 5679 Strand Court Naples, FL Phone Fax

2 CLAM PASS ANNUAL RESTORATION & MANAGEMENT PLAN TIDAL ANALYSIS ELEMENT REPORT NO. 13 HUMISTON & MOORE ENGINEERS H&M FILE NO November 2012 Table of Contents 1. Summary a. Recent Significant Changes Background Tide Phase Lag Tide Range Conclusions and Recommendations Channel Entrance Width Recommendations for Ongoing Monitoring References...16 List of Figures Figure 1: Gage Locations... 4 Figure 2: Low Tide Phase Lag... 6 Figure 3: High Tide Phase Lag... 7 Figure 4: Low Tide Phase Lag Annual Averages... 9 Figure 5: High Tide Phase Lag Annual Averages...10 Figure 6: Tidal Ranges...11 Figure 7: Tidal Ranges Annual Averages...13 Figure 8: Low Tide Phase Lag vs Pre-Dredge Conditions...14

3 CLAM PASS ANNUAL RESTORATION & MANAGEMENT PLAN TIDAL ANALYSIS ELEMENT REPORT NO Summary Analysis of tidal data has previously been presented in annual monitoring reports that also included analysis of changes in the bathymetry of the waterway and the beach shoreline. Bathymetric changes in channel shoals and tidal analysis both provide information that is useful in determining when maintenance dredging of the inlet should be considered in order to maintain flushing. Beginning three years ago there was a change in County policy and this tidal analysis is now being provided as a separate report from the bathymetric and beach monitoring. For a history of the comprehensive bathymetric, beach, and tidal monitoring, see Clam Pass Restoration and Management Plan Bathymetric Monitoring, Reports #1 through #9, 2000 through 2008, prepared for the Pelican Bay Services Division (PBSD) by Humiston & Moore Engineers (H&M). This is the fourth monitoring report that is limited to the tidal analysis only. For information on bathymetric monitoring refer to the separate County reports. The Clam Pass Restoration and Management Plan was implemented in 1999 to improve flushing of the Clam Bay system and the surrounding 570 acre mangrove preserve. A part of the management plan was to dredge portions of the flood tidal shoal and some of the interior waterways to improve the hydraulic efficiency of the inlet and increase the tidal prism, which is the volume of water exchanged through the inlet on each half tidal cycle. The improved tidal prism means more water goes in and out of Clam Pass on each tidal cycle, and this larger volume of water generates stronger currents in the inlet. Those stronger tidal currents are capable of scouring sand from the channel to help keep the inlet open and maintain the flushing improvements. Since the 1999 dredging, as shown in the annual Clam Pass Restoration and Management Plan Reports #1 through #9, implementation of the dredging element of the Clam Bay Restoration and Management Plan has significantly improved tidal exchange throughout the bay system. The maintenance dredging of the flood shoals in January 2002 was shown to be beneficial in maintaining the improved tidal flushing. In order to maintain the improved tidal exchange, based in part on the results of the tidal monitoring, the 2006 monitoring report recommended dredging of the entrance of the pass, and a portion of the flood shoal. That dredging was completed during the winter of The County has submitted an application to dredge the pass in the near future. The limits of the currently proposed dredging are the same as the limits dredged for the 2007 maintenance. The proposed placement of the dredged material, however differs from the 2007 project in two ways. The County is seeking to place fill on both the north and south side of the inlet, including infilling of the meandering channel entrance on the north side of the entrance dredge cut. 1

4 1a. Recent Significant Changes The previous annual monitoring report indicated that there was evidence of shoaling that was restricting flow at the inlet, however, not to the extent that was used to justify each of the two previous maintenance dredging efforts. However, the most recent tide data indicates that recent storm events have resulted in the most severe restriction to tidal flow that has occurred since implementation of the Restoration and Management Plan in Over the past year the Clam Pass System has been affected by two tropical systems, Tropical Storm Debby in late June and Tropical System Isaac in late August. These two systems sent large waves to the coastline and caused significant beach erosion, caused shoals to shift including formation of the spit at the entrance of Clam Pass which migrated north, and possibly caused an influx of sand to the interior shoals. It is the accumulation of sand in the interior shoals that causes shoaling that the inlet tides are unable to scour from the channel, and this therefore is the accumulation that makes dredging necessary. After the passing of these two systems, the data reflected a decline in tidal flushing within the Clam Pass system, indicating a strong possibility that sand did accumulate in the shoals along the interior portions of the channel. This decline in flushing indicates that there is extensive shoaling that is restricting flow between the Gulf of Mexico and the interior waterways of Clam Pass. The extent and location of the flow restriction would dictate the necessity to dredge. A small restriction located near the entrance to the inlet could cause temporary reduction in flushing, but overall the system could naturally recover through self scouring, which would restore adequate flushing. This has happened in the past. If the restriction is more extensive and extends far into the interior flood shoals, it would likely require a dredging to restore the flushing, which seems to be representative of the current condition. Although a hydrographic survey is required to determine the exact location and extents of the shoaling, the degree of restriction to flow demonstrated through analysis of the tide data indicates it is quite likely that dredging is necessary. Furthermore, it has been 5 years since the previous dredging which is consistent with previous maintenance intervals of 4 to 5 years. The maintenance dredging interval, however, remains very much dependent on weather events that occur between maintenance dredging events. This is why it is always recommended that the tide data presented in this report be considered in conjunction with hydrographic data in evaluating the need for maintenance dredging. 2. Background Prior to the commencement of the March 1999 dredging, water level recording gages were installed at selected locations within the Clam Bay estuarine system and Gulf of Mexico to measure tidal ranges. Tides along the southwest Florida coast are mixed, meaning that they exhibit either diurnal (one tide per day) or semidiurnal (two tides per day) characteristics at different times during each month, primarily dependant on the phase of the lunar cycle. There are seasonal variations as well. Pre-construction tidal data were collected for a full month to obtain average values representative of the general tidal characteristics for Clam Bay, and to establish baseline conditions against which post construction monitoring data could be measured to quantify improvements to tidal flow. The 2

5 locations of the gages are illustrated in Figure 1 1. This tidal monitoring program has been implemented through a cooperative effort with tidal data collection by PBSD, and data analysis and report preparation provided by H&M. Considering the mixed tide characteristics of this area is important for the tidal data analysis, because during the neap tide part of the month when tidal currents are not particularly strong, the inlet may take on wave dominant characteristics and appear to be shoaling near the entrance, particularly if the neap tide coincides with high wave energy events. During the ensuing spring tide roughly two weeks later, however, tidal currents are considerably stronger and may efficiently scour out shoals that formed during the neap tide interval. Short term channel shoaling and scouring that occurs in this manner causes short term variations in phase lag and tidal range data. This process therefore explains much of what appears as scatter in the phase lag and tide range data. However, when shoals are scoured out of the inlet channel, some of that sand is deposited on the ebb shoal restoring it to the littoral system which is the sand supply for adjacent beaches; however, some of that sand becomes redistributed as net accumulation onto the broader interior flood shoals. It is this net accumulation on the flood shoals over a period of years that eventually leads to the need for maintenance dredging. The purpose of the monitoring program is to evaluate inlet characteristics on a comprehensive long term basis, with less emphasis on day to day, week to week changes, or even month to month and seasonal changes. Because of the dynamics of this system, the findings of this report provide a reliable evaluation of project performance which, at times, may not seem consistent with visual observation of inlet conditions over relatively short time intervals, particularly conditions that may be observed during or immediately after a storm. Although the short term dynamics of the system may explain data variability or scatter, this is most effectively verified when coincident bathymetric data is available to quantify short term shoal and scour patterns. However, with the exception of several surveys that were conducted to evaluate post storm conditions during years immediately following the 1999 dredging, bathymetric surveys are typically conducted on an annual basis whereas the tide data has been collected over intervals of several months, with as many as six data sets in a year. This provides only limited opportunities to verify short term changes in tidal data with bathymetric data that may be used to document short term shoaling patterns. The accuracy of the data has therefore been carefully considered with each monitoring event, particularly on occasions where data variability appeared to be beyond what might be considered normal and reasonable for this dynamic system, and quality control over the thirteen years of this monitoring program has included periodic recalibration of gages by the manufacturer when data scatter appeared to be inconsistent with reasonable ranges of variability. These fluctuations might also be better explained by more comprehensive data collection. This is why it has previously been recommended that redundancy be introduced into the tide gage data collection program. Deploying two gages at each location would also allow for verification of data, to provide confirmation that each gage was working properly during the data collection interval. This would reduce the potential, for example, of bio-fouling resulting in compromised data, which has been known to occur when bio-fouling of gage sensors has apparently contributed to inaccurate 1 The tide gage located at the north end of Outer Clam Bay is located on the boardwalk between the Waldorf Astoria Hotel and Clam Pass Beach Park. This was referred to as the Registry gage in previous reports, and that convention is maintained in this report for consistency. 3

6 UPPER CLAM BAY 0 600' 1200' AERIAL PHOTOGRAPH WAS TAKEN IN DECEMBER 2010 AND IS PROPERTY OF COLLIER COUNTY APPRAISER'S OFFICE INNER CLAM BAY CLAM BAY NOTES: 1. THE TIDE GAGE LOCATED AT THE NORTH END OF OUTER CLAM BAY IS LOCATED ON THE BOARDWALK BETWEEN THE WALDORF ASTORIA HOTEL AND CLAM PASS BEACH PARK. THIS WAS REFERRED TO AS THE REGISTRY GAGE IN PREVIOUS REPORTS, AND THAT CONVENTION IS MAINTAINED IN THIS REPORT FOR CONSISTENCY. 2. AERIAL PHOTOGRAPH WAS TAKEN DECEMBER 2010 AND IS PROPERTY OF COLLIER COUNTY APPRAISER'S OFFICE. OUTER CLAM BAY 4

7 pressure readings. Collecting redundant data is the practice of the National Oceanic and Atmospheric Administration (NOAA), which has installed two tide gages at the NOAA tide station on the Naples Pier. 3. Tide Phase Lag One of the parameters monitored during the tidal study is tidal phase lag. This is the time difference between the high or low tide in the Gulf of Mexico and the corresponding high or low tide in the bay. The magnitude of this phase lag is an important indicator of inlet dynamics, because shoaling in an inlet that obstructs tidal flow will cause the phase lag to increase. Figures 2 and 3 show a comparison of the tidal phase lag at high and low tide at three tide gage locations within the bay system. The figures show a comparison of tidal phase lags for the following; 1998 Preconstruction Dredging Improvement Post Construction Dredging Improvement to Recent Monitoring Interval to Recent Monitoring Interval to Recent Monitoring Interval to Recent Monitoring Interval to Recent Monitoring Interval to Recent Monitoring Interval Notes: 1) For the purpose of evaluating project performance, only the pre and post construction data from the original 1999 dredging are included for comparison to the most recently collected data. All of the tide data collected during the life of this project can be referenced through Clam Pass Restoration and Management Plan Bathymetric Monitoring Reports #1 thru #11. 2) The Registry and South tide gage pressure sensors malfunctioned during the to and to data collection intervals, thus no tide data are available from this tide gage location for this time data collection interval. Although for almost the entire monitoring period since the 1999 dredging, the phase lag has remained below the pre-improvement levels, Figure 2 indicates this has changed during the two most recent monitoring intervals. The low tide phase lag levels had an upward progression, similar to other post dredging monitoring, however, after until the passing of tropical system Isaac at which time the average phase lag times spiked and were at levels that actually exceeded the phase lag prior to the initial dredging improvements in This spike is mostly likely from the pass having a severe restriction within the channel system. Also unlike what has been seen in previous monitoring, the average phase lag has not corrected itself. This also suggests a more severe shoaling problem that will probably require dredging. The low tide phase lag has exceeded the 1998 pre-dredging conditions and indicates that the filling and draining of the bay occurs at a slower rate than before dredging due to high resistance to flow in the channel due to shoaling. 5

8 CLAM PASS MONITORING Low Tide Phase Lag 1998 Pre Dredge 1999 Post Dredge to to to to to to :00:00 3:00:00 Hours 2:00:00 1:00:00 0:00:00 No tide data collected to No tide data collected to Registry South North Gage Location Figure 2 6

9 1998 Pre Dredge 1999 Post Dredge to to to to CLAM PASS MONITORING High Tide Phase Lag to to :00:00 3:00:00 Hours 2:00:00 1:00:00 0:00:00 No tide data collected to No tide data collected to Registry South North Gage Location Figure 3 7

10 Figure 3 It should be noted that the high tide phase lag tends to be a little less sensitive to minor amounts of shoaling in comparison to the low tide phase lag, simply because the flow cross section is larger at high tide, and a restriction evident at low tide may not be evident at high tide. However, the recent data shows a similar increase in the high tide phase lag. While this illustrates the importance of evaluating both the low tide and high tide phase lags, the recent data also reinforces the conclusion that it is quite likely that there is an urgent need for dredging. Figures 4 & 5 show the phase lag annual averages since the last dredging event that took place in Averaging the individual data sets for each monitoring year reduces the scatter in the data and helps identify trends. Both of these figures show a general trend of increasing phase lag after dredging. This is to be expected as it is understood that sand will accumulate in the system. Since the rate of accumulation is highly dependent on weather events, this is why collecting tide data at frequent intervals, and hydrographic data annually at a minimum, is important. Post storm hydrographic surveys would also provide valuable information if storm characteristics resulted in extensive shoaling, especially shoaling at the interior channel. It is therefore expected that overall phase lag will show a trend of increasing, indicating gradual decrease in the efficiency of flushing. This is what is expected between maintenance dredging events, and by itself is not cause for concern. It is the magnitude and duration of increases in phase lag that are markers that may indicate the need for maintenance dredging. It is important to consider the high tide phase lag and tide range data, as discussed below, along with the hydrographic monitoring to optimize the scheduling of maintenance dredging. 4. Tide Range As with the tide phase lag, the tide range data can be used in the determination of when maintenance dredging may be needed. A decrease in the tide range in the bays is an indication that flow through the inlet is being obstructed by shoaling. The data presented in Figure 6 compares the tide range in Clam Pass to the Gulf of Mexico tide range, and generally show that during the most recent data intervals the tide range appears to be declining since the post 1999 dredging tide range. This is what should be expected because of the ongoing gradual accumulation of material in the flood shoal. The data also suggest that the tidal range data, as discussed above for the phase lag data, can be variable over short data intervals. In general, periods of higher tides, during the spring phase of the tidal cycle, will themselves produce greater bay tide ranges; however, they also result in strong tidal currents which typically scour shoals from the inlet. The system responds to this scour action with longer intermediate increases in the tidal range. This shows, as illustrated in Figure 6, that the 1999 dredging and maintenance enhanced the ability of the inlet to scour sand from the channel in this manner. The data from the North and Upper gages show a decrease in tide range, which may be an indication that more shoaling is occurring in the meandering interior channels that connect those bays to the inlet channel. However, the phase lag data do not consistently show similar effects. Inner and Upper Clam Bays are more remote from the inlet and water must flow through long and narrow meandering channels to reach those water bodies, and consequently they may be more influenced by wind driven currents in comparison to Clam Bay and Outer Clam Bay which are more directly connected to the 8

11 1998 Pre Dredge 1999 Post Dredge Average 2008 Average 2009 Average 2010 Average 2011 Average 2012 CLAM PASS MONITORING Low Tide Phase Lag Averages 3:00:00 2:00:00 Hours 1:00:00 0:00:00 Registry South North Gage Location Figure 4 9

12 1998 Pre Dredge 1999 Post Dredge Average 2008 Average 2009 Average 2010 Average 2011 Average 2012 CLAM PASS MONITORING High Tide Phase Lag Averages 3:00:00 2:00:00 Hours 1:00:00 0:00:00 Registry South North Gage Location Figure 5 10

13 CLAM BAY TIDAL RANGES Pre Dredge Range 1999 Post Dredge Range Range Range Range Range Range Range 1.50 Tide Range (FT) No tide data collected to No tide data collected to GULF REGISTRY SOUTH NORTH UPPER Gage Location Figure 6 11

14 inlet. Atmospheric conditions could easily cause what might appear to be inconsistencies between phase lag and tide range data, particularly for the bay areas farthest from the inlet. The degree to which shoaling may have occurred in the interior channels affecting Inner and Upper Clam Bays can be verified through bathymetric monitoring. However, previous monitoring has shown the shoaling rates in those interior channels to be low in comparison to the inlet channel, and the inner channels may therefore be surveyed on a less frequent basis to reduce survey costs, since change has already been documented to occur relatively slowly in comparison to the more dynamic areas close to the inlet entrance. The data from the North and Upper gages, give a relatively constant tide range from March to August followed by a decrease in tide range in September and October This is consistent with the phase lag data, which indicates shoaling is occurring. However, the most recent data collection interval, to , showed a significant decrease in tide range. Again, the degree to which shoaling may have occurred in the interior channels is also verified through bathymetric monitoring at four year intervals. Tide data were not collected in Upper Clam Bay prior to the 1999 dredging, so the change in tide range from the pre-dredging conditions for this area cannot be quantified. If it is determined that flushing of Upper Clam Bay needs further improvement, based on the health of the mangrove community or other environmental data, that could be achieved by straightening selected meandering sections of the interior waterways which connect Clam Bay with Inner Clam Bay and Upper Clam Bay, as discussed further in Section 5 below. Figure 7 is a presentation of the tide range data that averages all the data within each calendar year since the 2007 dredging. This longer term averaging smoothes the data scatter that is evident in Figure 6, and illustrates that the tide ranges in the bays remain significantly above the pre-1999 dredging, and are similar to the post-1999 dredging. This demonstrates that the 1999 restoration and management plan design is still working. However, the 2012 average values for the tide ranges in the bays are skewed to a higher value due to the fact that 75% of the data was collected prior to the storm events this past summer which have reduced the tidal flow in and out of the inlet. 5. Conclusions and Recommendations The most recent tidal data indicate tidal flushing of Clam Bay is actually not as good as it was prior to the initial dredging in Figure 8 shows a comparison between recently measured low tide phase lag to the low tide phase lag preceding the 2002 and 2007 dredging events. This shows that the low tide phase lag exceeded what it was prior to the 2002 maintenance dredging at all stations. Overall, this indicates that the system is not flushing as well as it was prior to each of the two previous maintenance dredging events, indicating that maintenance dredging may be necessary to maintain efficient flushing. However, it is always recommended that the hydrographic survey data be evaluated as part of the process to determine when to schedule maintenance dredging. This data can also be used to estimate the quantities of material that need to be dredged from each station along the channel. From an inlet flushing standpoint, inlet closure has not been a concern since the 1999 dredging. However, due to significant storm events in the last several months, flow 12

15 CLAM BAY TIDAL RANGES ANNUAL AVERAGES 1998 Pre-Dredge Range 1999 Post-Dredge Range 2008 Average 2009 Average 2010 Average 2011 Average 2012 Average TIDE RANGE (FT) GULF REGISTRY SOUTH NORTH UPPER GAGE LOCATION TIDE GAGES UNAVAILABLE UNTIL 2000 Figure 7 13

16 CLAM PASS MONITORING Low Tide Phase Lag vs. Pre-Dredge Conditions 1998 Pre-Dredge 2002-Pre Dredge 2007 Pre-Dredge Average 2008 Average 2009 Average 2010 Average 2011 Average to to to to to to :00:00 Legend Indicates 2002 Predredging Value Indicates 2007 Predredging Value 3:00:00 Hours 2:00:00 1:00:00 0:00:00 No tide data collected to No tide data collected to Registry South North Note: No tide data collected to Gage Location Figure 8 14

17 through the pass is less than it was prior to the 1999 dredging, and this is a condition that increases potential for inlet closure, a condition which occurred several times in the 1990s. Tidal data from this most recent monitoring interval confirms this. Sand from the maintenance dredging has in the past been used to re-nourish the beach at Clam Pass County Park to the south, as well as the Pelican Bay beach to the north, and beach conditions as well as bathymetric data have been considered in scheduling the two previous maintenance dredging projects. However, the most recent tide data indicate that dredging is probably needed to maintain the inlet regardless of the sand needs for beach renourishment. The tidal studies should therefore be continued as an integral part of the annual monitoring because they provide an excellent indication of when shoaling of the inlet and other channels has occurred to the extent that tidal circulation in the bay system has been adversely affected. Inconsistencies in tidal data have previously been treated as random scatter in the data when there is no coincident bathymetric data available to quantify short term changes in channel shoaling patterns because this scatter has for the most part been relatively small in comparison to the overall ranges in the various tidal criteria. However, the scatter makes it difficult to identify small changes that would occur in response to the gradual shoaling in the inlet and the interior channels. Additionally, over the fourteen years of monitoring since 1998, tide gage failures have occasionally left gaps in the data which preclude making comparisons between other gages and different periods of time. It has therefore been recommended that the tidal data collection program be expanded to include redundant data collection with duplicate gages at each tide station to reduce potential for gaps in the data resulting from gage malfunction. The additional gages also provide a means to verify data accuracy, in the event of bio-fouling of gage sensors, which has at times been a problem in the past. Although limited dredging in portions of the existing meandering channels between the four bays appears to have contributed to improving the flushing of Inner and Upper Clam Bay, tidal exchange remains relatively low at the north end of the system. If biological studies or water quality monitoring indicate further enhancement to flushing of the remote northern portion of the bay system is necessary, that may be accomplished by increasing the tidal prism through selectively improving sections of the meandering interior channels which connect the bays. This approach would necessitate removing small areas of existing mangroves. This would mean either deepening or straightening selected sections of channel, or a combination of the two. Although this might be perceived as a negative impact to the mangrove community in the immediate vicinity of the dredge cuts, this alternative could include restoration of mangroves within bypassed channel meanders. However, other implications of this action should be considered as well. Leaving the bypassed meanders as parallel channels would aid flushing; it may result in a beneficial increase in diversity of habitat as a branching channel system would leave sections of quieter deep water channel in addition to the higher flow velocity achieved in a shorter main channel. It would result in a net increase in total length of mangrove fringed channel shoreline. These considerations should be evaluated in objectively determining if this alternative would provide a net environmental benefit to the broader goal of managing the ecology of the bay system. 6. Channel Entrance Width. There has been much discussion about the optimum width of the entrance channel cut across the beach. It should be understood that there is a maximum width that can be supported by the tidal flow of the bay system. That tidal flow is 15

18 determined by the size of the bay. The size of the bay is in fact much larger at high tide than it is at low tide. This, and other variables such as the diurnal and semidiurnal tidal periods of the lunar cycle, and exactly where along the channel the equilibrium section occurs (in fact it moves), make determination of a precise width easier said than done. The success of previous dredging without impact to adjacent shorelines, as well as the apparent equilibrium cross section from previous monitoring between dredging events, are the best way to evaluate an appropriate width of cut. It should also be understood that cutting the entrance slightly larger than the equilibrium width is better than cutting it too small. If the cut is too small, tidal currents will scour it to a larger section, and some of that sand that is scoured from the entrance will be carried into the inner shoals on flood tide, hastening the need for the next dredging event. It is probably appropriate to continue dredging the cut to the same width that has been dredged in the past, as long as monitoring shows it does not impact adjacent beaches. Dredging the cut too wide will result in slow tidal currents because they are limited by the size of the bay. Slow tidal currents promote shoaling, and the shoaling will occur by the trapping of sand from the beach, potentially causing beach erosion. Slower tidal currents can also result in collapse of the ebb shoal onshore creating more restriction to flow, yet also potentially increasing sand supply to adjacent beaches. 7. Recommendations for Ongoing Monitoring. The dredging plan for Clam Pass was designed to improve flushing while minimizing the impact dredging might have on adjacent beaches. Dredging impacts to adjacent beaches typically occur at inlets with navigation maintenance dredging projects that interrupt natural littoral bypass of the inlet by cutting a navigation channel across the ebb shoal. Dredging of the ebb shoal at Clam Pass has always been minimized for this reason. Any proposed increase in the scope of dredging at Clam Pass should include a comprehensive monitoring plan to continue to evaluate effects on adjacent beaches. Tidal monitoring should continue as it has been demonstrated to provide an excellent indicator as to when tidal circulation is affected by inlet shoaling, and when maintenance dredging should be considered to maintain flushing of the Clam Bay system. The tidal data should continue to be used in conjunction with the bathymetric data in evaluating the need for dredging. Lastly, as discussed herein, the tide data shows how the dynamic system adjusts to varying weather and tide conditions. It is not recommended that a specific threshold value for the tidal data or cross sectional area be chosen to trigger dredging as a comprehensive evaluation of both data should be considered in making that determination. 8. References 1.) Humiston and Moore Engineers, Clam Pass Restoration and Management Plan Bathymetric Monitoring Reports 1 through 10, ) Pelican Bay Services Division, Tide Data, ) Florida Department of Environmental Protection Joint Coastal Permit No JC. 4.) NOAA Station Naples Pier - Naples, FL, Tide Gage Data,