HomeMy Public PortalAbout100_040_Watershed Protection Plan Final 102711
Tybee Island Watershed Protection Plan Submitted to GA DNR -GA EPD Watershed Protection Branch Watershed Planning and Monitoring Program 4220 International Parkway, Suite 101 Atlanta,
Georgia 30354 Prepared by Hussey, Gay, Bell & DeYoung, Inc. 329 Commercial Drive Savannah, Georgia 31406 October 2011 (Revised October 27, 2011)
i Section 1 Introduction ............................................................................................................1 1.1 Purpose ....................................................
.................................................................1 1.2 Background ..............................................................................................................1
Section 2 Legal Authority ......................................................................................................2 2.1 Political Jurisdiction...........................................
......................................................2 2.1.1 Local Governments and Agencies ...............................................................2 2.1.2 Local Zoning and Development
Agencies ...................................................2 2.1.3 Resources Available for Implementation .....................................................2 2.2. Code and Regulation
Evaluation .............................................................................2 2.2.1 Ordinances ............................................................................................
.......2 2.2.2 Land Use Plans ............................................................................................3 2.2.3 New Development Plans ...............................................
...............................3 2.2.4 Storm Water Management Plans .................................................................3 2.2.5 Water and Sewer Upgrades .................................
.........................................4 2.2.6 Parks and Recreation....................................................................................4 2.2.7 Green Space Program ..................
................................................................4 Section 3 Funding ................................................................................................................5
3.1 Implementation Costs ..............................................................................................5 3.2 Potential Sources of Funding .............................................
......................................5 Section 4 Identification of Pollutant Sources .......................................................................6 4.1 Pollutant Sources Requiring
Control and Management...........................................6 4.2 Present Extent of Pollutant Sources .......................................................................13 4.3
Estimated Load Reductions ..................................................................................14 Section 5 Best Management Practices ....................................................
............................15 5.1 Structural Best Management Practices ..................................................................15 5.2 Non-Structural Best Management Practices
..........................................................16 Section 6 Management Measures for 303(d) Stream Segments .......................................18 Section 7 Schedule for
Implementation ..............................................................................19 Section 8 Long Term Monitoring Plan ...................................................................
............20 8.1 Purpose and Objectives ..........................................................................................20 8.2 Monitoring Practices .......................................
.......................................................21 8.2.1 Overview ....................................................................................................21 8.2.2
Sampling Locations ...................................................................................21 8.2.3 Monitoring Schedule ....................................................................
..............21 8.2.4 Biological Monitoring ................................................................................22
ii 8.2.5 Fish Sampling ............................................................................................22 8.2.6 Monitoring Procedures......................................................
.........................23 8.2.7 Analytical Parameters ................................................................................23 Section 9 Reporting Requirements ...........................
..........................................................24 9.1 Annual Certification of WPP Implementation .......................................................24 9.2 Electronic Submittal
of Monitoring Data ..............................................................24 9.2.1 Water Quality Reporting ............................................................................24
9.3 Progress Report ......................................................................................................24 9.3.1 Source and Treatment Controls ......................................
...........................24 9.3.2 Monitoring Program...................................................................................24 9.3.3 Watershed Protection Plan Evaluation
.......................................................24 9.3.4 Watershed Protection Plan Modification ...................................................25 Figure 1 Sewer Service Area
Watershed Protection Plan
-1 -Section 1 Introduction 1.1 Purpose The purpose of the Tybee Island Watershed Protection Plan is to present a strategy for protecting existing water quality within the Tybee Island
Wastewater Treatment Plant (WWTP) service area (Figure 1). The Watershed Protection Plan, or portions of the plan, will be incorporated into the Tybee Island WWTP National Pollutant
Discharge Elimination System (NPDES) Permit. The Watershed Protection Plan has been developed in accordance with Georgia Environmental Protection (EPD) “Watershed Assessment and Protection
Plan Guidance: Phase III, Watershed Protection Plans”, dated March 23, 2005. 1.2 Background A Watershed Assessment for Tybee Island was completed by Hussey, Gay, Bell & DeYoung, Inc.,
in conjunction with Coastal Environmental Analysis, in accordance with Georgia EPD guidelines and approval was received from EPD on May 24, 2011. The Watershed Assessment is the basis
for development of the Tybee Island Watershed Protection Plan. The Watershed Protection Plan identifies Best Management Practices and long term water quality monitoring to protect the
existing water quality with the Tybee Island sewer service area.
-2 -Section 2 Legal Authority 2.1 Political Jurisdiction 2.1.1 Local Governments and Agencies City of Tybee Island Mayor and Council P.O. Box 2749 Tybee Island, Georgia 31328 Phone:
(912) 786-4573 2.1.2 Local Zoning and Development Agencies City of Tybee Island Zoning Manager P.O. Box 2749 Tybee Island, Georgia 31328 Phone: (912) 786-4573 2.1.3 Resources Available
for Implementation Tybee Island Department of Planning and Zoning has code enforcement officers that conduct routine patrols, the Department of Public Works makes annual inspection of
stormwater facilities and responds to any reports of problems, and the Water and Sewer Department conducts and makes inspections at the wastewater treatment plant, conveyance lines and
lift stations. The Metropolitan Planning Commission also assists the city with the testing of stormwater outfalls and assists with the annual MS4 Annual Report. All of these resources
will be utilized for implementation of the Tybee Island Watershed Protection Plan where applicable. 2.2 Code and Regulation Evaluation 2.2.1 Ordinances Tybee Island has regulations in
place (i.e. Engineering Design Standards, Zoning Ordinances, etc.) that require compliance with all local and state regulations pertaining to water quality and stormwater management.
A complete listing of the City of Tybee’s ordinances can be found online at www.municode.com.
-3 -Ordinances have been developed to protect the environment, businesses and residents. Ordinances exist for development, stormwater regulation, pollution prevention, water use and
sewage disposal. Ordinances will continue to be enforced to ensure the protection of existing water quality surrounding Tybee Island. The infrastructure committee can make recommendations
to the city council for modifications to specific ordinances if necessary to ensure water quality is maintained within the Tybee Island sewer service area. 2.2.1 Land Use Plans The predominant
land use within the Tybee Island WWTP service area is residential. Residential development is largely made up of single family homes. In recent years, higher density residential developments
such as condos and duplexes have increased. There are pockets of commercial and institutional areas along main roads such as US Highway 80 (Butler Avenue), Tybrisa and the Strand. Non-residential
areas are typically located in the center of the island along the main roadways and on the south end of the island. Land use has been compiled from zoning maps and is not anticipated
to change in the future. There are some undeveloped tracts which will likely be developed into residential single or multi-family units. There are so few undeveloped land tracts that
a future land use map was not developed. . 2.2.3 New Development Plans Any new development plans will be reviewed and approved by the City of Tybee Island prior to construction. The
city has jurisdiction over all development within the Tybee Island WWTP service area. 2.2.4 Storm Water Management Plans This City of Tybee Island maintains a storm sewer system (Georgia
Phase I Medium MS4s, Permit Number GAS000212) throughout the island. Tybee Island is also a co-applicant with Chatham County, Bloomingdale, Garden City, Pooler, Port Wentworth, and Thunderbolt.
A significant portion of the surface drainage is collected through the storm sewer system. In 2009, the city implemented an oyster restoration project in partnership with the Skidaway
Institute and UGA Marine Extension Service to create an oyster reef downstream of the 6th Street stormwater outfall. In 2011, the city secured a grant to conduct bi-monthly water tests
to assess to effectiveness of this project in
-4 -filtering pollutants from stormwater. Testing began in June 2011, and initial results have been encouraging. The city has also installed bio-filters in major catch basins to filter
floatables and heavy metals from runoff before it is discharged into the tidal system, which is having a significant effect in improving water quality. 2.2.5 Water and Sewer System Upgrades
Tybee Island currently inspects all new water and sewer infrastructure prior to acceptance. In addition, the city routinely checks existing infrastructure for inflow and infiltration.
The city has complete jurisdiction over all water and sewer lines within its service area. Tybee Island develops a capital improvement project list to be included in the annual Water
and Sewer Fund budget. These capital improvements improve the collection and treatment of wastewater from the Tybee Island service area and ensure compliance with all water and sewer
regulations. 2.2.6 Parks and Recreation Tybee Island has control over its parks and recreation areas. In addition, some areas are maintained by Chatham County. All areas are routinely
monitored for any potential adverse affects to the environment. 2.2.7 Green Space Program The City of Tybee Island’s ordinances require green space be provided in all zoning districts.
The preservation of green space is important to the health and welfare of the city's citizens and aids in the reduction of drainage problems associated with development. In all zoning
districts except C-1, 65 percent of the designated setback area of a lot shall consist of permanent permeable surface to permit the absorption of water and shall not be paved, built
upon, or covered in such a way so as to interfere with the permeability of the surface.; The preservation of green space and permeable surfaces preserves aesthetic features of the landscape
and provides for the free flow of air, light and water. The city also has an ordinance requiring all driveways to be permeable.
-5 -Section 3 Funding 3.1 Implementation Costs Tybee Island will have to include additional resources in its water & sewer budget for any new best management practices or water quality
monitoring that is required to implement the Watershed Protection Plan. Existing personnel and resources will be used as much as possible to help defray the cost of implementation and/or
inspection of best management practices. The exact cost for implementation of the water quality monitoring each year will not be known until a specific contract is established with a
laboratory for sampling and analysis. 3.2 Potential Sources of Funding Local governments can utilize various funding methods including taxes, service charges, fees, exactions and assessments
to fund and implement the plan. Successful funding typically does not utilize a single funding method; rather a blend of several methods are utilized to fund the regulatory requirements,
operation and maintenance, planning, engineering, development of regulations and legal requirements. The following is a list various funding options: General Fund Appropriations Bond
for Capital Improvement General Obligation Bonds Revenue Bonds State Revolving Funds In-lieu of Construction Cost Impact Fees Developer Extension/Latecomer Fees Special Purpose Local
Option Sales Tax (SPLOST) Federal Highway Administration Grant Programs (TEA 21) United States Army Corps of Engineering (ACOE) grants It is likely that funding for implementation of
the Watershed Protection Plan will come largely from revenue generated by the water and sewer rate structure. It is possible, that a portion of the plan could be paid for from the public
works budget as the plan is designed to prevent non-point source pollution associated with development. The city will determine how best to fund the Watershed Protection Plan once the
annual costs are known.
-6 -Section 4 Identification of Pollutant Sources 4.1 Pollutant Sources Requiring Control and Management The following is a summary of the water quality data collected as part of the
Watershed Assessment. This summary will be used as a baseline for comparison with future water quality data collected as part of the Watershed Protection Plan. As described and illustrated
in the approved “Tybee Island Watershed Assessment Watershed Monitoring Plan, November 19, 2007,” two study sites along each of two tidal creeks were designated as locations for collecting
water quality samples, bacteria samples, and for setting up stream reaches for macroinvertebrate sampling, sediment sampling, cross-section measurements, and habitat assessments. Chemical
Water Quality Data: Field-collected data of in-situ water quality parameters are summarized below in Table 1 Summary table for in-situ water quality parameter, Table 2 Summary table
for in-situ nutrient concentrations, and Table 3 Water Quality Analysis – Metals. Data is also provided electronically in the “Water quality excel spreadsheet,” and the “DNR Water Quality
Spreadsheet Template.” Measurements were made at all sites during low tide periods. The salinity (and specific conductivity) data illustrate that these salt marsh tidal creeks function
as distributaries of sea water from the ocean and Tybee Inlet, and that they do not have significant “upstream” sources of fresh water. At low tide, the remaining water in the creeks
at the sampling sites would be water that had flowed “downstream” from the most upstream portions of the tidal creek systems. This remaining, low tide water had salinity values near
and above 30 ppt, and this value is typical of beach-front ocean water along Tybee Island. The salinity values thus indicate that these creeks function as tidal conveyances rather than
as transport systems of downstream flow from any significant freshwater sources. Furthermore, salinity in these creeks appears to be decreased little by local rainfall events, as illustrated
by comparing the salinity values during dry-period sampling dates with the one wet-weather sampling date (August 26, 2008) following a 0.4 inch rainfall. The tidal creeks do collect
and convey local storm water drainage and runoff, however these quantities of added freshwater do not impact the salinity in the main channels of the tidal creeks. It is expected that
these decreases in salinity are temporary and short due to the large impact of regular tidal flow and flushing within these systems. The greatest impact of rain events appears to be
in causing an increase in turbidity in Chimney Creek. This impact was not evident at the Horsepen Creek sampling sites. Dissolved oxygen values during the warmer months, regardless of
rainfall, were low (mostly <3 mg/l). Taking into consideration the warmer water and high salinity, the oxygen percent saturation values during the warmer months were also low. It is
important to note, however, that low dissolved oxygen values are typical and normal for coastal salt water rivers and tidal marsh creeks in Georgia during warmer months.
-7 -Values of 3 mg/l and 40-50 percent saturation are normal during these seasons in these habitats, and thus the dissolved oxygen values in these two tidal creeks are typical of June
through September values in Georgia salt marsh creeks. Additional information regarding fecal coliform and enterococci bacteria concentrations in these creeks is provided in the section
of this report dealing with bacteria sampling. As a part of the water quality sampling regime, bacteria samples were also collected, and these data are included in these tables. These
data indicate that fecal coliform bacteria concentrations were considerably lower during the colder season (November 24, 2008 sample); however enterococci bacteria concentrations did
not follow this apparent seasonal trend. In comparing the two sampling sites within a single creek, fecal coliform bacteria concentrations showed more within-stream similarity than did
enterococci concentrations. Samples collected following the rain event (ie. August 26, 2008 samples) samples) did not produce obviously higher bacteria concentrations; and in fact it
appears that in comparing this wet-weather sample with other warm season samples, the bacteria levels were somewhat lower following the rain event. Enterococci bacteria concentrations
were generally scattered both in time and within creeks. Perhaps the only pattern/trend indicated was that within Chimney Creek, enterococci concentrations were generally higher at the
northernmost (upstream) station (CH-N-1). Studies in Georgia barrier island marsh tidal creeks have documented that enterococci bacteria can lie dormant in upper intertidal sediments
and subsequently become re-suspended and re-enter the water column during periods of high tides. Thus the source of enterococci bacteria in marsh tidal creeks might be due to these residual
sources, local wildlife and birds, and not necessarily from human contamination.
-8 -Table 1. Summary table for in-situ water quality parameters. (see also: Water Quality Series excel spreadsheet; and DNR Water Quality Spreadsheet Template) CH-N-1 Low Rain Water
Salinty Spec Diss Oxygen Turbidity Fecal Entero-Air Date Time Tide (in.) Temp psu ppt Cond Ox mg/l % Sat NTU pH coliform cocci Temp 6/9/2008 8:50 7:35 0 28.2 33 50.5 2.63 41 13 7.67
520 1600 28 8/26/2008 10:50 10:45 0.4 29.1 28.8 44.7 2.94 45 20 7.74 115 310 30 9/9/2008 9:40 9:41 0 28.2 31.7 48.7 1.22 19 12 7.74 20 800 30 11/24/2008 12:50 11:50 0 13 30.8 47.38 7.73
90 9.3 7.57 <10 170 20 CH-S-2 Low Rain Water Salinty Spec Diss Oxygen Turbidity Fecal Entero-Air Date Time Tide (in.) Temp psu ppt Cond Ox mg/l % Sat NTU pH coliform cocci Temp 6/9/2008
9:15 7:35 0 28.5 33.6 51.3 2.98 47 18 7.69 130 180 28 8/26/2008 11:10 10:45 0.4 29.2 31.4 48.3 2.86 45 23 7.8 125 50 34 9/9/2008 9:55 9:41 0 29 33.5 51.2 2.35 37 18 7.74 50 280 33 11/24/2008
13:15 11:50 0 12.7 32 49.08 7.71 90 9.9 7.59 <10 70 20 HP-E-3 Low Rain Water Salinty Spec Diss Oxygen Turbidity Fecal Entero-Air Date Time Tide (in.) Temp psu ppt Cond Ox mg/l % Sat
NTU pH coliform cocci Temp 6/9/2008 9:35 7:35 0 28.1 33.5 51.2 3.69 57 13 7.73 270 350 30 8/26/2008 11:35 10:45 0.4 29.6 29.9 46.3 3.28 51 14 7.81 60 60 35 9/9/2008 10:20 9:41 0 29.3
32.5 49.8 2.59 41 12 7.88 110 400 34 11/24/2008 13:35 11:50 0 13.2 30.9 47.48 7.69 90 8.9 7.59 10 180 20 HP-W-4 Low Rain Water Salinty Spec Diss Oxygen Turbidity Fecal Entero-Air Date
Time Tide (in.) Temp psu ppt Cond Ox mg/l % Sat NTU pH coliform cocci Temp 6/9/2008 9:50 7:35 0 27.9 33.3 50.9 2.88 45 21 7.68 220 290 31 8/26/2008 11:55 10:45 0.4 29.8 28.4 44.26 2.64
41 21 7.8 100 190 35 9/9/2008 10:40 9:41 0 29 30.4 46.9 2.89 45 22 7.68 115 340 32 11/24/2008 13:55 11:50 0 13.7 30.5 46.92 8.41 99 9.7 7.52 <10 310 22
-9 -Table 2. Summary table for in-situ nutrient concentrations (concentrations in mg/l) (see also: Water Quality Series excel spreadsheet; and DNR Water Quality Spreadsheet Template).
u = undetected at detection limits. CH-N-1 Total Ortho-Date BOD-5 TSS Hardness COD Phosphorous Phosphate TKN Ammonia-N Nitrite-N Nitrite Nitrate Nitrate-N 6/9/2008 101 109 6550 2300
0.22 0.2 0.1 0.21 0.005 0.017 2.04 0.46 8/26/2008 3.7 73 5600 2802 0.39 0.32 0.47 0.31 0.012 0.039 0.35 0.08 9/9/2008 2 96 5800 2600 0.52 0.32 0.89 0.49 0.001 0.003 u u 11/24/2008 2.3
116 5700 3403 0.25 0.2 0.91 0.05 u u u u CH-S-2 Total Ortho-Date BOD-5 TSS Hardness COD Phosph Phosphate TKN Amm-N Nitrite-N Nitrite Nitrate Nitrate-N 6/9/2008 140 145 6000 2600 0.22
0.17 0.07 0.04 0.005 0.016 0.58 0.13 8/26/2008 4.4 116 5500 3102 0.24 0.2 0.07 0.28 0.012 0.039 0.35 0.08 9/9/2008 u 123 6100 2700 0.33 0.18 0.33 0.21 0.001 0.003 u u 11/24/2008 2 122
6000 2502 0.25 0.17 0.83 0.04 u u u u HP-E-3 Total Ortho-Date BOD-5 TSS Hardness COD Phosph Phosphate TKN TKN Amm-N Nitrite-N Nitrite Nitrate Nitrate-N 6/9/2008 130 144 6100 2500 0.22
0.15 0.04 0.06 0.005 0.016 0.58 0.13 8/26/2008 5 103 5600 2702 0.25 0.23 0.06 0.35 0.013 0.043 0.89 0.013 9/9/2008 1.4 110 6100 2500 0.52 0.27 0.37 0.25 0.001 0.003 u u 11/24/2008 1.9
101 5700 3303 0.2 0.17 1.03 0.04 u u u u HP-W-4 Total Ortho-Date BOD-5 TSS Hardness COD Phosph Phosphate TKN Amm-N Nitrite-N Nitrite Nitrate Nitrate-N 6/9/2008 158 193 6100 not reported
0.36 0.25 0.06 0.09 0.006 0.02 1.06 0.24 8/26/2008 4.5 121 5500 2452 0.37 0.35 0.1 0.63 0.013 0.043 0.84 0.19 9/9/2008 1.7 112 5500 2800 0.81 0.39 0.98 0.61 0.01 0.03 u u 11/24/2008
1.5 110 5650 2452 0.18 0.14 1.09 0.03 u u u u
-10 -Table 3. Water Quality Analysis – Metals. All values as mg/l. MDL = minimum detectible limit/concentration. U = Undetectable Station CH-N-1 Dissolved Cadmium Copper Lead Zinc Cadmium
Copper Lead Zinc MDL 0.00008 0.0001 0.0011 0.0003 0.00008 0.00010 0.0011 0.00004 Date 6/9/2008 U U U U U U U U 8/26/2008 U U U U U U U U 9/9/2008 U U U U U 0.009 U 0.019 11/24/2008 U
U U U U U U U Station CH-S-2 Dissolved Cadmium Copper Lead Zinc Cadmium Copper Lead Zinc MDL 0.00008 0.0001 0.0011 0.0003 0.00008 0.00010 0.0011 0.00004 Date 6/9/2008 U 0.003 U U U U
U U 8/26/2008 U U U U U U U U 9/9/2008 U 0.007 U 0.013 11/24/2008 U U U U U U U U
-11 -Bacterial Water Quality Data: As can be viewed in the two tables, “30-Day bacteria series, May 2008,” and “30-Day bacteria series, August-September 2008,” concentrations of fecal
coliform and enterococci bacteria vary considerably within the two tidal creeks and in time at single stations. The range of concentrations during this 30-day sampling series was similar
to the range of concentrations determined from the water quality sampling results (“Summary table for in-situ water quality parameters”). The following discussion describes the results
from the two 30-day sampling series. 1. May series (see table: “30-Day bacteria series, May 2008”) A. Enterococci No obvious trend, either increased or decreased concentrations, in enterococci
concentrations appear to be caused by recent rain events. Within Chimney Creek, higher concentrations were determined at the North station than at the South station, and this trend is
indicated for all dates as well as for the geometric means for these two locations. Within Horsepen Creek, little difference in enterococci concentrations existed between the East and
West stations. For enterococci geometric means during the May 2008 sampling series, the overall highest value was at the Chimney Creek North station, and the lowest value was at the
Chimney Creek South station, and the values at the two Horsepen Creek stations were relatively similar. B. Fecal coliform The rain event during this sampling series caused little difference
in fecal coliform bacteria concentrations within Chimney Creek. Conversely, the rain event caused a lower concentration at the Horsepen Creek East station, but caused a higher concentration
at the Horsepen Creek West station. Overall, the geometric mean values for fecal coliform concentrations during the May sampling series revealed little difference among the creeks and
between the stations, although the Chimney Creek South station had a slightly lower geometric mean. 2. August-September series (see table: “30-Day bacteria series, August-September 2008”)
A. Enterococci No obvious trend, either increased or decreased concentrations, in enterococci concentrations appear to be caused by recent rain events. Consistently higher concentrations
were determined at the Chimney Creek North station compared to the South station, and this trend is indicated for all dates as well as for the geometric means for these two locations.
Within Horsepen Creek, the
-12 -concentrations at the East station were very consistent within the sampling series, and the concentrations were more variable at the West station. Within Horsepen Creek, the West
station also had a higher geometric mean value compared to the East station. Overall, the highest geometric mean value was at the Chimney Creek North station, and the smallest geometric
mean value was at the Chimney Creek South station. This is the same trend determined during the May sampling series. B. Fecal coliform The rain event during this sampling series caused
a lower fecal coliform concentration at the Chimney Creek North station, but it caused a higher concentration at the South station. The rain event did not appear to affect the concentration
at the Horsepen Creek East station, but it caused a lower concentration at the Horsepen West station (which is the opposite effect determined in May). Overall, the highest geometric
mean value for fecal coliform during this series was at the Chimney Creek North station, and the lowest value was at the Chimney Creek South station. This is the same trend that was
determined for enterococci geometric means. Within Horsepen Creek, although the two stations had wide variations in fecal coliform concentrations during this sampling series, the overall
geometric means for the two stations were similar. 3. Overall comparison of the geometric means for the two sampling series In general, the enterococci geometric mean values were highest
at the Chimney Creek North station and the Horsepen West station, and the lowest geometric mean values were at the Chimney Creek South station. The fecal coliform geometric mean values
were also lowest at the Chimney Creek South station. Biological Water Quality Data: Benthic macroinvertebrate sampling produced samples dominated by two species, the Eastern Mud Snail
(Ilyanassa obsolete) and the Grass Shrimp (Palaemonetes pugio), at all four sampling stations. Because sampling was conducted during the cold season, when macroinvertebrate species richness
and and diversity are naturally low in Georgia salt marsh tidal creeks, these results are as expected and typical. Additionally, due to the use of D-net sampling only, and confining
sampling efforts only to low tide periods, the sampling method was not capable of capturing more motile species and those that might move in and out of the creeks with tidal pulses.
During warmer months, these tidal creeks would be expected to serve as habitats to a greater diversity of marine macroinvertebrates including penaeid shrimp, crabs and other arthropods.
Because of the oceanic salinity of tidal water
characteristic of the study sites, no benthic insects would
-13 -be expected and none were collected. Sampling method, time and season contributed to low diversity collections at the study sites. Although these biological sampling results are
typical, natural, and as expected for high salinity salt marsh tidal creeks during the colder months, when the collection data are analyzed with the “GADNR/EPD MacroInvertebrate Multi-metric
Indices Southern Coastal Plain Ecoregion (75) Sea Island/Coastal Marsh & Sea Island Flatwoods – Tidal (75j &75f) Metric Index” spreadsheets, the study sites receive low biological ranking
classification values. Based on the biological collection data, the “Tidal Site Ranking Classification” for each of the four study sites was “Poor.” Table 4 below summarizes the rankings
for each study site. Table 4. Tidal Site Ranking Classifications Site Site Index Score Numeric Ranking Narrative Description Stream Health Rating CH-N_1 24 4 Poor C CH-S-2 26 4 Poor
C HP-E-3 27 4 Poor C HP-W-4 21 4 Poor C Reference Site #5 57 2 Good A The Reference Site #5 5 results are included above for comparison purposes, however it is important to realize that,
based on water quality information regarding Reference Site #5, the study sites represent different ecosystems (marine intertidal) from the reference site, and these comparisons are
of limited value. In particular, the highest specific conductivity of any of the tidal reference sites listed was 8.92 mS/cm for Reference Site #5. At these Tybee Island salt marsh tidal
creek study sites, specific conductivity values were all greater than 44 mS/cm indicating much higher salinity (greater than 29 ppt) and typically euhaline marine ecosystems compared
to the oligo-haline reference sites. Very little, if any, similarities in benthic macroinvertebrate communities would be expected between these ecosystems. 4.2 Present Extent of Pollutant
Sources Future water quality violations could include enterococci, dissolved oxygen (particularly in the summer months), and phosphorous. The higher concentration of phosphorous was
detected in an area that had significant runoff from septic tank systems in unincorporated Chatham County, outside of the city’s jurisdiction. Low dissolved oxygen levels were also detected
during sampling at low tide periods when streams were most stagnant.
-14 -4.3 Estimated Load Reductions The city’s continued efforts to provide public education and implement best management practices will help minimize the impacts of non-point source
pollution on the environment.
-15 -Section 5 Best Management Practices 5.1 Structural Best Management Practices The City of Tybee Island will continue to require and maintain various structural best management practices
for protection from non-point source pollution. The city will implement the best management practices described below. Environmental Restoration and Maintenance All new development within
the service area must abide by the Tybee Island's development standards for green space, buffers and wetlands. The city continues to work proactively to protect environmentally sensitive
areas throughout the service area including marshes, wetlands, tidal creeks, sand dunes and beaches. All of these natural environments provide protection from non-point source pollution
on the Island. Stormwater Detention/Retention Ponds Any new development proposed within the Tybee Island WWTP service area requires compliance with all local, state and federal regulations
regarding pollutant discharges. All new construction, including single-family homes, requires an engineered drainage plan showing that runoff coming from the property will not be increased
by any addition of impervious surfaces; therefore, existing water quality should not be degraded by future development. Currently, no retrofits are required on existing structures within
the watershed. Septic Tank Maintenance and Repair Septic tanks are prohibited where public sewer is available. The city does everything possible to educate residents with private sewer
disposal systems on proper operation and maintenance. The city code requires that all private systems be operated and maintained in a sanitary manner.
-16 -5.2 Non-structural Best Management Practices The City of Tybee Island will also use a variety of non-structural best management practices to reduce the impacts from non-point source
pollution. The city currently does a lot of educational outreach due to the sensitive beach environment of the Island. Outreach programs are conducted in partnership with the Tybee Beautification
Association, Tybee Island Marine Science Center, Burton 4-H Center, and other organizations, and include Adopt-a-Highway, Adopt-a-Wetland, and beach sweeps, as well as public service
announcements on the city's cable access channel and local radio stations, and brochures available at city hall and short-term rental venues. These programs are designed to educate residents
and travelers to help maintain environmental standards on the Island. Listed below are several other non-structural programs currently in use by the City of Tybee Island. Outreach Programs
Tybee Island participates in a number of outreach programs to help better inform its residents of the need to protect water quality. Tybee Island will continue to provide literature
to its residents, water and sewer customers and schools to better inform the public about water quality, water conservation and wastewater treatment. Septic Tank Surveys Tybee Island
has identified existing septic tanks within the WWTP service area. The city requires all properties to connect to public sewer if it is available within 200' of the property. The city
makes every effort in its long term planning and capital improvement plan to continue to reduce the number of septic tanks within its service area. Illicit Discharge Detection and Elimination
Tybee Island has an on-going program for the reduction of inflow and infiltration (I&I), as well as the control of illicit discharges. In the last several years, the city has conducted
video inspections of the sewer system. That information was evaluated by the city’s engineering firm who prepared contract documents for the work. The city has completed the the work
and made repairs identified in those work projects. I&I repairs have reduced the amount of stormwater in the sanitary sewer system significantly. Tybee Island will continue to inspect
storm sewer collection systems during dry periods for illicit discharges of sewage. All illicit discharges will be corrected immediately.
-17 -Greenspace The City of Tybee Island’s ordinances require green space be provided in all zoning districts except C-1. The preservation of green space is important to the health and
welfare of the city's citizens and aids in the reduction of drainage problems associated with development. The preservation of green space and permeable surfaces will preserve aesthetic
features of the landscape and provide for the free flow of air, light and water. In all zoning districts except C-1, 65 percent of the designated setback area of a lot shall consist
of permanent, permeable, vegetated surface to permit the absorption of water and shall not be paved, built upon, or covered in such a way so as to interfere with the permeability of
the surface. Erosion and Sedimentation Inspections The local office of the Natural Resource Conservation Service (NRCS) currently conducts inspections for compliance with Erosion and
Sediment Control practices set by the state commission. These inspections will continue, as well as any necessary inspections by the city during construction of new developments.
-18 -Section 6 Management Measures for 303(d) Stream Segments Not applicable. There are no 303(d) Listed Stream Segments within the study area.
-19 -Section 7 Schedule for Implementation Tybee Island is working to coordinate long-term water quality monitoring, as required by the Watershed Monitoring Plan, and other regulatory
programs into one consolidated effort. Water quality sampling will begin following EPD’s approval of the Watershed Protection Plan. We anticipate sampling to begin by the first quarter
of 2012.
-20 -Section 8 Long Term Monitoring Plan 8.1 Purpose and Objectives The purpose of the long-term monitoring plan is to determine that existing water quality is being maintained with
the Tybee Island WWTP service area. Four monitoring stations were originally selected to assess the present conditions of the watersheds within the Tybee Island WWTP service area. Stations
were selected based on their relative tidal influence and anticipated future development within the watershed and are listed below in Table 6. Tidal influence was based on a combination
of hydrologic observations in the field (rising water level and stagnant or tidal flow into stream channels) and conductivity values measured in the field. Table 6. Biological and Habitat
Monitoring Station ID Station Name GPS Coordinates Macroinvertebrates Habitat* CH-N-1 Chimney Creek North: Hwy 80 Bridge 32° 01' 06" -80° 51' 03" X X CH-S-2 Chimney Creek South: 127
Eagles Nest Drive 32° 00' 52" -80° 51' 10" X X HP-E-3 Horsepen Creek East: 4-H Center 32° 00' 23" -80° 51' 05" X X HP-W-4 Horsepen Creek West: Sixth Street 32° 00' 30" -80° 50' 58" X
X * Includes habitat assessment, in-situ physical measurements (i.e., bank height, bankfull width, etc.), and a pebble count. Biological and habitat monitoring was conducted at all four
sites. Sampling was done in accordance with the protocols outlined in the 2002 GaEPD Standard Operating Procedures for Freshwater Macroinvertebrate Biological Assessment, and 2005 GaDNR,
Wildlife Resources Division, Fisheries Management Section Standard Operating Procedures for Conducting Biomonitoring on Fish Communities in Wadeable Streams in Georgia.
-21 -8.2 Long Term Monitoring Practices 8.2.1 Overview The Tybee Island Water Quality Monitoring Program is a continuation of water quality sampling completed for the Tybee Island Watershed
Assessment. Water quality samples will continue to be collected using the same procedures developed for the Watershed Assessment. Water quality data will be reviewed for possible modification
of the Watershed Protection Plan. The Tybee Island Water and Sewer Department will be responsible for implementing the monitoring program. 8.2.2 Sampling Locations The City of Tybee
Island proposes to use three of the four original monitoring sites for long term monitoring of the sewer service area. The city proposes to eliminate Site 1 – Chimney Creek North @Highway
80 due to the tidal influence of septic tanks outside of the jurisdiction of the city. In addition, the flow from Site 1 does not represent a true stream in the watershed. Water at this
location is tidally pushed into a wetlands system on the north side of Highway 80 which has no outlet. The city proposes to continue long term monitoring at the following locations:
Site 2 CH-S-2 Chimney Creek South: 127 Eagles Nest Drive Site 3 HP-E-3 Horsepen Creek East: 4-H Center Site 4 HP-W-4 Horsepen Creek West: Sixth Street 8.2.3 Monitoring Schedule Water
quality samples will be collected for both dry weather and wet weather events on a quarterly basis. Four samples are required from each sampling location and at least one sample must
be a wet weather sample. Wet weather samples are to be collected within 24-hours of rainfall greater than 0.2-inches. Dry weather samples are to be collected after a 72-hour period with
less than 0.1-inches of rainfall. Sampling Schedule is shown below in Table 6. Georgia’s Rules and Regulations for Water Quality Control now requires that fecal coliform testing be “based
on at least four samples from a given sampling site over a 30-day period at intervals no less than 24 hours.” Since sampling is
-22 -conducted once a quarter, four samples over a 30-day period must be collected each quarter for fecal coliform testing (i.e. three additional samples must be collected from each
site within 30 days of the initial quarterly sampling for fecal coliform analysis only). The annual sampling required for the Watershed Protection Plan is presented in Table 7. Additional
samples may be collected if significant changes in water quality are detected or if anomalies in the data are suspected. A significant change is defined as a violation of a water quality
standard not previously identified in the Watershed Assessment. Table 7. Tybee Island Annual Water Quality Sampling Site Number Sampling Site Annual Dry Weather Samples Required Annual
Wet Weather Samples Required 2 Chimney Creek South: 127 Eagles Nest Drive 3 1 3 Horsepen Creek East: 4-H Center 3 1 4 Horsepen Creek West: Sixth Street 3 1 8.2.4 Biological Monitoring
Biological assessment of the Tybee Island watershed was conducted as part of the Tybee Island Watershed Assessment. Biological assessment of the watershed will be conducted every two
(2) years at the each of the above sites. The city may add additional sites if water quality problems are noted from future sampling events. Biological assessments will follow the most
current water quality sampling SOP from EPD. The city will contact Tim Pugh of the Ambient Monitoring Unit at (404) 675-6236 for the current SOP. 8.2.5 Fish Sampling The validity of
fish sampling in tidally influenced streams is difficult to determine without frequent sampling. No fish sampling was conducted for the Watershed Assessment. Fish sampling has not been
proposed for the long term monitoring of the Tybee Island service area watershed.
-23 -8.2.6 Monitoring Procedures Water quality samples are to be collected from a single grab sample at each location. Grab samples are to be distributed among three sample collection
containers for the analysis of enterococci, nutrients and total suspended solids (TSS). Enterococci samples are to be collected first to minimize the risk of contamination. All sample
containers will be kept on wet ice in coolers before and after sample collection. All collection containers will be labeled in the field at the time of sample collection. In-stream dissolved
oxygen (DO) levels, in-stream water temperature, pH and air temperature will all be measured at the time of sample collection. Stream flow will be measured as the distance from the bridge
to the water surface at each of the sampling locations. Visual observations of the surrounding conditions will be recorded at each site at the time of sample collection. Digital photographs
of the sampling sites will be taken whenever possible. The city proposes to only include enterococci in the long term monitoring. Enterococci sampling would coincide with the required
sampling for the City of Tybee Island WWTP and compliance with the Beach Act. The city also proposes to not continue metals sampling due to all of the sampling sites being extremely
tidally influenced. 8.2.7 Analytical Parameters All samples are to be analyzed by a laboratory approved by the Georgia Environmental Protection Division and the City of Tybee Island.
Water quality samples are to be analyzed for the following constituents in accordance with Georgia EPD and EPA standard methods: Temperature, both water and air pH Dissolved oxygen
Specific conductance Turbidity BOD5 TSS Phosphorus (total and ortho) Nitrogen (TKN, ammonia, NO3/NO4) Hardness Enterococci All water quality data will be submitted to
EPD annually in electronic format.
-24 -Section 9 Reporting Requirements Once the Watershed Protection Plan is approved, the City of Tybee Island will submit the following to EPD on June 30th of each year: 9.1 Annual
Certification of Watershed Protection Plan 9.2 Electronic Submittal of the Long-Term Trend Monitoring Data Water quality data will be compiled annually in electronic format by the City
of Tybee Island. Data will be submitted electronically and by hard copy to the Georgia EPD in conjunction with the annual reporting required for the Tybee Island WWTP NPDES permit. 9.3
Progress Report 9.3.1 Source and Treatment Controls Source and treatment controls presented herein will be implemented by the City of Tybee Island in the city’s sewer service area. Source
and treatment controls are largely comprised of best management practices, development guidelines and ordinances currently used by Tybee Island. Specific details will be provided annually
as to which BMPs have been implemented or any specific actions that the city has taken to improve water quality in the service area. 9.3.2 Monitoring Program The Monitoring Program for
the Tybee Island WWTP service area will be implemented once the Tybee Island Watershed Protection Plan is approved by EPD and adopted by the Tybee Island city council. Samples will be
collected quarterly. Water Quality data will be reviewed annually to determine whether water quality has remained the same, improved or degraded. 9.3.3 Watershed Protection Plan Evaluation
Evaluation of the Watershed Protection Plan will help to ensure that the plan is maintaining existing water quality in the Tybee Island WWTP service area. At the end of each year, the
plan, including both goals and management practices will be evaluated in terms of the monitoring results from that year. This evaluation will be conducted by the City of Tybee Island.
If no significant change in water quality is observed, the Watershed Protection Plan is deemed effective. If a significant change in water quality is observed, the Watershed Protection
Plan
-25 -will be reviewed by the city to determine whether modification is necessary in order to maintain water quality within the service area. 9.3.4 Watershed Protection Plan Modification
The Watershed Protection Plan can easily be modified to ensure protection of existing water quality in the Tybee Island WWTP service area. The plan consists of controls for preventing
potential pollutants from entering receiving waters in the service area and a monitoring program to assess whether water quality objectives are being met. Additional controls can be
added to the plan to help accommodate for changes in technology or approaches to watershed management. The plan allows for additional samples, sampling locations and/or sampling parameters
to be added to ensure accurate and representative water quality data is collected. The plan can be tailored to the individual needs of the Tybee Island WWTP service area as well as any
changes in applicable local or state regulations. The Watershed Protection Plan will be reviewed reviewed whenever water quality objectives are not being met to determine whether modifications
are necessary. The City of Tybee Island will determine what changes, if any, need to be made to the plan, and decide if the modifications are to be made internally or by a third-party
consultant. Modification of the Watershed Protection Plan should be discussed with the Georgia EPD to ensure regulatory compliance, particularly if the plan is incorporated into the
Tybee Island WWTP NPDES permit.