### Background: 

# Description of Alligator Harbor

• Located in eastern Franklin County; Nearby towns or cities - Alligator Point, St. Theresa, Turkey Point, Lanark Village • Lies just east of the Apalachicola estuary • Surface water area of the entire preserve is approximately 14,366; 4,045 acre harbor • Along with being designated an aquatic preserve (1969) is also an Outstanding Florida Waterbody, Class II Shellfish Harvesting water body and EPA Gulf of Mexico Ecological Management Site (GEM)

### Watershed • Apalachicola - Chattahoochee - Flint The basin drains an area of more than 19,300 square miles (50,000 km2).•Harbor is approximately 4 1⁄2 miles long and 1 1⁄2

miles wide with a mean water depth of ~4 feet. The western end of the harbor, connecting with the Gulf, is almost closed by a shallow sandbar except for a deeper channel on the northern end. •Depths at the harbor mouth are about 8 - 10 feet (Yentsch, 1953). Depths from the harbor mouth to western boundaries of AP boundaries range between 4 to 17 feet. •Shallow, neutral bay with no significant freshwater inflow and relatively stable salinities. •Salinities in the area range from 30 - 35 ppt; essentially the same as the Gulf •Characteristics are due in part to extremely small drainage basin and to regular tidal exchange with the water of Apalachicola Bay. •Only during extremely heavy rains can any appreciable amount of freshwater enter the harbor. 

### Background: 

## Description of Alligator Harbor• Domestic Wastewater Treatment Plant Systems - 1 WWTP in the shoreline area Summer Camp WWTP is not currently in operation - will become operational when the Summer Camp Development has a community of 50 residents; KOA WWTP was removed in March 2006 • Marinas - Alligator Point Marina - 45 boats, restrooms, fueling, mean depth 8.5, has required buffer zones. • Stormwater - All stormwater enters the system via rainfall driven runoff and has the potential to affect the area - mainly from the developed southern shoreline. •Agricultural waste - No domestic animal farms in the harvesting area • Industrial waste - No permitted sources of industrial waste • Septic systems - 118 (indirect - the property serviced by the septic system is within 100 feet of the shoreline of the shellfish harvesting area) 

# Actual/Potential Pollution SourcesWater Quality Monitoring- Dataloggers

• Monitoring eastern AH 2007 - 2008 • Continuous data - 30 minute intervals; sonde retrieved/deployed every 2 weeks •Parameters include - dissolved oxygen, salinity, temperature, turbidity, pH • Current state of water quality in eastern portion of harbor



# * FDACS

# Datalogger Water Quality Data 10/2007

- 8/2008 Daily Averages

• Water temperatures range from 5.8 - 31.1° C with peak temperatures generally occurring in July/August and lowest temperatures occurring in December and January • pH in the harbor averages 8.0 • Dissolved oxygen (DO) varied from 40 - 100% +saturation; peak levels occurring in the winter and spring and lower levels occurring in the summer and fall when temperatures are higher • Salinity values ranged from 28 - 38 ppt with an average of 34 ppt • Turbidity values typically range from 0 - 264 NTU’s ; higher values are usually associated with storm events • Average depth in eastern harbor is 3.5 feet

# Site Specific Summaries by Station • YSI 85 hand - held unit on a monthly basis at each location (plus scallop spat monitoring stations - 11) for DO, salinity, pH, temperature (2006 - 2009)

AHCW1– Ave pH is 8; Ave Salinity 31.3ppt; Ave DO 90% (s)

## Water Quality Monitoring- Nutrients • AP monitors 7 sites on a monthly basis - since 2001 • Partnership through the University of Florida’s LAKEWATCH/Coastwatch program - total nitrogen, total phosphorus, chlorophyll a nd clarity

###  Average TN: 247 -495 μg/L

Average Chlorophyll: 2 -9 μg/L 

 Average TP: 13 -41 μg/L Alligator Harbor Aquatic Preserve Monthly Nutrient Monitoring Site Specific Annual Averages 2001 -2009

# Valued Biological Resources

- Seagrass

• Monitoring specific stations using fixed transects and random point sampling methods: 2002 - 2009 • 7 stations (4 quads) = 28 locations • Data collected - seagrass/algae species present, percent coverage using Braun Blaquet method, blade lengths, depth, classify epiphyte coverage (clean, light, medium, heavy), sediment type, other organisms present, photosynthetic active radiation (PAR) - amt. of light reaching the bed... LAB - collect 3 shoots for epiphyte weight (g), 4 cores to determine above/below ground biomass, sediment sample for grain - size analysis, turbidity sample.....• Map each location - using GeoXT Trimble unit

### • Historical seagrass coverage from 1995 FWRI layer indicate there are 3,661 acres of seagrass habitat within the Alligator Harbor Aquatic Preserve boundaries. • Preserve staff are currently mapping seagrass habitat from 2007 DOQQ imagery (Dept. of Revenue) to determine extent of habitat

# Valued Biological Resources

- Clam Aquaculture Leases

• Established in 2002 • 40 leases implemented; ~10 of these are being cultivated • Resulting in small product; those still active are producing a valuable product • AHAP is a great growing area due to high salinity and good water quality • Values of this resource have dropped due to reduced demand; decrease in production seen; but is still new and growing - takes a 10 -year period to determine success • FDACS monitors 20 bacteriological water quality- sampling stations in the harbor; datalogger at clam site

### Alligator Harbor Data Sonde FDACS - 

## Live Water Monitoring

http://sondes.floridaaquaculture.com/sondes/sonde_maphome.htm 

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# Historical Research & Data: Publications FSU Marine Lab 

# Revision of Alligator Harbor Management Plan • Current version 1986 • Discussing site - specific management issues and pulling together historical data, monitoring data, etc. • 2011/2012