# Jeremy Johnson Russ Frydenborg Florida Department of Environmental Protection Division of Environmental Assessment and Restoration

# Lake Worth Lagoon

# Lake Worth Lagoon 

# Geographical and Physical Description

 

### The watershed of the lagoon includes the communities of North Palm Beach, Lake Park, Riviera Beach, Palm Beach Shores, West Palm Beach, Palm Beach, South Palm Beach, Lake Worth, Lantana, Hypoluxo, Manalapan, Boynton Beach, Ocean Ridge, and unincorporated Palm Beach County.

 

### Currently, the Lake Worth Lagoon receives drainage from an area of approximately 450 square miles

 

### . Major freshwater inflows from the watershed include:  

### Earman River (C

-17) Canal, which discharges to the north or upper segment of the lagoon  

### the West Palm Beach Canal (C

- 51), which discharges to the central segment  

### Boynton Beach Canal (C

-16), which discharges to the southern segment

 

### These canals discharge significant volumes of fresh water that contain nutrients, suspended and dissolved organic matter, and other contaminants that may affect the flora and fauna of the lagoon ( Crigger et al. 2005)Physical Characteristic Value Source
Estuarine surface area (acres) 4,045 acres PBCERM pH (standard units [SU]) Average 7.54 FDEP Mean depth (m) 2 m PBCERM Temperature (° C) 20° C to 32° C Florida Atlantic University (FAU) Harbor Branch Salinity and salinity zones (practical salinity units [psu]) .~20 average (range is + or
- 10) Highly correlated to discharge at (C
- 51) FAU Harbor Branch

# Lake Worth Lagoon Segmentation Lake Worth Lagoon North (LWN) includes waters north of the Flagler Memorial Bridge in West Palm Beach. Lake Worth Inlet (also referred to as Palm Beach Inlet) is the largest inlet and primary source of ocean water in the LWN and it is also the primary outlet for fresh water. Lake Worth Lagoon Central (LWC) segment includes waters from the Flagler Memorial Bridge to Lake Worth Bridge Lake Worth Lagoon South (LWS) The south segment includes waters between Lake Worth Bridge and the Boynton Beach Bridge at Ocean Avenue

# Historical Info.
 

## Historically was predominately fresh water

 

## Human activities over the past 100 years, including construction of permanent inlets, dredging and filling of wetlands along the shoreline, channel dredging, wastewater discharges, and the construction of sea walls, canals, causeways, and marinas, have adversely the Lagoon's habitat

 

## Today, 81% of the shoreline is bulkheaded, and much of the stormwater from the urbanized watershed is not fully treated prior to discharging to the Lagoon.Response Variable Observed Historically? Observed Currently? Explanation Source Low dissolved oxygen (DO) (hypoxia/anoxia) No No Currently DO is considered high in the Lake Worth Lagoon and is meeting the Class III DO criteria. PBCERM (1994–2007)

Reduced clarity Yes Yes Increased development has caused upland disturbances, increasing sediment loading and reducing clarity in certain portions of the system. PBCERM (1994–2007)

Increased chlorophyll a concentrations No Yes A rather large spike occurred following the 2004–05 hurricane season. PBCERM (2002–06)
Phytoplankton blooms (nuisance or toxic) No No No harmful phytoplankton blooms have been reported for the system. -Response variable Observed historically? Observed currently? Explanation Source
Problematic epiphyte growth No No No problematic epiphyte growth has been reported for the system. -

Problematic macroalgal growth No No No problematic macroalgal growth has been reported for the system. -
Submersed aquatic vegetation (SAV) community changes or loss Yes Yes SAV loss appears to be related to development in the watershed that has caused hydrologic alterations and increased loading of sediments, thus adversely affecting water clarity. PCBERM

Emergent vegetation community changes or loss Yes Yes Bulkheading has affected emergent vegetation community -**Response Variable**  **Observed Historically?**  **Observed Currently?**  **Explanation Source**  Coral/ hardbottom community changes or loss N/A N/A N/A -

Impacts to benthic community No No None reported, although not well studied. -

Fish kills No No No fish kills have been reported in the system. -Factors Observed? Explanation Source

Increased nutrient loading or concentrations from historical levels Yes Canal discharge and stormwater runoff has increased from historic levels but decreased as technology has improved and allowed for better management practices. PBCERM

Mitigating factors that could prevent nutrient expression No None that have been observed. Other significant stressors to biological communities Yes Sediment smothering from stormwater run - off and Salinity Issues attributed to canal discharges. PBCERM

Natural episodic events contributing to nutrient regime (e.g., seasonal or hydrologically driven) Yes Hurricanes and other storms have impacts. PBCERM

# The Lake Worth Lagoon 

# Biological Summary Year Seagrass (acres) % Change from Most Recent Previous Assessment*** 1940* 4,271**
- 1975 161 - 96% 1990 2,110 1,210% 2001 1,626 - 23%

- = Empty cell/no data *Arbitrary date reflects conditions prior to intense urbanization; conditions allow for maximum coverage of seagrass . **Acres is the maximum possible area of seagrass given pre -World War II conditions. ***Due to gross differences in survey methods, these values should only be used to indicate an order–of
- magnitude change . In 1975, a resource inventory found that only 161 acres of seagrass remained in the lagoon. While there is uncertainty about the accuracy of the methods used, this indicates a substantial loss of seagrass since 1940. The loss was hypothesized to result from extensive dredging

-and

- filling activities, sewage disposal outfalls that directly discharged to the lagoon, and changes in salinity

# Lake Worth Lagoon Biological Summary Current Seagrass Coverage Lake Worth Lagoon Segment 2001 Seagrass (acres) Segment (acres) % Seagrass Cover North 1,134 3,386 33.50% Central 192 2,102 9%

South 300 1,747 17% Totals 1,626 7,235 22%

# Biological Summary

 

## The most recent assessment of seagrass beds was conducted in 2001  

## Used true color aerial photographs  

## This assessment did not include extensive ground truthing (verification); therefore, sparse seagrass beds, or those located in areas with poor water visibility, were not mapped

# The Lake Worth Lagoon 

# Biological Summary cont.

 

## Oysters  

## Although the oyster bars were healthy, the areal extent of natural oyster reefs in the lagoon was very limited (about 5 acres).  

## The distribution of oysters in the Lake Worth Lagoon is confined primarily to the intertidal zone, with the densest concentrations found in the central segment of the lagoon  

## The accumulation of muck on available substrate or nearby areas makes the substrate unsuitable for oyster larval settlement and thus for the recruitment and growth of larval oysters (CERP 2007a).

# Lake Worth Lagoon 

# Sources of Nutrients

 

# Canals  

# Stormwater Runoff  

# 14 Wastewater Treatment Plants  

# 2 package plants have direct surface water discharges to Lake Worth Lagoon  

# The remaining 12 domestic facilities dispose of secondary wastewater via land applications (ponds, drain fields, injection wells, etc.)


#  

# Atmospheric Deposition

# Water Quality Studies Mean Annual TN

# Water Quality Studies Mean Annual TP

# Water Quality Studies Mean Chl
- a

# Proposed numeric nutrient criteria for Lake Worth Lagoon...
 

## FDEP proposes that a method analogous to the one employed at the adjacent Indian River Lagoon be used to establish numeric nutrient criteria for the Lake Worth lagoon.  

## Depth to seagrass targets should be established and the parameter most limiting the transparency regime should be controlled to fully restore seagrass populations.  

## This analysis may determine that the most effective management action may be a combination of turbidity reduction and hydrological restoration, although some nutrient/chlorophyll reductions may also be needed to achieve the depth to seagrass targets.

# The Lake Worth Lagoon 

# What’s next?

• 

# Provide additional comments on estuary report to Jeremy Johnson

• 

# Phone: 850

- 245 - 8129

• 

# Email: Jeremy.K.Johnson@dep.state.fl.us

• 

# Finalize estuary reports.