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.