# Lake Worth Lagoon

– Palm Beach Coast Basin Lakes, Rivers, Streams, and Aquifers

Florida Department of

Environmental Protection

**Division of Environmental Assessment**

**and Restoration**

Bureau of Assessment and Restoration Support, Watershed Monitoring Section



### Good science is the foundation of the Florida Department of Environmental Protection’s (FDEP) programs to assess and protect water quality. FDEP is committed to characterizing the environmental conditions of Florida’s freshwater resources through several monitoring programs. The Watershed Monitoring Section administers the Status Monitoring Network

, which oversees the statewide sampling of surface and ground water. This report summarizes the 2006 Status Monitoring Network results for the Lake Worth Lagoo n

– Palm Beach Coast Basin.



## Lake Worth Lagoon

– Palm Beach Coast Basin

The Lake Worth Lagoon

– Palm Beach Coast Basin includes the eastern portion of Palm Beach County south of the Loxahatchee River Basin, and extends southward to include the Hillsboro

Canal watershed of southern Palm Beach County and northern Broward County

. Its boundary extends from the Everglades Agricultural Area and Water Conservation Area 1 on the western side to the Atlantic Ocean on the eastern side. The basin covers approximately 7 00 square miles.

Eastern Palm Beach County is one of the most urbanized areas of the sta te. Land use imagery

from 20 04

– 05 identifies over 45 % of the total area of the basin as urban. The coastal portion of Palm Beach County was the first to be develop ed because of a natural ridge that was historically

well drained. Much of the land to the west of the coastal urban area is now drained by a network of

canals and is covered by urban development

, or has been converted to agricultural cropland

. Water qual ity in the basin is affected by the urban/residential and agricultural runoff that enters the canal system and is ultimately conveyed to the Lake Worth Lagoon (LWL) and the Atlantic Intracoastal Waterway.

The LWL, the major estuarin e resource of Palm Be ach County, is approximately 21 miles long and up to a mile wide. It provides recreational activities but is also an important habitat for native plants, fish

, and wildlife . T he water quality of this system is threatened by s tormwater pollutants

and exce ss ive freshwater inflows from canals

. Other natural areas in the basin include the J.W. Corbett Wildlife Management Area, the Palm Beach Pines State Recreation Area, the Jensen

Beach

- Jupiter Inlet Aquatic Preserve

, and the John D. MacArthur State Beach. Increases in population, land use changes, and alterations of natural drainage patterns have resulted in impacts to the ecological health of these areas and water quality in the basin.

The following table summarizes land use statistics calculated for the Lake Worth Lagoon

– Palm

Beach Coast Basin from 2004

– 05 satellite imagery.

Land Use Agriculture Forest Urban Wetlands Other

Percentage 9.6 6.7 45.7 13.2 24.8 *

The percentage reported as “Other” consists of water, rangeland, barren land, transportation, communication, and utilities.

* Water contributes 20 % to the category listed as “ Other. ”

## Monitoring Design of the Status Monitoring Network
FDEP has worked with the water management districts, local governments, and other entities to

establi sh an Integrated Water Resource Monitoring (IWRM) Program. This program combines surface and ground water monitoring efforts, consist ing of water chemistry, biolog y , and sediment analyses. It is fiscally and logistically prohibitive to sample every river, stream, lake, or individual well in the state on a regular basis. A probabilistic monitoring design is a cost

- effective approach to produce a statistically valid estimate of the condition of wa ter resources. The IWRM Program is made up of three levels of monitoring designs: (1) the Status Monitoring Network designed to

allow statistical inferences about all state waters; (2) more intensive basin monitoring used to identify and confirm impaired waterbodies that do not meet Florida’s water quality standards ; and (3) site

- specific regulatory compliance monitoring.

The Status Monitoring Network uses a random site monitoring design to assess the state’s surface and ground water quality. The object ive of this design is to broadly characterize aquatic resources

with a known statistical confidence. Samples are collected from randomly selected points, which is

a cost

- effective way to provide a geographic snapshot of the condition of all waters in a ba sin. T his monitoring program is not designed to answer site

- specific questions about individual lakes, rivers,

streams , or wells.

The Status Monitoring Network categorizes Florida’s fresh waters into 6 different resource type s. Four of these are surface water: small lakes, large lakes, rivers, and streams. The other 2 resources are ground water: unconfined and confined aquifers. The 2004

– 2009 Status Monitoring Network design divides the state into 29 basins, with 5 or 6 basins sampled each year. App roximately 30 samples are collected annually from each resource in the selected basins. Thus, in each basin, approximately 120 samples are collected for surface water resources, and 60 samples for ground water resources, in addition to quality assurance s amples.



## Lakes

The Lake Worth Lagoon

– Palm Beach Coast Basin has few natural large or small lakes and many artificially constructed small lakes. Artificial lakes are not part of the target population and therefore were not sampled. FDEP has divided lakes by size into 2 categories: small lakes of 2.5 to 25 acres and large lakes over 25 acres. This division allows a better characterization of the

status of the basin’s lake resources.



## Rivers and Streams

Six c anals in the basin, totaling 98 miles, were chosen to represent the river resource : C

- 1 7, C

- 51,

L

- 8, L

- 8 Tieback, L

- 39, and L

- 40 . The remaining streams and canals a re designat ed the stream

resource. These total about 692 miles, although some may be dry during drought. The 2

resources can have different habitats and uses.



## Aquifers
Aquifers are permeable layers of sand, gravel, or rock that contain water. Unconfined aquifers are

n ear the land surface and are easily affected by human activities. Confined aquifers lie below a layer of material, such as fine

- grained clay, that limits the downward flow of water. Water in confined aquifers usually filters slowly through sediment and r ock layers and is older and less affected by human activities. FDEP’s Watershed Monitoring Section samples ground water in the Lake Worth Lagoon

– Palm Beach Coast Basin through wells in the unconfined aquifer

. The confined aquifer in th e basin is highly mineralized

, and there are no known monitoring wells for this

resource

.

The Lake Worth Lagoon

– Palm Beach Coast Basin contains three major aquifer systems : t he Biscayne aquifer system (BAS ) ; the surficial aquifer system (SAS ) ; and the Flo ridan aquifer system (FAS)

. The BAS is an unconfined aquifer that consists of highly permeable limestone and less permeable sand and sandstone. It is often interlayered with or considered to be the surficial

### aquifer. T he unconfined aquifer, consisting o f the BAS or SAS, is the primary source of fresh water for all of Dade and Broward Counties and the southern portion of Palm Beach County. A confining

unit composed of less permeable marl, limestone, and clay separates the FAS from the SAS. Finally, t h e confined FAS is productive but the water is not potable due to its high mineral content

. 

## Summary and Results
The tables below show the sampling carried out fo r each resource in the Lake Worth Lagoon

– Palm

Beach Coast Basin, in terms of acres of large lak es, number of small lakes, miles of rivers and streams, and number of wells for confined and unconfined aquifers. Not all randomly selected stations can be sampled for various reasons. Those that can be sampled are termed accessible.

Those stations that cannot be sampled are considered either dry or inaccessible. Reduced rainfall or periods of drought occur on a cyclical basis in many areas of Florida. Prolonged or intense periods of drought can adversely affect water chemistry. During the sampling pe riod, precipitatio n was reduced by 12% compared with the 30

- y ea r annual average.

Surface Water Resource Large Lakes ( ≥ 25 acres) Small Lakes (2.5

– 25 acres) Rivers (6 rivers/canals) Streams (all other streams/ canals)

Resource Size (a rea, number

, length ) 603 acres 13 lakes 98 miles 692 miles

Accessible 100% 83% 100% 83%

Dry 0% 0% 0% 0%

Inaccessible 0% 17% 0% 17%

Number of Samples 30 10 30 30

Ground Water Resource Unconfined Aquifers Confined Aquifers

Number of Wells 343 0

Accessible 31% 0%

Inaccessible 69% 0%

Samples 30 0

Basin Precipitation Average Annual (1971

– 2000) Annual (2006)

Lake Worth Lagoon

- Palm Beach Coast Basin 61.4 inches 54.2 inches

Rainfall data were obtained from the National Climatic Data Cen ter database for the West Palm Beach Airport WSO Station

. 

### The discussion and figures below provide results for the basin’s surface and ground water resources for a number of important indicators (see the Definitions and Criteria pages for explanations of the indicators used). As discussed in Definitions and Criteria , natural conditions such as higher water temperatures, fresh water and stormwater inflows, and different soil s can affect the results shown below. The e xceed a nce of a standard or threshold is not necessarily caused by a pollutant.



### Lakes : Dissolved oxygen (DO) is below the standard in 3% of the large lakes sampled . Low DO can be harmful to aquatic life. Fecal coliform bacteria levels are above the standard for 3% of the large lakes sampled. pH and un

- ionized ammonia levels are within standard s . All large lakes score well on the Trophic State Index, a combined measure of nutrients and chlorophyll that is an indicator of lake health. There were not enough data to assess small lakes.

### Rivers and Streams : DO is below the standard in 17% of the rivers and 70% of the streams sampled. Canal/ditch construction and ground water inflows can contribute to low DO

concentrations. Low DO can be harm ful to aquatic life. Fecal coliform bacteria is above the
standard in 3% of the rivers and 40% of the streams sampled . Un

- ionized ammonia and pH levels

are within standards for the rivers. Un

- ionized ammonia is within the standard for streams

, and pH

le vels are low for 3% of the streams. Chlorophyll exceeds the standard in 33% of the rivers and
57% of the streams sampled

. 

### Aquifers : Exceedances of a rsenic (9%) and lead (10%) are found in a small percentage of the

unconfined wells sampled . Total coliform bacteria exceed the standard in 28% of the unconfined wells. These bacteria are indicators of possible human health effects if the water is used for drinking. Other analytes are within standards. There are no known confined aquifer wel ls to

assess in th e basin.

Surface

Water

Resource Dissolved Oxygen Fecal Coliform pH Un

- ionized

Ammonia Trophic State

Index

Large

Lakes

Small

Lakes ID ID ID ID ID

Surface

Water

Resource Dissolved Oxygen Fecal Coliform pH Un

- ionized

Ammonia Chlorophyll

Rivers

Streams

Ground

Water

Resource Arsenic Cadmium Chromium Lead Nitrate

– Nitrite Sodium Fluoride Total

Coliform

Unconfined

Wells

Confined

Wells na na na na na na na na

Note: The gr ay segments of the pie charts represent the percentage of water resources that meet s water quality standards . Blue segments represent the percentage that does not meet the standards. See the Definitions and Criteria pages for more informatio n.

na

– Not applicable. 

### ID

– 

### Insufficient data for statistically valid analysis

This survey does not represent a comprehensive analysis of any individual waterbody.

The Watershed Monitoring Section would like to thank the Southwest Florida Water Management

District for its contributions to this report.

For more information, contact: Florida Department of Environmental Protection, Watershed Monitoring Section, MS 3525 2600 Blair Stone Road, Tallahassee, FL 32399 (850) 245

– 8 439 ; http://www.dep.state.fl.us/water/monitoring/status.htm

## Surface Water Definitions and Criteria

Each indicator listed below was chosen because it has an appl icable state criterion, found in Criteria for Surface Water Quality Classifications, Rules 62

- 302 and 62

- 303, Florida Administrative Code.

Indicators Criterion/Threshold 1 Designated Use

Fecal Coliform Bacteria < 400 counts/100mL Recreation

Dissolved Oxygen ≥ 5 mg/L Aquatic Life pH ≥ 6 and ≤ 8.5 SU Aquatic Life

Un

- ionized Ammonia ≤ 0.02 mg/L Aquatic Life Chlorophyll a ≤ 20 μ g/L Aquatic Life Trophic State Index (TSI) Color ≤ 40 PCUs, then TSI ≤ 40 Color > 40 PCUs, then TSI ≤ 60 Aquatic Life

1 mL

– milliliters; mg/L

– milligrams per liter; SU

– standard units; μ g/L

– micrograms per liter; PCUs

– platinum cobalt units

Fecal coliform bacteria : The single

- sample threshold for fecal coliform is 400 counts per 100 milliliters of

water. These bact eria can enter water through the discharge of waste from mammals and birds, agricultural and stormwater runoff, and untreated human sewage. The presence of fecal coliform bacteria may indicate that the water is contaminated by other disease

- causing organi sms.

Dissolved oxygen (DO) : T he state criterion for DO is a minimum of 5 milligrams per liter to maintain healthy conditions for aquatic life. Lower levels do not affect human recreation. Algae and plants produce oxygen through photosynthesis. Oxygen is also dissolved in water by wind and wave action. Respiration by aquatic animals, decomposition, wastewater, stormwater runoff from urban streets or farmland, and failing septic tanks consume oxygen. Natural conditions

— such as ground water from springs , water from swamps/wetlands, higher water temperatures, and calm and cloudy weather

— can also decrease DO levels

in waterbodies.

pH : The surface water criterion for pH is between 6 and 8.5 standard units. The pH scale, which ranges from 0 to 14, is a measure of the degree of acidity or alkalinity of a solution. Numbers below 7.0 indicate acidity; numbers above 7.0 indicate alkalinit y. The midpoint of 7.0 on the pH scale represents neutrality

— that is, a neutral solution is neither acidic nor alkaline. pH affects many chemical and biological processes in water, and aquatic organisms are adapted to a certain range of pH. When pH leve ls are outside this range, it stresses these organisms’ physiological systems and can reduce reproduction. Atmospheric deposition (acid rain), geology, vegetation, and pollution can cause changes in pH.

Un

- ionized ammonia : The threshold for un

- ionized a mmonia is less than or equal to 0.02 milligrams per liter. This is calculated from total ammonia and adjusted for temperature, salinity, and pH. Ammonia occurs in different forms; water temperature and pH affect which form predominates at any given time in an aquatic system. Un

- ionized ammonia can be toxic to fish and invertebrates.

Chlorophyll a* : The threshold for chlorophyll is less than or equal to 20 micrograms per liter. Chlorophyll is the pigment that allows algae and plants to convert sunlight into organic compounds during the process of photosynthesis. Excess nutrients, such as nitrogen and phosphorus, can stimulate algal blooms. Excess algae sink to the bottom and decay, using up the oxygen that other plants and organisms require to survive

. High concentrations of chlorophyll reduce water clarity and limit the light available to shallow

- water ecosystems.

Trophic State Index (TSI)* : TSI and chlorophyll are the primary measures used to assess nutrient impairment in a waterbody. There are two thresholds for TSI, based on the color of a lake. Dark

- water lakes with a mean color greater than 40 platinum cobalt units (PCUs) are impaired when their annual mean TSI

exceeds 60. Clear and low

- color lakes with a mean color less than or equal to 40 PCUs are impaired when their annual mean TSI exceeds 40. TSI is measured using chlorophyll, nitrogen, and phosphorus

concentrations. A 10

- unit increase or decrease in the index represents a doubling or halving, respectively, of the number of algal cells present.

________________________________ * Both TSI and chlorophyll a are not standards, but thresholds used to estimate the impairment of state waters. These thresholds are used in the analysis of Status Network data, based on single samples in a basi n at a predetermined time of year. The analysis and representation of these data are not intended to infer the verification of impairment, as defined in Rule

62

- 303, Florida Administrative Code, in these waters.

## Aquifer Definitions and Criteria

The table below shows the thresholds for eight indicators regulated under drinking water standards.

Indicators Criterion/Threshold 1 Designated Use

Arsenic ≤ 10 μ g/L Potable Water(drinking water)

Cadmium ≤ 5 μ g/L Potable Water(drinking water)

Chromium ≤ 100 μ g/L Potable Water(drinking water)

Lead ≤ 15 μ g/L Potable Water(drinking water)

Nitrate

– Nitrite ≤ 10 mg/L Potable Water(drinking water)

Sodium ≤ 160 mg/L Potable Water(drinking water)

Fluoride ≤ 4 mg/L Potable Water(drinking water)

Total Coliform Bacteria (counts per 100 milliliters) ≤ 4 (sample maximum) Potable Water(drinking water)

1 μ g/L

– micrograms per liter; mg/L

– milligrams per liter

Arsenic, cadmium, chromium, and lead are all naturally occurring metals in the earth’s crust. These and

other metals are used in manufacturing and can be produced and used in pesticides, preservatives, and industrial operations. They may enter water as a pollutant. Florida has primary standards (criteria) for these metals to protect human health. Excess levels in drinking water can cause adverse health effects.

Nitrate

– nitrite is used in fertilizer and is found in sewage and wastes from human and/or farm animals. Florida’s drinking water standard is 10 milligrams per liter (mg/L) for nitrate and 1 mg/L for nitrite. In addition, to allow for the fact that the toxicity of nitrate and nitrite is additive, the standard for the sum of nitrate and nitrite is 10 mg/L. In the l ong term, nitrates and nitrites have the potential to cause serious adverse effects in

h umans.

Sodium (salt) has a drinking water standard to protect individuals who are susceptible to sodium

- sensitive hypertension or diseases that cause difficulty in regulating body fluid volume. Sodium is monitored so that

individuals on sodium

- restricte d diets may take the sodium in their water into account. Drinking water contributes only a small fraction (less than 10%) of an individual’s overall sodium intake.

Fluoride , a natural element, is added to drinking water systems to reduce dental cavities . Prolonged exposure to levels above 4 milligrams per liter may result in crippling skeletal fluorosis, a serious bone disorder. Lower levels may cause dental fluorosis when children are developing teeth. In its moderate and severe forms, dental fluoros is is a brown staining and/or pitting of the permanent teeth.

Total coliform bacteria are common in the environment and are generally not harmful. The presence of these bacteria in drinking water, however, is an indicator that disease

- causing organisms may be present. The U.S. Environmental Protection Agency and Florida have set an enforceable drinking water standard for total coliform of 4 counts per 100 milliliters to reduce the risk of adverse health effects. Drinking water that

meets this standard is usually not associated with a health risk from disease

- causing bacteria and is

considered safe.