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Ambient Pesticide Monitoring Network: 

1992 to 2007 

Technical Publication SFWMD 105 

Prepared by 

Richard J. Pfeuffer 

October 2009 

South Florida Water Management District 

West Palm Beach, Florida 33406 

 
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Abstract 

The South Florida Water Management District has collected surface water and sediment 

samples for analysis of over 80 pesticides since 1992. Residues of atrazine and p,p’-DDE 

are nearly ubiquitous throughout the sampling area. Surface water concentrations of 

atrazine at nine of the fourteen monitoring locations exhibited a downward trend and 

none of the detected concentrations exceeded established levels of concern. Seventy-five 

percent of the sampled locations had average sediment residues of p,p’-DDE at levels that 

may impact sediment-dwelling organisms. Monitoring locations with the highest average 

p,p’-DDE concentrations (based on detected values) and the highest percentage of 

pesticide detections did not exhibit consistent trends. Some locations exhibited increasing 

trends while trends at other locations showed a decrease in concentrations. Additionally, 

specific location concentrations for ethion, diazinon, and endosulfan documented periods 

of surface water quality exceedances. However, product label changes and grower 

education have substantially contributed to the reduced number of exceedances over time. 

Introduction 

The South Florida Water Management District (SFWMD) is a regional governmental 

agency responsible for water quality, flood control, water supply, and environmental 

restoration for 16 counties from Orlando to the Florida Keys. Pesticide monitoring 

within SFWMD has been ongoing since 1976 (Pfeuffer, 1985) with the routine ambient 

monitoring program beginning in 1984 (Pfeuffer, 1991). The original monitoring 

program consisted of 13 locations, but overtime it has grown to 34 sampling sites. The 

current program includes stations designated in the Settlement Agreement, the Lake 

Okeechobee Operating Permit, and the non-Everglades Construction Project (non-ECP) 

permit. The sampling locations are throughout South Florida, and range from Lake 

Okeechobee through the Everglades Agricultural Area (EAA), and down to the 

Everglades National Park (Figure 1). Water flow within the monitoring area is generally 

in a north to south direction. 

The main areas of agriculture include citrus (Martin/St. Lucie County area, 

Caloosahatchee River area), sugarcane (EAA), and the row crop area of South MiamiDade County. Also the coastal urban areas were an additional source of pesticide 

residues. 

The District's canals and marshes are protected under Florida Administrative Code 

(F.A.C.) Chapter 62-302 as Class III (fishable and swimmable) surface waters, while 

Lake Okeechobee and a segment of the Caloosahatchee River are protected as a Class I 

drinking water supply. Water Conservation Area 1 (WCA-1), which encompasses the 

Arthur R. Marshall Loxahatchee Nation Wildlife Refuge and the Everglades National 

Park are also designated as Outstanding Florida Waters, under Chapter 62-302, F.A.C., to 

which anti-degradation standards apply. 

The pesticide monitoring program has evolved over time. Sampling for new pesticides 

and from new locations has been added due to increasing concerns over pesticide use. 

Over 80 pesticides and degradation products are determined in these samples. This 

document summarizes pesticide data for surface water and sediment samples collected 

from April 1992 to December 2007. 
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Methods 

To assess ambient pesticide concentrations, surface water samples were generally 

collected on a quarterly basis (four times annually) and sediment samples semi-annually 

(two times per year). The exact sampling date was dependent on staff and equipment 

availability as well as available capacity of the analytical laboratory. Samples were 

collected from a small boat or pier, upstream of each water control structure and away 

from canal banks. Water column samples were unfiltered surface grab samples (0.5 

meter depth), while sediment samples were the top layer (approximately 10 centimeters) 

of sediment and obtained using a stainless steel petite Ponar dredge. Samples were stored 

on ice before being shipped to the analytical laboratory by overnight courier. All field 

and sampling procedures are described in current or previous versions of the SFWMD 

Field Sampling Quality Manual (2008), which requires field quality control checks 

including field replicates, field blanks, trip spikes (specific concentrations of selected 

analytes added to deionized or selected sample water), and equipment blanks (sediment 

only). These quality control samples were handled identically to field samples. 

Samples have been analyzed for over 80 pesticides and degradation products (Table 1). 

The list of compounds has been dynamic over time, with compounds added based on a 

potential concern or removed after evaluating the compiled data and demonstrating no 

concern. The current analytical list is divided into chemical groupings (chlorinated 

[phenoxy acid] herbicides, urea herbicides, organochlorine pesticides, and 

organonitrogen/phosphorus pesticides) that are used by farmers and homeowners, which 

also includes restricted-use pesticides. Although listed, polychlorinated biphenyl’s are 

not pesticides, but are generally reported during organochlorine pesticide analysis. 

Selected compounds with a state-defined numeric water quality standard (Chapter 62-302 

F.A.C.) are provided in Table 2. The United States Environmental Protection Agency 

(USEPA) National Recommended Water Quality Criteria (2006b) are also listed for 

comparison purposes. For any other compound, an acute or chronic value can be 

calculated using procedures outlined in state law (62-302.200 (1)(a) and (4)(a) F.A.C.). 

Section 62-302.200 F.A.C. provides for acute and chronic toxicity standards to be 

calculated as one-third and one-twentieth, respectively, of the lowest concentration lethal 

to 50 percent of the test population (LC50) exposed for 96 hours for a species significant 

to the indigenous aquatic community. The calculated toxicity values are listed for the 

frequently detected compounds in Table 2. Sediment concentrations were compared to 

freshwater sediment quality assessment guidelines (MacDonald Environmental Sciences 

Ltd. and United States Geological Survey, 2003) (Table 3). A value below the threshold 

effect concentration (TEC) should not have a harmful effect on sediment-dwelling 

organisms. However, values above the probable effect concentration (PEC) demonstrate 

that harmful effects to sediment-dwelling organisms are likely to be frequently or always 

observed. 

All analytical work associated with the pesticide monitoring network was performed by 

the Florida Department of Environmental Protection Central Laboratory in Tallahassee, 

Florida. Analytical methods (Chemistry Standard Operating Procedures by Subsection: 

Organics) are available on the laboratory’s Web site (www.dep.state.fl.us/labs/cgibin/sop/chemsop.asp). The reported sediment concentrations were on a dry weight basis. 
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Since December 1994, modified analytical methods have been used that lowered the 

method detection limits about tenfold (Miles and Pfeuffer, 1997). 

The tables summarizing the detected compounds were compiled using the results the 

monitoring events from April 1992 to December 2007. Average, geometric mean, and 

median concentrations were calculated using only the detections for all locations. The 

number of detections was based on the values above the minimum detection limit for 

each sampling event at all locations within the land use or drainage basin type. With a 

few exceptions, as noted below, the summary data presented for the locations represent 

68 surface water and 30 sediment sampling events. 

Network Results and Discussion 

It is important to note that an evaluation of detection limits is critical when assessing 

pesticide data. For the surface water samples, the average number of compounds 

detected during a sampling event appeared to increase when the detection limits were 

decreased (Table 4). Scott et al. (2002) also noted increases in pesticide surface water 

detections in South Florida when the detection limits were decreased. Conversely, the 

number of detected concentrations in sediment samples decreased when detection limits 

were lowered. This apparent discrepancy may be attributed to the fact that only four 

sampling events occurred during the period of higher detection limits versus 26 for the 

lower detection limit time period (Table 4). Potentially, the most readily detected 

compounds (i.e., organochlorine compounds) in the sediment were prevalent during the 

earlier timeframe, since their use was only recently restricted. Lower detection limits 

reduces false negatives. 

For 44 percent of the monitoring locations, an average of three or more compounds was 

detected in the surface water during each sampling event (Table 5). The monitoring 

locations receiving drainage from citrus agriculture had the highest average (4) of 

different compounds detected, followed by the northern EAA, southern EAA, urban, 

Lake Okeechobee inflows, South Miami-Dade County, and the reference drainage/land 

use type basins. 

The percentage of detections by month, for the surface water samples ranged from 2.2 to 

4.5 percent, with the period of record averaging 3.3 percent (Figure 2). A small seasonal 

difference in the number of detections was also observed between the wet and dry season 

averaging 3.1 and 3.4 percent, respectively. No pattern was evident due to the fact that 

the pesticide application period for the wide range of crops and their locations varies 

considerably throughout South Florida. For example, pesticide applications for citrus can 

occur year-round while row crop pesticide applications occur only in the appropriate 

timeframe during the specific growing season. Additionally, the seasonal temperature 

ranges for the growing season in the agricultural areas create a difference in the optimal 

start and end dates from the northern to the southern part of the region. 

The percent detections by month, for the sediment ranged from 1.1 to 2.1 percent, with a 

period of record average of 1.6 percent (Figure 3). The average number of detections for 

the wet and dry seasons was 1.3 and 1.6 percent, respectively. As was observed for the 

surface water, no pattern was evident since the application period for the wide variety of 
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crops and locations varied significantly. Additionally, the majority of detections 

consisted of p,p’-DDE and p,p’-DDE (Table 7). 

The most frequently detected pesticides in surface water are the triazine herbicides 

(atrazine, ametryn, and simazine) (Table 6). These herbicides are applied to significant 

acreages in South Florida (Miles and Pfeuffer, 1997) and have a higher transport due to 

surface solution or leaching (Gross and Wauchope, 1992). Atrazine and its associated 

degradation products, atrazine desethyl and atrazine desisopropyl, were the most 

frequently detected compounds in the surface water. The most frequently detected 

pesticides in the sediment included the DDT metabolites (p,p’-DDE and p,p’-DDD) and 

ametryn (Table 7). Although banned in the early 1970s (USEPA, 1990), DDT and DDD 

were used widely, degrade slowly, and bind readily to soil. Atrazine, ametryn, atrazine 

desethyl, norflurazon, and p,p’-DDE were detected in samples from at least one 

monitoring station during every event. The United States Geological Survey, as part of 

the South Florida National Ambient Water Quality Assessment (NAWQA), collected 

samples from 1996 to 1998 and identified similar compounds for the most frequently 

detected pesticides (McPherson et al., 2000). 

Table 8 summarizes the atrazine surface water detections by location. Structure S7 

exhibited the highest detected maximum concentration of 18 micrograms per liter [μg/L] 

(Figure 4). Peak concentrations routinely occurred during April, coinciding with the 

application season for sugarcane. The draft ambient aquatic life water quality criterion 

identifies a one-hour average concentration that does not exceed 1,500 μg/L more than 

once every three years on the average (USEPA, 2003a). Additionally, the lowest 

calculated chronic toxicity for the water flea, Daphnia magna, is 345 μg/L (Table 2). 

Based on these criteria, surface water concentrations presented in Table 8 should not have 

an acute or chronic detrimental impact on fish or invertebrates. 

The highest atrazine average location concentration in surface water was observed at 

S38B, which can receive runoff from an urban drainage basin (Table 8). The peak 

atrazine detections occur in June, which coincides with the summer application season 

(Figure 5). The monitoring locations with the next four highest average concentrations 

received drainage from the EAA. Nine of the top ten monitoring locations with the 

highest percentage of detections were either receiving runoff from the urban areas or the 

EAA. The location with the highest percent of detections was observed at S6 with peak 

concentrations occurring during April, which is the application season for sugarcane 

(Figure 6). 

Results from the NAWQA program (McPherson et al., 2000) for atrazine surface water 

detections at S7 and S6 were very similar to the SFWMD’s detections at the same 

locations. The peak concentrations measured during the NAWQA program also occurred 

during the spring months. However, NAWQA’s highest detected concentration was 12 

μg/L at S6. 

Average annual atrazine concentrations from four northern and four southern boundary 

monitoring locations receiving drainage from the EAA are presented in Figures 7 and 8, 

respectively. Since 1992, a trend towards lower detectable concentrations was observed 
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for the southern and northern locations. A non-parametric regression (Theil) (Hollander, 

1973) identified a significant (p value <0.05) decrease in concentration at all monitoring 

locations except S3 and S6. Theil regression makes no assumptions about the population 

distribution and it does not assume the errors are only in the y-direction or are normally 

distributed. 

The average atrazine annual concentration from six monitoring locations receiving 

drainage from urban areas is presented in Figure 9. A statistically significant (p value 

<0.05) decrease in concentration based on the Theil regression (Hollander, 1973) was 

observed at all stations except S38B, G123, and S9. 

The number of detections of p,p’-DDE in sediment is summarized by location in Table 9. 

Sediment samples were not collected at GORDYRD and CR33.5T due to access 

restrictions. The average concentration at S6, S2, S5A, and S178 for this parameter was 

higher than the PEC (i.e., 31 μg/Kg) suggesting that harmful effects to sediment-dwelling 

organisms are likely to be frequently or always observed at these monitoring locations. 

The locations with the highest percentage of detections and average concentration of 

p,p’-DDE were S5A, S2, S178, S177, S3, and S6 (Table 9 and Figure 10). Using a Theil 

non-parametric regression (Hollander, 1973), significant (p value <0.05) increases in 

concentration were observed at S2 and S3, while a decreasing trend in concentration was 

noted at S178 and S177. The thirteen locations exhibited p,p’-DDE detections 50 percent 

of the time or greater (Table 9) with the majority of sampling locations having average 

concentrations above the TEC (i.e., 3.2 μg/Kg). Only eight locations (S331, L3BRS, 

S191, FECSR78, S9, US41-25, S65E, and S140) did not exceed the TEC. 

Basin Results and Discussion

Three locations (S65E, S191, and FECSR78) were sampled upstream of potential 

discharge into Lake Okeechobee (Figure 11). The agricultural activity in this basin is 

primarily cattle/dairy operations. Atrazine and its major degradation product (atrazine 

desethyl) were the dominant compounds detected in the surface water followed by the 

herbicides bromacil, hexazinone, and simazine (Table 10). However, the average 

concentration for all these compounds were less than 1 ug/L and were appreciably below 

any level of concern for aquatic invertebrates and fish (Table 2). Only p,p’-DDE was 

present with any frequency in the sediments (Table 11). The maximum concentration 

exceeds the Florida freshwater sediment quality assessment guideline TEC but not the 

PEC. A concentration above the TEC but less than the PEC has a potential for harmful 

effects on freshwater sediment dwelling organisms. 

Six monitoring locations (S99, GORDYRD, S80, S78, CR33.5T, and S79) (Figure 12) 

were used to evaluate citrus agriculture drainage. Sampling locations GORDYRD and 

CR33.5T did not have sediment collected for analysis due to access restrictions. A wide 

variety of herbicides and a few insecticides was detected at low concentrations in the 

surface water (Table 12). The herbicides norflurazon, simazine, atrazine, and bromacil 

were most frequently detected. Using a multiple substance risk approach, based on a 

concentration addition model, Schuler and Rand (2008) identified a high risk to plant and 

algal communities at S79, S80, and S99 from the herbicide mixtures detected at the 
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respective locations. 

The chemical of concern when evaluated on a single chemical to potential species 

toxicity is the organophosphate pesticide ethion, particularly at the S99 structure. Ethion 

is a non-systemic acaricide and insecticide previously registered for use on several fruits, 

citrus, and vegetables. Ethion is acutely toxic to aquatic organisms in low part per billion 

ranges (Mayer and Ellersieck, 1986, Table 2) and is slightly toxic to mammals (Hartley 

and Kidd, 1987). Furthermore, it is stable to hydrolytic and photolytic degradation in 

water (Montgomery, 1993). Ethion is strongly adsorbed to soil and therefore can 

accumulate in sediments (Gross and Wauchope, 1992). Ethion can bioconcentrate to a 

limited extent (Lyman et al., 1990). 

However, ethion does not have a state numeric standard. The most sensitive species for 

aquatic macroinvertebrates in acute toxicity tests of ethion is the cladoceran, Daphnia 

magna, with a 48-hour EC50 of 0.06 μg/L (Table 2). The acute and chronic standards are 

0.02 and 0.003 μg/L, respectively, calculated according to the promulgated procedure 

(Section 62-302.200 F.A.C.). Based on these values, excursions of ethion concentration 

above the established acute and chronic standards were observed (Figures 13a-d). Most 

of the surface water detections occurred during the growing season. Additionally, ethion 

detections were not routinely preceded by considerable rainfall. With a method detection 

limit of approximately 0.019 μg/L, any detection will automatically exceed the calculated 

chronic toxicity. At this level, long-term exposure can cause impacts to 

macroinvertebrate populations, but the pulsed nature of agricultural runoff releases to the 

canal system precludes drawing any conclusions about the effects of long-term average 

exposures. Since June 1992, 17 out of 41 sampling events at S99 had a detectable level 

of ethion in the surface water (Figures 13a-d). 

The use of ethion on citrus has been banned (Federal Register, March 22, 2002). By 

December 31, 2004, all use of existing stocks of the end-use products was prohibited. 

With the voluntary cancellation of all registered products and the availability of 

alternative pesticides, the last surface water detection occurred during the August 2001 

sampling event (Figure 13d). A few sediment detections occurred after this time, with 

the last ethion residue quantified during the October 2003 sampling event (Figure 13d). 

In sediment samples from citrus drainage locations, p,p’-DDE was present along with 

ethion, PCB-1254, and p,p’-DDD (Table 13). Dieldrin and PCB-1254 were primarily 

detected at S79. The p,p’-DDE, dieldrin, and all of the PCB compounds had average and 

maximum concentrations that exceeded the Florida freshwater sediment quality 

assessment guideline TEC (Table 13). No sediment guidelines are available for ethion. 

Four locations, S2, S3, S4, and S235 (Figure 14), were used to evaluate drainage from the 

northern portion of the EAA, which is predominately sugarcane production, with some 

row crops such as corn and lettuce (vegetable crops) or rice being grown. The most 

frequently detected pesticides were the herbicides atrazine, ametryn, hexazinone, and 

simazine (Table 14). For all of these, the concentrations were below any levels of 

concern (Table 2). For the sediment samples, p,p’-DDE, p,p’-DDD, p,p’-DDT, 

chlordane, and the herbicide ametryn dominated the number of detections (Table 15). 
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Some of the p,p’-DDE, p,p’-DDD, chlordane, and toxaphene concentrations exceeded the 

PEC guideline. However, no sediment guidelines exist for ametryn. 

Sampling locations S5A, S6, S7, S8, L3BRS, S190, S142, and S140 (Figure 15) were 

used to evaluate surface runoff from the southern portion of the EAA. Structures S142 

and S140 were added to the monitoring network during the February 1997 sampling 

event and therefore the summary data represent only 44 events. The surface water 

pesticide detections in this region consisted primarily of herbicides (Table 16). The 

concentrations were usually less than 1.0 μg/L, with atrazine, simazine, and diuron being 

the exceptions. With the exception of the maximum diuron concentration, none of the 

values exceeded any level of concern (Table 2). The 76 μg/L diuron detection exceeds 

the calculated chronic toxicity value for the invertebrate, Daphnia magna. 

Structures S7 and S8 were the only network sampling locations directly impacted by the 

operation of a Stormwater Treatment Area (STA). Since STA-3/4 was completed in 

December 2004, flows from the North New River Canal are diverted into the over 

16,000-acre treatment area before discharging back to S7 and S8. Within STA-3/4, the 

vegetative communities were designed to provide water quality treatment through an 

emergent macrophyte community as well as submerged aquatic vegetation. A 

comparison of atrazine and ametryn surface water concentrations before and after 

completion of STA-3/4 showed that the average concentration had decreased (Table 17). 

However, the percent of detections had increased. STA-3/4 may have attenuated the 

herbicide concentration peaks and provided a more uniform distribution of the surface 

water residues. 

Herbicides and DDT metabolites were most frequently detected in the sediment samples 

from the southern portion of the EAA (Table 18). Atrazine and ametryn residues in 

sediment corresponded with the consistent surface water detections. The average p,p’-

DDE, p,p’-DDD, p,p’-DDT, PCB-1242, PCB-1254, and PCB-1260 concentrations 

exceeded the TEC while the chlordane concentration exceeded the PEC. 

The majority of the sampling locations that receive drainage from urban areas have been 

recently added to the network (S9, G94D, ACME1DS, G123, S31, and S38B) (Figure 

16). With the exception of water control structure S9 and S31, the remaining locations 

have only been sampled since 1997/1998 and only represent 42 to 45 sampling events. 

After the March 2008 sampling event, the permit mandate for G94D, ACME1DS, and 

S38B was modified, deleting the requirement for sampling. 

A wide variety of pesticides were detected, but the herbicides atrazine (and its major 

degradation products) and ametryn were most frequently detected in surface water, 

followed by hexazinone and simazine (Table 19). Like ethion, diazinon can have an 

acute or chronic toxicity standard calculated based on one-third or one-twentieth of the 

96-hour LC50 for sensitive aquatic species. The most sensitive species is Daphnia magna

(i.e., 48-hour EC50 = 0.8 μg/L; Table 2) and the calculated acute and chronic standards 

are 0.3 and 0.04 μg/L, respectively. For the S38B sampling location, four events 

(9/29/98-0.044; 1/6/99-0.067; 11/8/99-0.059; 8/8/00-0.06; method detection limit for all 

events: 0.019 μg/L) had detectable concentrations above the chronic calculated standard. 
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Whenever diazinon was present, it exceeded the 0.04 μg/L calculated chronic criteria. 

However, the USEPA (USEPA, 2005) derived ambient freshwater quality criteria should 

not affect aquatic organisms if the one-hour average concentration does not exceed 0.17 

μg/L more than once every three years on the average and if the four-day average 

concentration does not exceed 0.017 μg/L more than once every three years on the 

average. 

The most abundant of the measured sediment contaminants for urban basins were p,p’-

DDE and p,p’-DDD (Table 20). The average concentrations of p,p’-DDE and PCB-1016 

exceed the TEC for freshwater sediment. 

The South Miami-Dade County agricultural area supports a wide variety of 

predominately row crops (e.g., tomatoes, beans, and squash) and had five sampling 

locations (S332DX/S176, S177, S178, S18C, and S331) (Figure 17). Endosulfan has 

been identified as the chemical of concern in this area, especially at S178 (Miles and 

Pfeuffer, 1997; Scott et al., 2002; Fulton et al., 2004), although atrazine had the highest 

frequency of detection (Table 21). The maximum atrazine concentration was 

considerably lower than any levels of concern. Scott et al. (2002) reported atrazine 

detections over 92 percent of the time from 1996 to 1997 using a substantially lower 

detection level. Their peak concentration detected for atrazine was similar to the average 

concentration reported by SFWMD. 

Endosulfan is used to control whiteflies on vegetable crops like tomatoes. It is a mixture 

of two insecticidal stereoisomers: alpha endosulfan and beta endosulfan. Endosulfan can 

be oxidized to endosulfan sulfate and hydrolyzed to endosulfan diol. These metabolites 

have been observed in surface waters near agricultural activity (National Research 

Council Canada, 1975). Endosulfan is highly toxic to aquatic organisms (Johnson and 

Finley, 1980; Mayer and Ellersieck, 1986). Furthermore, in a national summary of 

pesticides in coastal areas, endosulfan had the highest hazard rating of pesticides 

inventoried (Pait et al., 1992). 

Endosulfan (alpha and beta) has a promulgated state standard of 0.056 μg/L (Table 2). A 

plot of the complete period of record of endosulfan detections at water control structure 

S178 showed eight endosulfan water quality excursions occurring out of the 67 sampling 

events primarily between early 1993 and 1996 (Figures18a-e). Endosulfan surface water 

detections were not routinely preceded by significant rainfall. Also the majority of the 

endosulfan and endosulfan sulfate surface water detections corresponded with the 

growing season, which runs from September to April. Typically, sediment detections of 

endosulfan occurred after the surface water detections. However, the frequency and 

magnitude of endosulfan detections have decreased since the 1994-95 growing seasons. 

This may be attributed primarily to the availability of an alternative product 

(imidacloprid), grower education, and product label changes. The March 2007 detection 

(Figure 18e) was the last excursion since the February 2000 sampling event (Figure 18c). 

McPherson et al. (2000) reported frequent endosulfan detections at S177 during 1996, but 

no excursions above the state standard. Detections became less frequent in the following 

two years of the monitoring program (McPherson et al., 2000). 
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The DDT family of compounds was most often detected in the sediment in the South 

Miami-Dade County agricultural area along with numerous endosulfan detections (Table 

22). The p,p’-DDE and p,p’-DDD average concentration was greater than the TEC while 

the p,p’-DDE average maximum concentration was greater than the PEC. A 

concentration above the TEC but less than the PEC has a possibility of harmful effects on 

freshwater sediment dwelling organisms. A level above the PEC demonstrates that 

harmful effects to sediment-dwelling organisms are likely to be frequently or always 

observed. No sediment guidelines are available for endosulfan. However, a two-tiered 

ecological risk assessment identified endosulfan as having the highest potential for 

chronic risk to aquatic arthropods at S178 (Carriger et al., 2006). 

The last area of sampling by the SFWMD pesticide monitoring network covered the 

locations (US41-25 and S12A/S12C) (Figure 19) that are considered relatively pristine, 

since these locations are the furthest from any agricultural activity. The water source for 

these structures is primarily the remnant Everglades. These sampling locations are used 

as reference. However, even at these remote locations atrazine was still present (Table 

23). The average maximum concentration however is only 0.52 μg/L, compared to 0.284 

to 6.32 μg/L in agricultural areas. Sampling performed by Miller et al. (1999) at S12D 

over a two year period, detected atrazine concentrations very similar to those detected 

under the SFWMD monitoring program. Although not determined, atmospheric 

deposition may be the most probable source of atrazine detected at these locations 

(USEPA, 2006a). Also present in the sediment at these locations is the ubiquitous p,p’-

DDE as well as PCB-1260 (Table 25). Even at these remote locations, the average 

maximum p,p’-DDE concentration was greater than the TEC. 

Conclusions 

Due to the diverse variety of crops and the extensive spatial coverage of agriculture and 

urban areas as well as the large areal coverage of the monitoring program, no discernable 

pattern of detections was evident unless the data for a specific drainage basin are 

examined. Pesticide detections occur more frequently during the application season for a 

crop or location. Due to this diversity, it is critical that the timing of sampling be varied. 

Although the monitoring was performed on a quarterly basis, sampling could occur any 

time within that quarter. For the surface water sampling events, each month was sampled 

between four and seven times (Figure 2). For the sediment sampling, with the exception 

of September, between two and six sampling events were conducted per month (Figure 

3). This randomness captured the varied periods of pesticide application. 

The level of detection is also critical for data evaluation. As identified for the 

insecticides ethion and diazinon, the concentrations at which a pesticide is of concern can 

be very low. Additionally lower detection limits also reduces the chance of false 

negatives. 

For endosulfan and ethion, SFWMD data were used for the product label changes, which 

restricted or curtailed pesticide application, helping to reduce environmental exposure. 

Additionally, SFWMD data were utilized in nine USEPA Reregistration Eligibility 

Decisions (RED) documents (USEPA, 1996a; USEPA, 1996b; USEPA, 1998c; USEPA, 

1998d; USEPA, 1999; USEPA, 2002b; USEPA, 2003b; USEPA, 2006c; and USEPA, 
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2007). The RED documents summarize the risk assessment conclusions and outline any 

risk reduction measures necessary for a pesticide to continue to be registered in the 

United States. 

Atrazine and its associated degradation products (atrazine desethyl and atrazine 

desisopropyl) were the most frequently detected compounds in the surface water while 

p,p’-DDE (the degradation product of DDT) was most frequently detected in the 

sediment. 

Atrazine was detected at all locations at least once. The top nine locations for detections 

or those with over 90 percent were locations receiving drainage from either the EAA or 

urban areas. However, none of the detected concentrations were at a level of concern as 

they did not exceed the draft ambient aquatic life water quality criterion or the calculated 

acute or chronic toxicity values. Nine of the 14 locations selected for evaluation 

demonstrated a decreasing concentration over time for this reporting period. 

The p,p’-DDE residues were ubiquitous and the majority of sampling locations had 

concentrations that could have harmful effects on freshwater sediment-dwelling 

organisms. Of the 32 locations evaluated, only eight had average location concentrations 

that were less than the TEC (i.e., the value at which sediment concentration should not 

have a harmful effect on sediment-dwelling organisms). The average concentration at 

S6, S2, S5A, and S178 was higher than the PEC, which means that harmful effects to 

sediment-dwelling organisms are likely to be frequently or always observed. Trend 

analysis for these structures, as well as S177 and S3, demonstrated increasing 

concentration at S2 andS3, while decreasing trends were demonstrated at S178 and S177. 

Although lawful uses of DDT in the United States were curtailed by the USEPA in the 

early 1970s (USEPA, 1990), the persistence of its predominant environmental metabolite 

p,p’-DDE, has resulted in residue concentrations that are still at a potentially harmful 

level. 

Since the sediment sampling upstream of the structures was performed at a fixed location, 

it is difficult to determine what the sediment represents due to potential scouring during 

pumping or gate openings. Any sediment accumulation or removal upstream is 

dependent on the operation of the structure. To actually determine contemporary p,p’-

DDE residues being transported by the operation of the canal system, a suspended 

particle trap could be deployed to capture particulate material being transported in the 

canal. This would help identify which pesticides are being transported via suspended 

particulates in the respective canal. Sediment traps could be deployed over a specific 

time period to determine an integrated sediment pesticide contamination. 

To determine exceedances of sediment or water quality criteria, pesticides concentrations 

from grab samples are typically compared to numerical standards or guidelines for 

sediment or water. However, specific criteria are lacking for most of the pesticides. 

Calculated criteria are based on the lowest acute toxicity value from the most sensitive 

aquatic species tested in a short-term test. However, these values are often from species 

that are not native to south Florida ecosystems. In general, aquatic databases are limited 

for native species. 
12

Additionally, pesticide detections frequently occur with more than one compound at a 

time. The most frequently detected pesticides in surface water were the triazine 

herbicides, while the DDT family was most often detected in the sediment. Although 

evaluated on a single compound to a single species criterion, a discernable impact is not 

always evident. However, if the same family of compounds is detected, a synergistic or 

cumulative impact may be occurring. The current approach can be used to screen for 

chemicals of potential ecological concern. Probabilistic distributions of the detected 

concentrations could be compared to a probability distribution of effects data from 

relevant species. The resulting species sensitivity distributions could be used to 

characterize acute and chronic effects and the susceptibility of organism to different 

chemical stressors. This would determine what fraction of species is expected to be 

potentially affected above its acute or chronic effect level at a given environmental 

concentration. 
13

References 

Carriger, J.F., G.M. Rand, P.R. Gardinali, W.B. Perry, M.S. Tompkins, and A.M. 

Fernandez. 2006. Pesticides of Potential Ecological Concern in Sediment from South 

Florida Canals: An Ecological Risk Prioritization for Aquatic Arthropods. Soil and 

Sediment Contamination. 15:21-45. 

Davis, R.A. (Ed.). 1970. Water Quality Criteria Data Book; Vol I-Organic Chemical 

Pollution of Freshwater. Prepared for the USEPA, Water Pollution Control Research 

Series 18010DPV12/70, Arthur D. Little, Inc. Cambridge, MA. 

Federal Register: March 22, 2002 Volume 67, Number 56. pp. 13327 – 13328. 

Fulton, M.H., G.I. Scott, M.E. DeLorenzo, P.B. Key, D.W. Bearden, E.D. Strozier, and 

C.J. Madden. 2004. Surface Water Pesticide Movement from the Dade County 

Agricultural Area to the Everglades and Florida Bay via the C-111 Canal. Bulletin of 

Environmental Contamination and Toxicology. 73:527-534. 

Goss, D. and R. Wauchope. (Eds.). 1992. The SCS/ARS/CES Pesticide Properties 

Database: II Using It With Soils Data In A Screening Procedure. Soil Conservation 

Service. Fort Worth, TX. 

Hartley, D. and H. Kidd. (Eds.). 1987. The Agrochemicals Handbook. Second Edition, 

The Royal Society of Chemistry. Nottingham, England. 

Hollander, M. 1973. Nonparametric Statistical Methods. John Wiley and Sons, Inc. pp. 

200 – 208. 

Johnson, W.W. and M.T. Finley. 1980. Handbook of Acute Toxicity of Chemicals to Fish 

and Aquatic Invertebrates. U.S. Department of the Interior, Fish and Wildlife Service 

Resource Publication 137. Washington, DC. 

Lyman, W.J., W.F. Reehl, and D.H. Rosenblatt. 1990. Handbook of Chemical Property 

Estimation Methods. American Chemical Society, Washington, DC. 

MacDonald Environmental Sciences Ltd. and United States Geological Survey. 2003. 

Development and Evaluation of Numerical Sediment Quality Assessment Guidelines for 

Florida Inland Waters. Report to Florida Department of Environmental Protection. 

Tallahassee, FL. 

Mayer, F.L. and M.R. Ellersieck. 1986. Manual of Acute Toxicity: Interpretation and 

Database for 410 Chemicals and 66 Species of Freshwater Animals. United States Fish 

and Wildlife Service, Publication No. 160. 

McPherson, B.F., R.L. Miller, K.H. Haag, and A. Bradner. 2000. Water Quality in 

Southern Florida, 1996-98: U.S. Geological Survey Circular 1207, 32 p. 
14

Miles, C.J. and R. J. Pfeuffer. 1997. Pesticides in canals of South Florida. Archives 

Environmental Contamination and Toxicology. 32, 337-45. 

Miller, R.L., B.F. McPherson, and K.H. Haag. 1999. Water Quality in the Southern 

Everglades and Big Cypress Swamp in the Vicinity of the Tamiami Trail, 1996-97. U.S. 

Geological Survey Water-Resources Investigation Report 99-4062, 16 p. 

Montgomery, J.H. 1993. Agrochemicals Desk Reference: Environmental Data. Lewis 

Publishers. Chelsea, MI. 

National Research Council Canada. 1975. Endosulfan: Its Effects on Environmental 

Quality. NRCC No. 14098. Ottawa, Canada. 

Pait, A.S., A. E. De Souza, and D.R.G., Farrow. 1992. Agricultural pesticide in coastal 

areas: a national summary. Report for Strategic Environmental Assessment Division, 

Office of Ocean Resources Conservation and Assessment, National Ocean Service, 

NOAA: Rockville, MD. 81 p. 

Pfeuffer, R.J. 1985. Pesticide Residue Monitoring in Sediment and Surface Water Within 

the South Florida Water Management District. Technical Publication 85-2, DRE 214, 

South Florida Water Management District, West Palm Beach, FL. 

Pfeuffer, R.J. 1991. Pesticide Residue Monitoring in Sediment and Surface Water Within 

the South Florida Water Management District: Volume 2. Technical Publication 91-01, 

DRE 293, South Florida Water Management District, West Palm Beach, FL. 

Schneider, B.A. (Ed.) 1979. Toxicology Handbook, Mammalian and Aquatic Data, Book 

1: Toxicology Data. U.S. Environmental Protection Agency. U.S. Government Printing 

Office. Washington, DC. USEPA-5400/9-79-003. 

Schuler L.J. and G.M. Rand. 2008. Aquatic Risk Assessment of Herbicides in Freshwater 

Ecosystems of South Florida, Archives Environmental Contamination and Toxicology.

54, No. 4. 

Scott G.I., M.H. Fulton, E.F. Wirth, G.T. Chandler, P.B. Key, J.W. Daugomah, D. 

Bearden, K.W. Chung, E.D. Strozier, M. DeLorenzo, S. Sivertsen, A. Dias, M. Sanders, 

J.M. MaCauley, L.R. Goodman, M.W. LaCroix, G.W. Thayer, and J. Kucklick. 2002. 

Toxicological Studies in Tropical Ecosystems: an Ecotoxicological Risk Assessment of 

Pesticide Runoff in South Florida Estuarine Ecosystems. Journal Agricultural and Food 

Chemistry 50, 4400-4408. 

South Florida Water Management District. 2008. Field Sampling Quality Manual, 

SFWMD-FIELD-QM-001-04, effective date May 30, 2008. 

United States Environmental Protection Agency. 1972. Effects of Pesticides in Water: A 

Report to the States. U.S. Government Printing Office. Washington, DC. 
15

_____ 1977. Silvacultural Chemicals and Protection of Water Quality. Seattle, WA. 

EPA-910/9-77-036. 

_____ 1990. Suspended, Cancelled, and Restricted Pesticides. Pesticides and Toxic 

Substances, 20T-1002, February 1990. 

_____ 1991. Pesticide Ecological Effects Database. Ecological Effects Branch, Office of 

Pesticide Programs, Washington, DC. 

_____ 1994a. Reregistration Eligibility Decision (RED) Hexazinone, EPA 738-R-94-022. 

September 1994. 

_____ 1994b. Reregistration Eligibility Decision (RED) Metalaxyl, EPA 738-R-94-017. 

September 1994. 

_____1996a. Registration Eligibility Decision Norflurazon List A Case 0229. 

_____ 1996b. Registration Eligibility Decision (RED) Bromacil. EPA 738-R-96-013. 

August 1996. 

_____ 1996c. Registration Eligibility Decision (RED) Prometryn. EPA 738-R-95-033. 

February 1996. 

_____ 1998a. Transmittal of EFAD (Environmental Fate and Effects Division) List A 

Summary Report for Ethion (Chemical #58401) Case #0090. August 7, 1998. 

_____ 1998b. Reregistration Eligibility Decision (RED) Metribuzin. EPA 738-R-97-006. 

February 1998. 

_____ 1998c. Reregistration Eligibility Decision (RED) Dicofol. EPA 738-R-98-018. 

November 1998. 

_____ 1998d. Reregistration Eligibility Decision (RED) Methomyl. EPA 738-R-98-021. 

December 1998. 

_____ 1998e. Reregistration Eligibility Decision (RED) Alachlor. EPA 738-R-98-020. 

December 1998. 

_____ 1999. Reregistration Eligibility Decision (RED) Chlorothalonil EPA 738-R-99-

004. April 1999. 

_____ 2002a. Reregistration Eligibility Decision for Endosulfan. EPA 738-R-02-013. 

November 2002. 

_____ 2002b. Interim Reregistration Eligibility Decision (IRED) Fenamiphos. EPA 738-

R-02-004. May 2002. 
16

_____ 2002c. Interim Reregistration Eligibility Decision for Chlorpyrifos; EPA 738-R01-007. February 2002. 

_____ 2002d. Interim Reregistration Eligibility Decision for Naled; EPA 738-R-02-008. 

January 2002. 

_____ 2003a. Ambient Aquatic Life Water Criteria for Atrazine. Revised Draft EPA822-R-03-023. October 2003. 

_____ 2003b. Reregistration Eligibility Decision (RED) for Diuron. September 30, 2003. 

_____ 2004. Interim Reregistration Eligibility Decision Diazinon. EPA 738-R-04-006. 

May 2004. 

_____ 2005. Aquatic Life Ambient Water Quality Criteria, Diazinon Final. EPA-822-R05-0906. December 2005. 

_____ 2006a. Decisions Document for Atrazine. 

_____ 2006b. National Recommended Water Quality Criteria. Office of Water and 

Office of Science and Technology. 

_____ 2006c. Addendum to the 2001 Ethoprop Interim Reregistration Eligibility 

Decision (IRED) EPA 738-R-06-018. February 2006. 

_____ 2007. Appendix 1 to 2007 Addendum: Environmental Fate and Ecological Risk 

Assessment of Endosulfan EPA-HQ-OPP-2002-0262-0063.1. October 2007. 

Verschueren, K. 1983. Handbook of Environmental Data on Organic Chemicals. Second 

Edition, Van Nostrand Reinhold Co. Inc. New York, NY. 
17

Figure 1. South Florida Water Management District Pesticide Monitoring Network. 
18

Table 1. Pesticides determined in samples taken by the South Florida Water Management 

District ambient pesticide monitoring network. 

Pesticide Surface Water Sediment Pesticide Surface Water Sediment 

Chlorinated (phenoxy acid) Herbicides Organochlorine Pesticides 

2,4-D X X aldrin X X 

2,4,5-T X X alpha hexachlorocyclohexane (BHC) X X 

2,4,5-TP (silvex) X X beta hexachlorocyclohexane (BHC) X X 

acifluorfen X(1) X(2) delta hexachlorocyclohexane (BHC) X X 

Urea Herbicides and Imidacloprid gamma BHC (lindane) X X 

diuron X X carbophenothion X X 

linuron X X chlordane X X 

imidacloprid X(3) - chlorothalonil X X 

Organonitrogen and Phosphorus Pesticides cypermethrin X X(6)

alachlor X X p,p’-DDD X X 

ametryn X X p,p’-DDE X X 

atrazine X X p,p’-DDT X X 

atrazine desethyl X(4) - dicofol (kelthane) X X 

atrazine desisopropyl X(4) - dieldrin X X 

azinphos methyl (guthion) X X alpha endosulfan X X 

bromacil X X beta endosulfan X X 

butylate X - endosulfan sulfate X X 

chlorpyrifos ethyl X X endrin X X 

chlorpyrifos methyl X X endrin aldehyde X X 

demeton X X heptachlor X X 

diazinon X X heptachlor epoxide X X 

disulfoton X X methoxychlor X X 

ethion X X mirex X X 

ethoprop X X permethrin X X(6)

fenamiphos X X PCB-1016 X X 

fonophos X X PCB-1221 X X 

hexazinone X(7) X(7) PCB-1232 X X 

malathion X X PCB-1242 X X 

metalaxyl X - PCB-1248 X X 

methamidophos X(5) X PCB-1254 X X 

metolachlor X X PCB-1260 X X 

metribuzin X X toxaphene X X 

mevinphos X X trifluralin X X 

monocrotophos X(5) X Dipyridillium Herbicides 

naled X(8) X(8) paraquat X(5) X(5)

norflurazon X(7) X(7) diquat X(5) X(5)

parathion ethyl X X Water Soluble Pesticides 

parathion methyl X X acephate X(5) - 

phorate X X dimethoate X(5) - 

prometon X(6) - monocrotophos X(5) X 

prometryn X X Phosphonoglycine Herbicide 

simazine X X glyphosate X(5) - 

Carbamates Benzimidazole Fungicide 

aldicarb X(5) X(5) benomyl X(5) X(5)

carbaryl X(5) X(5) Ethylenebisdithiocarbamate Degradation Product 

carbofuran X(5) X(5) ethylene thiourea X(5) - 

methomyl X(5) X(5)

oxamyl X(5) X(5)

Compounds in italics have a Florida Administrative Code 62-302 Water Quality Class I or III criterion. 

- : pesticide not analyzed in matrix 

(1) added November 2002 sampling event 

(2) added May 2001 sampling event 

(3) added February 1997 sampling event 

(4) added November 1999 sampling event 

(5) not analyzed after May 1997 sampling event 

(6) added December 2001 sampling event 

(7) added December 1994 sampling event 

(8) added March 2001 sampling event
Table 2. Freshwater surface water quality criteria and toxicity of selected pesticides to freshwater aquatic invertebrates an

* CMC (criteria maximum concentration) is the highest concentration of a pollutant in surface water to which aquatic life can be exposed for a short period of time (1-hour average) without deleterious effec

** CCC (criteria continuous concentration) is the highest concentration of a pollutant in surface water to which aquatic life can be exposed for an extended period of time (4 days) without deleterious effects *** Florida Administrative Code Section 62-302.200, for compounds not specifically listed, acute and chronic toxicity standards are calculated as one-third and one-twentieth, respectively, of the amount let

hours, where the 96 hour LC50 is the lowest value which has been determined for a species significant to the indigenous aquatic community. 

(1) Johnson and Finley, 1980; (2) Schneider, 1979; (3) USEPA, 1972; (4) Hartley and Kidd, 1987; (5) Montgomery, 1993; (6) Verschueren, 1983; (7) USEPA, 1991; (8) Mayer and Ellersieck, 1986; (9) USE

USEPA, 2003b; (12) USEPA, 2002a; (13) USEPA, 1994a; (14) USEPA, 1994b; (15) USEPA, 1998a; (16) USEPA, 1998b; (17) USEPA, 1996a; (18) USEPA, 1996b; (19) USEPA, 2006b; (20) USEPA, 2001970; (23) USEPA, 1996c; (24) USEPA, 1998e; (25) USEPA, 2002d 

Pesticide 

Florida Administrative 

Code 62-302 

USEPA(19) Water Flea

Daphnia magna

Bluegill

Lepomis macrochirus

Largemouth Bass

Micropterus salmoides

Class I Class III CMC* CCC** 48 hr EC50 Acute 

Toxicity***

Chronic 

Toxicity***

96 hr LC50 Acute 

Toxicity 

Chronic 

Toxicity 

96 hr LC50 Acute 

Toxicity

Chron

Toxic

2,4-D ≤ 100 - - - 25,000 (9) 8,333 1,250 180,000 (8) 60,000 9,000 - - - 

- - - 900 (48 hr) (6) 113 25 - - - 

alachlor - - - - 21,000 (7) 7,000 1,050 2,800 (4) 933 140 - - - 

10,000 (24) 3,333 500 4,300 (24) 1,433 215 - - - 

ametryn - - - - 28,000 (7) 9,333 1,400 4,100 (4) 1,367 205 - - - 

atrazine - - - - 6,900 (7) 2,300 345 16,000 (4) 5,333 800 - - - 

bromacil - - - - - - - 127,000 (7) 42,333 6,350 - - - 

121,000 (18) 40,333 6,050 127,000 (18) 42,333 6,350 - - - 

chlorpyrifos 

(ethyl) 

- - 0.083 0.041 1.7 (7) 0.57 0.085 2.6 (4) 0.87 0.13 - - - 

0.1 (7) 0.03 0.005 5.8 (7) 1.9 0.3 - - - 0.1 (20) 0.03 0.005 1.8 (20) 0.6 0.1 - - - 

diazinon - - 0.17 0.17 0.8 (1) 0.3 0.04 168 (1) 56 8.4 - - - 

0.9 (3) 0.3 0.045 165 (2) 55 8.3 - - - 

- - - 16,000 (4) 5,333 800 - - - 

0.83 (10) 0.28 0.04 460 (10) 153 23 - - - 

diuron - - - - 1,400 (7) 457 70 5,900 (4) 1,967 295 - - - 

1,400 (11) 457 70 - - - - - - 

endosulfan ≤ 0.056 ≤ 0.056 0.22 0.056 166 (7) 55 8 1 (1) 0.3 0.05 - - - 

- - - 2 (2) 0.67 0.10 - - - 

166 (12) 55 8 1.7 (12) 0.57 0.09 - - - 

ethion - - - - 0.06 (1) 0.02 0.003 210 (1) 70 11 173 (1) 58 9 

- - - 13 (2) 4.3 0.65 150 (3) 50 8 - - - 22 (3) 7.3 1.1 - - - 

0.056 (15) 0.02 0.003 210 (15) 70 11 173 (15) 58 9 

ethoprop - - - - 93 (7) 31 4.7 - - - - - - 

hexazinone - - - - 151,600 (7) 50,533 7,580 100,000 (7) 33,333 5,000 - - - 

151,600 (13) 50,533 7,580 505,000 (13) 168,333 25,250 - - - 

malathion ≤ 0.1 ≤ 0.1 - 0.1 1 (1) 0.3 0.05 103 (1) 34 5.2 285 (1) 95 14 

1.8 (3) 0.6 0.09 100 (21) 37 5.5 - - - 

 12 (22) 4 0.6 - - - 

metalaxyl - - - - 28,000 (7) 9,333 1,400 139,000 (7) 46,333 6,950 - - - 

29,000 (14) 9,667 1,450 139,000 (7) 46,333 6,950 - - - 

metolachlor - - - - 23,500 (7) 7,833 1,175 15,000 (4) 5,000 750 - - - 

metribuzin - - - - 4,200 (7) 1,400 210 80,000 (4) 26,667 4,000 - - - 

4,200 (16) 1,400 210 75,900 (16) 25,300 3,795 - - - 

naled - - - - 0.3 (25) 0.1 0.02 2,200 (25) 733 110 1,900 (25) 633 95 

norflurazon - - - - 15,000 (7) 5,000 750 16,300 (7) 5,433 815 - - - 

>15,000 (17) >5,000 >750 16,300 (17) 5,433 815 - - - 

prometryn - - - - 18,590 (23) 6,197 930 10,000 (23) 3,333 500 - - - 

prometon - - - - - - - 40,000 (5) 13,333 2,000 - - - 

simazine - - - - 1,100 (7) 367 55 90,000 (4) 30,000 4,500 - - - 
20

Table 3. Freshwater sediment assessment guidelines (1). 

Parameter Threshold Effect 

Concentration(2) 

(μg/Kg) 

Probable Effect 

Concentration(3)

(μg/Kg) 

atrazine 0.30 NG 

azinphos ethyl 0.018 NG 

azinphos methyl 0.062 NG 

total chlordane 3.2 18 

diazinon 0.38 NG 

dieldrin 1.9 62 

sum DDD 4.9 28 

sum DDE 3.2 31 

sum DDT 4.2 63 

total DDT 5.3 570 

endrin 2.2 210 

heptachlor epoxide 2.5 16 

lindane 2.4 5.0 

malathion 0.67 NG 

simazine 0.34 NG 

toxaphene 0.10 32 

total PCB’s 60 680 

NG: no guideline 

(1) MacDonald Environmental Sciences, Ltd. and United States Geological Survey (2003) 

(2) Threshold Effect Concentration: The threshold effect concentration is intended to identify concentrations 

below which harmful effects on freshwater sediment–dwelling organisms are unlikely to be observed. 

(3) Probable Effect Concentration: The probable effect concentration is intended to identify concentrations 

above which harmful effects on freshwater sediment-dwelling organisms are likely to be frequently or 

always observed. 

Table 4. Number of pesticide detections per sampling event. 

 Higher Detection Levels 

April 1992 to September 1994 

Lower Detection Levels 

December 1994 to December 2007 

Surface Water Sediment Surface Water Sediment 

Number of 

Sampling 

Events 

15 4 53 26 

Average 

Number of 

Detections 

22 32 84 30 

Percent 

Detections 1.2 2.2 3.7 1.5 

 
21

Table 5. Number of pesticides detected during a surface water sampling event by location 

from April 1992 to December 2007. 

Land Use or 

Drainage Basin 

Type 

Location Average Number of 

Pesticides Detected 

per Sampling Event 

Median Number of 

Pesticides Detected 

per Sampling Event 

Lake Okeechobee 

inflow 

S65E 1 1 

S191 1 1 

FECSR78 1 1 

citrus S99 3 3 

GORDYRD 3 3 

S80 3 3 

CR33.5T 5 5 

S78 4 4 

S79 5 5 

northern EAA S2 3 3 

S3 3 3 

S4 3 3 

S235 3 3 

southern EAA S5A 3 3 

S6 3 3 

S7 2 2 

S8 2 2 

L3BRS 2 2 

S190 2 2 

S142 2 2 

S140 2 2 

urban S9 1 1 

G94D 3 3 

ACME1DS 3 3 

G123 1 1 

S31 1 1 

S38B 3 4 

South Miami-Dade 

County 

S332DX/S176 1 1 

S177 1 1 

S178 2 2 

S18C 1 1 

S331 1 1 

reference US421-25 0 0 

S12A/S12C 1 1 

EAA: Everglades Agricultural Area

 
22

Figure 2. Average percentage of pesticide surface water detections by month sampled 

(April 1992 to December 2007). 

Figure 3. Average percentage of pesticide sediment detections by month sampled (April 

1992 to December 2007). 

 

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0

1

2

3

4

5

6

7

8

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Percent Detection

Number Sampling Events

Month

number sampling events average percent detection monthly average

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

0

1

2

3

4

5

6

7

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Percent Detection

Number Sampling Events

Month

number sampling events average percent detection monthly average
23

Table 6. Twenty most frequently detected pesticides and degradation products 

in surface water (April 1992 to December 2007). 

Action Pesticide or 

Degradation Product 

Number Detections Number Sampling 

Events With No 

Detections 

herbicide atrazine 1,517 0 

herbicide ametryn 714 0 

herbicide simazine 472 1 

 atrazine desethyl 448 0 

herbicide norflurazon 397 0 

herbicide hexazinone 364 3 

herbicide bromacil 342 3 

 atrazine desisopropyl 173 6 

herbicide diuron 97 28 

insecticide alpha endosulfan 82 38 

 endosulfan sulfate 81 19 

herbicide metolachlor 58 36 

insecticide beta endosulfan 42 44 

herbicide 2,4-D 30 47 

insecticide ethion 27 45 

insecticide ethoprop 22 56 

herbicide metribuzin 18 53 

insecticide metalaxyl 15 54 

insecticide diazinon 15 56 

herbicide prometon 11 19 
24

Table 7. Twenty most frequently detected pesticides and degradation products in 

sediment (April 1992 to December 2007). 

Action Pesticide or 

Degradation Product

Number Detections Number Sampling 

Events With No 

Detections 

 p,p’-DDE 367 0 

insecticide p,p’-DDD 150 1 

herbicide ametryn 92 3 

 PCB-1254 41 9 

insecticide p,p’-DDT 32 7 

insecticide beta endosulfan 26 12 

 endosulfan sulfate 26 11 

insecticide ethion 24 13 

insecticide chlordane 23 15 

herbicide atrazine 22 17 

insecticide alpha endosulfan 18 16 

insecticide dieldrin 15 19 

 PCB-1260 11 20 

insecticide dicofol 10 27 

herbicide diquat 9 8 

herbicide bromacil 8 25 

herbicide norflurazon 7 20 

 PCB-1242 5 27 

herbicide diuron 5 27 

 PCB-1016 3 28 

insecticide aldrin 3 27 
25

Table 8. Atrazine surface water detection summary by sampling location from April 1992 

to December 2007. 

Location Drainage Basin Type Percent 

Detections 

Number 

of Times 

Sampled 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

S6 southern EAA 97 67 0.88 6.8 

S38B urban 95 40 1.42 4.4 

ACME1DS urban 95 42 0.21 1.3 

G94D urban 95 43 0.20 1.5 

S3 northern EAA 94 68 0.26 0.78 

S5A southern EAA 93 67 1.07 11 

S4 northern EAA 91 68 0.56 7.1 

S2 northern EAA 91 68 0.41 4.9 

S7 southern EAA 90 67 0.86 18 

S78 citrus 90 68 0.36 2.2 

S235 northern EAA 88 68 0.48 8.5 

S8 southern EAA 87 67 1.01 12 

CR33.5T citrus 87 68 0.67 12 

S79 citrus 85 68 0.36 2.3 

S142 southern EAA 83 43 0.13 0.58 

G123 urban 71 40 0.14 1.9 

S80 citrus 68 68 0.17 1 

L3BRS southern EAA 66 67 0.24 1.7 

S331 South Miami-Dade County 64 43 0.04 0.22 

S65E Lake Okeechobee inflow 60 68 0.07 0.2 

S31 urban 57 67 0.2 1.5 

S9 urban 54 67 0.101 0.32 

S12A/S12C reference 53 67 0.08 0.93 

S140 southern EAA 53 43 0.062 0.17 

S332DX/S178 South Miami-Dade County 50 67 0.062 0.4 

S18C South Miami-Dade County 50 67 0.049 0.31 

S177 South Miami-Dade County 47 67 0.058 0.4 

S191 Lake Okeechobee inflow 46 68 0.08 0.4 

S190 southern EAA 46 67 0.063 0.32 

S178 South Miami-Dade County 46 67 0.035 0.089 

FECSR78 Lake Okeechobee inflow 40 68 0.07 0.26 

US41-25 reference 21 67 0.023 0.10 

S99 citrus 9 68 0.018 0.032 

GORDYRD citrus 3 33 0.03 0.03 

EAA: Everglades Agricultural Area 
26

Figure 4. Atrazine surface water concentrations detected at S7. 

Figure 5. Atrazine surface water concentrations detected at S38B. 

0

2

4

6

8

10

12

14

16

18

20

Concentration (μg/L)

Date

0

0.5

1

1.5

2

2.5

3

3.5

Concentration (μg/L)

Date
27

Figure 6. Atrazine surface water concentrations detected at S6. 

Figure 7. Annual atrazine surface water concentrations at locations receiving drainage 

from the northern Everglades Agricultural Area. 

 

0

1

2

3

4

5

6

7

Concentration (μg/L)

Date

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

Average Annual Concentration (μg/L)

Year

S2 S3 S4 S235
28

Figure 8. Annual atrazine surface water concentrations at selected locations receiving 

drainage from the southern Everglades Agricultural Area. 

Figure 9. Annual atrazine surface water concentrations at locations receiving drainage 

from urban areas. 

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

Average Annual Concentration (μg/L)

Year

S5A S6 S7 S8

0

0.25

0.5

0.75

1

1.25

1.5

1.75

2

2.25

Average Annual Concentration (μg/L)

Year

S38B ACME1DS G94D G123 S31 S9
29

Table 9. Summary of p,p’-DDE sediment detections by sampling location from April 

1992 to December 2007. 

Location Percent 

Detections 

Number of 

Times 

Sampled 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

S5A 93 30 53 300 

S2 90 30 78 393 

S178 90 30 40 89

S177 87 30 21.6 70 

S3 83 30 26 92

S6 77 30 98 390

S4 73 30 19.3 58

S31 70 30 9.8 21

S79 63 30 9.9 18

S80 63 30 6.2 11

S8 53 30 4.5 13

S7 50 30 11 55

G94D 50 22 4.4 10

S332DX/S176 33 30 5 18

ACME1DS 48 21 4.3 7.9

S142 41 22 8 21

S99 23 30 4.5 11

S18C 23 30 3.5 8.7

S331 32 22 2.6 3.9

S190 20 30 4.6 15

L3BRS 13 30 2.7 3.4

G123 15 20 6.9 11

S78 10 30 3.2 4.5

S191 10 30 2.9 4.7

S235 7 30 10 18

S12A/S12C 7 30 4.3 6.3

S38B 5 19 4.6 4.6

FECSR78 3 30 2.8 2.8 

S9 3 29 2.2 2.2 

US41-25 3 30 1.4 1.4 

S65E 0 30 0 0 

S140 0 22 0 0 

Italicized values exceed the Threshold Effect Concentration (TEC): 3.2 μg/Kg

Bold values exceed the Probable Effect Concentration (PEC): 31 μg/Kg)

(MacDonald Environmental Sciences, Ltd. and United States Geological Survey, 2003) 
Figure 10. Biannual p,p’-DDE sediment concentrations from selected locations from April 1992 to December 20

0

50

100150200250300350400

Concentration (μg/Kg)

Date

S5A S2 S178 S177 S3 S6 Threshold Effect Concentration 
31

Figure 11. Lake Okeechobee basin sampling locations. 
32

Table 10. Surface water pesticide detections for Lake Okeechobee basin sampling 

locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 99 0.08 0.40 0.05 0.06 

bromacil 57 0.11 1.2 0.08 0.08 

hexazinone 37 0.13 1.3 0.07 0.06 

atrazine 

desethyl 

25 0.02 0.042 0.023 0.023 

simazine 24 0.06 0.50 0.04 0.03 

norflurazon 15 0.07 0.16 0.05 0.05 

2,4-D 5 0.96 3.3 0.80 0.79 

metolachlor 5 0.10 0.24 0.09 0.08 

ametryn 2 0.034 0.049 0.034 0.034 

metribuzin 2 0.052 0.071 0.048 0.052 

Table 11. Sediment pesticide detections for Lake Okeechobee basin sampling locations 

from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 4 2.8 4.7 3.2 31 

diquat 2 940 1100 - - 

Italicized values exceed the Threshold Effect Concentration (TEC) 

- No guideline available
33

Figure 12. Citrus agriculture sampling locations. 
34

Table 12. Surface water pesticide detections for citrus agriculture sampling locations 

from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

norflurazon 264 0.48 3.9 0.34 0.35 

simazine 258 0.22 7.3 0.08 0.07 

atrazine 231 0.27 12 0.13 0.13 

bromacil 208 0.64 8.6 0.31 0.32 

atrazine 

desethyl 

101 0.03 1.0 0.024 0.022 

hexazinone 94 0.041 0.75 0.029 0.024 

ametryn 85 0.03 0.21 0.022 0.018 

diuron 67 0.99 16 0.51 0.49 

atrazine 

desisopropyl 

60 0.02 0.13 0.02 0.02 

ethion 25 0.11 0.83 0.065 0.055 

metolachlor 12 0.16 1.2 0.11 0.11 

metalaxyl 9 0.09 0.21 0.11 0.10 

2,4-D 6 1.96 4.1 1.7 1.7 

endosulfan 

sulfate 

4 0.027 0.048 0.026 0.027 

malathion 4 0.06 0.14 0.053 0.048 

alpha 

endosulfan 

3 0.0036 0.0065 0.0031 0.0022 

metribuzin 3 0.04 0.056 0.041 0.041 

beta 

endosulfan 

2 0.0043 0.0052 0.0043 0.0043 

ethoprop 2 0.036 0.039 0.036 0.036 
Figure 13a. Ethion detections in surface water at S99 from March 1992 to March 1995. 

7-Day Antecendent Rainfall, Inches

0123456

growing seasonsampling event7-day antecendent rainfall

Ethion in Surface Water, μg/L

0.00.10.20.30.4

growing seasonsampling eventethionethion 48 hr EC50 Daphnia magnaethion calculated acute toxicityethion calculated chronic toxicity

Mar-92

Jun-92

Sep-92

Dec-92

Mar-93

Jun-93

Sep-93

Dec-93

Mar-94

Jun-94

Sep-94

Dec-94

Ethion in Sediment, μg/Kg

0

1020304050

growing seasonsampling eventethion
Figure 13b. Ethion detections in surface water at S99 from March 1995 to March 1998. 

7-Day Antecendent Rainfall, Inches

0123456

growing seasonsampling event7-day antecendent rainfall

Ethion in Surface Water, μg/L

0.00.10.20.30.4

growing seasonsampling eventethionethion 48 hr EC50 Daphnia magnaethion calculated acute toxicityethion calculated chronic toxicity

Mar-95

Jun-95

Sep-95

Dec-95

Mar-96

Jun-96

Sep-96

Dec-96

Mar-97

Jun-97

Sep-97

De

Ethion in Sediment, μg/Kg

0

1020304050

growing seasonsampling eventethion
Figure 13c. Ethion detections in surface water at S99 from March 1998 to May 2001. 

7-Day Antecendent Rainfall, Inches

0123456

growing seasonsampling event7-day antecendent rainfall

Ethion in Surface Water, μg/L

0.00.10.20.30.4

growing seasonsampling eventethionethion 48 hr EC50 Daphnia magnaethion calculated acute toxicityethion calculated chronic toxicity

Mar-98 

Jun-98 

Sep-98 

Dec-98

Mar-99 

Jun-99 

Sep-99 

Dec-99 

Mar-00 

Jun-00 

Sep-00 

Dec

Ethion in Sediment, μg/Kg

0

1020304050

growing seasonsampling eventethion
Figure 13d. Ethion detections in surface water at S99 from June 2001 to May 2004. 

7-Day Antecendent Rainfall, Inches

0123456

growing seasonsampling event7-day antecendent rainfall

Ethion in Surface Water, μg/L

0.00.10.20.30.4

growing seasonsampling eventethionethion 48 hr EC50 Daphnia magnaethion calculated acute toxicityethion calculated chronic toxicity

Jun-01

Sep-01

Dec-01

Mar-02

Jun-02

Sep-02

Dec-02

Mar-03

Jun-03

Sep-03

Dec-03

Ethion in Sediment, μg/Kg

0

1020304050

growing seasonsampling eventethion
39

Table 13. Sediment pesticide detections for citrus agriculture sampling locations from 

April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 41 6.4 18 3.2 31 

ethion 20 9.8 46 - - 

PCB-1254 20 133 290 60 680 

p,p’-DDD 11 4 11 4.9 28 

norflurazon 7 17.9 15 - - 

dicofol 5 12.9 26 - - 

dieldrin 5 7.0 11 1.9 62 

diuron 2 19.5 21 - - 

PCB-1242 2 79.5 89 60 680 

Italicized values exceed the Threshold Effect Concentration (TEC) 

- No guideline available 
40

Figure 14. Everglades Agricultural Area northern sampling locations. 

 
41

Table 14. Surface water pesticide detections for Everglades Agricultural Area northern 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 248 0.43 8.5 0.24 0.23 

ametryn 174 0.11 1.0 0.05 0.05 

atrazine 

desethyl 

110 0.03 0.1 0.028 0.029 

hexazinone 80 0.03 0.41 0.03 0.03 

simazine 65 0.06 0.79 0.03 0.02 

atrazine 

desisopropyl 

36 0.02 0.079 0.015 0.014 

norflurazon 15 0.11 1.3 0.07 0.07 

bromacil 12 0.13 1.1 0.09 0.08 

ethoprop 12 0.07 0.22 0.05 0.06 

metolachlor 7 0.30 1.4 0.17 0.14 

diazinon 3 1.05 1.9 1.0 1.0 

diuron 3 0.61 0.8 0.6 0.6 

2,4-D 2 3.1 4.9 3.1 3.1 

chlorpyrifos 

ethyl 

2 0.051 0.085 0.051 0.051 

metribuzin 2 0.021 0.022 0.021 0.021 

 
42

Table 15. Sediment pesticide detections for Everglades Agricultural Area northern 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 76 33 393 3.2 31 

p,p’-DDD 57 12 80 4.9 28 

ametryn 39 20 56 - - 

p,p’-DDT 12 14 78 4.2 63 

chlordane 10 64 260 3.2 18 

atrazine 6 8 17 - - 

dieldrin 4 7 20 1.9 62 

aldrin 2 7 11 - - 

PCB-1254 2 66 82 60 680 

Italicized values exceed the Threshold Effect Concentration (TEC) 

Bold values exceed the Probable Effect Concentration (PEC) 

- No guideline available 
43

Figure 15. Everglades Agricultural Area southern sampling locations. 

 
44

Table 16. Surface water pesticide detections for Everglades Agricultural Area southern 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 378 0.53 18 0.19 0.17 

ametryn 257 0.052 0.67 0.03 0.03 

norflurazon 95 0.061 0.21 0.05 0.05 

atrazine 

desethyl 

79 0.05 0.37 0.02 0.02 

hexazinone 90 0.06 1.7 0.03 0.03 

simazine 82 0.105 9.3 0.03 0.02 

bromacil 49 0.163 1.4 0.10 0.11 

metolachlor 32 0.158 0.44 0.14 0.15 

atrazine 

desisopropyl 

20 0.019 0.031 0.017 0.018 

metribuzin 7 0.19 0.51 0.19 0.17 

diuron 6 9.69 76 1.5 3.3 

ethoprop 6 0.136 0.67 0.09 0.09 

prometryn 6 0.139 0.59 0.06 0.03 

endosulfan 

sulfate 

5 0.010 0.015 0.010 0.010 

p,p’-DDE 4 0.0042 0.0051 0.0041 0.0040 

chlorpyrifos 

ethyl 

3 0.021 0.023 0.020 0.021 

2,4-D 2 0.37 0.40 0.37 0.37 

alachlor 2 0.040 0.068 0.027 0.040 

 
45

Table 17. Selected pesticide data at S7 and S8 structures before and after Stormwater 

Treatment Area 3/4 completion. 

 Ametryn Atrazine 

Pre-operation Post-operation Pre-operation Post-operation

S7 

Average Concentration 

(μg/L) 0.08 0.05 1.18 0.43 

Percent Detections 69 82 87 93 

S8 

Average Concentration 

(μg/L) 0.13 0.04 1.31 0.47 

Percent Detections 54 64 82 93 

Table 18. Sediment pesticide detections for Everglades Agricultural Area southern 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 92 29 390 3.2 31 

p,p’-DDD 63 15 180 4.9 28 

ametryn 48 14 100 - - 

PCB-1254 18 124 890 60 680 

atrazine 14 14 50 - - 

p,p’-DDT 14 21 150 4.2 63 

chlordane 10 55 190 3.2 18 

PCB-1260 8 76 190 60 680 

dieldrin 6 7 22 1.9 62 

dicofol 3 5.8 9.1 - - 

diquat 3 1717 2750 - - 

PCB-1242 2 67 101 60 680 

Italicized values exceed the Threshold Effect Concentration (TEC) 

Bold values exceed the Probable Effect Concentration (PEC) 

- No guideline available 
46

Figure 16. Urban basin sampling locations. 
47

Table 19. Surface water pesticide detections for urban basin sampling locations from April 

1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 223 0.35 3.3 0.26 0.26 

ametryn 149 0.02 0.17 0.02 0.02 

atrazine 

desethyl 

76 0.04 0.21 0.03 0.03 

hexazinone 48 0.08 1.7 0.04 0.03 

atrazine 

desisopropyl 

24 0.020 0.029 0.020 0.021 

simazine 15 0.07 0.43 0.05 0.04 

diuron 13 0.65 1.4 0.61 0.62 

2,4-D 10 7.7 29 5.6 6.8 

endosulfan 

sulfate 

8 0.029 0.11 0.018 0.017 

diazinon 7 0.041 0.097 0.61 0.62 

alpha 

endosulfan 

5 0.022 0.076 0.016 0.014 

prometon 5 0.029 0.043 0.028 0.023 

beta 

endosulfan 

4 0.026 0.077 0.019 0.026 

metolachlor 3 0.09 0.11 0.1 0.1 

naled 2 0.22 0.24 0.22 0.22 

Table 20. Sediment pesticide detections for urban basin sampling locations from April 

1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 47 5.4 21 3.2 31 

p,p’-DDD 9 2.5 4.3 4.9 28 

bromacil 3 92 200 - - 

PCB-1016 2 60 78 60 680 

Italicized values exceed the Threshold Effect Concentration (TEC) 

- No guideline available 
48

Figure 17. South Miami-Dade County agriculture sampling locations. 
49

Table 21. Surface water pesticide detections for South Miami-Dade County agriculture 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 159 0.049 0.4 0.031 0.025 

alpha 

endosulfan 

63 0.014 0.22 0.011 0.010 

endosulfan 

sulfate 

59 0.039 0.45 0.028 0.025 

beta 

endosulfan 

32 0.010 0.078 0.008 0.009 

hexazinone 9 0.027 0.052 0.025 0.028 

atrazine 

desethyl 

7 0.016 0.033 0.015 0.014 

chlorpyrifos 

ethyl 

4 0.035 0.056 0.031 0.028 

metolachlor 4 0.11 0.22 0.10 0.10 

metribuzin 3 0.11 0.29 0.60 0.30 

2,4-D 3 0.95 1.7 0.95 0.95 

atrazine 

desisopropyl 

2 0.014 0.016 0.014 0.014 

ethion 2 0.037 0.053 0.037 0.037 
Figure 18a. Endosulfan detections at S178 from March 1992 to April 1995. 

7-Day Antecedent Rainfall, Inches

012345

growing seasonsampling event7-day antecedent rainfall

Endosulfan in Surface Water, μg/L 0.0 0.1 0.2 0.3 0.4 0.5 growing season sampling event alpha+beta endosulfan sulfate 62-302 Class III Standard

Mar-92

Jun-92

Sep-92

Dec-92

Mar-93 

Jun-93

Sep-93

Dec-93

Mar-94 

Jun-94

Sep-94

Dec-94

Ma

Endosulfan in Sediment, μg/Kg

0

20406080

100120140

growing seasonsampling eventalpha+beta endosulfansulfate
Figure 18b. Endosulfan detections at S178 from June 1995 to July 1998. 

7-Day Antecedent Rainfall, Inches

012345

growing seasonsampling event7-day antecedent rainfall

Endosulfan in Surface Water, μg/L 0.0 0.1 0.2 0.3 0.4 0.5 growing season sampling event alpha+beta endosulfan sulfate 62-302 Class III Standard

Jun-95

Sep-95

Dec-95

Mar-96

Jun-96

Sep-96

Dec-96

Mar-97

Jun-97

Sep-97

Dec-97

Mar-98

Endosulfan in Sediment, μg/Kg

0

20406080

100120140

growing seasonsampling eventalpha+beta endosulfansulfate
Figure 18c. Endosulfan detections at S178 from July 1998 to August 2001. 

7-Day Antecedent Rainfall, Inches

012345

growing seasonsampling event7-day antecedent rainfall

Endosulfan in Surface Water, μg/L 0.0 0.1 0.2 0.3 0.4 0.5 growing season sampling event alpha+beta endosulfan sulfate 62-302 Class III Standard

Aug-98

Nov-98

Feb-99

May-99

Aug-99

Nov-99

Feb-00

May-00

Aug-00

Nov-00

Feb-01

May-01

Endosulfan in Sediment, μg/Kg

0

20406080

100120140

growing seasonsampling eventalpha+beta endosulfansulfate
Figure 18d. Endosulfan detections at S178 from September 2001 to September 2004. 

7-Day Antecedent Rainfall, Inches

012345

growing seasonsampling event7-day antecedent rainfall

Endosulfan in Surface Water, μg/L 0.0 0.1 0.2 0.3 0.4 0.5 growing season sampling event alpha+beta endosulfan sulfate 62-302 Class III Standard

Sep-01

Dec-01

Mar-02

Jun-02

Sep-02

Dec-02

Mar-03

Jun-03

Sep-03

Dec-03

Mar-04

Jun-04

Endosulfan in Sediment, μg/Kg

0

20406080

100120140

growing seasonsampling eventalpha+beta endosulfansulfate
Figure 18e. Endosulfan detections at S178 from September 2004 to December 2007. 

7-Day Antecedent Rainfall, Inches

012345

growing seasonsampling event7-day antecedent rainfall

Endosulfan in Surface Water, μg/L 0.0 0.1 0.2 0.3 0.4 0.5 growing season sampling event alpha+beta endosulfan sulfate 62-302 Class III Standard

Sep-04

Dec-04

Mar-05

Jun-05

Sep-05

Dec-05

Mar-06

Jun-06

Sep-06

Dec-06

Mar-07

Jun-07

Sep-07

Dec

Endosulfan in Sediment, μg/Kg

0

20406080

100120140

growing seasonsampling eventalpha+beta endosulfansulfate
55

Table 22. Sediment pesticide detections for South Miami-Dade County agriculture 

sampling locations from April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 77 15 89 3.2 31 

endosulfan 

sulfate 

25 16 120 - - 

beta 

endosulfan 

24 5 24 - - 

alpha 

endosulfan 

17 6 30 - - 

p,p’-DDD 12 7 15 4.9 28 

p,p’-DDT 5 2 3.2 4.2 63 

bromacil 3 93 130 - - 

ethion 3 10 17 - - 

Italicized values exceed the Threshold Effect Concentration (TEC) 

Bold values exceed the Probable Effect Concentration (PEC) 

- No guideline available 
56

Figure 19. Reference basin sampling locations. 
57

Table 23. Surface water pesticide detections for reference basin sampling locations from 

April 1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/L) 

Maximum 

Concentration 

(μg/L) 

Concentration 

Geometric 

Mean 

Median 

Concentration 

atrazine 49 0.052 0.93 0.027 0.019 

ametryn 3 0.014 0.018 0.014 0.013 

Table 24. Sediment pesticide detections for reference basin sampling locations from April 

1992 to December 2007. 

Chemical 

Number 

of 

Detections 

Average 

Concentration 

(μg/Kg) 

Maximum 

Concentration 

(μg/Kg) 

Threshold 

Effect 

Concentration 

(μg/Kg) 

Probable 

Effect 

Concentration 

(μg/Kg) 

p,p’-DDE 2 2.8 6.2 3.2 31 

PCB-1260 2 21 26 60 680 

Italicized values exceed the Threshold Effect Concentration (TEC)