Total Maximum Daily Load (TMDL) 

for the Palatlakaha River 

 to Address 

Dissolved Oxygen Impairment 

Lake County, Florida 

Prepared by: 

Kevin Petrus 

Florida Department of Environmental Protection 

Watershed Assessment Section 

2600 Blair Stone Road 

Tallahassee, FL

September 22, 2003 

 
Table of Contents 

1.0 INTRODUCTION...................................................................................1 

1.1 Purpose of Report...........................................................................1

1.2 Identification of Waterbody................................................................1 

2.0 STATEMENT OF PROBLEM...................................................................2 

3.0 DESCRIPTION OF APPLICABLE WATER QUALITY STANDARDS.................5 

4.0 LOADING CAPACITY.............................................................................6 

4.1 Types of Sources..........................................................................6 

4.2 Point Source Descriptions..............................................................7 

 4.2.1 NPDES Permitted Wastewater Facilities....................................7 

 4.2.2 NPDES MS4 Areas ............................................................7 

4.3 Nonpoint Source Descriptions.........................................................8 

4.3.1 Wildlife...............................................................................8 

4.3.2 Agricultural Animals..............................................................8 

4.3.3 Onsite Sewerage Treatment and Disposal Systems....................8 

4.3.4 Urban Development..............................................................9 

4.4 Pollutant Loading Assessment........................................................9 

5.0 CRITICAL CONDITIONS.......................................................................11 

6.0 DETERMINATION OF TMDL................................................................. 11 

6.1 Load Allocation...........................................................................12 

6.2 WasteLoad Allocation..................................................................13 

6.3 Margin of Safety..........................................................................13 

7.0 SEASONAL VARIATION.......................................................................13 

8.0 NEXT STEPS: IMPLEMENTATION PLAN DEVELOPMENT AND BEYOND....13 

9.0 REFERENCES....................................................................................15 

 
1.0 INTRODUCTION 

1.1 Purpose of Report 

This report presents Total Maximum Daily Loads (TMDLs) for biochemical oxygen demand 

(BOD), total nitrogen, and total phosphorus developed to address the dissolved oxygen (DO) 

impairment in the Palatlakaha River. Using the methodology to identify and verify water quality 

impairments described in the Impaired Waters Rule (IWR), Chapter 62-303, Florida 

Administrative Code (FAC), the river was verified impaired for DO as well as nutrients, and was 

included on the verified list of impaired waters for the Ocklawaha Basin that was adopted by 

Secretarial Order on August 28, 2002. The TMDL process quantifies the amount of a pollutant 

that can be assimilated in a waterbody, identifies the sources of the pollutant, and recommends 

regulatory or other actions to be taken to achieve compliance with applicable water quality 

standards based on the relationship between pollution sources and in-stream water quality 

conditions.

1.2 Identification of Waterbody

The Palatlakaha River is located in the Ocklawaha River Basin in central Florida and is 

approximately 12.3 miles long. It is connected to the Clermont Chain of Lakes through Lake 

Emma and to the Harris Chain of Lakes through Lake Harris at its downstream-most point. The 

small cities of Clermont and Minneola lie within the watershed of the Palatlakaha River. The 

predominant land cover in the watershed are wetlands, agriculture, and residential areas. The 

distribution of land cover for the Palatlakaha River is tabulated in Table 1 and displayed in

Figure 1. Several small domestic wastewater facilities operate within its watershed, however 

there are no permitted surface water discharges to this waterbody. 

The Palatlakaha River Basin is located in the Central Highlands geomorphic region of the 

Florida peninsula. The Central Highlands are characterized by a series of relict beach ridges 

and valleys that run approximately parallel to the Atlantic Coast. The largest physiographic 

feature of the region is the Central Valley, which is a low area with flat to gently rolling terrain. 

Lakes, swamps, and streams, including the Palatlakaha River, are common. Most of the 

Central Valley is underlain by sand with a minor amount of silt and clay that acts as a veneer 

over the underlying limestone bedrock. 

Figure 2 shows the Palatlakaha River Basin and its long- term water quality monitoring stations 

and flow gages. The Palatlakaha River is a highly meandered river, and the water flow is 

controlled by six dams that maintain water levels and provide irrigation water for agricultural 

activities. An earthen dam at the outlet of Cherry Lake maintains the elevation of upstream 

lakes during prolonged periods of dry weather. There are five gated dams along the river 

between Cherry Lake and Lake Harris. 

For assessment purposes, the watersheds within the Ocklawaha River Basin have been broken 

out into smaller watersheds, with a unique waterbody identification (WBID) number for each 

watershed. The impaired segment of the Palatlakaha River that is the subject of this TMDL was 

assigned WBID 2839. 

 1 
 

2.0 STATEMENT OF PROBLEM

The Palatlakaha River was listed as impaired for dissolved oxygen in Florida’s 1998 303(d) list 

of impaired waters. Through analysis according to Rule 62-303, FAC (Identification of Impaired 

Surface Waters or IWR), the river was subsequently verified impaired for DO as well as 

nutrients, and it was included on the list of impaired surface waters adopted by Secretarial 

Order on August 28, 2002, and then submitted to EPA as part of the 2002 update to Florida’s 

303(d) list. 

The river was verified as impaired for DO because greater than 10 percent of the Palatlakaha 

River DO values exceeded the Class III freshwater DO criterion of 5.0 mg/L during the period 

used to identify impaired water segments for the 2002 303(d) listing (1995-2002). During this 

period, 55 DO measurements out of 117 samples exceeded the criterion. Figure 3 displays the 

DO data collected over the last 12 years at the three long-term monitoring stations (the values 

are tabulated in Appendix A). The DO levels are typically less than the criterion throughout the 

river segment. 

Table 1. Palatlakaha River Land Use and Land Cover in 20001 

Land Use and Land Cover Total Acres % Distribution 

Urban and Built Up 4,137.1 17.0 

Agriculture 5,377.4 22.1 

Rangeland2 3,922.0 16.1 

Upland Forests 2,238.8 9.2 

Water 2,499.9 10.3 

Wetlands 5,861.8 24.1 

Barren Land 54.7 0.2 

Transportation, Communication 

and Utilities 

260.3 1.1 

Total 24,352.0 100.0 

1. Acreage represents the land use distribution in the impaired WBID and not the entire drainage area. 

2. Rangeland includes shrubland, grassland, and herbaceous land cover. 

2
 

Figure 1. Palatlakaha River Land Use and Land Cover in 2000 

3
 

Figure 2. Palatlakaha River Monitoring Locations 

4
 

Palatlakaha River - WBID 2839 

Dissolved Oxygen at Hwy 19, Bridges Road, and Hwy 48 (1990-2001)

0

1

2

3

4

5

6

7

8

9

10

11

12

1/1/19907/1/19901/1/19917/1/19911/1/19927/1/19921/1/19937/1/19931/1/19947/1/19941/1/19957/1/19951/1/19967/1/19961/1/19977/1/19971/1/19987/1/19981/1/19997/1/19991/1/20007/1/20001/1/20017/1/2001

Date

Dissolved Oxygen (mg/L)

Daily Values

Highway 48 (21FLLCPCPRC9)

Highway 19 (21FLLCPCPRC5)

Bridges Road (21FLLCPCPRC8)

2 per. Mov. Avg. (Highway 48 (21FLLCPCPRC9))

2 per. Mov. Avg. (Highway 19 (21FLLCPCPRC5))

2 per. Mov. Avg. (Bridges Road (21FLLCPCPRC8))

Figure 3. Dissolved Oxygen Measurements at the Long-term Monitoring Stations 

3.0 DESCRIPTION OF APPLICABLE WATER QUALITY STANDARDS AND NUMERIC 

WATER QUALITY TARGET 

The Palatlakaha River is a Class III waterbody with designated uses of recreation, propagation 

and maintenance of a healthy, well balanced population of fish and wildlife. The Class III 

freshwater criterion for DO, as established by Rule 62-302.530(31), Florida Administrative 

Code, states that the dissolved oxygen shall not be less than 5 mg/L and that normal daily and 

seasonal fluctuations above these levels shall be maintained. 

While the river was verified to not meet the Class III DO criterion, there is evidence indicating 

DO levels are less than the freshwater criterion due to natural conditions. The lower DO levels 

in the Palatlakaha River can be partly attributed to drainage from wetland areas that border the 

river channel. As noted in Table 1, wetlands is the largest land use and makes up 24 percent of 

the Palatlakaha River WBID area. Further, Palatlakaha River DO measurements are 

comparable to the DO levels in the Big Creek segment located upstream of the Palatlakaha 

River segment. Big Creek was used as a reference stream in the 1980s to develop site specific 

alternative criteria for DO in Reedy Creek. The cumulative frequency plots of DO in the 

Palatlakaha River and Big Creek show that DO levels in both systems typically fall below the 

DO criterion of 5 mg/L (Figure 4). Additionally, the Palatlakaha River passed a Stream 

Condition Index (SCI) bioassessment in January 1992, which indicates that, although the DO 

levels were consistently below 5 mg/L during that period, the macroinvertebrate biota were 

adapted to these low DO conditions and the river is likely meeting its designated use for aquatic 

life-use support. Based on this information, the development of an alternative DO criterion 

appears to be warranted in the Palatlakaha River. 

5
 

-Dissolved Oxygen Comparison ChartPalatlakaha River (WBID 2839) for Verified Period 1995-2002 

vs. Big Creek (WBID 1406) from 1981-1988 & 1995-2002

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7 8 9 10 11 12

Dissolved Oxygen (mg/L)

Cumulative Frequency (%)

Palatlakaha River 1995-2002

Big Creek 1995-2002

Big Creek 1981-1988 (M ean Values)

Figure 4. Dissolved Oxygen in the Palatlakaha River and Big Creek 

4.0 LOADING CAPACITY – LINKING WATER QUALITY AND POLLUTANT SOURCES 

The loading capacity for the river is based on the premise that the low DO levels observed 

around the time of the January 1992 bioassessment are due to natural conditions and that the 

river met its designated uses for aquatic life use support. To develop a loading capacity that 

addresses the low DO levels, pollutant loadings for the year prior to the bioassessment, 1991, 

were established for biochemical oxygen demand, total nitrogen, and total phosphorus. 

4.1 Types of Sources 

An important part of the TMDL analysis is the identification of source categories, source 

subcategories, or individual sources of biochemical oxygen demand, total nitrogen, and total 

phosphorus in the watershed and the amount of pollutant loading contributed by each of these 

sources. Sources are broadly classified as either “point sources” or “nonpoint sources.” 

Historically, the term point sources has meant discharges to surface waters that typically have a 

continuous flow via a discernable, confined, and discrete conveyance, such as a pipe. 

Domestic and industrial wastewater treatment facilities (WWTFs) are examples of traditional 

point sources. In contrast, the term “nonpoint sources” was used to describe intermittent, 

rainfall driven, diffuse sources of pollution associated with everyday human activities, including 

runoff from urban land uses, runoff from agriculture, runoff from silviculture, runoff from mining, 

discharges from failing septic systems, and atmospheric deposition. 

6
 

However, the 1987 amendments to the Clean Water Act redefined certain nonpoint sources of 

pollution as point sources subject to regulation under EPA’s National Pollutant Discharge 

Elimination Program (NPDES). These nonpoint sources included certain urban stormwater 

discharges, including those from local government master drainage systems, construction sites 

over five acres, and from a wide variety of industries (see Appendix B for background 

information about the State and Federal Stormwater Programs). 

To be consistent with Clean Water Act definitions, the term “point source” will be used to 

describe traditional point sources (such as domestic and industrial wastewater discharges) AND 

stormwater systems requiring an NPDES stormwater permit when allocating pollutant load 

reductions required by a TMDL (see Section 6). However, the methodologies used to estimate 

nonpoint source loads do not distinguish between NPDES stormwater discharges and nonNPDES stormwater discharges, and as such, this source assessment section does not make 

any distinction between the two types of stormwater. 

4.2 Point Source Descriptions 

4.2.1 NPDES Permitted Wastewater Facilities 

There are no NPDES permitted dischargers in the Palatlakaha River basin. 

 

4.2.2 NPDES MS4 Areas 

Municipal Separate Storm Sewer Systems (MS4s) may also discharge nutrients to waterbodies 

in response to storm events. EPA developed the federal National Pollutant Discharge 

Elimination System (NPDES) stormwater permitting program in two phases. Phase I, 

promulgated in 1990, addresses large and medium municipal separate storm sewer systems 

(MS4s) located in incorporated places and counties with populations of 100,000 or more; and 

eleven categories of industrial activities, one of which is large construction activity that disturbs 

5 or more acres of land. Phase II, promulgated in 1999, addresses additional sources, including 

MS4s not regulated under Phase I, and small construction activity disturbing 1 and 5 acres. 

Phase II began permitting in 2003. Regulated Phase II MS4s are defined in Section 62-

624.800, F.A.C. and typically cover urbanized areas serving jurisdictions with a population of at 

least 10,000 and discharge into either Class I, Class II, or waters designated as Outstanding 

Florida Waters. The Leesburg-Eustis area, which covers a part of the Palatlakaha River 

segment, is included in the Phase II NPDES stormwater permitting program. 

In October 2000, EPA authorized FDEP to implement the NPDES stormwater program in all 

areas of Florida except Indian Country lands. FDEP’s authority to administer the NPDES 

program is set forth in Section 403.0885, Florida Statutes (F.S.). The NPDES stormwater 

program regulated point source discharges of stormwater into surface waters of the State of 

Florida from certain municipal, industrial, and construction activities. The NPDES stormwater 

permitting program is separate from the State’s stormwater/environmental resource permitting 

program, and local stormwater/water quality programs, which have their own regulations and 

permitting requirements. 

7
 

4.3 Nonpoint Source Descriptions 

4.3.1 Wildlife 

Wildlife deposit nutrients and bacteria with their feces onto land surfaces where it can be 

transported during storm events to nearby streams. The nutrient and bacteria load from wildlife 

is assumed background, as the contribution from this source is small relative to the load from 

urban and agricultural areas. In addition, any strategy employed to control this source would 

probably have a negligible impact on obtaining water quality standards. 

4.3.2 Agricultural Animals 

 

Agricultural animals are the source of nutrient, oxygen demanding substances, and coliform 

loadings to streams. Agricultural activities including runoff from pastureland and cattle in 

streams impact water quality. Livestock data from the 1997 Census of Agriculture for the 

counties encompassing the impaired WBIDs are listed in Table 2. Cattle, including beef and 

dairy cows, is the predominate livestock in these counties. In Lake County, horses represent a 

significant portion of the livestock. Confined Animal Feeding Operations (CAFOs) are not 

known to operate in the impaired WBIDS. The US Department of Agriculture (USDA) is 

currently in the process of updating the agricultural census for 2002. Data from the 2002 

Census will be released in Spring 2004. 

Table 2. Livestock Distribution by County (Source: NASS, 1997) 

Livestock (inventory) Lake County 

Cattle and calves 34,442 

Beef Cows 17,693 

Dairy Cows 2,577 

Swine 414 

Poultry (broilers sold) 58 

Sheep 232 

Horses and Ponies 1,461 

 

4.3.3 Onsite Sewerage Treatment and Disposal Systems 

Onsite sewage treatment and disposal systems (OSTDs), including septic tanks, are commonly 

used where providing central sewer is not cost-effective or practical. When properly sited, 

designed, constructed, maintained, and operated, OSTDs are a safe means of disposing of 

domestic waste. The effluent from a well-functioning OSTD is comparable to secondarily 

treated wastewater from a sewage treatment plant. When not functioning properly, OSTDs can 

be a source of nutrient (nitrogen and phosphorus), pathogens, and other pollutants to both 

ground water and surface water. Table 3 provides the number of septic systems in Lake 

County estimates of countywide failure rates and total daily discharge of wastewater from septic 

tanks. 

8
 

Table 3. County Estimates of Septic Tanks (FDEP, 2001) 

County Number of Septic 

Tanks1

Percent of 1995 

Population Using 

Septic Tanks2

Failure Rate 

per 10003

Estimated 

Discharge 

(MGD)

4

Lake 63,656 50.1 11.81 8.59 

Notes: 

1. Total number is based on 1970 census figures plus the number of systems installed since 1970 through June 30, 

2000. Numbers do not reflect the removal of septic systems by connection to central sewers. 

2. Source: St. Johns River Water Management District, May 2000, p. 97, cited in FDEP, 2001. 

3. Defined as the number of repairs divided by the number of installed systems for July 1, 1999 to June 30, 2000. 

4. Based on value of 135 gallons per day per tank (FDEP, 2001). 

4.3.4 Urban Development 

Nutrient and oxygen demanding substances loadings from urban areas is attributable to multiple 

sources including storm water runoff, leaks and overflows from sanitary sewer systems, illicit 

discharges of sanitary waste, runoff from improper disposal of waste materials, leaking septic 

systems, and domestic animals. 

4.4 Pollutant Loading Assessment 

As noted previously, there are no NPDES wastewater permitted facilities that discharge to 

surface waters in the Palatlakaha River. The total nonpoint source loads for each pollutant were 

quantified based on land use areas in the river segment. The loadings include runoff from 

agricultural areas, urban areas, and transportation and utility areas. Part of the surface runoff 

loads are loads coming from atmospheric deposition that fall directly onto the land surface. 

Although not specifically quantified, the runoff from residential areas include leachate from 

septic systems. 

The 1991 nonpoint source loadings used to estimate the loading capacity were estimated by 

applying a watershed loading model using 1991 land use coverages. The land use and land 

cover data for 2000 were then applied in the model to estimate the existing loads, and the 

differences in the nonpoint source pollutant loading estimates between 1991 and 2000 were 

used to determine the percent reduction in loading necessary to meet the loading capacity. 

The Watershed Management Model (WMM, 1998) was used to estimate the annual loadings 

derived from the land cover and land use activities in the river segment. Each land use is a 

combination of pervious and impervious areas, and runoff coefficients for pervious area and for 

impervious area control runoff volume. The annual rainfall amount applied in the model is 

converted into surface runoff. Runoff coefficients, land use types, surface areas, and 

percentage of pervious and impervious areas for each land use are included in estimating 

surface runoff. The nonpoint loadings are the products of total surface runoff and event mean 

concentrations (EMC) of runoff for a given land use. Table 4 provides the runoff coefficients, 

impervious area percentages, and EMCs used in the WMM model. 

9
 

Table 4. Runoff Loading Parameters Used in the WMM Model 

Land Use Pervious 

Runoff 

Coefficient 

Impervious 

Runoff 

Coefficient 

Percent 

Impervious

EMC BOD 

(mg/L) 

EMC TN 

(mg/L) 

EMC TP 

(mg/L) 

Forest/Rural Open 0.019737 0.92 0.08 1.00 0.35 0.050 

Urban Open 0.019737 0.92 0.08 8.20 1.18 0.150 

Agriculture 0.019737 0.92 0.08 3.80 2.32 0.344 

Low Density Residential 0.019737 0.92 1.64 4.40 1.77 0.177 

Medium Density 

Residential 

0.019737 0.92 4.93 7.40 2.29 0.300 

High Density Residential 0.019737 0.92 8.22 11.00 2.42 0.490 

Communication and 

Transportation 

0.019737 0.92 5.92 5.60 2.08 0.340 

Rangeland 0.019737 0.92 0.08 3.80 2.32 0.344 

Water/ Wetlands 0.019737 0.92 4.93 4.63 1.60 0.190 

Land use information from 1988 and 1995 were used to estimate watershed loadings in 1991 

because there was no aerial imagery available from 1991. To estimate 1991 land use, the 

annual rates of change in the selected land use categories were calculated between 1988 and 

1995. The rate of change between 1988 and 1991 were then added to the 1988 land use areas 

to derive the 1991 land use. Table 5 provides the observed land use information along with the 

results for the estimated 1991 land use areas. Land use data are available for 2000 (presented 

in Table 5), and this information was applied to estimate the existing loads. 

 

Table 5. Palatlakaha River Land Use Applied in Loading Model 

Land Use 2000 

Observed 

(acres) 

1995 

Observed 

(acres) 

1988 

Observed 

(acres) 

1988 to 1995 

Rate of 

Change 

(acres/year) 

1991 

Estimate 

(acres) 

Forest/Rural Open 2238.8 1531.3 1089.8 63.1 1,279.0 

Urban Open 1387.0 1346.8 1003.6 49.0 1,150.7 

Agriculture 5377.4 5926.4 12117.9 -884.5 9,464.4 

Low Density Residential 1209.1 1145.4 510.6 90.7 782.7 

Medium Density Residential 700.1 713.5 305.8 58.3 480.5 

High Density Residential 840.9 211.2 406.9 -28.0 323.0 

Communication and 

Transportation 

260.3 242.7 224.2 2.6 232.1 

Rangeland 3976.7 5307.4 518.2 684.2 2,570.7 

Water/ Wetlands 8361.7 7974.2 8183.7 -29.9 8,093.9 

Totals 24352.0 24398.9 24360.6 24,377.0 

10
 

The watershed loadings for the 1991 land uses were calculated using the annual precipitation 

measured in 1991 at Clermont (43.18 inches). To provide an estimate of the existing watershed 

loads that are comparable to the 1991 loads, the 1991 rainfall was also applied in the model 

scenario using year 2000 land use areas. By using the same rainfall amounts in the analysis, 

the nonpoint source load differences (i.e. allowable load minus existing load) are solely the 

result of land use activity changes in the WBID. Table 6 presents the loading estimates for 

1991 and 2000 using the WMM. The percent reductions in existing loads needed to meet the 

1991 land use load are 12.8 %, 5.2 %, and 7.2 % for BOD, TN, and TP, respectively. 

Table 6. Palatlakaha River Watershed Annual Loadings 

Pollutant Loading (lbs/year) 

Year Biochemical 

Oxygen Demand 

Total Nitrogen Total Phosphorus 

1991 43,042 16,696 2,207 

2000 49,351 17,604 2,377 

5.0 CRITICAL CONDITIONS

Since only one bioassessment has been performed in this water segment, there is insufficient 

information to determine if critical DO conditions have occurred in the river that would effect the 

aquatic macroinvertebrates. Further study is needed to determine what the appropriate DO 

levels are for this river segment and if there are any specific critical DO periods that influence 

the biota. 

The TMDL is based on the 1991 annual loadings. Rainfall and river flow were below normal in 

1991, so the hydrologic conditions may have negatively effected the macroinvertebrate 

community. 

6.0 DETERMINATION OF TMDL 

The objective of a TMDL is to provide a basis for allocating acceptable loads among all of the 

known pollutant sources in a watershed so that appropriate control measures can be 

implemented and water quality standards achieved. A TMDL is expressed as the sum of all 

point source loads (Waste Load Allocations), nonpoint source loads (Load Allocations), and an 

appropriate margin of safety (MOS), which takes into account any uncertainty concerning the 

relationship between effluent limitations and water quality: 

TMDL = ∑ WLAs + ∑ LAs + MOS

As mentioned in Section 4.1, the WLA is broken out into separate subcategories for wastewater 

discharges and stormwater discharges regulated under the NPDES Program: 

 

TMDL ≅ ∑ WLAswastewater + ∑ WLAsNPDES Stormwater + ∑ LAs + MOS 

11
 

It should be noted that the various components of the TMDL equation may not sum up to the 

value of the TMDL because a) the WLA for NPDES stormwater is typically based on the percent 

reduction needed for nonpoint sources and is accounted for within the LA, and b) TMDL 

components can be expressed in different terms [for example, the WLA for stormwater is 

typically expressed as a percent reduction and the WLA for wastewater is typically expressed as 

a mass per day]. 

WLAs for stormwater discharges are typically expressed as “percent reduction” because it is 

very difficult to quantify the loads from MS4s (given the numerous discharge points) and to 

distinguish loads from MS4s from other nonpoint sources (given the nature of stormwater 

transport). The permitting of stormwater discharges is also different than the permitting of most 

wastewater point sources. Because stormwater discharges cannot be centrally collected, 

monitored and treated, they are not subject to the same types of effluent limitations as 

wastewater facilities, and instead are required to meet a performance standard of providing 

treatment to the “maximum extent practical” through the implementation of Best Management 

Practices. 

This approach is consistent with federal regulations [40 CFR § 130.2(I)], which state that TMDLs 

can be expressed in terms of mass per time (e.g. pounds per day), toxicity, or other 

appropriate measure. The TMDLs for the Palatlakaha River (Table 7) are expressed in terms 

of pounds/year and percent reduction. 

Table 7. Palatlakaha River TMDL Components 

WLA 

WBID Parameter 

Wastewater 

(lbs/year) 

NPDES 

Stormwater 

(% reduction) 

LA 

(lbs/year) MOS TMDL1(lbs/year) 

Percent 

Reduction2

2839 BOD NA 12.8 43,042 Implicit 43,042 12.8 

2839 TN NA 5.2 16,696 Implicit 16,696 5.2 

2839 TP NA 7.2 2,207 Implicit 2,207 7.2 

1. TMDL represents annual watershed loads in 1991. 

2. Overall reduction in the existing load (year 2000) needed to achieve the TMDL.

6.1 Load Allocation 

The allowable LA is 43,042 lbs/year for BOD, 16,696 lbs/year for TN, and 2,207 lbs/year for TP. 

This corresponds to reductions from the existing loads of 12.8 percent for BOD, 5.2 percent for 

TN, and 7.2 percent for TP. It should be noted that the LA includes loading from stormwater 

discharges regulated by the Department and the Water Management Districts that are not part 

of the NPDES Stormwater Program (see Appendix B). 

The total nonpoint source loads represent both the load allocation and TMDL for each pollutant. 

The loadings include runoff from agricultural areas, urban areas, and transportation and utility 

areas. Part of the surface runoff loads are loads coming from atmospheric deposition that fall 

directly onto the land surface. 

12
 

Florida’s Stormwater Rule requires the treatment of stormwater from all new development. 

Additionally, the SJRWMD regulates certain pumped agricultural operations to minimize their 

impacts. Finally, the Florida Watershed Restoration Act requires the Department of Agriculture 

and Consumer Services to adopt, by rule, best management practices to reduce agricultural 

nonpoint source pollution. 

6.2 WasteLoad Allocation

NPDES Stormwater Discharges

As previously noted in Sections 4 and 6, loads from stormwater discharges permitted under the 

NPDES Stormwater Program are placed in the WLA, rather than the LA. This includes loads 

from municipal separate storm sewer systems (MS4). Based on the 2000 census, the 

Palatlakaha River watershed includes areas (Leesburg-Eustis) that will be covered by the MS4 

Program. The WLA for stormwater discharges is a 12.8 percent reduction of current BOD 

loading, a 5.2 percent reduction of current TN loading, and a 7.2 percent reduction of current TP 

loading from the MS4. It should be noted that any MS4 permittees will only be responsible for 

reducing the loads associated with stormwater outfalls for which it owns or otherwise has 

responsible control, and is not responsible for reducing other nonpoint source loads within its 

jurisdiction. 

NPDES Wastewater Discharges

There are no NPDES permitted wastewater treatment facilities that discharge to surface waters 

in the Palatlakaha River so the wasteload allocation is zero. 

6.3 Margin of Safety (MOS) 

There are two methods for incorporating a MOS in a TMDL analysis: 1) implicitly incorporate 

the MOS using conservative model assumptions to develop allocations; or 2) explicitly specify a 

portion of the TMDL as the MOS and use the remainder for allocations. In this TMDL, an 

implicit MOS was used. An implicit margin of safety was incorporated by not accounting for 

treatment controls required by Florida stormwater regulations in calculating the allowable loads 

(TMDL) and existing loads. There is a greater amount of urban area in the year 2000 that would 

be effected by the stormwater regulations. 

7.0 SEASONAL VARIATION 

There were no apparent seasonal differences in the occurrence of the low DO levels that do not 

meet the state criterion. Seasonality is partly accounted for using the annual loadings to 

establish the TMDLs. 

8.0 NEXT STEPS: IMPLEMENTATION PLAN DEVELOPMENT AND BEYOND 

Following adoption of this TMDL by rule, the next step in the TMDL process is to develop an 

implementation plan for the TMDL, which will be a component of the Basin Management Action 

Plan for the Oklawaha River Basin. This document will be developed in cooperation with local 

stakeholders and will attempt to reach consensus on more detailed allocations and on how load 

reductions will be accomplished. 

13
 

The Basin Management Action Plan (B-MAP) will include: 

• Appropriate allocations among the affected parties. 

• A description of the load reduction activities to be undertaken. 

• Timetables for project implementation and completion. 

• Funding mechanisms that may be utilized. 

• Any applicable signed agreements. 

• Local ordinances defining actions to be taken or prohibited. 

• Local water quality standards, permits, or load limitation agreements. 

• Monitoring and follow-up measures. 

It should be noted that TMDL development and implementation is an iterative process, and this 

TMDL will be re-evaluated during the BMAP development process and subsequent Watershed 

Management cycles. The Department acknowledges the uncertainty associated with TMDL 

development and allocation, particularly in estimates of nonpoint source loads and allocations 

for NPDES stormwater discharges, and fully expects that it may be further refined or revised 

over time. If any changes in the estimate of the assimilative capacity AND/OR allocation 

between point and nonpoint sources are required, the rule adopting this TMDL will be revised, 

thereby providing a point of entry for interested parties. 

14
 

9.0 REFERENCES 

National Agricultural Statistics Service (NASS), Agricultural Census for 1997. U.S. Department 

of Agriculture. 

Watershed Management Model (WMM) User’s Manual, Version 4.1. 1998. Rouge River 

national wet weather demonstration project. Wayne County, Michigan. PRO-NPS-TM27.02. 

15
 

Appendix A 

Station Station Description Date Time DO 

Result 

(mg/L) 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 3/21/90 1505 5 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 7/11/90 1115 1.5 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 10/16/90 1420 0 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 1/9/91 1100 3.8 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 4/8/91 1110 3.9 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 10/22/91 1520 4.6 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 1/15/92 1255 6.4 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 6/24/92 1045 2.5 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 1/13/93 1438 2.7 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 4/14/93 1449 3.1 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 8/19/93 1440 2.7 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 10/27/93 1530 3.4 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 3/8/94 1636 3.5 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 6/9/94 1345 0 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 8/18/94 1455 2.7 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 11/2/94 1500 1.7 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 3/7/95 1440 2.3 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 6/13/95 1600 4.2 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 9/12/95 1500 4.3 

2839 21FLLCPC20020331 PALATLAKAHA (RIVER) @ HWY 19 BRIDGE 12/12/95 1515 5.5 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 3/13/96 1522 8.6 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 6/12/96 1433 2.1 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 9/11/96 1200 1.6 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 3/11/97 1535 3.3 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 6/5/97 1430 2.3 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 9/23/97 1520 7 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 12/10/97 1133 5.3 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 3/17/98 1538 5.3 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 6/11/98 1414 2.1 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 9/23/98 1500 1.9 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 12/9/98 1500 8 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 3/11/99 1458 4.2 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 10/26/99 955 3.9 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 12/7/99 1600 3.6 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 6/26/00 1240 5.9 

2839 21FLLCPCPRC5 PALATLAKAHA RIVER @ SR 19 BRIDGE 9/13/00 1615 6.7 

16
 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 3/20/90 1155 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 7/11/90 1350 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 10/17/90 1220 4.1 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 1/9/91 1130 4 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 4/8/91 1135 3.2 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 7/9/91 1250 3.4 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 10/22/91 1545 6.5 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 1/15/92 1320 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 6/24/92 1105 1.1 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 1/14/93 1020 2.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 4/15/93 1020 6.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 8/18/93 1505 4.9 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 10/26/93 940 2.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 3/1/94 1650 7.4 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 6/14/94 1515 7.6 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 8/18/94 1530 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 3/11/94 1255 2.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 3/8/95 1320 5 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 6/14/95 1205 5.9 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 9/13/95 1135 4.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 12/13/95 1225 7.3 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 3/14/96 1300 5 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 6/13/96 1210 1.5 

2839 21FLLCPC20020330 PALATLAKAHA (RIVER) @ STRUCTURE 9/12/96 1100 0 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 6/13/96 1210 4.8 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 12/13/96 1050 3.5 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 3/12/97 1120 3 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 6/4/97 1105 6.2 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 9/24/97 1125 4.6 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 12/10/97 1055 3.5 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 3/18/98 1130 5.9 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 6/10/98 1125 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 9/22/98 1115 5.5 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 12/10/98 1305 2.7 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 3/10/99 1130 3 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 6/9/99 1150 2.7 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 9/9/99 1405 2.2 

2839 21FLLCPCPRC8 PALATLAKAHA RIVER @ BRIDGES ROAD 12/8/99 1025 

17
 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 3/20/90 1205 3.8 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 7/11/90 1410 9.3 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 10/17/90 1240 6.9 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 1/9/91 1150 3.2 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 4/8/91 1150 4.3 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 7/9/91 1315 5.2 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 10/22/91 1615 4.7 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 1/15/92 1335 4.6 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 6/24/92 1125 3.4 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 1/14/93 1000 3.8 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 4/15/93 955 2.2 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 8/18/93 1445 5.7 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 10/26/93 915 1.4 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 3/1/94 1700 4.1 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 6/10/94 1400 3.9 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 8/19/94 935 2.3 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 11/3/94 1345 3.6 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 3/8/95 1140 5.8 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 6/14/95 1105 2.9 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 9/13/95 1045 6.5 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 12/13/95 1125 3.6 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 3/14/96 1150 9.5 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 6/13/96 1455 5.5 

2839 21FLLCPC20020324 PALATLAKAHA (RIVER) @ 48 BRIDGE 9/12/96 1000 2.7 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 3/14/96 1150 9.5 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 6/13/96 1455 5.5 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/12/96 1000 2.7 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 12/13/96 955 3 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 3/12/97 1035 2.7 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 6/4/97 1020 2.2 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/24/97 1045 2.5 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 12/10/97 1030 2.8 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 3/18/98 1030 6.6 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 6/10/98 1045 5 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/22/98 1030 2.7 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 12/10/98 1130 3.6 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 3/10/99 1055 3.4 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 6/9/99 1110 3.2 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/9/99 1320 6.4 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/13/00 1420 6.5 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 3/20/01 1505 3.4 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 6/25/01 1410 3.3 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 9/11/01 1435 5.6 

2839 21FLLCPCPRC9 PALATLAKAHA RIVER @ CR48 BRIDGE 4/4/02 1400 3.4 

 18 
 

Appendix B 

In 1982, Florida became the first state in the country to implement statewide regulations to 

address the issue of nonpoint source pollution by requiring new development and 

redevelopment to treat stormwater before it is discharged. The Stormwater Rule, as authorized 

in Chapter 403, Florida Statutes (F.S.), was established as a technology-based program that 

relies upon the implementation of BMPs that are designed to achieve a specific level of 

treatment (i.e., performance standards) as set forth in Chapter 62-40, Florida Administrative 

Code (F.A.C.). 

The rule requires Water Management Districts (WMDs) to establish stormwater pollutant load 

reduction goals (PLRGs) and adopt them as part of a SWIM plan, other watershed plan, or rule. 

Stormwater PLRGs are a major component of the load allocation part of a TMDL. To date, 

stormwater PLRGs have been established for Tampa Bay, Lake Thonotosassa, Winter Haven 

Chain of Lakes, the Everglades, Lake Okeechobee, and Lake Apopka. No PLRG has been 

developed for the Palatlakaha River at the time this study was conducted.

In 1987, the U.S. Congress established section 402(p) as part of the Federal Clean Water Act 

Reauthorization. This section of the law amended the scope of the federal NPDES to designate 

certain stormwater discharges as “point sources” of pollution. These stormwater discharges 

include certain discharges that are associated with industrial activities designated by specific 

Standard Industrial Classification (SIC) codes, construction sites disturbing five or more acres of 

land, and master drainage systems of local governments with a population above 100,000 

[which are better known as “municipal separate storm sewer systems” (MS4s)]. However, 

because the master drainage systems of most local governments in Florida are interconnected, 

EPA has implemented Phase 1 of the MS4 permitting program on a county-wide basis, which 

brings in all cities (incorporated areas), Chapter 298 urban water control districts, and the DOT 

(Department of Transportation) throughout the 15 counties meeting the population criteria. 

An important difference between the federal and the state stormwater permitting programs is 

that the federal program covers both new and existing discharges while the state program 

focuses on new discharges. Additionally, Phase 2 of the NPDES stormwater permitting 

program will expand the need for these permits to construction sites between one and five 

acres, and to local governments with as few as 10,000 people. These revised rules require that 

these additional activities obtain permits by 2003. While these urban stormwater discharges are 

now technically referred to as “point sources” for the purpose of regulation, they are still diffuse 

sources of pollution that can not be easily collected and treated by a central treatment facility 

similar to other point sources of pollution, such as domestic and industrial wastewater 

discharges. The DEP recently accepted delegation from EPA for the stormwater part of the 

NPDES program. It should be noted that most MS4 permits issued in Florida include a reopener clause that allows permit revisions to implement TMDLs once they are formally adopted 

by rule. 

 19