Echo Park Lake TMDLs January 2011 

6-1 

6 Echo Park Lake TMDLs

Echo Park Lake (#CAL4051501020000228155002) is listed as impaired by algae, ammonia, copper, 

eutrophication, lead, odor, PCBs, pH, and trash (SWRCB, 2010). In addition, chlordane and dieldrin 

impairments have been identified by new data analyses since the 2008-2010 303(d) list data cut off. This 

section of the TMDL report describes the impairments, and the TMDLs developed to address them: 

nutrients (see Section 6.2), organochlorine (OC) pesticides and PCBs (Section 6.5 through Section 6.7), 

and trash (Section 6.8). Nutrient TMDLs are identified here based on existing conditions since nitrogen 

and phosphorus levels are achieving the chlorophyll a target level. Comparison of metals data to their 

associated hardness-dependent water quality objectives indicates that copper and lead are currently 

achieving numeric targets at Echo Park Lake; therefore, TMDLs are not included for these pollutants. 

Analyses are presented below for lead (Section 6.3) and copper (Section 6.4).

6.1 ENVIRONMENTAL SETTING

Echo Park Lake is located in the Los Angeles River (HUC 18070105) (Figure 6-1). The waterbody was 

originally constructed as the Arroyo de los Reyes reservoir in 1898 and became Echo Park Lake in 1907. 

The lake now has a surface area of 14.1 acres (based on Southern California Association of Governments 

[SCAG] 2005 land use), an average depth of five feet (estimated from 2009 sampling events and the 

Urban Lakes Study [UC Riverside, 1994]), and a volume of 70.5 ac-ft (calculated from the land use 

estimated surface area and estimated average depth). Two primary storm drains provide inflows to the 

lake; the lake then discharges to a storm drain that ultimately reaches the Los Angeles River. 

Figure 6-1. Location of Echo Park Lake 
Echo Park Lake TMDLs January 2011 

6-2 

Mixing and aeration of the lake is currently performed by a mechanical aeration system, including the 

lake’s notable fountain located near the tip of the western peninsula. Objectives of aeration include 

increasing dissolved oxygen and decreasing nuisance surface scum and algal growth. In addition to 

aeration, four floating hydroponic wetlands were constructed for additional water quality treatment. An 

island, managed by the city of Los Angeles, located in the northeastern lobe of the lake, also provides 

habitat for waterfowl and turtles. Figure 6-2 shows the fountain and one of the hydroponic islands in the 

lake; Figure 6-3 shows the bubbles that result from one of the aerators. 

Figure 6-2. Fountain and Hydroponic Island at Echo Park Lake 

Figure 6-3. An Aerator North of the Bridge at Echo Park Lake 
Echo Park Lake TMDLs January 2011 

6-3 

Echo Park Lake harbors a historically and culturally significant population of lotus beds; it is believed 

that the current population is a descendent of lotus plants imported in 1920. Once believed to be the 

largest population in the western United States, recent decline of the lotus beds has been attributed to 

buildup of hydrogen-sulfide in the sediment. Due to the stress associated with the hydrogen-sulfide, it is 

not expected that the existing-historic lotus beds will reestablish. For this reason, a lotus restoration plan, 

completed in 2009, will be vital to the future sustainability of the lotus beds (Black & Veatch, 2009). A 

critical feature to reduce the concentration of hydrogen sulfide and augment the success of the lotus beds 

is proper lake circulation and improved aeration. 

A small strip of parkland surrounds the lake, offering a slight buffer from the surrounding roads and dense 

residential development. The park provides public access to the lake and restrooms located in the park 

are connected to the city sewer system. According to California Department of Fish and Game, trout are 

periodically stocked (CDFG, 2009). Catch and release fishing and paddle boating are the primary 

recreational uses (Figure 6-4). Bird feeding is another recreational activity at Echo Park Lake and heavy 

feeding has been observed during recent fieldwork, likely contributing to larger resident bird populations. 

Visitors are not allowed to swim in the lake. Lake managers use algaecides to control algal growth in the 

lake on an as-needed basis. 

Note: recreational uses include catch and release fishing and paddle boating. 

Figure 6-4. Echo Park Lake Recreational Uses 

Additional characteristics of the watershed are summarized below. 

6.1.1 Elevation, Storm Drain Networks, and Subwatershed Boundaries 

The Echo Park Lake watershed is 784 acres in size and ranges in elevation from 115 meters to 229 meters 

(Figure 6-5). The TMDL subwatershed boundaries selected for Echo Park Lake were based on 

boundaries obtained from the county of Los Angeles and are labeled on the figure accordingly. The 
Echo Park Lake TMDLs January 2011

6-4

county of Los Angeles southern-subwatershed was sub-delineated based on a digital elevation model to 

remove the drainage area downstream of the lake. The subwatershed draining the northern part of the 

watershed is 614 acres, and the southern subwatershed drains 170 acres. The majority of wet weather and 

dry weather flows from the northwestern and northeastern storm drains are diverted around the lake 

(Appendix D, Wet Weather Loading; Appendix F, Dry Weather Loading). Because both subwatersheds 

drain to a storm drain system and because many storm drains drain to the lake, all allocations except 

atmospheric deposition will be wasteload allocations. The trash TMDL includes load allocations due to 

direct dumping of trash along the shoreline and in the water by park visitors in the area indicated in 

Figure 6-6. 

Figure 6-5. Elevation, Storm Drain Network, and TMDL Subwatershed Boundaries for Echo Park 

Lake

6.1.2 MS4 Permittees

Figure 6-6 shows the MS4 stormwater permittees in the Echo Park Lake watershed. Both subwatersheds 

are located entirely within the city of Los Angeles with a small portion in Caltrans area. Figure 6-7 shows 

one of the main storm drain inlets at the lake. The park is comprised of 15.5 acres of land adjacent to the 

lake.
Echo Park Lake TMDLs January 2011 

6-5 

Figure 6-6. MS4 Permittees and the County of Los Angeles Storm Drain Network in the Echo 

Park Lake Subwatersheds 

Figure 6-7. Echo Park Lake Northeast Storm Drain Input 
Echo Park Lake TMDLs January 2011 

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6.1.3 Non-MS4 NPDES Dischargers 

The primary permitted discharger in the watershed is the county of Los Angeles MS4 system. There is 

one additional NPDES permitted discharger (non-MS4) in the Echo Park Lake watershed (Table 6-1 and 

Figure 6-8) that is a discharger covered under a general industrial stormwater permit (see Section 3.1 for a 

detailed discussion of this permit type). This permit was identified by querying excel files of permits 

from the Regional Board website (Excel files for each watershed are available from this link, 

www.waterboards.ca.gov/losangeles/water_issues/programs/regional_program/index.shtml#watershed,

accessed on October 5, 2009). This permittee is located in the city of Los Angeles in the northern 

subwatershed (Section 6.1.1) and has two disturbed acres. The disturbed area associated with this permit 

drains to the northwestern storm drain which is diverted around the lake in most cases except during high 

flow events. Loads from this permittee were therefore not calculated; however, concentration-based 

wasteload allocations for this permittee are included in the TMDLs. 

Table 6-1. Non-MS4 Permits in the Echo Park Lake Subwatersheds 

Type of NPDES Permit

Number 

of 

Permits Subwatershed Jurisdiction

Disturbed 

Area

General Industrial Stormwater 

(Order No. 97-03-DWQ, CAS000003)

1 Northern City of Los 

Angeles

2 acres

Figure 6-8. Non-MS4 Permits in the Echo Park Lake Subwatersheds 

6.1.4 Land Uses and Soil Types 

The analysis for this watershed includes source loading estimates obtained from the Los Angeles River 

Basin LSPC Model discussed in Appendix D (Wet Weather Loading) of this TMDL report. Land uses 
Echo Park Lake TMDLs January 2011 

6-7 

identified in the Los Angeles River Basin LSPC model are shown in Figure 6-9. The watershed is 

comprised primarily of residential development as well as commercial, other urban, industrial, and open 

space areas. Table 6-2 and Table 6-3 summarize the land use areas by TMDL subwatershed and 

jurisdiction. 

Figure 6-9. LSPC Land Use Classes for the Echo Park Lake Subwatersheds 

Table 6-2. Land Use Areas (ac) Draining to Echo Park Lake from the Northern Subwatershed 

Land Use Los Angeles Caltrans Total

Agriculture 0 0 0

Commercial 78.4 0 78.4

Industrial 12.2 13.0 25.2

Open 27.5 0 27.5

Other Urban 4.67 0 4.67

Residential 479 0 479

Total 601 13.0 614
Echo Park Lake TMDLs January 2011 

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Table 6-3. Land Use Areas (ac) Draining to Echo Park Lake from the Southern Subwatershed 

Land Use Los Angeles Caltrans Total

Agriculture 0 0 0

Commercial 31.6 0 31.6

Industrial 0 1.10 1.10

Open 15.5 0 15.5

Other Urban 0 0 0

Residential 122 0 122

Total 169 1.10 170

There are no Resource Conservation and Recovery Act (RCRA) contaminated industrial facilities located 

near the Echo Park Lake watershed. The USDA STATSGO state soils coverage identifies all soils within 

the Echo Park Lake watershed as Urban Land – Lithic Xerorthents – Hambright – Castaic (MUKEY 

660489). These soils are classified as belonging to soil hydrologic group D, which is characterized by 

high runoff potential, very low infiltration rates, and generally high clay content. 

6.1.5 Additional Inputs 

In addition to stormwater runoff, a natural spring exists in the center of Echo Park Lake (UC Riverside, 

1994); however, the addition of potable water is required to maintain the lake level. A potable water 

source at Echo Park Lake is used for both supplemental water additions to the lake and irrigation of 

surrounding parklands (Figure 6-10). According to a hydrologic study of the park lake conducted by 

Black & Veatch (2008), 162 ac-ft/yr of potable water is pumped annually for these purposes. Staff at 

Echo Park indicate that a portion of the pumped water is used to irrigate approximately 9 acres in the 

vicinity of the lake at a rate of approximately 1 foot per year. Some of this irrigation water may reach the 

lake (4.6 percent of the total irrigation volume is assumed to reach the lake). 

Figure 6-10. Echo Park Lake Potable Water Source and Northwestern Storm Drain Input 
Echo Park Lake TMDLs January 2011

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6.2 NUTRIENT RELATED IMPAIRMENTS

A number of the assessed impairments for Echo Park Lake are associated with nutrients and 

eutrophication. Nutrient-related impairments for Echo Park Lake include algae, ammonia, eutrophication, 

odor, and pH (SWRCB, 2010). The loading of excess nutrients enhances algal growth (eutrophication). 

Algal photosynthesis removes carbon dioxide from the water, which can lead to elevated pH in poorly 

buffered systems. Algal blooms may also contribute to odor problems.

6.2.1 Beneficial Uses

California state water quality standards consist of the following elements: 1) beneficial uses, 2) narrative 

and/or numeric water quality objectives, and 3) an antidegradation policy. In California, beneficial uses 

are defined by the Regional Water Quality Control Boards (Regional Boards) in the Water Quality 

Control Plans (Basin Plans). Numeric and narrative objectives are specified in each region’s Basin Plan, 

designed to be protective of the beneficial uses of each waterbody in the region. The existing beneficial 

uses assigned to Echo Park Lake include REC1, REC2, WARM, WILD, and MUN. Descriptions of these 

uses are listed in Section 2 of this TMDL report. Elevated nutrient levels impair the REC1, WARM, 

WILD, and MUN uses by stimulating algal growth that may form mats that impede recreational and 

drinking water use, alter pH and dissolved oxygen (DO) levels, and alter biology that impair the aquatic 

life use, and cause odor and aesthetic problems. 

6.2.2 Numeric Targets

The Basin Plan for the Los Angeles Region (LARWQCB, 1994) outlines the numeric targets and 

narrative criteria that apply to Echo Park Lake. The following targets apply to the algae, ammonia, 

eutrophication, odor, and pH impairments (see Section 2 for additional details and Table 6-4 for a 

summary):

 The Basin Plan expresses ammonia targets as a function of pH and temperature because unionized ammonia (NH3) is toxic to fish and other aquatic life. In order to assess compliance with 

the standard, the pH, temperature and ammonia must be determined at the same time. For the 

purposes of setting a target for Echo Park Lake in these TMDLs, a median temperature of 19.7 oC 

and a 95th percentile pH of 9.1 were used, as explained in Section 2. The resultant acute (onehour) ammonia target is 1.14 mg-N/L, the four-day average is 0.76 mg-N/L, and the 30-day 

average (chronic) target is 0.30 mg-N/L (Note: The median temperature and 95th percentile pH 

values were calculated from the observed surface depth data and used in the calculation of 

ammonia targets. These are presented as example calculations since the actual target varies with 

the temperature and pH values determined during sample collection). 

 The Basin Plan addresses excess aquatic growth in the form of a narrative objective for nutrients. 

Excessive nutrient (e.g., nitrogen and phosphorous) concentrations in a waterbody can lead to 

nuisance effects such as algae, odors, and scum. The objective specifies, “waters shall not 

contain biostimulatory substances in concentrations that promote aquatic growth to the extent that 

such growth causes nuisance or adversely affects beneficial uses.” The Regional Board has not 

adopted numeric targets for biostimulatory nutrients or chlorophyll a in Echo Park Lake; 

however, as described in Tetra Tech (2006), summer (May to September) mean and annual mean

chlorophyll a concentration of 20 μg/L are selected as the maximum allowable level consistent 

with full support of contact recreational use and is also consistent with supporting warm water 

aquatic life. The mean chlorophyll a target must be met at half of the Secchi depth during the 

summer (May – September) and annual averaging periods.
Echo Park Lake TMDLs January 2011

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 The Basin Plan states that “waters shall not contain taste or odor-producing substances in 

concentrations that impart undesirable tastes or odors to fish flesh or other edible aquatic 

resources, cause nuisance, or adversely affect beneficial uses.”

 The Basin Plan states “at a minimum the mean annual dissolved oxygen concentrations of all 

waters shall be greater than 7 mg/L, and no single determinations shall be less than 5.0 mg/L,

except when natural conditions cause lesser concentrations.” In addition, the Basin Plan states, 

“the dissolved oxygen content of all surface waters designated as WARM shall not be depressed 

below 5 mg/L as a result of waste discharges.” Shallow, well-mixed lakes, such as Echo Park 

Lake, must meet the DO target in the water column from the surface to 0.3 meters above the 

bottom of the lake. 

 The Basin Plan states that “the pH of inland surface waters shall not be depressed below 6.5 or 

raised above 8.5 as a result of waste discharges. Ambient pH levels shall not be changed more 

than 0.5 units from natural conditions as a result of waste discharge.” Shallow, well-mixed lakes, 

such as Echo Park Lake, must meet the pH target in the water column from the surface to 

0.3 meters above the bottom of the lake.

Nitrogen and phosphorus target concentrations within the lake are based on existing conditions as 

explained in Sections 6.2.5 and 6.2.6:

 1.2 mg-N/L summer average (May – September) and annual average

 0.12 mg-P/L summer average (May – September) and annual average

Table 6-4. Nutrient-Related Numeric Targets for Echo Park Lake

Parameter Numeric Target Notes

Ammonia1 1.14 mg-N/L acute (one-hour) 

0.76 mg-N/L four-day average 

0.30 mg-N/L chronic (30-day average)

Based on median temperature and 95th

percentile pH

Chlorophyll a 20 μg/L summer average (May – September) and 

annual average

Dissolved 

Oxygen

7 mg/L minimum mean annual concentrations and

5 mg/L single sample minimum except when 

natural conditions cause lesser concentrations

pH The pH of inland surface waters shall not be 

depressed below 6.5 or raised above 8.5 as a 

result of waste discharges. Ambient pH levels 

shall not be changed more than 0.5 units from 

natural conditions as a result of waste discharge.

Total Nitrogen 1.2 mg-N/L summer average (May – September) 

and annual average

Conservatively based on existing conditions, 

which are maintaining chlorophyll a levels 

below the target of 20 μg/L

Total 

Phosphorous

0.12 mg-P/L summer average (May – September) 

and annual average

Conservatively based on existing conditions, 

which are maintaining chlorophyll a levels 

below the target of 20 μg/L

1The median temperature and 95th percentile pH values were calculated from the observed surface depth data and 

used in the calculation of ammonia targets. These are presented as example calculations since the actual target is 

the water quality objective which is dependent on pH and temperature. When assessing compliance refer to the 

water quality objective as expressed in the Basin Plan..
Echo Park Lake TMDLs January 2011

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6.2.3 Summary of Monitoring Data

Water quality monitoring has occurred in Echo Park Lake in 1992, 1993, and 2003 through 2009. This 

section summarizes the monitoring data relevant to the nutrient impairments. Additional details regarding 

monitoring are discussed in Appendix G (Monitoring Data). 

During the 1992/1993 Urban Lakes Study, sampling occurred near the center of the lower half of the lake 

(UC Riverside, 1994). Total Kjeldahl nitrogen (TKN) concentrations during this sampling period ranged 

from 0.9 mg-N/L to 1.9 mg-N/L. Ammonium concentrations were less than the reporting limit for 22 of 

31 samples, and the maximum observed ammonium concentration was 0.7 mg-N/L which is less than the 

acute target assuming the analysis methodology converted all ammonia to ammonium. Nitrite 

concentrations were less than the detection limit (0.1 mg-N/L) in all samples and 24 of 31 nitrate samples 

were less than the detection limit (0.1 mg-N/L). The maximum observed nitrate concentration was 

0.2 mg-N/L. Orthophosphate concentrations were generally less than or equivalent to the detection limit 

(0.1 mg-P/L) with some observations of 0.2 mg-P/L. Total phosphorus concentrations ranged from less 

than the detection limit (0.1 mg-P/L) to 0.3 mg-P/L. pH measurements ranged from 7.7 to 9.4 throughout 

the water column, and TOC ranged from 4.8 mg/L to 7.6 mg/L. The summary table from the 1994 Lakes 

Study Report (UC Riverside, 1994) lists chlorophyll a concentrations ranging from 6 μg/L to 66 μg/L 

with an average of 24 μg/L. For this period, exceedances of the pH and chlorophyll a targets were 

observed. The report stated that aquatic weeds were present near the fountain, lotus plants were located at 

the northwest end of the lake, and algal blooms were observed during the summer. A strong odor 

resulting from duck feces was also reported. Nutrient levels were generally low during the study period 

and it was reported that the level of algae in the lake was not problematic.

There were no stations in Echo Park Lake or its drainage area in the Regional Board Water Quality 

Assessment Database. The Water Quality Assessment Report, however, states that pH was not 

supporting the contact recreation use and partially supporting the aquatic life use: 69 measurements of pH 

were collected which ranged from 7.0 to 9.4. Thirty-one ammonium samples were collected with values 

ranging from non-detect to 0.71 mg-N/L; ammonia was listed as not supporting the aquatic life and 

contact recreation uses. Raw data are not available to assess location, date, time, depth, temperature, or 

pH with regard to these samples. Odor and algae were both listed as not supporting the contact and noncontact recreation uses. Eutrophication was listed as not supporting the aquatic life use.

In 2003, the City of Los Angeles Bureau of Sanitation, Watershed Protection Division began collecting 

water quality samples from Echo Park Lake at three in-lake stations. Of the 57 samples collected during 

this period, 23 were non-detect for ammonia (less than 0.1 mg-N/L); the maximum ammonia 

concentration was 0.93 mg-N/L which does not exceed the acute or chronic ammonia criteria based on the 

associated pH and temperature measurements. Organic nitrogen concentrations ranged from 0.28 mg-N/L 

to 3.14 mg-N/L. Thirty-five nitrate samples were below the detection limit (0.02 mg-N/L), and the 

maximum observed nitrate concentration was 1.0 mg-N/L. Fifty-five of the nitrite samples were below 

the detection limit (0.02 mg-N/L); the other two samples had concentrations of 0.02 mg-N/L and 0.09 

mg-N/L. Total nitrogen concentrations, calculated from the sum of ammonia, organic nitrogen, nitrate, 

and nitrite, ranged from 0.28 mg-N/L to 3.48 mg-N/L. Total phosphate measurements generally ranged 

from 0.06 mg-P/L to 0.51 mg-P/L with three measurements less than detection (0.05 mg-P/L). No 

chlorophyll a data were reported.

Vertical profile data using datasondes were also collected by the City of Los Angeles Bureau of 

Sanitation during 2003. For a given collection day, there was little variability between the stations or

depths for temperature, specific conductivity, dissolved oxygen, or pH, indicating absence of significant 

stratification. Dissolved oxygen concentrations ranged from 5.62 mg/L to 15.9 mg/L; pH ranged from

7.46 to 9.04 throughout the water column. Twenty-seven percent of pH measurements exceeded the 

maximum allowable value.
Echo Park Lake TMDLs January 2011

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In 2008, the Regional Board sampled Echo Park Lake on two occasions. As the lake is relatively shallow 

and well mixed by wind action and aerators, the sampling team collected analytical samples from the lake 

surface only. On June 25, 2008, ammonia concentrations in Echo Park Lake were fairly similar at all 

three sampled locations and ranged from 0.131 mg-N/L to 0.136 mg-N/L. TKN at the lake midpoint and 

near the hydroponic island ranged from 1.38 mg-N/L to 1.49 mg-N/L; the concentration was higher in the 

lotus beds at 4.72 mg-N/L. Concentrations of nitrate, nitrite, orthophosphate, and total phosphate were all 

less than the reporting limits of 0.1 mg-N/L, 0.1 mg-N/L, 0.4 mg-P/L, and 0.5 mg-P/L, respectively. 

Dissolved oxygen concentrations ranged from 4.95 mg/L to 9.82 mg/L, and pH ranged from 8.21 to 8.56. 

The pH levels showed slight exceedances relative to the target. The DO target for waters designated 

WARM is 5 mg/L and after rounding to the appropriate decimal place the lowest observed measurement 

of 4.95 mg/L meets the target. Note that the pH meter was not producing calibration results within the 

acceptable range and that exceedances of the pH target were only observed along the shoreline near two 

storm drain outlets. Chlorophyll a samples generally ranged from 10.9 μg/L to 26.7 μg/L. There were 

two outlier chlorophyll a concentrations of 0.8 μg/L and 53.6 μg/L. The average concentration in the lake 

on this sampling day, including the outliers, was 17.3 μg/L. A description of the methodology or 

equipment used to measure chlorophyll a concentrations in the field was not provided. 

Regional Board also collected samples on December 18, 2008 from five shoreline locations at a depth of 

approximately 4 inches. pH ranged from 7.7 to 8.1. No exceedances of the acute ammonia target or 

chlorophyll a target were observed on this day. These samples are not discussed in detail in this section 

as shoreline samples may not be reflective of conditions in the lake as a whole. 

On March 10, 2009, USEPA and the Regional Board sampled Echo Park Lake at three locations. 

Ammonia concentrations ranged from 0.04 mg-N/L to 0.06 mg-N/L, and TKN ranged from 0.7 mg-N/L 

to 1.3 mg-N/L. Nitrate was approximately 0.15 mg-N/L at each station, and nitrite was less than the 

detection limit (0.01 mg-N/L). Orthophosphate was less than the detection limit (0.008 mg-P/L) at each 

station, and total phosphorus generally ranged from 0.033 mg-P/L to 0.071 mg-P/L. One total 

phosphorus sample measured 0.762 mg-P/L, though the field duplicate had a value of 0.071 mg-P/L. 

Chlorophyll a measurements in the lake ranged from 14.2 μg/L to 15.2 μg/L. 

Two in-lake stations were sampled by USEPA and the Regional Board on August 4th, 2009. All nitrogen 

parameters (ammonia, TKN, nitrate, and nitrite) were below detection limits (0.03 mg-N/L, 0.456 mgN/L, 0.01 mg-N/L, 0.01 mg-N/L, respectively) at both sites. Total phosphorus measurements were

0.196 mg-P/L and 0.195 mg-P/L. The orthophosphate concentrations were 0.0850 mg-P/L and 

0.0917 mg-P/L. The chlorophyll a measurements were 15.0 μg/L and 15.5 μg/L.

Profile data were collected in Echo Park Lake during both USEPA/Regional Board sampling events. On 

both days the lake appeared well-mixed both vertically and spatially. On March 10th, DO concentrations 

in the lake generally ranged from 7.0 mg/L to 8.6 mg/L with one reading of 10.0 mg/L from a surface 

sample; pH ranged from 7.5 to 7.9. On August 4th, DO concentrations in the lake ranged from 6.4 mg/L 

to 7.6 mg/L. The pH ranged from 8.3 to 8.6 throughout the water column and therefore exceeded the 

allowable range during the August 4th sampling event. Potable water measured during the August 4th

sampling event was 7.54 pH units. 

In summary, recent samples show the chlorophyll a target is being met. The 1994 Urban Lakes Study 

suggested that the fountain and aeration system were effective in managing DO concentrations (UC 

Riverside, 1994). That appears to be the case today as well, as the DO measurements are above 5 mg/L 

and averaged greater than the target of 7 mg/L. No odors were observed during five recent sampling 

events by USEPA and/or Regional Board. It is unlikely that the source of the odor reported at Echo Road 

Park Lake is due to elevated nutrient and algal biomass levels. They are likely associated with the trash 

impairment addressed in Section 6.8. 
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6.2.3.1 Summary of pH Non-Impairment

The Basin Plan states “The pH of inland surface waters shall not be depressed below 6.5 or raised above 

8.5 as a result of waste discharges. Ambient pH levels shall not be changed more than 0.5 units from 

natural conditions as a result of waste discharge.” There were nine elevations of pH in 36 recent 

samples. All elevations occurred during dry weather and therefore are not due to stormwater flow. 

Potable water which accounts for 89 percent of influent water measured 7.54 pH units. There are no other 

waste discharges that could be elevating the pH. Therefore, the elevated pH levels are meeting the water 

quality objective. In addition, the chlorophyll a target is being met, so nutrient loading is not elevating 

pH. Based on these multiple lines of evidence, Echo Park Lake is attaining beneficial uses and meets pH 

water quality standards. USEPA concludes that preparing a TMDL for pH is unwarranted at this time. 

USEPA recommends that Echo Park Lake not be identified as impaired by pH in California’s next 303(d) 

list.

6.2.3.2 Summary of Ammonia Non-Impairment

Echo Park Lake was listed as impaired for ammonia in 1996 based on an assessment in the Regional 

Board's Water Quality Assessment and Documentation Report (LARWQCB, 1996). Consistent with 

project plan recommendations provided in California's Impaired Waters Guidance (SWRCB, 2005), EPA 

and local agencies collected 34 additional samples (7 wet weather) between May 2003 and February 2010 

to evaluate current water quality conditions. There was one ammonia exceedance in 34 samples 

(Appendix G, Monitoring Data). Therefore, Echo Park Lake meets ammonia water quality standards and 

USEPA concludes that preparing a TMDL for ammonia is unwarranted at this time. USEPA recommends 

that Echo Park Lake not be identified as impaired for ammonia in California’s next 303(d) listing. 

6.2.4 Source Assessment

The source assessment for Echo Park Lake includes load estimates from the surrounding watershed 

(Appendix D, Wet Weather Loading; Appendix F, Dry Weather Loading) including irrigation (4.6 percent 

of the total irrigation volume is assumed to reach the lake), potable water used supplementing lake levels 

(Appendix F, Dry Weather Loading), and atmospheric deposition (Appendix E, Atmospheric Deposition). 

Loads generated from upland areas located in the city of Los Angeles in the northern and southern 

watersheds contribute 29 percent of the total phosphorus load and 28 percent of the total nitrogen load 

(the majority of runoff from these areas is diverted downstream of the lake). The potable water used for 

supplemental water additions contributes 46 percent of the total phosphorus load and 64 percent of the 

total nitrogen load to Echo Park Lake. In addition to these sources, there are other sources of loading to 

Echo Park Lake for which loading estimates were not available (Appendix F, Dry Weather Loading). 

These may include excessive fertilization relative to product recommendations, internal loading from lake 

sediments, natural wildlife populations, excessive resident bird populations caused by the improper 

disposal of food waste, and pet wastes. During calibration of the NNE BATHTUB model, loads in the 

category, “Additional Parkland Loading,” were increased until simulated concentrations of total 

phosphorus and total nitrogen matched those observed (see Section 6.2.5). For this waterbody, these 

additional sources of loading comprise 24 percent of the total phosphorus load and 5.5 percent of the total 

nitrogen load. All existing loads to Echo Park Lake are summarized in Table 6-5. 
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Table 6-5. Summary of Average Annual Flows and Nutrient Loading to Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Flow 

(ac-ft)

Total 

Phosphorus 

(lb-P/yr) (percent 

of total load)

Total Nitrogen 

(lb-N/yr)

(percent of 

total load)

Northern Caltrans State Highway 

Stormwater1

0.385 0.608 (0.6) 4.77 (0.7)

Northern City of Los Angeles MS4 Stormwater1 13.2 24.7 (22.7) 156 (21.3)

Southern Caltrans State Highway 

Stormwater1

0.033 0.051 (0.05) 0.403 (0.06)

Southern City of Los Angeles MS4 Stormwater1 4.16 6.99 (6.4) 48.4 (6.6)

Southern City of Los Angeles Supplemental Water 

Additions (Potable 

Water)

153 50.8 (46.6) 471 (64.4)

Southern City of Los Angeles Parkland Irrigation 0.418 0.139 (0.1) 1.29 (0.2)

Southern City of Los Angeles Additional Parkland 

Loading

NA 26.1 (23.9) 40 (5.4)

Lake Surface Atmospheric 

Deposition2

18.0 NA 9.0 (1.2)

Total 188 109 731

1This input includes effluent from storm drain systems during both wet and dry weather.

2 Loads for atmospheric deposition are based on direct precipitation to the lake (calculated by the annual average 

precipitation multiplied by the surface area of the lake).

A significant portion of loading from the additional parkland sources is likely due to excessive resident 

bird populations. According to a recent water quality modeling study conducted by Black and Veatch 

(2010), there is a year-round, resident bird population of approximately 1,000 Rock Doves and American 

Coots. Estimates of nutrient loading from these birds were based on literature values and an assumption 

that all waste generated by the birds would reach the lake (i.e., no uptake or trapping on adjacent areas). 

The estimated total phosphorus loading from these birds is 78 lb-P/yr, and the estimated total nitrogen 

loading is 780 lb-N/yr. Both loading estimates are greater than the additional parkland loading estimated 

from the BATHTUB model. This overestimation may be due to 1) an inaccurate estimate of the yearround bird population at Echo Park Lake, and 2) the conservative assumption that 100 percent of bird 

waste and associated nutrient loading reach the lake. Regardless of the accuracy of the estimated loading 

associated with bird waste, this analysis indicates that nutrient loading associated with the excess bird 

population comprises a significant portion of the additional parkland loading.

6.2.5 Linkage Analysis

The linkage analysis defines the connection between numeric targets and identified pollutant sources and 

may be described as the cause-and-effect relationship between the selected indicators, the associated 

numeric targets, and the identified sources. This provides the basis for estimating total assimilative 

capacity and any needed load reductions. To simulate the impacts of nutrient loading on Echo Park Lake, 

the nutrient numeric endpoints (NNE) BATHTUB Tool was set up and calibrated to lake-specific 

conditions. The NNE BATHTUB Tool is a version of the US Army Corps of Engineers (USACE) 
Echo Park Lake TMDLs January 2011

6-15

BATHTUB model and was developed to support risk-based nutrient numeric endpoints in California 

(Tetra Tech, 2006). 

BATHTUB is a steady-state model that calculates nutrient concentrations, chlorophyll a concentration (or 

algal density), turbidity, and hypolimnetic oxygen depletion based on nutrient loadings, hydrology, lake 

morphometry, and internal nutrient cycling processes. BATHTUB uses a typical mass balance modeling 

approach that tracks the fate of external and internal nutrient loads between the water column, outflows, 

and sediments. External loads can be specified from various sources including stream inflows, nonpoint 

source runoff, atmospheric deposition, groundwater inflows, and point sources. Internal nutrient loads 

from cycling processes may include sediment release and macrophyte decomposition. The net 

sedimentation rates for nitrogen and phosphorus reflect the balance between settling and resuspension of 

nitrogen and phosphorus within the waterbody. Thus, internal loading is implicitly accounted for in the 

model. Since BATHTUB is a steady-state model, it focuses on long-term average conditions rather than 

day-to-day variations in water quality. 

Target nutrient loads and resulting allocations are determined based on the secondary target – summer

mean chlorophyll a concentration. The NNE spreadsheet tool allows the user to specify a chlorophyll a

target and predicts the probability that current conditions will exceed the target, as well as showing a 

matrix of allowable nitrogen and phosphorus loading combinations to meet the target. The user-defined 

chlorophyll a target can be input directly by the user, or can be calculated based on an allowable change 

in water transparency measured as Secchi depth. Appendix A (Nutrient TMDL Development) describes 

additional details on the NNE BATHTUB Tool and its use in determining allowable loads of nitrogen and 

phosphorus. 

In addition to loading rates of nitrogen and phosphorus, the NNE BATHTUB Tool requires basic 

bathymetry data for the simulation of chlorophyll a during the summer. For Echo Park Lake, the 

following inputs apply: surface area of 14.1 acres, average depth of 5 ft, and volume of 70.5 ac-ft. Based 

on the turnover ratios for both nitrogen and phosphorus (Walker, 1987), the annual averaging period is 

most appropriate (i.e., annual loads are input to the model rather than summer season loads). Based on 

the results of a recent exfiltration and flow monitoring study of the lake (Black and Veatch, 2008), 

exfiltration losses through the lake liner are approximately 52.6 ac-ft/yr. Loads of nitrogen and 

phosphorus associated with these losses were estimated from average in-lake water quality data 

multiplied by the annual rate of exfiltration. 

The NNE BATHTUB Tool was calibrated to average summer season water quality data observed over 

twice the Secchi depth (2*0.8 m = 1.6 m). Because simulated phosphorus concentrations could not be 

calibrated within the default range specified in the BATHTUB User’s Manual (Walker, 1987), loads from 

additional parkland sources were increased to predict the average summer concentrations of total 

phosphorus (0.115 mg-P/L) and total nitrogen (1.16 mg-N/L), leaving the net sedimentation rates at 1.0 

for both nutrients. Additional loading associated with parkland areas is 40 lb-N/yr and 40 lb-P/yr. The 

amount of the additional parkland loading of phosphorus due to internal recycling was calculated with the 

method discussed in Appendix A (Nutrient TMDL Development) and is 13.9 lb-P/yr. This portion of the 

phosphorus load was subtracted out of the additional parkland sources category, and the model was 

recalibrated with a loading of 26.1 lb-P/yr. The resulting calibration factor on the net phosphorus settling 

rate is 0.74, which allows the model to account for internal loading implicitly. Though internal loading is 

not explicitly assigned a load allocation, reductions in external loading of phosphorus will ultimately 

result in reductions of internal cycling processes. Internal loading of nitrogen was not calculated because 

1) internal loading is typically insignificant relative to external loading, and 2) empirical relationships for 

the estimation of internal nitrogen loading have not been developed. Thus, the additional parkland source 

loading and calibration factor for nitrogen were not changed. To simulate the average observed summer 

chlorophyll a concentration, the calibration factor on chlorophyll a concentration was set to 0.45 for a 

predicted concentration of 17.8 μg/L. 
Echo Park Lake TMDLs January 2011 

6-16

Because of the way Echo Park Lake is currently managed (fountain, aeration system, hydroponic islands, 

etc.), the density of algae is typically below the target summer average concentration (20 μg/L). However 

pH and chlorophyll a exceedances have occurred. To be adequately protective, nutrient TMDLs are 

allocated at existing levels as an antidegradation measure to ensure that future loading does not increase 

the chlorophyll a concentration. 

6.2.6 TMDL Summary 

A waterbody’s loading capacity represents the maximum load of a pollutant that can be assimilated 

without violating water quality standards (40 CFR 130.2(f)). This is the maximum nutrient load 

consistent with meeting the numeric target of 20 μg/L of chlorophyll a as a summer average. The 

methodology for determining the loading capacity is described briefly in this section. For more detail, 

refer to Appendix A (Nutrient TMDL Development). 

Based on observed levels of chlorophyll a and DO in Echo Park Lake, existing levels of nitrogen and 

phosphorus loading result in attainment of both the chlorophyll a and DO targets. Monitoring data 

indicate that the average in-lake total nitrogen concentration is 1.16 mg-N/L (Appendix G, Monitoring 

Data). Because the majority of in-lake phosphorous samples have been less than the detection limits for 

the analytical laboratory, the phosphorus target concentration is based on an in-lake ratio of total nitrogen 

concentration to total phosphorus concentration close to 10. This ratio was selected to match that 

typically observed in natural systems and to balance biomass growth and prevent limitation by one 

nutrient (Thomann and Mueller, 1987). The corresponding in-lake concentrations of nitrogen and 

phosphorus are 

 1.2 mg-N/L summer average (May – September) and annual average 

 0.12 mg-P/L summer average (May – September) and annual average 

To prevent degradation of this waterbody, nutrient TMDLs will be allocated based on existing loading. 

These TMDLs are broken down into the wasteload allocations (WLA), load allocations (LA), and 

Margins of Safety (MOS) using the general TMDL equation. Note that the MOS is zero because the 

TMDLs are equal to the existing load. 

TMDL WLA LA MOS

For total nitrogen, the allocatable load is equal to the existing load and is divided among WLAs and LAs. 

The resulting TMDL equation for total nitrogen is then: 

731 lb-N/yr = 682 lb-N/yr + 49.0 lb-N/yr + 0 lb-N/yr 

For total phosphorus, the allocatable load is equal to the existing load and allocated to WLAs only; LAs 

are zero as explained in Section 6.2.6.2. The resulting TMDL equation for total phosphorous is then: 

109 lb-P/yr = 83.3 lb-P/yr + 26.1 lb-P/yr + 0 lb-P/yr 

Allocations are assigned for these TMDLs by requiring equal percentage reductions of all sources. 

Details associated with the WLAs, LAs, and MOS are presented in the following three sections. 

As previously mentioned, in-lake concentrations of nitrogen and phosphorus have been determined for the 

lake based on recent and historical monitoring data (see Section 6.2.3). These in-lake concentrations 

reflect internal cycling processes (see Appendix A, Nutrient TMDL Development) and, therefore, differ 

from concentrations associated with various inflows. Nutrient concentrations associated with the WLA 

and LA inputs are described below. These values are provided as examples as they are calculated based 
Echo Park Lake TMDLs January 2011

6-17

on existing flow volumes (and will need to be recalculated if flow volumes change). Because the input 

concentrations do not consider internal cycling processes and are based on existing flow volumes, they do 

not match the allowable in-lake nitrogen and phosphorous concentrations.

6.2.6.1 Wasteload Allocations

Responsible jurisdictions are encouraged to consider the construction of wetland systems and bioswales 

(or other biofiltration options) to treat the stormwater and supplemental water flows entering the lake, as 

well as stormwater diversion and infiltration using methods such as porous pavements and rain gardens. 

Implementing these options can reduce the lake’s nutrient loads and, in the case of recirculation through 

constructed wetlands, reduce in-lake nutrient concentrations. Additionally, persons that apply algaecides 

as part of an overall lake management strategy must comply with the Aquatic Pesticide General Permit 

(General Permit Order No. 2004-0009-DWQ, CAG990005).

The City of Los Angeles has modeled expected nutrient concentration reductions to stormwater flows to 

Echo Park Lake from constructed wetlands, and plans to finalize the design and begin construction in the 

near future. Information about this and other City of Los Angeles water quality improvement projects are 

available on Proposition O website: http://www.lapropo.org/sitefiles/lariver.htm. 

These TMDLs establish individual wasteload allocations (WLAs) and alternative WLAs for each of the 

inputs listed in Table 6-5. In addition, these TMDLs establish an alternative wasteload allocation for total 

phosphorous and an alternative wasteload allocation for total nitrogen. The alternative wasteload 

allocations (the “Grouped Allocations”) WLAs will be effective and supersede the individual wasteload 

allocations WLAs listed in Table 6-6 if the conditions described in Section 6.2.6.1.2 are met.

Under any of the wasteload allocation schemes responsible jurisdictions are encouraged to consider the 

construction of wetland systems and bioswales (or other biofiltration options) to treat the stormwater and 

supplemental water flows entering the lake, as well as stormwater diversion and infiltration using 

methods such as porous pavements and rain gardens. Implementing these options can reduce the lake’s 

nutrient loads and, in the case of recirculation through constructed wetlands, reduce in-lake nutrient 

concentrations. In the case of Echo Park Lake, the City of Los Angeles has already modeled expected 

nutrient concentration reductions to stormwater flows to Echo Park Lake from such best management 

practices and plans to finalize the design and begin construction in the near future of a major lake 

rehabilitation project. 

Additionally, persons that apply algaecides as part of an overall lake management strategy must comply 

with the Aquatic Pesticide General Permit (General Permit Order No. 2004-0009-DWQ, CAG990005).

6.2.6.1.1 Individual Wasteload Allocations

The Echo Park Lake watershed drains to a series of storm drains prior to discharging to the lake. 

Therefore, all nutrient loads associated with the surrounding drainage area are assigned WLAs (Note: the 

loading associated with irrigation is included with the loading for in the Ccity of Los Angeles’ in the 

southern subwatershedWLA). The potable water input used for supplemental water addition to the lake

discharges at a single point and is also assigned a WLA along with the Caltrans areas. Relevant permit 

numbers are 

 County of Los Angeles (including the city of Los Angeles): Board Order 01-182 (as amended by 

Order No. R4-2006-0074 and R4-2007-0042), CAS004001

 Caltrans: Order No 99-06-DWQ, CAS000003

Note that WLAs are equal to existing loading rates because no reductions in loading are required. WLAs 

are presented in Table 6-6. These loading values (in pounds per year) represent the TMDLs wasteload 
Echo Park Lake TMDLs January 2011

6-18

allocations and must be met as a three year average (Table 6-6). All responsible jurisdictions must meet 

the WLAs at the point of discharge as a mass load except for stormwater permittees under the general 

industrial stormwater permit that are receiving concentration-based WLAs. In Table 6-6 below, 

stormwater permittees under the general industrial stormwater permit must meet the concentration values 

to achieve compliance with the WLAs. The phosphorous and nitrogen WLA concentrations were 

calculated by dividing the allowable load (in lbs/yr; Table 6-6) by total inflow volume (Table 6-5). 

Table 6-6. Individual Wasteload Allocations of Phosphorus and Nitrogen Loading to Echo Park 

Lake

Subwatershed

Responsible 

Jurisdiction Input

Wasteload Allocation 

Total Phosphorus 

(lb-P/yr)4

Wasteload 

Allocation Total 

Nitrogen (lb-N/yr)4

Northern Caltrans State Highway 

Stormwater1

0.608 4.77

Northern City of Los Angeles MS4 Stormwater1 24.7 156

Northern General Industrial 

Stormwater 

Permittees (in the 

City of Los Angeles)3

General Industrial 

Stormwater1

0.16 mg/L P2 1.33 mg/L N2

Southern Caltrans State Highway 

Stormwater1

0.051 0.403

Southern City of Los Angeles MS4 Stormwater1 7.129 49.69

Southern City of Los Angeles Supplemental Water 

Additions

50.8 471

Total 83.3 682

1This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

3For these responsible jurisdictions, the concentration-based WLA will be use to evaluate compliance.

4A three year average will be used to evaluate compliance.

6.2.6.1.2 Alternative “Grouped Allocations” 

The individual wasteload allocations WLAs Table 6-7 are effective and supersede the WLAs in Table 6-6

are superseded, and the alternative wasteload allocations listed in Table 6-7 are established, if:

1. The city of Los Angeles and Caltrans request that the WLAs in Table 6-7 apply to them;: submit 

to USEPA and the Regional Board material showing describing how the City and Caltrans will 

assure that the alternative grouped WLAs allocations will be met; and agree that the City and 

Caltrans will jointly be responsible for meeting those allocations;

1.2.The Regional Board approves the request; and 

2.3.USEPA does not object to the Regional Board’s determination within sixty days of receiving 

notice of it.

Table 6-7. Alternative Grouped Wasteload Allocations of Phosphorus and Nitrogen Loading to 

Echo Park Lake
Echo Park Lake TMDLs January 2011

6-19

Subwatershed

Responsible 

Jurisdiction Input

Wasteload Allocation 

Total Phosphorus (lbP/yr)1

Wasteload 

Allocation Total 

Nitrogen (lb-N/yr)1

All Subwatersheds City of Los Angeles, 

Caltrans

Grouped Allocations 83.3 682

1 A three year average will be used to evaluate compliance.

6.2.6.2 Load Allocations

Atmospheric deposition of nitrogen to the lake surface is a nonpoint source and is assigned a load 

allocation (LA). Table 6-8 presents the LA for atmospheric deposition, which is equivalent to existing 

loading rates because no reductions in loading are required. Atmospheric deposition does not contribute 

significant loads of phosphorus (Appendix E, Atmospheric Deposition). LAs are provided for each 

responsible jurisdiction and input. These loading values (in pounds per year) represent the TMDLs load 

allocations (Table 6-8). 

Table 6-8. Load Allocations of Phosphorus and Nitrogen Loading to Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Load Allocation 

Total Phosphorus 

(lb-P/yr)1

Load Allocation 

Total Nitrogen 

(lb-N/yr)1

Southern City of Los Angeles Additional Parkland 

Loading

26.1 40

Lake Surface Atmospheric 

Deposition2

NA 9.0

Total 26.1 49.0

1 A three year average will be used to evaluate compliance.

2 Loads for atmospheric deposition are based on direct precipitation to the lake (calculated by the annual average 

precipitation multiplied by the surface area of the lake).

6.2.6.3 Margin of Safety

TMDLs must include a margin of safety (MOS) to account for any lack of knowledge concerning the 

relationship between load and wasteload allocations and water quality. The MOS may be implicit, i.e., 

incorporated into the TMDL through conservative assumptions in the analysis, or explicit, i.e., expressed 

in the TMDL as loadings set aside for the MOS. This lake is currently achieving the in-lake chlorophyll a

target and TMDLs are being established at the existing loads. This conservative anti-degradation measure 

is the implicit margin of safety for these TMDLs.

6.2.6.4 Critical Conditions/Seasonality

TMDLs must include consideration of critical conditions and seasonal variation to ensure protection of 

the designated uses of the waterbody at all times. Critical conditions for nutrient impaired lakes typically 

occur during the warm summer months when water temperatures are elevated and algal growth rates are 

high. Elevated temperatures not only reduce the saturation levels of DO, but also increase the toxicity of 

ammonia and other chemicals in the water column. Excessive rates of algal growth may cause large 

swings in DO, elevated pH, odor, and aesthetic problems. Loading of nutrients to lakes during winter 

months are often biologically available to fuel algal growth in summer months. These nutrient TMDLs 

account for summer season critical conditions by using the NNE Bathtub model to calculate possible 
Echo Park Lake TMDLs January 2011

6-20

annual loading rates consistent with meeting the summer chlorophyll a target concentration of 20 μg/L. 

These TMDLs are based on existing conditions as an anti-degradation measure since nitrogen and 

phosphorus levels are currently achieving the chlorophyll a target level. These TMDLs therefore protect 

for critical conditions.

6.2.6.5 Daily Load Expression

USEPA recommends inclusion of a daily load expression for all TMDLs to comply with the 2006 D.C. 

Circuit Court of Appeals decision for the Anacostia River. These TMDLs present a maximum daily load 

according to the guidelines provided by USEPA (2007). The majority of nutrient loading to Echo Park 

Lake comes from the supplemental water additions. These maximum loads are not allowed each day of 

the year because the annual loads specified by the TMDLs must also be achieved. The WLA and LA 

loads presented above are annual loading caps that cannot be exceeded.

The maximum daily loads from the supplemental water additions were calculated from average daily 

water volume and the long-term average concentration consistent with meeting the TMDLs. For the 

supplemental water addition, the allowable concentrations are 1.13 mg-N/L and 0.122 mg-P/L (Section 

6.2.6.1). The daily average flow rate is 0.419 ac-ft/d (153 ac-ft/yr divided by 365 d/yr). The maximum 

daily nutrient loads from this source are 1.29 lb-N/d and 0.139 lb-P/d. 

As described above, in order to achieve in-lake nutrient targets as well as annual load-based allocations, 

the maximum allowable daily loads cannot be discharged to the lake every day. The WLA and LA loads 

presented above are annual loading caps that cannot be exceeded.

6.2.6.6 Future Growth/Conditions

The Echo Park Lake watershed is nearly fully developed, with the exception of small park areas that are 

not likely to be converted in the near future. If land use changes do occur in the watershed, BMPs will be 

required such that loading rates are consistent with the allocations established by these TMDLs. 

Therefore, no load allocation has been set aside for future growth.

Though future growth is not expected to impact conditions in Echo Park Lake, the city of Los Angeles is 

in the process of designing and constructing a large scale rehabilitation project at the park, which will 

impact the conditions of the lake system. In addition to treating runoff flows with a hydrodynamic 

separator and constructed wetland system, the City is considering the use of reclaimed/recycled water for 

supplemental water additions to the lake rather than the potable water source that is currently used. 

The design engineers indicate that the rehabilitation project will have the following impacts on the system 

(personal communication, James Rasmus, Black and Veatch, April 16, 2010):

 Wet weather flows to the lake from the storm drain system will increase from 16.7 ac-ft/yr to 

131 ac-ft/yr. Dry weather flows to the lake from the storm drain system will increase from 

0 ac-ft/yr to 123 ac-ft/yr.

 Exfiltration losses through the lake liner will decrease to 0.896 ac-ft/yr.

 The vortex and constructed wetland treatment system will treat 121 ac-ft/yr of wet weather flows, 

123 ac-ft/yr of dry weather flows, and all water used for supplementing lake levels. Lake water 

will be recirculated through the constructed wetland system at a rate of 600 gpm. 

 The vortex/constructed wetland system will remove 68 percent of the total nitrogen and 

77 percent of the total phosphorus loads from treated flows. Recirculation of lake water will 

increase reduction efficiencies to 80 percent for total nitrogen and 86 percent for total 

phosphorus. These values represent updated efficiencies from the City of Los Angeles (personal 

communication, City of Los Angeles, June 2010). 
Echo Park Lake TMDLs January 2011

6-21

To simulate the impacts of the rehabilitation project on lake water quality, the following conservative 

assumptions were made:

 Reclaimed water from the Glendale Water Reclamation Plant will be used for irrigation of park 

areas and supplemental water additions (see Appendix G [Monitoring Data] for water quality data 

for this source).

 The volume of reclaimed water used for supplemental water additions will be 15.5 ac-ft/yr based 

on a worst case scenario of evaporative losses of 55,000 gpd for three months straight with no wet 

or dry weather flows to offset these losses. 

Simulating this future scenario for Echo Park Lake with the calibrated NNE BATHTUB model yields a 

total nitrogen concentration of 0.79 mg-N/L, a total phosphorus concentration of 0.10 mg-P/L, and a 

chlorophyll a concentration of 12μg/L. These simulated in-lake concentrations are based on the reduction 

efficiencies reported for the vortex/constructed wetland/recirculation system. If reductions are based on 

the vortex/constructed wetland system without recirculation, the simulated in-lake total phosphorus 

concentration is not predicted to meet the target of 0.12 mg-P/L regardless of the assumptions regarding 

supplemental water additions (potable versus reclaimed, with or without supplemental water additions, 

etc.). If the rehabilitation project does not result in the assumed reduction efficiencies of 80 percent for 

total nitrogen and 86 percent for total phosphorus, pre-treatment or additional treatment of the wet 

weather and dry weather flows may be necessary to meet the in-lake target concentrations. 

If any sources currently assigned load allocations are later determined to be point sources requiring 

NPDES permits, those load allocations are to be treated as wasteload allocations for purposes of 

determining appropriate water quality-based effluent limitations pursuant to 40 CFR 122.44(d)(1).

6.3 LEAD IMPAIRMENT

Echo Park Lake was listed as impaired for lead in 1996 based on an assessment in the Regional Board's 

Water Quality Assessment and Documentation Report (LARWQCB, 1996). Consistent with project plan 

recommendations provided in California's Impaired Waters Guidance (SWRCB, 2005), USEPA and local 

agencies collected 61 additional samples (12 wet weather) between November 2004 and March 2010 to 

evaluate current water quality conditions. There were only four dissolved lead exceedances in 61 samples 

(Appendix G, Monitoring Data). Therefore, Echo Park Lake meets lead water quality standards, and 

USEPA concludes that preparing a TMDL for lead is unwarranted at this time. USEPA recommends that 

Echo Park Lake not be identified as impaired by lead in California’s next 303(d) list.

6.4 COPPER IMPAIRMENT

Echo Park Lake was listed as impaired for copper in 1996 based on an assessment in the Regional Board's 

Water Quality Assessment and Documentation Report (LARWQCB, 1996). Consistent with project plan 

recommendations provided in California's Impaired Waters Guidance (SWRCB, 2005), USEPA and local 

agencies collected 60 additional samples (12 wet weather) between November 2004 and March 2010 to 

evaluate current water quality conditions. There were only four dissolved copper exceedances in 60 

samples (Appendix G, Monitoring Data). Therefore, Echo Park Lake meets copper water quality 

standards, and USEPA concludes that preparing a TMDL for copper is unwarranted at this time. USEPA 

recommends that Echo Park Lake not be identified as impaired by copper in California’s next 303(d) list.

6.5 PCB IMPAIRMENT

Polychlorinated biphenyls (PCBs) consist of a family of many related congeners. The individual 

congeners are often referred to by their “BZ” number. Environmental analyses may address individual 
Echo Park Lake TMDLs January 2011

6-22

congeners, homologs (groups of congeners with the same number of chlorine atoms), equivalent 

concentrations of the commercial mixtures of PCBs known by the trade name Aroclors, or total PCBs. 

The environmental measurements and targets described in this section are in terms of total PCBs, defined 

as the “sum of all congener or isomer or homolog or Aroclor analyses” (CTR, 40 CFR 131.38(b)(1) 

footnote v).

The PCB impairment of Echo Park Lake affects beneficial uses related to recreation, municipal water 

supply, wildlife health, and fish consumption. PCBs are no longer in production. While some loading of 

PCBs continues to occur in watershed runoff, the primary source of PCBs in the water column and 

aquatic life in Echo Park Lake is from historic loads stored in the lake sediments. Like other 

organochlorine compounds, PCBs accumulate in aquatic organisms and biomagnify in the food chain. As 

a result, low environmental exposure concentrations can result in unacceptable levels in higher trophic 

level fish in the lake.

6.5.1 Beneficial Uses

California state water quality standards consist of the following elements: 1) beneficial uses, 

2) narrative and/or numeric water quality objectives, and 3) an antidegradation policy. In California, 

beneficial uses are defined by the Regional Water Quality Control Boards (Regional Boards) in the Water 

Quality Control Plans (Basin Plans). Numeric and narrative objectives are specified in each region’s 

Basin Plan, designed to be protective of the beneficial uses of each waterbody in the region. The existing 

beneficial uses assigned to Echo Park Lake include REC1, REC2, WARM, WILD, and MUN. 

Descriptions of these uses are listed in Section 2 of this TMDL report. Elevated levels of PCBs 

potentially impair the REC1, REC2, WARM, WILD, and MUN uses by causing toxicity to aquatic 

organisms and raising fish tissue concentrations to levels that are unsafe for human consumption (which 

can result in fish consumption advisories) and impair sport fishing recreational uses.

6.5.2 Numeric Targets

The Basin Plan designates water column concentrations associated with MUN and WARM beneficial 

uses. There are no numeric criteria specified for sediment or fish tissue concentrations of PCBs in the 

Basin Plan. For the purposes of this TMDL, additional numeric targets for these endpoints are based on 

the consensus-based sediment quality guidelines defined in MacDonald et al. (2000) and the fish tissue 

concentration goal, referred to as the fish contaminant goal (FCG), defined by the OEHHA (2008) for fish 

consumption. The numeric targets used for PCBs are listed below. The fish tissue concentration goal 

was also used to back calculate site-specific targets in sediment, with the most stringent target applying. 

See Section 2 of this TMDL report for additional details.

The water column criteria for PCBs in the Basin Plan are associated with a specific beneficial use. For 

waters designated MUN, the Basin Plan lists a maximum contaminant level of 0.0005 mg/L, or 0.5 μg/L, 

total PCBs in water. The Plan also contains a narrative criterion that toxic chemicals not be present at 

levels that are toxic or detrimental to aquatic life (LARWQCB, 1994). Each waterbody addressed in this 

report is designated WARM, at a minimum, and must meet this requirement. A chronic criterion for the 

sum of PCB compounds in freshwater systems to protect aquatic life is included in the CTR as 0.014 μg/L 

(USEPA, 2000a). The CTR also provides a human health-based water quality criterion for the 

consumption of both water and organisms and organisms only of 0.00017 μg/L (0.17 ng/L). The human 

health criterion of 0.17 ng/L is the most restrictive applicable criteria specified for water column 

concentrations and is selected as the water column target. 

For sediment, the consensus-based sediment quality guidelines provided in Macdonald et al. (2000) for 

the threshold effects concentration (TEC) for total PCBs in sediment is 59.8 μg/kg (ng/dry g) dry weight. 

The consensus-based guidelines have been incorporated into the most recent set of NOAA Screening 
Echo Park Lake TMDLs January 2011

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Quick Reference Tables (SQuiRT) (Buchman, 2008) and are recommended by the State Water Resources 

Control Board for interpretation of narrative sediment objectives under the 303(d) listing policy. This 

target is designed to protect benthic dwelling organisms and explicitly does not consider “the potential for 

bioaccumulation in aquatic organisms nor the associated hazards to the species that consume aquatic 

organisms (i.e., wildlife and humans).” The existing sediment PCB concentrations in Echo Park Lake are 

lower than the consensus-based TEC target, and existing fish tissue concentrations are higher than the fish 

tissue target. Thus, a separate sediment target calculation based on a biota-sediment accumulation factor 

(BSAF) is carried out to ensure that fish tissue concentration goals are met. 

The fish contaminant goal for PCBs defined by the OEHHA (2008) is 3.6 ppb wet weight in muscle tissue 

(filets). Elevated fish tissue concentrations are largely attributable to foodweb bioaccumulation derived 

from contaminated sediment. A biota-sediment accumulation factor (BSAF) approach is appropriate to 

correlate sediment and fish tissue targets. For total PCBs, the corresponding sediment concentration 

target determined using the BSAF is 1.77 μg/kg dry weight, as described in detail in Section 6.5.5. All 

applicable targets are shown below in Table 6-9. For sediment, the lower value of the consensus-based 

TEC target or the BSAF-derived target is selected as the final sediment target.

Table 6-9. PCB Targets Applicable to Echo Park Lake

Medium Source Target

Fish (ppb wet weight) OEHHA FCG 3.6

Sediment (μg/kg dry weight) Consensus-based TEC 59.8

Sediment (μg/kg dry weight) BSAF-derived target 1.77

Water (ng/L) CTR 0.17

Note: Shaded cells represent the selected targets for this TMDL.

6.5.3 Summary of Monitoring Data

This section summarizes the monitoring data for Echo Park Lake related to the PCB impairment.

Additional details regarding monitoring data are discussed in Appendix G (Monitoring Data). For PCBs, 

as well as other organochlorine compounds, sample analyses include both a detection limit and a method 

reporting limit. For example, a typical detection limit for total PCBs in sediment reported by UCLA is 

0.53 μg/kg dry weight, while the reporting limit is 15 μg/kg dry weight. 

Water column sampling was conducted as part of an organics study performed by UCLA (funded by a 

grant managed by the Regional Board) in the summer of 2008. In all three samples PCB congeners were 

detected, but below reporting limits of 15 ng/L. Water samples from Echo Park Lake were also collected 

by the Regional Board on December 18, 2008 at four stations. PCBs at all stations were below the 

detection limit of 1 ng/L. A summary of the water column data is shown in Table 6-10.

Table 6-10. Summary of Water Column Samples for PCBs in Echo Park Lake

Station

Average Water 

Concentration 

(ng/L)1

Number of 

Samples

Number of 

Samples above 

Detection Limits

Number of Samples 

between Detection and 

Reporting Limits

NE near LA City Storm Drain (0.5) 1 0 0

W near County Storm Drain (0.5) 1 0 0

South [2.72] 3 2 2
Echo Park Lake TMDLs January 2011

6-24

North, Lotus Bed [4.47] 2 1 1

Northeast (0.5) 1 0

In-Lake Average2[1.74]

CTR Water Column Target 0.17

1Total PCBs in a sample represents the sum of all quantified PCB congeners, including results reported below the 

method reporting limit. If all congeners were non-detect, the total is represented as one-half the detection limit. 

Results of any laboratory duplicate analyses of the same sample were averaged. Results for each station represent 

the average of individual samples. Results in parentheses indicate that the sample average is based only on the

detection limits of the samples and that no PCBs were quantified in any of the collected samples. Sample averages 

based only on detected results below the reporting limit plus non-detects are shown in square brackets.

2Overall average is the average of individual station averages.

Echo Park Lake samples from summer 2008 were analyzed for pollutant concentrations associated with 

suspended sediments in the lake. Samples were analyzed at two stations with detection limits ranging 

from 3.19 μg/kg to 10.05 μg/kg dry weight, and reporting limits ranging from 31.95 μg/kg to 100.5 μg/kg 

dry weight. In one sample, PCB congener BZ-31 was detected at 117 μg/kg dry weight, while congener 

BZ-153 was also detected, but not above the reporting limit. 

UCLA collected bed sediment samples at four locations in Echo Park Lake in summer and fall 2008. 

Samples related to tributaries were collected in the lake near the tributary outfalls. Several PCB 

congeners were detected in the summer 2008 sediment samples, with only one station with all congeners 

below detection limits. 

Sediment sampling was also conducted by the Regional Board at three stations on December 1, 2009. 

PCBs were quantified at all three stations. PCB congeners BZ-18, BZ-95, BZ-101, and BZ-110 were 

quantified at all locations. Other congeners were also quantified at one or two locations. A summary of 

the sediment data is shown in Table 6-11. The lake-wide average of 40.29 μg/kg dry weight is greater 

than the concentration near outfalls (24.16 μg/kg dry weight), and both are less than the consensus-based

TEC of 59.8 μg/kg dry weight.

Table 6-11. Summary of Sediment Samples for PCBs in Echo Park Lake, 2008-2009

Station

Average Sediment 

Concentration 

(μg/kg dry weight)

1

Number 

of 

Samples

Number of 

Samples above 

Detection Limits

Number of Samples

between Detection 

and Reporting Limits

NE near LA City Storm Drain 2.98 3 3 2

W near County Storm Drain 31.41 2 1 0

South 29.85 1 1 0

North, Lotus Bed 70.01 2 1 0

Northeast (0.30) 1 0 0

NW Arm near outfall 38.10 1 1 0

Center Lake 72.55 2 2 0

Center Lake South 77.10 1 1 0

In-Lake Average2 40.29

Influent Average 24.16
Echo Park Lake TMDLs January 2011

6-25

Station

Average Sediment 

Concentration 

(μg/kg dry weight)

1

Number 

of 

Samples

Number of 

Samples above 

Detection Limits

Number of Samples

between Detection 

and Reporting Limits

Consensus-based TEC 59.8

1Total PCBs in a sample represents the sum of all quantified PCB congeners, including results reported below the 

method reporting limit. If all congeners were non-detect, the total is represented as one-half the detection limit. 

Results of any laboratory duplicate analyses of the same sample were averaged. Results for each station represent 

the average of individual samples. Results in parentheses indicate that the sample average is based only on the 

detection limits of the samples and that no PCBs were quantified in any of the collected samples. Sample averages 

based only on detected results below the reporting limit plus non-detects are shown in square brackets.

2Overall average is the average of individual station averages.

Four fish samples (composites of filets from five fish) were collected and analyzed for PCBs as Aroclor 

equivalents between 1987 and 1991. In 1987, a largemouth bass and bullhead sample reported 84 ppb 

and 50 ppb wet weight, respectively. Another largemouth bass sample was analyzed in 1991 and reported 

as 0 ppb (the detection limits for the historical fish samples are not reported). In 1992, the PCB 

concentration in a largemouth bass composite sample was 60 ppb. The average reported PCB 

concentration in all samples from the 1980s and 1990s was 48.5 ppb, including the reported zero. Results 

from the individual samples are shown in Appendix G (Monitoring Data). 

Considering only data collected in the past 10 years, the average concentration of total PCBs in 

largemouth bass was 49.0 ppb wet weight, based on the two largemouth bass composite samples collected 

by SWAMP in the summer of 2007 with an average lipid fraction of 0.396 percent and an additional 

sample from April 2010 with a lipid fraction of 0.315 percent. Three composite samples of bottomfeeding carp (Trophic Level 3) were also analyzed. These yielded an average total PCB concentration of 

81.8 ppb wet weight with an average lipid fraction of 1.263 percent. The recent fish-tissue data for Echo 

Park Lake are summarized in Table 6-12.

Table 6-12. Summary of Recent Fish Tissue Samples for PCBs in Echo Park Lake

Sample Date Fish Species Total PCBs (ppb wet weight)1

11 June 2007 Largemouth Bass 64.7

11 June 2007 Largemouth Bass 31.5

13 April 2010 Largemouth Bass 50.9

11 June 2007 Common Carp 119.0

11 June 2007 Common Carp 82.6

13 April 2010 Common Carp 43.9

2007 - 2010 Average – Largemouth Bass 49.0

2007 - 2010 Average – Common Carp 81.8

FCG 3.6

1Composite sample of filet from five individuals.

In sum, recent fish tissue samples collected from Echo Park Lake are all elevated above the OEHHA fish 

consumption guidelines for total PCBs. Concentrations in sediment are, on average, below the 

consensus-based TEC, although individual samples exceed this value. Concentrations in water have not 

been quantified; however, several 2008 samples were above detection limits that exceed the CTR 

criterion, although less than the reporting limit.
Echo Park Lake TMDLs January 2011

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6.5.4 Source Assessment

PCBs in Echo Park Lake are primarily due to historical loading and storage within the lake sediments, 

with some ongoing contribution by watershed wet weather loads. Dry weather loading is assumed to be 

negligible because hydrophobic contaminants primarily move with particulate matter that is mobilized by 

higher flows. Stormwater loads from the watershed were estimated based on simulated sediment load and 

observed PCB concentrations on sediment near inflows to the lake. Watershed loads of PCBs may arise 

from spills from industrial and commercial uses, improper disposal, and atmospheric deposition. 

Industrial and commercial spills will tend to be associated with specific land areas, such as older 

industrial districts, junk yards, and transformer substations. Improper disposal could have occurred at 

various locations (indeed, waste PCB oils were sometimes used for dust control on dirt roads in the 

1950s). Atmospheric deposition occurs across the entire watershed. 

There is no definitive information on specific sources of elevated PCB load within the watershed at this 

time. Therefore, an average concentration on sediment is applied to all contributing areas. Although 

supplemental water additions of potable water makes up a significant amount of the flow to Echo Park 

Lake it does not contribute sediment load and is considered to not contribute significantly to PCB loading 

(total suspended sediment measured non-detect in two samples collected August 4th 2009). 

The average concentration of PCBs on incoming sediment was estimated to be 24.16 μg/kg dry weight

and the estimated annual sediment load to Echo Park Lake is 1.32 tons/yr (see Appendix D, Wet Weather 

Loading). The resulting estimated wet weather load of PCBs is approximately 0.029 g/yr. Table 6-13

shows the annual PCB load estimated from each jurisdiction. 

Table 6-13. Total PCB Loads Estimated for Each Jurisdiction and Subwatershed in the Echo 

Park Watershed (g/yr)

Subwatershed

Responsible 

Jurisdiction Input

Sediment Load 

(tons/yr)

Total PCB 

Load (g/yr)

Percent of 

Total Load

Northern Caltrans State Highway 

Stormwater1

0.044 0.0010 3.35%

Northern City of Los 

Angeles

MS4 

Stormwater1

0.98 0.021 74.24%

Southern Caltrans State Highway 

Stormwater1

0.0037 0.0001 0.28%

Southern City of Los 

Angeles

MS4 

Stormwater1

0.29 0.0064 22.13%

Total Load from Watershed 1.32 0.029 100%

1This input includes effluent from storm drain systems during both wet and dry weather.

As described in Appendix E (Atmospheric Deposition), Section E.5, the net atmospheric deposition of 

PCBs directly to the lake surface is estimated to be close to zero, with deposited loads balanced by 

volatilization losses. Atmospheric deposition onto the watershed is implicitly included in the estimates of 

watershed load. 

6.5.5 Linkage Analysis

The linkage analysis provides the quantitative basis for determining the loading capacity of PCBs into 

Echo Park Lake consistent with achieving water quality standards. The loading capacity is used to 

calculate the TMDL and corresponding allocations of that load to permitted point sources (wasteload 

allocations) and nonpoint sources (load allocations). 
Echo Park Lake TMDLs January 2011

6-27

Lake sediments are often the predominant source of PCBs in biota. The bottom sediment serves as a sink 

for organochlorine compounds that can be recycled through the aquatic life cycle. PCBs are strongly 

sorbed to sediments and have long half-lives in sediment and water. Incoming loads of PCBs will mainly 

be adsorbed to particulates from stormwater runoff (eroded sediments from legacy contamination sites or 

from atmospheric deposition).

The use of bioaccumulation models and the fish tissue data from Echo Park Lake are discussed in detail in 

Appendix H (Organochlorine Compounds TMDL Development) and Appendix G (Monitoring Data), 

respectively. The existing sediment PCB concentrations in Echo Park Lake are lower than the consensusbased TEC target, and existing fish tissue concentrations are higher than the fish tissue target. Therefore, 

a sediment target based on biota-sediment bioaccumulation (a BSAF approach) is calculated from the 

smaller of the ratio of the FCG to existing fish tissue concentrations obtained from trophic level 4 fish 

(TL4; e.g., largemouth bass) and bottom-feeding, trophic level 3 fish (TL3; e.g., common carp). In 

general, the TL3 number is expected to be more restrictive due to additional uptake of organochlorine 

compounds from the sediment by bottom feeding fish. The existing fish tissue concentrations were 

calculated using only recent data (collected in the past 10 years) because the loads and exposure 

concentrations of PCBs are likely to have declined steadily since the cessation of production and use of 

the chemical. For PCBs in Echo Park Lake the ratios of the FCG to existing concentrations are:

TL4: 3.6/49.0 = 0.0735

TL3: 3.6/81.8 = 0.0440

The lower ratio, obtained for the TL3 fish, corresponds to the trophic level requiring the greatest 

reductions to achieve the fish tissue target. This ratio is applied to the observed in-lake sediment 

concentration of 40.29 μg/kg dry weight to obtain the site-specific sediment target concentration to 

achieve fish tissue goals of 1.77 μg/kg dry weight (Table 6-14). 

Table 6-14. Fish Tissue-Based Total PCB Concentration Targets for Sediment in Echo Park Lake

Total PCB Concentration Sediment (μg/kg dry weight)

Existing 40.29

BSAF-derived Target 1.77

Required Reduction 95.6%

The BSAF-derived sediment target is less than the consensus-based sediment quality guideline TEC of 

59.8 μg/kg dry weight. (The consensus-based sediment quality guideline is for the protection of benthic 

organisms, and explicitly does not address bioaccumulation and human-health risks from the consumption 

of contaminated fish.) The lower value of the consensus-based TEC target or the BSAF-derived target is 

selected as the final sediment target. In addition, the CTR criterion for human health (0.17 ng/L) is the 

selected numeric target for the water column and protects both aquatic life and human health.

The toxicant loading model described in Appendix H (Organochlorine Compounds TMDL Development) 

can be used to estimate the loading rate that would be required to yield the existing sediment

concentration under steady-state conditions. This yields an estimate that a load of 3,230 g/yr would be 

required to maintain observed sediment concentrations under steady-state conditions. The estimated 

current watershed loading rate is 0.76 g/yr, or 0.02 percent of this amount. Therefore, impairment due to 

elevated fish tissue concentrations of PCBs in Echo Park Lake is primarily due to the storage of historic 

loads of PCBs in the lake sediment.
Echo Park Lake TMDLs January 2011 

6-28

6.5.6 TMDL Summary 

Because PCB impairment in Echo Park Lake is predominantly due to historic loads stored in the lake 

sediment, this impairment is not amenable to a standard, load-based TMDL analysis. Instead, allocations 

are first assigned on a concentration basis, with the goal of attaining the concentrations identified above 

for water and sediment as well as fish tissue. The concentration targets apply to water and sediment 

entering the lake and within the lake 

The PCB TMDL will be allocated to ensure achievement of the loading capacity. TMDLs are broken 

down into the wasteload allocations (WLAs), load allocations (LAs), and Margins of Safety (MOS) using 

the general TMDL equation. 

Note that since this TMDL is being expressed as a concentration in sediment, in this scenario, the loading 

capacity is equal to 1.77 μg/kg dry weight total PCBs. The wasteload allocations and load allocations are 

also equal to 1.77 μg/kg dry weight total PCBs in sediment. There is no explicit MOS. Allocations are 

assigned for this TMDL by requiring equal concentrations of all sources. Details associated with the 

WLAs, LAs, and MOS are presented in the following three sections. 

6.5.6.1 Wasteload Allocations 

This TMDL establishes wasteload allocations (WLAs) at their point of discharge. This TMDL also 

establishes alternative wasteload allocations for total PCBs (“Alternative WLAs if Fish Tissue Targets are 

Met”) described in Section 6.5.6.1.2. The alternative wasteload allocations will supersede the wasteload 

allocations in Section 6.5.6.1.1 if the conditions described in Section 6.5.6.1.2 are met. 

6.5.6.1.1 Wasteload Allocations 

The entire watershed of Echo Park Lake is contained in an MS4 jurisdiction, and watershed loads are 

therefore assigned wasteload allocations (WLAs). Relevant permit numbers are 

 County of Los Angeles (including the city of Los Angeles): Board Order 01-182 (as amended by 

Order No. R4-2006-0074 and R4-2007-0042), CAS004001 

 Caltrans: Order No 99-06-DWQ, CAS000003 

PCBs in water flowing into Echo Park Lake are below detection limits, and most PCB load is expected to 

move in association with sediment. Therefore, suspended sediment in water flowing into the lake is 

assigned wasteload allocations. Additionally, the TMDL establishes wasteload allocations for PCBs in 

the water column equal to the CTR based water column target. The CTR based water column target 

includes both dissolved PCBs and PCBs associated with suspended sediment. The existing average 

concentration of sediment entering the lake is 24.16 μg/kg dry weight. Therefore, a reduction of (24.16 –

1.77)/24.16 = 92.7 percent is required on the sediment-associated load from the watershed. 

The wasteload allocations are shown in Table 6-15. 

Table 6-15. Wasteload Allocations for Total PCBs in Echo Park Lake 

Subwatershed

Responsible 

Jurisdiction Input

Wasteload 

Allocation for PCBs 

Associated with 

Suspended 

Sediment 

(μg/kg dry weight)

Wasteload 

Allocation for 

PCBs in the Water 

Column (ng/L)

TMDL WLA LA MOS
Echo Park Lake TMDLs January 2011

6-29

Subwatershed

Responsible 

Jurisdiction Input

Wasteload 

Allocation for PCBs 

Associated with 

Suspended 

Sediment 

(μg/kg dry weight)

Wasteload 

Allocation for 

PCBs in the Water 

Column (ng/L)

Northern Caltrans State Highway 

Stormwater1 1.77

0.17

Northern City of Los Angeles MS4 Stormwater1 1.77 0.17

Northern General Industrial 

Stormwater 

Permittees (in the 

City of Los Angeles)2

General Industrial 

Stormwater1

1.77 0.17

Southern Caltrans State Highway 

Stormwater1

1.77 0.17

Southern City of Los Angeles MS4 Stormwater1 1.77 0.17

1This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

6.5.6.1.2 Alternative Wasteload Allocations if Fish Tissue Targets Are Met

The wasteload allocations listed in Table 6-15 will be superseded, and the wasteload allocations in Table 

6-16 will apply, if:

1. The responsible jurisdictions submit to USEPA and the Regional Board material describing how 

the fish tissue target of 3.6 ppb wet weight have been met for the preceding three or more years. 

A demonstration that fish tissue targets have been met in any given year must at minimum 

include a composite sample of skin off fillets from at least five common carp each measuring at 

least 350 mm in length, and

2. USEPA does not object to the Regional Board’s determination within 60 days of receiving notice 

of it.

Table 6-16. Alternative Wasteload Allocations for Total PCBs in Echo Park Lake if Fish Tissue 

Targets are Met

Subwatershed

Responsible 

Jurisdiction Input

Wasteload 

Allocation for PCBs 

Associated with 

Suspended 

Sediment 

(μg/kg dry weight)

Wasteload 

Allocation for 

PCBs in the Water 

Column (ng/L)

Northern Caltrans State Highway 

Stormwater1 59.8

0.17

Northern City of Los Angeles MS4 Stormwater1 59.8 0.17

Northern General Industrial 

Stormwater 

Permittees (in the 

City of Los Angeles)2

General Industrial 

Stormwater1

59.8 0.17
Echo Park Lake TMDLs January 2011

6-30

Subwatershed

Responsible 

Jurisdiction Input

Wasteload 

Allocation for PCBs 

Associated with 

Suspended 

Sediment 

(μg/kg dry weight)

Wasteload 

Allocation for 

PCBs in the Water 

Column (ng/L)

Southern Caltrans State Highway 

Stormwater1

59.8 0.17

Southern City of Los Angeles MS4 Stormwater1 59.8 0.17

1 This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

6.5.6.2 Load Allocations

No part of the watershed of Echo Park Lake is outside MS4 jurisdiction; therefore no load allocations 

(LAs) are assigned to watershed loads. No load is allocated to atmospheric deposition of PCBs. The 

legacy PCB stored in lake sediment is the major cause of use impairment associated with elevated fish 

tissue concentrations, and is assigned a load allocation. The in-lake allocation is in concentration terms: 

specifically, the responsible jurisdiction (city of Los Angeles) should achieve a PCB concentration of 1.77

μg/kg dry weight in lake bottom sediments (Table 6-17).

Table 6-17. Load Allocations for Total PCBs in Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Load Allocation 

(μg/kg dry weight)

Lake Surface City of Los Angeles Lake bottom sediments 1.77

6.5.6.3 Margin of Safety

TMDLs must include a margin of safety (MOS) to account for any lack of knowledge concerning the 

relationship between load and wasteload allocations and water quality. The MOS may be implicit, i.e., 

incorporated into the TMDL through conservative assumptions in the analysis, or explicit, i.e., expressed 

in the TMDL as loadings set aside for the MOS. This TMDL contains an implicit MOS based on 

conservative assumptions. The allocations are set based on the lower of either the BSAF-derived 

sediment target or the consensus-based TEC sediment target to ensure achievement of the OEHHA FCG 

target in fish tissue. The selected BSAF-derived target concentration in sediment is considerably lower 

than the consensus-based TEC target. 

6.5.6.4 Critical Conditions/Seasonality

TMDLs must include consideration of critical conditions and seasonal variation to ensure protection of 

the designated uses of the waterbody at all times. This TMDL protects beneficial uses by reducing fish 

tissue concentrations to the FCG target and protecting benthic biota in sediment. Because fish 

bioaccumulate PCBs, concentrations in tissues of edible sized game fish integrate exposure over a number 

of years. As a result, overall average loading is more important for the attainment of standards than 

instantaneous or daily concentrations. WLAs and LAs in this TMDL are assigned as concentrations and 

protect during all seasons and in both high and low flow conditions. This TMDL therefore protects for 

critical conditions.
Echo Park Lake TMDLs January 2011

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6.5.6.5 Daily Load Expression

USEPA recommends inclusion of a daily load expression for all TMDLs to comply with the 2006 D.C. 

Circuit Court of Appeals decision for the Anacostia River. This TMDL includes a maximum daily load 

estimated according to the guidelines provided by USEPA (2007). 

Because the PCB WLAs are expressed as concentrations on sediment, the daily maximum allowable load 

is calculated from the maximum daily sediment load multiplied by the TMDL WLA concentration. The 

maximum daily sediment load is estimated from the 99th percentile daily flow and the sediment event 

mean concentration that yields the estimated annual sediment load. 

No USGS gage currently exists in the Echo Park Lake watershed. USGS Station 11102000, Mission

Creek near Montebello, CA, was selected as a surrogate for flow determination. This gage is the closest 

USGS StreamStats gage in the Los Angeles River Basin with a relatively small drainage area (2,662 

acres). The 99

th percentile flow was chosen to represent the peak flow for this drainage. Choosing the 

99th percentile flow eliminates errors due to outliers and is reasonable for development of a daily load 

expression. 

The USGS StreamStats program was used to determine the 99th percentile flow for Mission Creek 

(30.2 cfs) (Wolock, 2003). To estimate the peak flow to Echo Park Lake, the 99

th percentile flow for 

Mission Creek was scaled down by the ratio of drainage areas (784 acres/2,662 acres; Echo Park Lake 

watershed area/Mission Creek watershed area at the gage). The resulting peak flow estimate for Echo 

Park Lake is 8.89 cfs. 

The event mean concentration of sediment in stormwater (55.8 mg/L) was calculated from the estimated 

existing watershed sediment load of 1.32 tons/yr (Table 6-13) divided by the total storm flow volume

entering the lake (17.4 ac-ft/yr). Multiplying the sediment event mean concentration by the 99th

percentile peak daily flow (8.98 cfs) yields a daily maximum sediment load from stormwater of1226 kg/d 

(1.35 tons/d). Applying the wasteload allocation concentration of 1.77 μg total PCBs per dry kg of 

sediment yields the stormwater daily maximum allowable load of 0.0022 g/d of total PCBs. This load is

associated with the MS4 stormwater permittees. The maximum allowable daily load must be met on all 

days, and the concentration-based WLAs must be met to ensure compliance with the TMDL.

6.5.6.6 Future Growth

USEPA regulates PCBs under the Toxic Substances Control Act (TSCA), which generally bans the 

manufacture, use, and distribution in commerce of the chemicals in products at concentrations of 50 parts 

per million or more, although TSCA allows USEPA to authorize certain uses, such as to rebuild existing 

electrical transformers during the transformers’ useful life. Therefore, no additional allowance is made 

for future growth in the PCB TMDL.

If any sources currently assigned load allocations are later determined to be point sources requiring 

NPDES permits, those load allocations are to be treated as wasteload allocations for purposes of 

determining appropriate water quality-based effluent limitations pursuant to 40 CFR 122.44(d)(1).

6.6 CHLORDANE IMPAIRMENT

Total chlordane consists of a family of related chemicals, including cis- and trans-chlordane, 

oxychlordane, trans-nonachlor, and cis-nonachlor. Observations and targets discussed in this section all 

refer to total chlordane. Chlordane was used as a pesticide in field, commercial, and residential uses. 

Chlordane is no longer in production, but persists in the environment from legacy loads.

The chlordane impairment of Echo Park Lake affects beneficial uses related to recreation, municipal 

water supplies, wildlife health, and fish consumption. While some loading of chlordane continues to 
Echo Park Lake TMDLs January 2011

6-32

occur in watershed runoff, the primary source of chlordane in the water column and aquatic life in Echo 

Park Lake is from historic loads stored in the lake sediments. Chlordane, like other OC pesticides and 

PCBs, accumulates in aquatic organisms and biomagnifies in the food chain. As a result, low 

environmental concentrations can result in unacceptable levels in higher trophic level fish in the lake. 

The approach for chlordane is similar to that for PCBs.

6.6.1 Beneficial Uses

California state water quality standards consist of the following elements: 1) beneficial uses, 

2) narrative and/or numeric water quality objectives, and 3) an antidegradation policy. In California, 

beneficial uses are defined by the Regional Water Quality Control Boards (Regional Boards) in the Water 

Quality Control Plans (Basin Plans). Numeric and narrative objectives are specified in each region’s 

Basin Plan, designed to be protective of the beneficial uses of each waterbody in the region. The existing 

beneficial uses assigned to Echo Park Lake include REC1, REC2, WARM, WILD, and MUN. 

Descriptions of these uses are listed in Section 2 of this TMDL report. Elevated levels of chlordane 

potentially impair the REC1,REC2, WARM, WILD, and MUN uses by causing toxicity to aquatic 

organisms and raising fish tissue concentrations to levels that are unsafe for human consumption (which 

can result in fish consumption advisories) and impair sport fishing recreational uses.

6.6.2 Numeric Targets

The Basin Plan designates water column concentrations associated with MUN and WARM beneficial 

uses. There are no numeric criteria specified for sediment or fish tissue concentrations of chlordane listed 

in the Basin Plan. For the purposes of this TMDL, additional numeric targets for these endpoints are 

based on the consensus-based sediment quality guidelines defined in MacDonald et al. (2000) and the fish 

tissue concentration goal, referred to as the fish contaminant goal (FCG), for chlordane defined by the 

Office of Environmental Health Hazard Assessment (OEHHA) for fish consumption. The numeric 

targets used for chlordane are listed below. The fish tissue concentration goal was also used to back 

calculate site-specific targets in sediment, with the most stringent target applying. See Section 2 of this 

TMDL report for additional details.

The water column criteria for chlordane in the Basin Plan are associated with a specific beneficial use. 

For waters designated MUN, the Basin Plan lists a maximum contaminant level of 0.0001 mg/L, or 

0.1 μg/L. The Basin Plan also contains a narrative criterion that toxic chemicals not be present at levels 

that are toxic or detrimental to aquatic life (LARWQCB, 1994). Acute and chronic criterion for 

chlordane in freshwater systems are defined by the California Toxics Rule as 2.4 μg/L and 0.0043 μg/L, 

respectively (USEPA, 2000a). The CTR also includes human health criteria for the consumption of water 

and organisms and for the consumption of organisms only as 0.00057 μg/L and 0.00059 μg/L, 

respectively (USEPA, 2000a). For Echo Park Lake, the Regional Board has determined that the 

appropriate human health criterion is 0.00059 μg/L (0.59 ng/L) as the MUN use is not an existing use and 

may be removed.

For sediment, the consensus-based sediment quality guidelines provided in Macdonald et al. (2000) for 

the threshold effects concentration (TEC) for chlordane is 3.24 μg/kg (μg/kg dry weight) dry weight. The 

consensus-based guidelines have been incorporated into the most recent set of NOAA Screening Quick 

Reference Tables (SQuiRT) (Buchman, 2008) and are recommended by the State Water Resources 

Control Board for interpretation of narrative sediment objectives under the 303(d) listing policy. This 

target is designed to protect benthic dwelling organisms and explicitly does not consider “the potential for 

bioaccumulation in aquatic organisms nor the associated hazards to the species that consume aquatic 

organisms (i.e., wildlife and humans).” The existing sediment chlordane concentrations in Echo Park 

Lake are lower than the consensus-based TEC target, and existing fish tissue concentrations are higher 
Echo Park Lake TMDLs January 2011

6-33

than the fish tissue target. Thus, a separate sediment target calculation based on a biota-sediment 

accumulation factor (BSAF) is carried out to ensure that fish tissue concentration goals are met. 

The fish contaminant goal for chlordane defined by the OEHHA (2008) is 5.6 ppb wet weight in muscle 

tissue (filets). Elevated fish tissue concentrations are largely attributable to foodweb bioaccumulation 

derived from contaminated sediment. A biota-sediment accumulation factor (BSAF) approach is 

appropriate to correlate sediment and fish tissue targets. For chlordane, the corresponding sediment 

concentration target determined using the BSAF is 2.10 μg/kg dry weight, as described in Section 6.6.5. 

All applicable targets are shown below in Table 6-18. For sediment the lower value of the consensusbased TEC target or the BSAF-derived target is selected as the final sediment target.

Table 6-18. Total Chlordane Targets for Echo Park Lake

Media Source Target

Fish (ppb wet weight) OEHHA FCG 5.6

Sediment (ng /dry g) Consensus-based TEC 3.24

Sediment (μg/kg dry 

weight)

BSAF-derived target 2.10

Water (ng/L) CTR 0.59

Note: Shaded cells represent the selected targets for this TMDL.

6.6.3 Summary of Monitoring Data

This section summarizes the monitoring data for Echo Park Lake related to the chlordane impairment.

Addition details regarding monitoring data are discussed in Appendix G (Monitoring Data). 

Water column sampling was conducted as part of an organics study performed by UCLA (funded by a 

grant managed by the Regional Board) in the summer of 2008 at two locations within Echo Park Lake. 

These analyses measured cis- and trans-chlordane, but not oxychlordane or nonachlor. All water column 

samples were less than the detection limit for chlordane (1.5 ng/L; the detection limit for chlordane is 

higher than the water column criterion of 0.59 ng/L). No additional water column sampling for chlordane 

has been conducted in Echo Park Lake.

A summary of the water column data is shown in Table 6-19.

Table 6-19. Summary of Water Column Samples for Total Chlordane in Echo Park Lake

Station

Average Water 

Concentration(ng/L)

Number of 

Samples

Number of Samples 

Above Detection Limits1

South (0.75)2 2 0

North, Lotus Bed (0.75) 1 0

In-Lake Average3(0.75)

CTR Criterion 0.59

1Non-detect samples were included in reported averages at one-half of the sample detection limit.

2Numbers in parentheses indicate that sample is based only on the detection limits of the samples, and that no 

chlordanes were quantified in any of the collected samples.

3Overall average is the average of individual station averages.
Echo Park Lake TMDLs January 2011

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Concentrations of chlordane on suspended sediment were also analyzed at two in-lake stations during the 

summer of 2008 by UCLA; both were less than the detection limits (3.19 μg/kg to 10.05 μg/kg dry 

weight). Porewater was sampled by UCLA in both the fall and spring of 2008. Specifically, chlordane 

concentrations in the porewater sampled at four sites during the summer of 2008 were all less than the 

detection limit of 15 ng/L; both sites sampled during the fall of 2008 were also below detection limits of 

15 ng/L to 1,500 ng/L.

UCLA also collected sediment samples at five locations in Echo Park Lake during summer and fall 2008. 

As with the water column analyses by UCLA, these report cis- and trans-chlordane, but not oxychlordane 

or nonachlor. Of the nine total samples, all but one resulted in chlordane concentrations below the 

detection limit (which ranged from 0.44 μg/kg to 1.23 μg/kg dry weight). One sediment sample collected 

during summer 2008 resulted in a sample average concentration of 4.14 μg/kg dry weight, which is 

greater than the consensus-based TEC of 3.24 μg/kg dry weight. Three in-lake locations were sampled by 

the Regional Board and USEPA on December 1, 2009, resulting in reportable concentrations of 4.1 μg/kg 

to 22.25 μg/kg dry weight. These analyses do include oxychlordane and nonachlor.

All lake stations were averaged to estimate an exposure concentration for total chlordane in Echo Park 

Lake sediments of 4.43 μg/kg dry weight (with non-detects included at one-half the detection limit for 

each sample). Stations located near outfalls are taken as an estimate of the concentrations on incoming 

sediment. A summary of the sediment data is shown in Table 6-20.

Table 6-20. Summary of Sediment Samples for Total Chlordane in Echo Park Lake

Station

Average Sediment 

Concentration (μg/kg 

dry weight)

1

Number 

of 

Samples

Number of 

Samples above 

Detection Limits

Number of Samples 

between Detection and 

Reporting Limits

NE near LA City Storm 

Drain (0.44) 3 0 0

W near County Storm 

Drain 2.25 2 1 0

South (0.46) 1 0 0

North, Lotus Bed (0.53) 2 0 0

Northeast (0.30) 1 0 0

NW Arm, near outfall 22.25 1 1 0

Center Lake 5.15 2 1 0

Center Lake S 4.10 1 1 0

In-Lake Average2 4.43

Influent Average 8.31

Consensus-based TEC 3.24

1Total chlordane in a sample represents the sum of all reported measurements for alpha and gamma chlordane, 

oxychlordane, and cis- and trans-nonachlor, including results reported below the method reporting limit. If all 

components were non-detect, the total is represented as one-half the detection limit. Results of any laboratory 

duplicate analyses of the same sample were averaged. Results for each station represent the average of individual 

samples. Results in parentheses indicate that the sample average is based only on the detection limits of the 

samples and that no chlordane quantified in any of the collected samples. Sample averages based only on 

detected results below the reporting limit plus non-detects are shown in square brackets.

2Overall average is the average of individual station averages.
Echo Park Lake TMDLs January 2011

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Fish tissue concentrations of total chlordane from Echo Park Lake have been analyzed in largemouth 

bass, common carp, and bullhead (SWAMP and TSMP). Four fish samples (composites of filets from 

five fish) were collected and analyzed for total chlordane between 1987 and 1991. In 1987, 

concentrations in a largemouth bass and a bullhead composite sample were reported at 17.8 and 66 ppb 

wet weight, respectively. Two additional largemouth bass samples were analyzed in 1991, with 

concentrations reported as 0 ppb (the detection limits for the historical fish samples are not reported).

Considering only data collected in the past 10 years, the average concentration of chlordane in largemouth 

bass was 4.70 ppb wet weight, based on the three largemouth bass composite samples collected in the 

summer of 2007 and April 2010 with an average lipid fraction of 0.37 percent. Three composite samples 

of bottom-feeding common carp (Trophic Level 3) were also analyzed. These yielded an average total 

chlordane concentration of 11.85 ppb wet weight with an average lipid fraction of 1.26 percent. The 

recent fish-tissue data for Echo Park Lake are summarized in Table 6-21.

Table 6-21. Summary of Recent Fish Tissue Samples for Total Chlordane in Echo Park Lake

Sample Date Fish Species Total Chlordane (ppb wet weight)1

11 June 2007 Largemouth Bass 8.534

11 June 2007 Largemouth Bass 2.037

13 April 2010 Largemouth Bass 2.517

11 June 2007 Common Carp 18.41

11 June 2007 Common Carp 12.92

13 April 2010 Common Carp 4.216

2007 - 2010 Average – Largemouth Bass 4.70

2007 - 2010 Average – Common Carp 11.85

FCG 5.6

1Composite samples of filet from five individuals.

In sum, recent fish tissue concentrations in Echo Park Lake are above the FCG in two of three samples for 

common carp, and in one of three largemouth bass composite samples. The average concentration in 

sediment is below the consensus-based TEC, although individual samples exceed the TEC. Water 

column samples have all been below detection limits.

6.6.4 Source Assessment

Chlordane in Echo Park Lake is primarily due to historical loading and storing within the lake sediments, 

with some ongoing contribution by watershed wet weather loads. Dry weather loading is assumed to be 

negligible because hydrophobic contaminants primarily move with particulate matter that is mobilized by 

higher flows. Stormwater loads from the watershed were estimated based on simulated sediment load and 

observed chlordane concentrations on sediment near inflows to the lake. Watershed loads of chlordane 

may arise from past pesticide applications, improper disposal, and atmospheric deposition. Pesticide 

applications were most likely associated with agricultural, commercial, and residential areas. Improper 

disposal could have occurred at various locations, while atmospheric deposition occurs across the entire 

watershed.

There is no definitive information on specific sources within the watershed at this time. Therefore, an 

average concentration on sediment is applied to all contributing areas. Although supplemental water 
Echo Park Lake TMDLs January 2011

6-36

additions of potable water makes up a significant amount of the flow to Echo Park Lake it does not 

contribute sediment load and is considered to no contribute significantly to chlordane loading (total 

suspended sediment measured non-detect in two samples collected August 4th 2009). 

The average concentration of total chlordane on incoming sediment is estimated to be 8.31 μg/kg dry 

weight (Table 6-20) and the annual sediment load to Echo Park Lake is 1.32 tons/yr (see Appendix D, 

Wet Weather Loading). The resulting estimated wet weather load of chlordane is approximately 

0.0099 g/yr (Table 6-22).

Table 6-22. Total Chlordane Loads Estimated for Each Jurisdiction and Subwatershed in the 

Echo Park Watershed (g/yr)

Subwatershed

Responsible 

Jurisdiction Input

Sediment 

Load 

(tons/yr)

Total Chlordane

Load (g/yr)

Percent 

of Total 

Load

Northern Caltrans State Highway 

Stormwater1

0.044 0.0003 3.35%

Northern City of Los 

Angeles MS4 Stormwater1

0.98 0.0074 74.24%

Southern Caltrans State Highway 

Stormwater1

0.0037 0.00003 0.28%

Southern City of Los 

Angeles MS4 Stormwater1

0.29 0.0022 22.13%

Total Load from Watershed 1.32 0.0099 100.00%

1This input includes effluent from storm drain systems during both wet and dry weather.

As described in Appendix E (Atmospheric Deposition), Section E.5, the net atmospheric deposition of 

total chlordane directly to the lake surface is estimated to be close to zero, with deposited loads balanced 

by volatilization losses. Atmospheric deposition onto the watershed is implicitly included in the estimates 

of watershed load. 

6.6.5 Linkage Analysis

The linkage analysis provides the quantitative basis for determining the loading capacity of total 

chlordane into Echo Park Lake consistent with achieving water quality standards. The loading capacity is 

used to calculate the TMDL and corresponding allocations of that load to permitted point sources 

(wasteload allocations) and nonpoint sources (load allocations). 

Lake sediments are often the predominant source of total chlordane in biota. The bottom sediment serves 

as a sink for organochlorine compounds that can be recycled through the aquatic life cycle. Chlordanes 

are strongly sorbed to sediments and have long half-lives in sediment and water. Incoming loads of total 

chlordane will mainly be adsorbed to particulates from stormwater runoff (eroded sediments from legacy 

contamination sites or from atmospheric deposition).

The use of bioaccumulation models and the fish tissue data from Echo Park Lake are discussed in detail in 

Appendix H (Organochlorine Compounds TMDL Development) and Appendix G (Monitoring Data), 

respectively. The existing sediment chlordane concentrations in Echo Park Lake are lower than the 

consensus-based TEC target, and existing fish tissue concentrations are higher than the fish tissue target. 

Therefore, a sediment target based on biota-sediment bioaccumulation (a BSAF approach) is calculated 

from the smaller of the ratio of the FCG to existing fish tissue concentrations obtained from trophic level 

4 fish (TL4; e.g., largemouth bass) and bottom-feeding, trophic level 3 fish (TL3; e.g., common carp). In 
Echo Park Lake TMDLs January 2011

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general, the TL3 number is expected to be more restrictive due to additional uptake of organochlorine 

compounds from the sediment by bottom feeding fish. The existing fish tissue concentrations were 

calculated using only recent data (collected in the past 10 years) because the loads and exposure 

concentrations of chlordane are likely to have declined steadily since the cessation of production and use 

of the chemical. For chlordane in Echo Park Lake the ratios of the FCG to existing concentrations are:

TL4: 5.6/4.70 = 1.191

TL3: 5.6/11.85 = 0.473

The lower ratio, obtained for the TL3 fish, corresponds to the trophic level requiring the greatest 

reductions to achieve the fish tissue target. This ratio is applied to the observed sediment concentration of 

4.43 μg/kg dry weight to obtain the site-specific sediment target concentration to achieve fish tissue goals 

of 2.10 μg/kg dry weight (Table 6-23).
Echo Park Lake TMDLs January 2011

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Table 6-23. Fish Tissue-Based Chlordane Concentration Targets for Sediment

in Echo Park Lake

Total Chlordane Concentration Sediment (μg/kg dry weight)

Existing 4.43

BSAF-derived Target 2.10

Required Reduction 52.8%

The BSAF-derived sediment target is less than the consensus-based sediment quality guideline TEC of 

3.24 μg/kg dry weight. (The consensus-based sediment quality guideline is for the protection of benthic

organisms, and explicitly does not address bioaccumulation and human-health risks from the consumption 

of contaminated fish.) The lower value of the consensus-based TEC target or the BSAF-derived target is 

selected as the final sediment target. In addition, the CTR criterion for human health (0.59 ng/L) is the 

selected numeric target for the water column and protects both aquatic life and human health.

The toxicant loading model described in Appendix H (Organochlorine Compounds TMDL Development)

can be used to estimate the loading rate required to yield the existing sediment concentration under 

steady-state conditions. This yields an estimate that a load of 63.8 g/yr would be required to maintain 

observed sediment concentrations under steady-state conditions. The estimated current watershed loading 

rate is 0.0099 g/yr, or 0.02 percent of this amount. Therefore, impairment due to elevated fish tissue 

concentrations of chlordane in Echo Park Lake is primarily due to the storage of historic loads of 

chlordane in the lake sediment.

6.6.6 TMDL Summary

Because chlordane impairment in Echo Park Lake is predominantly due to historic loads stored in the lake 

sediment, this impairment is not amenable to a standard, load-based TMDL analysis. Instead, allocations 

are first assigned on a concentration basis, with the goal of attaining the concentrations identified above 

for water and sediment, as well as fish tissue. The concentration targets apply to water and sediment 

entering the lake and within the lake.

The chlordane TMDL will be allocated to ensure achievement of the loading capacity. TMDLs are 

broken down into the wasteload allocations (WLAs), load allocations (LAs), and Margins of Safety 

(MOS) using the general TMDL equation. 

Note that since this TMDL is being expressed as a concentration in sediment, in this scenario, the loading 

capacity is equal to 2.10 μg/kg dry weight chlordane. The wasteload allocations and load allocations are 

also equal to 2.10 μg/kg dry weight chlordane in sediment. There is no explicit MOS. Allocations are 

assigned for this TMDL by requiring equal concentrations of all sources. Details associated with the 

WLAs, LAs, and MOS are presented in the following three sections.

6.6.6.1 Wasteload Allocations

This TMDL establishes wasteload allocations (WLAs) at their point of discharge. This TMDL also 

establishes alternative wasteload allocations for chlordane (“Alternative WLAs if Fish Tissue Targets are 

Met”) described in Section 6.6.6.1.2. The alternative wasteload allocations will supersede the wasteload 

allocations in Section 6.6.6.1.1 if the conditions described in Section 6.6.6.1.2 are met.

TMDL WLA LA MOS
Echo Park Lake TMDLs January 2011

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6.6.6.1.1 Wasteload Allocations

The entire watershed of Echo Park Lake is contained in an MS4 jurisdiction, and therefore receives 

wasteload allocations (WLAs). Relevant permit numbers are 

 County of Los Angeles (including the city of Los Angeles): Board Order 01-182 (as amended by 

Order No. R4-2006-0074 and R4-2007-0042), CAS004001

 Caltrans: Order No 99-06-DWQ, CAS000003

Total chlordane concentrations in water flowing into Echo Park Lake are below detection limits, and most 

chlordane load is expected to move in association with sediment. Therefore, the suspended sediment in 

water flowing into the lake is assigned wasteload allocations. Additionally, the TMDL establishes 

wasteload allocations for chlordane in the water column equal to the CTR based water column target. 

The CTR based water column target includes both dissolved chlordane and chlordane associated with 

suspended sediment. The existing concentration of sediment entering the lake is 8.31 μg/kg dry weight. 

Therefore, a reduction of (8.31 – 2.10)/8.31 = 74.7 percent is required on the sediment-associated load 

from the watershed. The reduction in watershed load is slightly greater than the reduction needed for inlake sediments because the estimated concentration on influent sediment is greater than the lake-wide 

average.

The wasteload allocations are shown in Table 6-24.

Table 6-24. Wasteload Allocations for Total Chlordane in Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Wasteload Allocation for 

Chlordane Associated with 

Suspended Sediment

(μg/kg dry weight)

Wasteload Allocation 

for Chlordane in the 

Water Column (ng/L)

Northern Caltrans State 

Highway 

Stormwater1 2.10

0.59

Northern City of Los 

Angeles

MS4 

Stormwater1 2.10 0.59

Northern General Industrial 

Stormwater 

Permittees (in the 

City of Los 

Angeles)2

General 

Industrial 

Stormwater1 2.10

0.59

Southern Caltrans State 

Highway 

Stormwater1

2.10

0.59

Southern City of Los 

Angeles

MS4 

Stormwater1 2.10 0.59

1This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

6.6.6.1.2 Alternative Wasteload Allocations if Fish Tissue Targets Are Met

The wasteload allocations listed in Table 6-24 will be superseded, and the wasteload allocations in Table 

6-25 will apply, if:
Echo Park Lake TMDLs January 2011

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1. The responsible jurisdictions submit to USEPA and the Regional Board material describing how 

the fish tissue target of 5.6 ppb wet weight have been met for the preceding three or more years. 

A demonstration that fish tissue targets have been met in any given year must at minimum 

include a composite sample of skin off fillets from at least five common carp each measuring at 

least 350mm in length, and

2. USEPA does not object to the Regional Board’s determination within sixty days of receiving 

notice of it.

Table 6-25. Alternative Wasteload Allocations for Total Chlordane in Echo Park Lake if Fish 

Tissue Targets are Met

Subwatershed

Responsible 

Jurisdiction Input

Wasteload Allocation for 

Chlordane Associated with 

Suspended Sediment

(μg/kg dry weight)

Wasteload Allocation 

for Chlordane in the 

Water Column (ng/L)

Northern Caltrans State 

Highway 

Stormwater1 3.24

0.59

Northern City of Los 

Angeles

MS4 

Stormwater1

3.24 0.59

Northern General Industrial 

Stormwater 

Permittees (in the 

City of Los 

Angeles)2

General 

Industrial 

Stormwater1

3.24 0.59

Southern Caltrans State 

Highway 

Stormwater1

3.24 0.59

Southern City of Los 

Angeles

MS4 

Stormwater1

3.24 0.59

1 This input includes effluent from storm drain systems during both wet and dry weather.

2 The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

6.6.6.2 Load Allocations

No part of the watershed of Echo Park Lake is outside MS4 jurisdiction; therefore no load allocations 

(LAs) are assigned to the watershed loads. No load is allocated to atmospheric deposition of chlordane. 

The legacy chlordane stored in lake sediment is the major cause of impairment associated with elevated 

fish tissue concentrations, and is assigned a load allocation. The in-lake allocation is in concentration 

terms: specifically, the responsible jurisdiction (city of Los Angeles) should achieve a total chlordane 

concentration of 2.10 μg/kg dry weight in lake bottom sediments (Table 6-26).

Table 6-26. Load Allocations for Total Chlordane in Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Load Allocation 

(μg/kg dry weight)

Lake Surface City of Los Angeles Lake bottom sediments 2.10
Echo Park Lake TMDLs January 2011

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6.6.6.3 Margin of Safety

TMDLs must include a margin of safety (MOS) to account for any lack of knowledge concerning the 

relationship between load and wasteload allocations and water quality. The MOS may be implicit, i.e., 

incorporated into the TMDL through conservative assumptions in the analysis, or explicit, i.e., expressed 

in the TMDL as loadings set aside for the MOS. This TMDL contains an implicit MOS based on 

conservative assumptions. The allocations are set based on the lower of either the BSAF-derived 

sediment target or the consensus-based TEC sediment target to ensure achievement of the OEHHA FCG 

target in fish tissue. The selected BSAF-derived target concentration in sediment is considerably lower 

than the consensus-based TEC target. 

6.6.6.4 Critical Conditions/Seasonality

TMDLs must include consideration of critical conditions and seasonal variation to ensure protection of 

the designated uses of the waterbody at all times. This TMDL protects beneficial uses by reducing fish 

tissue concentrations to the FCG target and protecting benthic biota in sediment. Because fish 

bioaccumulate chlordane, concentrations in tissues of edible sized game fish integrate exposure over a 

number of years. As a result, overall average loading is more important for the attainment of standards 

than instantaneous or daily concentrations. WLAs and LAs in this TMDL are assigned as concentrations 

and protect during all seasons and in both high and low flow conditions. This TMDL therefore protects 

for critical conditions.

6.6.6.5 Daily Load Expression

USEPA recommends inclusion of a daily load expression for all TMDLs to comply with the 2006 D.C. 

Circuit Court of Appeals decision for the Anacostia River. This TMDL includes a maximum daily load 

estimated according to the guidelines provided by USEPA (2007). 

Because the total chlordane WLAs are expressed as concentrations on sediment, the daily maximum 

allowable load is calculated from the maximum daily sediment load multiplied by the TMDL WLA 

concentration. The maximum daily sediment load is estimated from the 99th percentile daily flow and the 

sediment event mean concentration that yields the estimated annual sediment load.

The daily maximum allowable load in Echo Park Lake is calculated from the estimated 99th percentile 

flow to the Lake multiplied by the event mean concentration consistent with achieving the long-term 

loading targets, described above in the PCBs section. USGS Station 11102000, Mission Creek near 

Montebello, CA, was selected as a surrogate for flow determination for flow to the lake, as described in 

the PCBs section (Section 6.5.6.5).

The event mean concentration of sediment in stormwater (55.8 mg/L) was calculated from the estimated 

existing watershed sediment load of 1.32 tons/yr (Table 6-22) divided by the total storm flow volume

reaching the lake (17.4 ac-ft/yr). Multiplying the sediment event mean concentration by the 99th

percentile peak daily flow (8.98 cfs) yields a daily maximum sediment load from stormwater of 1226 kg/d 

(1.35 tons/d). Applying the wasteload allocation concentration of 2.10 μg total chlordane per dry kg of 

sediment yields the stormwater daily maximum allowable load of 0.0026 g/d of total chlordane. This

load is associated with the MS4 stormwater permittees. The maximum allowable daily load must be met 

on all days, and the concentration-based WLAs must be met to ensure compliance with the TMDL.

6.6.6.6 Future Growth

The manufacture and use of chlordane is currently banned. Therefore, no additional allowance is made 

for future growth in the chlordane TMDL.
Echo Park Lake TMDLs January 2011

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If any sources currently assigned load allocations are later determined to be point sources requiring 

NPDES permits, those load allocations are to be treated as wasteload allocations for purposes of 

determining appropriate water quality-based effluent limitations pursuant to 40 CFR 122.44(d)(1).

6.7 DIELDRIN IMPAIRMENT

Dieldrin is a chlorinated insecticide originally developed as an alternative to DDT and was in wide use 

from the 1950s to the 1970s. Dieldrin in the environment also arises from use of the insecticide aldrin. 

Aldrin is not itself toxic to insects, but is metabolized to dieldrin in the insect body. The use of both 

dieldrin and aldrin was discontinued in the 1970s.

The dieldrin impairment of Echo Park Lake affects beneficial uses related to recreation, municipal water 

supplies, wildlife health, and fish consumption. Dieldrin, like PCBs and chlordane, is an organochlorine 

compound that is strongly sorbed to sediment and is no longer in production. As such, the approach for 

dieldrin impairment is similar to that for PCBs and chlordane.

6.7.1 Beneficial Uses

California state water quality standards consist of the following elements: 1) beneficial uses, 

2) narrative and/or numeric water quality objectives, and 3) an antidegradation policy. In California, 

beneficial uses are defined by the Regional Water Quality Control Boards (Regional Boards) in the Water 

Quality Control Plans (Basin Plans). Numeric and narrative objectives are specified in each region’s 

Basin Plan, designed to be protective of the beneficial uses of each waterbody in the region. The existing 

beneficial uses assigned to Echo Park Lake include REC1, REC2, WARM, WILD, and MUN. 

Descriptions of these uses are listed in Section 2 of this TMDL report. Elevated levels of dieldrin can 

impair the REC1,REC2, WARM, WILD, and MUN by causing toxicity to aquatic organisms, raising fish 

tissue concentrations to levels that are unsafe for human consumption (which can result in fish 

consumption advisories), and impair sport fishing recreational uses.

6.7.2 Numeric Targets

The Basin Plan designates water column concentrations associated with MUN and WARM beneficial 

uses. There are no numeric criteria specified for sediment or fish tissue concentrations of dieldrin in the 

Basin Plan. For the purposes of this TMDL, additional numeric targets for these endpoints are based on 

the consensus-based sediment quality guidelines defined in MacDonald et al. (2000) and the fish tissue 

concentration goal, referred to as the fish contaminant goal (FCG), defined by the OEHHA (2008) for fish 

consumption. The numeric targets for dieldrin are listed below. The fish tissue concentration goal was 

also used to back calculate site-specific targets in sediment, with the most stringent target applying. See 

Section 2 of this TMDL report for additional details.

The water column targets for dieldrin in the Basin Plan are associated with a specific beneficial use. The 

Plan also contains a narrative criterion that toxic chemicals not be present at levels that are toxic or 

detrimental to aquatic life (LARWQCB, 1994). Each waterbody addressed in this TMDL is designated 

WARM, at a minimum, and must meet this requirement. Acute and chronic criteria for the protection of 

aquatic life and wildlife in freshwater systems are included in the CTR for dieldrin as 0.24 μg/L and 

0.056 μg/L, respectively (USEPA, 2000a). The CTR also provides a human health-based water quality

criterion for the consumption of organisms only and the consumption of water and organisms as 0.00014 

μg/L (USEPA, 2000a). The human health criterion of 0.00014 μg/L (0.14 ng/L) is the most restrictive of 

the applicable criteria specified for water column concentrations and is selected as the water column 

target.
Echo Park Lake TMDLs January 2011

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For sediment, the consensus-based sediment quality guidelines provided in MacDonald et al. (2000) for 

the threshold effects concentration (TEC) of dieldrin in sediment is 0.46 μg/kg (μg/kg dry weight). The 

consensus-based guidelines have been incorporated into the most recent set of NOAA Screening Quick 

Reference Tables (SQuiRT) (Buchman, 2008) and are recommended by the State Water Resources 

Control Board for interpretation of narrative sediment objectives under the 303(d) listing policy. This 

target is designed to protect benthic dwelling organisms and explicitly does not consider “the potential for 

bioaccumulation in aquatic organisms nor the associated hazards to the species that consume aquatic 

organisms (i.e., wildlife and humans).” The estimated existing sediment dieldrin concentrations in Echo 

Park Lake are lower than the consensus-based TEC target, and existing fish tissue concentrations are 

higher than the fish tissue target. Thus, a separate sediment target calculation based on a biota-sediment 

accumulation factor (BSAF) is carried out to ensure that fish tissue concentration goals are met.

The fish contaminant goal for dieldrin defined by the OEHHA (2008) is 0.46 ppb wet weight in muscle 

tissue (filets). Elevated fish tissue concentrations are largely attributable to foodweb bioaccumulation 

derived from contaminated sediment. A biota-sediment accumulation factor (BSAF) approach is 

appropriate to correlate sediment and fish tissue targets. For dieldrin, the corresponding sediment 

concentration target estimated using the BSAF approach is 0.80 μg/kg dry weight, as described in Section 

6.7.5. All applicable targets are shown below in Table 6-27. For sediment the lower value of the 

consensus-based TEC target or the BSAF-derived target is selected as the final sediment target.

Table 6-27. Dieldrin Targets for Echo Park Lake

Media Source Target

Fish (ppb wet weight) OEHHA FCG 0.46

Sediment (μg/kg dry 

weight)

Consensus-based TEC 1.90

Sediment (μg/kg dry 

weight)

BSAF-derived target 0.80

Water (ng/L) CTR 0.14

Note: Shaded cells represent the selected targets for this TMDL.

6.7.3 Summary of Monitoring Data

This section summarizes the monitoring data for Echo Park Lake related to the dieldrin impairment.

Additional details regarding monitoring data are discussed in Appendix G (Monitoring Data). 

Water column sampling was conducted as part of an organics study performed by UCLA (funded by a 

grant managed by the Regional Board) in the summer of 2008 with three samples at two locations within

Echo Park Lake. All three water column samples were less than the detection limit for dieldrin (3 ng/L; 

the detection limit for dieldrin is higher than the water column criterion of 0.14 ng/L). No additional 

water column sampling for dieldrin has been conducted in Echo Park Lake.

A summary of the water column data is shown in Table 6-28.

Concentrations of dieldrin in suspended sediment were also analyzed at two in-lake stations during the 

summer of 2008 by UCLA, both were less than the detection limits (6.39 μg/kg to 20.10 μg/kg dry 

weight). Porewater was sampled by UCLA in both the summer and fall of 2008; dieldrin concentrations 

in all samples were less than the detection limits of 30 ng/L to 3,000 ng/L.
Echo Park Lake TMDLs January 2011

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Table 6-28. Summary of Water Column Samples for Dieldrin in Echo Park Lake

Station

Average Water 

Concentration (ng/L)1

Number of 

Samples

Number of Samples 

Above Detection Limits

South (1.50)2 2 0

North, Lotus Bed (1.50) 1 0

In-Lake Average2(1.50)

CTR Criterion 0.14

1Non-detect samples were included in reported averages at one-half of the sample detection limit. Numbers in 

parentheses indicate that sample is based only on the detection limits of the samples, and that no dieldrin was 

quantified in any of the collected samples.

2Overall average is the average of individual station averages.

UCLA collected bed sediment samples at five locations in Echo Park Lake in summer and fall 2008. All 

nine samples analyzed by UCLA resulted in dieldrin concentrations below the detection limit (which 

ranged from 0.83 μg/kg to 2.46 μg/kg dry weight). Since the upper end of this range is greater than the 

consensus-based TEC for dieldrin sediment (1.9 μg/kg dry weight), exceedances cannot be ruled out. 

Three in-lake locations were sampled by the Regional Board and USEPA on December 1, 2009; all were 

below the detection limit (1 μg/kg dry weight). Stations located near outfalls are taken as an estimate of 

the concentrations on incoming sediment. Because dieldrin does appear in fish at levels greater than the 

FCG, and because these body burdens of dieldrin are believed to arise from the sediment, EPA decided to 

represent statistical estimates for the sediment concentrations of dieldrin by setting the concentration of 

non-detected samples to the detection limit. The estimated lake-wide average of < 1.39 μg/kg dry weight

is less than the consensus-based TEC of 1.90 μg/kg dry weight. A summary of the sediment sampling is 

provided in Table 6-29.

Table 6-29. Summary of Sediment Samples for Dieldrin in Echo Park Lake

Station

Average Sediment 

Concentration (μg/kg

dry weight)

1

Number of 

Samples

Number of Samples 

Above Detection Limits

NE near LA City Storm Drain (1.76) 3 0

W near County Storm Drain (1.19) 2 0

South (1.83) 1 0

North, Lotus Bed (2.13) 2 0

Northeast (1.20) 1 0

NW Arm, near outfall (1.00) 1 0

Center Lake (1.00) 1 0

Center Lake S (1.00) 1 0

In-Lake Average2(1.39)

Influent Average (1.32)

Consensus-based TEC 1.90

1Non-detect samples are included in reported averages at the detection limit. Numbers in parentheses indicate that 

sample is based only on the detection limits of the samples, and that no dieldrin was detected in any of the collected 

samples.

2Overall average is the average of individual station averages. 
Echo Park Lake TMDLs January 2011

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Fish tissue concentrations of dieldrin from Echo Park Lake have been analyzed in largemouth bass, 

common carp, and bullhead (SWAMP and TSMP). Four fish samples (composites of filets from five 

fish) were collected and analyzed for total dieldrin between 1987 and 1991. In 1987, concentrations in a 

largemouth bass and a bullhead composite sample were reported at 0 and 7 ppb wet weight, respectively. 

Two additional largemouth bass samples were analyzed in 1991, with concentrations reported as 0 ppb 

(the detection limits for the historical fish samples are not reported).

Considering only data collected in the past 10 years, the average concentration of dieldrin in largemouth 

bass was 0.716 ppb wet weight, based on the three largemouth bass composite samples collected by 

SWAMP in the summer of 2007 and April 2010 with an average lipid fraction of 0.37 percent. Three 

composite samples of bottom-feeding common carp (Trophic Level 3) were also analyzed. These yielded 

an average dieldrin concentration of 0.935 ppb wet weight with an average lipid fraction of 1.26 percent. 

The recent fish-tissue data for Echo Park Lake are summarized in Table 6-30.

Table 6-30. Summary of Recent Fish Tissue Samples for Dieldrin in Echo Park Lake

Sample Date Fish Species Dieldrin (ppb wet weight)1

11 June 2007 Largemouth Bass 0.848

11 June 2007 Largemouth Bass 0.585

13 April 2010 Largemouth Bass [0.453]

2

11 June 2007 Common Carp 1.08

11 June 2007 Common Carp 0.79

13 April 2010 Common Carp 0.538

2007 - 2010 Average – Largemouth Bass 0.650

2007 - 2010 Average – Common Carp 0.803

FCG 0.46

1Composite samples of filet from five individuals.

2 Values in square brackets are reported concentrations below the practical reporting limit and are included in the 

averages.

In sum, five of six recent fish tissue concentrations in Echo Park Lake are above the FCG for dieldrin in 

both common carp and largemouth bass composite samples. Sediment and water column concentrations 

have all been below detection limits; however, the maximum detection limit in sediment is less than the 

consensus-based TEC.

6.7.4 Source Assessment

Dieldrin in Echo Park Lake is suspected to be primarily due to historical loading and storage within the 

lake sediments, with some ongoing contribution by watershed wet weather loads. Dry weather loading 

and direct atmospheric deposition to the lake are considered negligible sources of dieldrin. Stormwater

loads from the watershed could not be directly estimated because all sediment and water samples were 

below detection limits. Watershed loads of dieldrin may arise from past pesticide applications, improper 

disposal, and atmospheric deposition. Pesticide applications were most likely associated with 

agricultural, commercial, and residential areas. Improper disposal could have occurred at various 

locations, while atmospheric deposition occurs across the entire watershed.
Echo Park Lake TMDLs January 2011

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There is no definitive information on specific sources within the watershed at this time. Therefore, an 

average concentration of sediment is applied to all contributing areas. Although supplemental water 

additions of potable water makes up a significant amount of the flow to Echo Park Lake it does not 

contribute sediment load and is considered to not contribute significantly to dieldrin loading (total 

suspended sediment measured non-detect in two samples collected August 4th 2009). 

An upper-bound analysis for dieldrin is performed using the sediment load and detection limit to 

determine the maximum potential loading rate of dieldrin from the watershed. The dieldrin sediment 

concentration is assigned based on the estimate of concentration on influent sediment from sample 

detection limits of 1.32 μg/kg dry weight and the annual sediment load to Echo Park Lake is 1.32 tons/yr 

(see Appendix D, Wet Weather Loading). The resulting estimated upper bound on the wet weather load 

from the watershed is 0.0016 g/yr or less (Table 6-31). 

Table 6-31. Maximum Potential Dieldrin Loads for Each Jurisdiction and Subwatershed in the 

Echo Park Watershed (g/yr)

Subwatershed

Responsible 

Jurisdiction Input

Upper-Bound Potential 

Current Dieldrin Load (g/yr)

Northern Caltrans State Highway 

Stormwater1

<0.00005

Northern City of Los Angeles MS4 Stormwater1 <0.00117

Southern Caltrans State Highway 

Stormwater1

<0.00000

Southern City of Los Angeles MS4 Stormwater1 <0.00035

Total Load from Watershed <0.0016

This input includes effluent from storm drain systems during both wet and dry weather. As described in 

Appendix E (Atmospheric Deposition), Section E.5, the net atmospheric deposition of dieldrin directly to 

the lake surface is estimated to be close to zero, with deposited loads balanced by volatilization losses. 

Atmospheric deposition onto the watershed is implicitly included in the estimates of watershed load. 

6.7.5 Linkage Analysis

The linkage analysis provides the quantitative basis for determining the loading capacity of dieldrin into 

Echo Park Lake consistent with achieving water quality standards. The loading capacity is used to 

calculate the TMDL and corresponding allocations of that load to permitted point sources (wasteload 

allocations) and nonpoint sources (load allocations).

Lake sediments are often the predominant source of dieldrin in biota. The bottom sediment serves as a 

sink for organochlorine compounds that can be recycled through the aquatic life cycle. Dieldrin is 

strongly sorbed to sediments and has a long half-life in sediment and water. Incoming loads of dieldrin 

will mainly be adsorbed to particulates from stormwater runoff (eroded sediments from legacy 

contamination sites or from atmospheric deposition).

The use of bioaccumulation models and the fish tissue data from Echo Park Lake are discussed in detail in 

Appendix H (Organochlorine Compounds TMDL Development) and Appendix G (Monitoring Data), 

respectively. The estimated existing sediment dieldrin concentrations in Echo Park Lake are lower than 

the consensus-based TEC target, and existing fish tissue concentrations are higher than the fish tissue 

target. Therefore, a sediment target based on biota-sediment bioaccumulation (a BSAF approach) is

calculated from the smaller of the ratio of the FCG to existing fish tissue concentrations obtained from 

trophic level 4 fish (TL4; e.g., largemouth bass) and bottom-feeding, trophic level 3 fish (TL3; e.g., 
Echo Park Lake TMDLs January 2011 

6-47

common carp). In general, the TL3 number is expected to be more restrictive due to additional uptake of 

OC pesticides and PCBs from the sediment by bottom feeding fish. The existing fish tissue 

concentrations were calculated using only recent data (collected in the past 10 years) because the loads 

and exposure concentrations of dieldrin are likely to have declined steadily since the cessation of 

production and use of the chemical. For dieldrin in Echo Park Lake the ratios of the FCG to existing 

concentrations are: 

 TL4: 0.46/0.650 = 0.708 

 TL3: 0.46/0.803 = 0.573 

The lower ratio, obtained for the TL3 fish, corresponds to the trophic level requiring the greatest 

reductions to achieve the fish tissue target. This ratio is applied to the estimated in-lake sediment 

concentration. Analyses of sediment concentrations are, however, below detection limits. Using an 

estimated concentration of 1.39 μg/kg dry weight based on the sample detection limits, the resulting target 

concentration would be 0.80 μg/kg dry weight to obtain FCGs. Calculation with a literature-based BSAF 

(Appendix G, Monitoring Data) suggests that even lower concentrations might be needed. However, the 

literature-based BSAF is highly uncertain and may not be directly applicable to conditions in Echo Park 

Lake. Therefore, the target based on the detection limits is used, with acknowledgment that the estimate 

may need to be refined if additional data are collected at lower detection limits. The resulting fish tissue 

based target concentration of dieldrin in the sediment of Echo Park Lake is shown in Table 6-32. 

Table 6-32. Fish Tissue-Based Dieldrin Concentration Targets for Sediment in Echo Park Lake 

Dieldrin Concentration Sediment (μg/kg dry weight)

Existing < 1.39

BSAF-derived Target 0.80

Required Reduction < 50.7%

The BSAF-derived sediment target is less than the consensus-based sediment quality guideline TEC of 

1.90 μg/kg dry weight. (The consensus-based sediment quality guideline is for the protection of benthic 

organisms, and explicitly does not address bioaccumulation and human-health risks from the consumption 

of contaminated fish.) The lower value of the consensus-based TEC target or the BSAF-derived target is 

selected as the final sediment target. In addition, the CTR criterion for human health (0.14 ng/L) is the 

selected numeric target for the water column and protects both aquatic life and human health. 

6.7.6 TMDL Summary 

Because the dieldrin impairment in Echo Park Lake is most likely due to historic loads stored in the lake 

sediment, this impairment is not amenable to a standard, load-based TMDL analysis. Instead, allocations 

are first assigned on a concentration basis, with the goal of attaining the concentrations identified above 

for water and sediment, as well as fish tissue. The concentration targets apply to water and sediment 

entering the lake and within the lake 

The dieldrin TMDL will be allocated to ensure achievement of the loading capacity. TMDLs are broken 

down into the wasteload allocations (WLAs), load allocations (LAs), and Margins of Safety (MOS) using 

the general TMDL equation. 

TMDL WLA LA MOS
Echo Park Lake TMDLs January 2011

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Note that since this TMDL is being expressed as a concentration in sediment, in this scenario, the loading 

capacity is equal to 0.80 μg/kg dry weight dieldrin. The wasteload allocations and load allocations are 

also equal to 0.80 μg/kg dry weight dieldrin in sediment. There is no explicit MOS. Allocations are 

assigned for this TMDL by requiring equal concentrations of all sources. Details associated with the 

WLAs, LAs, and MOS are presented in the following three sections. 

6.7.6.1 Wasteload Allocations

This TMDL establishes wasteload allocations (WLAs) at their point of discharge. This TMDL also 

establishes alternative wasteload allocations for dieldrin (“Alternative WLAs if Fish Tissue Targets are 

Met”) described in Section 6.7.6.1.2. The alternative wasteload allocations will supersede the wasteload 

allocations in Section 6.7.6.1.1 if the conditions described in Section 6.7.6.1.2 are met.

6.7.6.1.1 Wasteload Allocations

The entire watershed of Echo Park Lake is contained in an MS4 jurisdiction, and therefore receives 

wasteload allocations (WLAs). Relevant permit numbers are 

 County of Los Angeles (including the city of Los Angeles): Board Order 01-182 (as amended by 

Order No. R4-2006-0074 and R4-2007-0042), CAS004001

 Caltrans: Order No 99-06-DWQ, CAS000003

Dieldrin concentrations in sediment and water flowing into Echo Park Lake are below detection limits, 

but most dieldrin load is expected to move in association with sediment. Therefore, suspended sediment 

in water flowing into the lake is assigned wasteload allocations. Additionally, the TMDL establishes 

wasteload allocations for dieldrin in the water column equal to the CTR based water column target. The 

CTR based water column target includes both dissolved dieldrin and dieldrin associated with suspended 

sediment. Comparing the sediment concentration target to the average detection limit for the influent 

samples of 1.32 μg/kg dry weight suggests that a reduction of approximately 39 percent in dieldrin loads 

is needed. The wasteload allocations are shown in Table 6-33.

Table 6-33. Wasteload Allocations for Dieldrin in Echo Park Lake

Subwatershed Responsible Jurisdiction Input

Wasteload Allocation 

for Dieldrin 

Associated with 

Suspended Sediment 

(μg/kg dry weight)

Wasteload 

Allocation for 

Dieldrin in the 

Water Column

(ng/L)

Northern Caltrans State Highway 

Stormwater1 0.80 0.14

Northern City of Los Angeles MS4 

Stormwater1 0.80 0.14

Northern General Industrial Stormwater 

Permittees (in the City of Los 

Angeles)2

General 

Industrial 

Stormwater1

0.80 0.14

Southern Caltrans State Highway 

Stormwater1 0.80 0.14

Southern City of Los Angeles MS4 

Stormwater1 0.80 0.14

1This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.
Echo Park Lake TMDLs January 2011

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6.7.6.1.2 Alternative Wasteload Allocations if Fish Tissue Targets Are Met

The wasteload allocations listed in Table 6-33 will be superseded, and the wasteload allocations in Table 

6-34 will apply, if:

1. The responsible jurisdictions submit to USEPA and the Regional Board material describing how 

the fish tissue target of 0.46 ppb wet weight have been met for the preceding three or more years. 

A demonstration that fish tissue targets have been met in any given year must at minimum 

include a composite sample of skin off fillets from at least five common carp each measuring at 

least 350mm in length, and

2. USEPA does not object to the Regional Board’s determination within 60 days of receiving notice 

of it.

Table 6-34. Alternative Wasteload Allocations for Dieldrin in Echo Park Lake if Fish Tissue 

Targets are Met

Subwatershed

Responsible 

Jurisdiction Input

Wasteload Allocation 

for Dieldrin 

Associated with 

Suspended Sediment 

(μg/kg dry weight)

Wasteload Allocation 

for Dieldrin in the 

Water Column (ng/L)

Northern Caltrans State Highway 

Stormwater1 1.90

0.14

Northern City of Los Angeles MS4 

Stormwater1

1.90 0.14

Northern General Industrial 

Stormwater Permittees (in 

the City of Los Angeles)2

General 

Industrial 

Stormwater1

1.90 0.14

Southern Caltrans State Highway 

Stormwater1

1.90 0.14

Southern City of Los Angeles MS4 

Stormwater1

1.90 0.14

1This input includes effluent from storm drain systems during both wet and dry weather.

2The discharges governed by the general industrial stormwater permit are currently in the City of Los Angeles. Any 

future discharges governed by the general construction and general industrial stormwater permits will receive the 

same concentration-based wasteload allocations.

6.7.6.2 Load Allocations

None of the watershed of Echo Park Lake is outside MS4 jurisdiction; therefore no load allocations (LAs) 

are assigned to watershed loads. No load is allocated to atmospheric deposition of dieldrin. The legacy 

dieldrin stored in lake sediment is believed to be the major cause of impairment associated with elevated 

fish tissue concentrations, and is assigned a load allocation. The in-lake allocation is in concentration 

terms: specifically, the responsible jurisdiction (city of Los Angeles) should achieve a dieldrin 

concentration of 0.80 μg/kg dry weight in lake bottom sediments (see Table 6-35).

Table 6-35. Load Allocations for Dieldrin in Echo Park Lake

Subwatershed

Responsible 

Jurisdiction Input

Load Allocation 

(μg/kg dry weight)

Lake Surface City of Los Angeles Lake bottom sediments 0.80
Echo Park Lake TMDLs January 2011

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6.7.6.3 Margin of Safety

TMDLs must include a margin of safety (MOS) to account for any lack of knowledge concerning the 

relationship between load and wasteload allocations and water quality. The MOS may be implicit, i.e., 

incorporated into the TMDL through conservative assumptions in the analysis, or explicit, i.e., expressed 

in the TMDL as loadings set aside for the MOS. This TMDL contains an implicit MOS based on 

conservative assumptions. The allocations are set based on the lower of either the BSAF-derived 

sediment target or the consensus-based TEC sediment target to ensure achievement of the OEHHA FCG 

target in fish tissue. The selected BSAF-derived target concentration in sediment is considerably lower 

than the consensus-based TEC target. 

6.7.6.4 Critical Conditions/Seasonality

TMDLs must include consideration of critical conditions and seasonal variation to ensure protection of 

the designated uses of the waterbody at all times. This TMDL protects beneficial uses by reducing fish 

tissue concentrations to the FCG target and protecting benthic biota in sediment. Because fish 

bioaccumulate dieldrin, concentrations in tissues of edible sized game fish integrate exposure over a 

number of years. As a result, overall average loading is more important for the attainment of standards 

than instantaneous or daily concentrations. WLAs and LAs in this TMDL are assigned as concentrations 

and protect during all seasons and in both high and low flow conditions. This TMDL therefore protects 

for critical conditions.

6.7.6.5 Daily Load Expression

USEPA recommends inclusion of a daily load expression for all TMDLs to comply with the 2006 D.C. 

Circuit Court of Appeals decision for the Anacostia River. This TMDL includes a maximum daily load 

estimated according to the guidelines provided by USEPA (2007). 

Because the dieldrin WLAs are expressed as concentrations on sediment, the daily maximum allowable 

load is calculated from the maximum daily sediment load multiplied by the TMDL WLA concentration. 

The maximum daily sediment load is estimated from the 99th percentile daily flow and the sediment event 

mean concentration that yields the estimated annual sediment load.

The daily maximum allowable load in Echo Park Lake is calculated from the estimated 99th percentile 

flow to the Lake multiplied by the event mean concentration consistent with achieving the long-term 

loading targets, described above in the PCBs section. USGS Station 11102000, Mission Creek near 

Montebello, CA, was selected as a surrogate for flow determination for flow to the lake, as described in 

the PCBs section (Section 6.5.6.5).

The event mean concentration of sediment in stormwater (55.8 mg/L) was calculated from the estimated 

existing watershed sediment load of 1.32 tons/yr (Table 6-13) divided by the total storm flow volume

reaching the lake (17.4 ac-ft/yr). Multiplying the sediment event mean concentration by the 99th

percentile peak daily flow (8.98 cfs) yields a daily maximum sediment load from stormwater of 1226 kg/d 

(1.35 tons/d). Applying the wasteload allocation concentration of 0.80 μg dieldrin per dry kg of sediment 

yields the stormwater daily maximum allowable load of 0.00098 g/d of dieldrin. This load is associated 

with the MS4 stormwater permittees. The maximum allowable daily load must be met on all days, and 

the concentration-based WLAs must be met to ensure compliance with the TMDL.

6.7.6.6 Future Growth

The manufacture and use of dieldrin is currently banned. Therefore, no additional allowance is made for 

future growth in the dieldrin TMDL. 
Echo Park Lake TMDLs January 2011

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If any sources currently assigned load allocations are later determined to be point sources requiring 

NPDES permits, those load allocations are to be treated as wasteload allocations for purposes of 

determining appropriate water quality-based effluent limitations pursuant to 40 CFR 122.44(d)(1).

6.8 TRASH IMPAIRMENT

6.8.1 Beneficial Uses

California state water quality standards consist of the following elements: 1) beneficial uses, 2) narrative 

and/or numeric water quality objectives, and 3) an antidegradation policy. In California, beneficial uses 

are defined by the Regional Water Quality Control Boards (Regional Boards) in the Water Quality 

Control Plans (Basin Plans). Numeric and narrative objectives are specified in each region’s Basin Plan, 

designed to be protective of the beneficial uses of each waterbody in the region. The existing beneficial 

uses assigned to Echo Park Lake include REC1, REC2, WARM, and WILD. Descriptions of these uses 

are listed in Section 2 of this TMDL report. Trash can potentially impair the REC1, REC2, WARM, and 

WILD in a variety of ways, including causing toxicity to aquatic organisms, damaging habitat, impairing 

aesthetics, and impeding recreation.

6.8.2 Numeric Targets

The numeric target is derived from the narrative water quality objective in the Los Angeles Basin Plan 

(LARWQCB, 1994) for floating material:

“Waters shall not contain floating materials, including solids, liquids, foams, and scum, in 

concentrations that cause nuisance or adversely affect beneficial uses”;

and for solid, suspended, or settleable materials:

“Waters shall not contain suspended or settleable material in concentrations that cause nuisance 

or adversely affect beneficial uses.”

The numeric target for the Echo Park Lake Trash TMDL is 0 (zero) trash in or on the water and on the 

shoreline. Zero trash is defined as no allowable trash discharged into the waterbody of concern, 

shoreline, and channels. No information has been found to justify any value other than zero that would 

fully support the designated beneficial uses. Furthermore, court rulings have found that a numeric target 

of zero trash is legally valid (City of Arcadia et al. v. Los Angeles Regional Water Quality Control Board 

et al. (2006) 135 Cal.App.4th 1392). The numeric target was used to calculate the waste load allocations 

for point sources and load allocations for nonpoint sources, as described in the following sections of this 

report. 

6.8.3 Summary of Monitoring Data

The existing beneficial uses are impaired by the accumulation of suspended and settled debris. Common 

items observed include plastic pieces, paper items, Styrofoam, food waste, glass pieces, aluminum foil, 

and cigarette butts. 

According to California’s 2006 303(d) Impaired Waterbodies list, trash is causing water quality 

problems in Echo Park Lake. USEPA and Regional Water Quality Control Board staff confirmed the 

trash impairment during a site visit to Echo Park Lake on March 9, 2009. Staff conducted quantitative 

trash assessments and documented the trash impairment with photographs. Trash was observed in the 

lake, along the shorelines, and at the outlet of storm drains discharging into the lake. 
Echo Park Lake TMDLs January 2011 

6-52

Two quantitative trash assessments were conducted according to the Rapid Trash Assessment protocol 

which gives each shoreline a numeric score out of a possible 120 points (SWAMP, 2007). Higher scores 

correspond to cleaner areas, with 120 points representing a clean area. The severity of the trash problem 

was scored based upon the condition of the following parameters: level of trash, actual number of trash 

items found, threat to aquatic life, threat to human health, illegal dumping and littering, and 

accumulation of trash. Trash assessments were conducted within a 100 feet long by 10 feet wide area. 

The site visit evaluated different land use types surrounding Echo Park Lake, including recreational uses 

near a roadway and near picnic tables. 

Echo Park has many visitors and is located in a densely populated urban area surrounded by busy streets. 

The lake is down a short steep slope from the streets which delineates the nonpoint source subwatershed 

boundary. Echo Park Lake has a shallow lotus bed on the northwest side, an inaccessible island on the 

northeast side, multiple small wetlands in the center, and a large fountain. The Park includes picnic tables 

near the lake, a playground on the northern shore, paddle boats for rent along the eastern shore, a fence 

along the southern corner, and a paved path around the entire lake, used for jogging and walking. 

Uncovered trash cans are located along the park path approximately every 100 feet, potentially leading to 

the transport of trash by wildlife or wind. Staff also observed approximately 300 birds in this small lake 

resulting in excessive bird droppings. Scum and small floatable pieces of trash were observed to 

accumulate in corners of the lake with stagnant water (Figure 6-11 and Figure 6-12). 

Figure 6-11. Trash Accumulation in the Lotus Bed Section of Echo Park Lake 
Echo Park Lake TMDLs January 2011 

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Figure 6-12. Floating Debris Observed on December 2, 2009 

6.8.3.1 Picnic Area 

A 100 ft. trash assessment was conducted near the playground and picnic tables on the northern shore of 

the lake. This area scored a 95/120. Only small trash items were observed. Trash was likely transported 

due to people littering in the picnic area and along the path. Some items were found in the water but no 

accumulation of trash was observed. 

6.8.3.2 Near Glendale Boulevard 

A trash assessment, conducted on the western shore near Glendale Boulevard, scored a 95/120. Trash was 

likely transported from the road and people littering along the park path. 

6.8.3.3 Wildlife Feeding 

Dumping of food waste, such as piles of rice or whole loaves of bread, to feed the birds was observed. 

Human food is unhealthy to wildlife and the massive quantities discarded cause an overabundance of 

birds to inhabit this area. An unnaturally large bird population leads to greater excrement quantities, 

which can worsen the nutrient problem in the lake. 

Locations of the quantitative monitoring sites are shown in the map below (Figure 6-13).
Echo Park Lake TMDLs January 2011 

6-54

Figure 6-13. Quantitative Trash Assessment Locations at Echo Park Lake 

During a follow-up visit to Echo Park Lake on August 4, 2009, trash was similarly observed in the lake 

and on the shore. No quantitative surveys were conducted. 

In summary, trash was present in and along the shore of Echo Park Lake during all visits. The prevalence 

of trash was evenly distributed around the lake. The main trash problems were caused by feeding wildlife 

and small trash items, such as cigarette butts. 

6.8.4 Source Assessment 

The major source of trash in Echo Park Lake results from litter, which is intentionally or accidentally 

discarded to the lake and watershed. Potential sources are categorized as point and nonpoint sources, 

depending on the transport mechanisms. For example: 

1. Storm drains: trash deposited throughout the watershed and carried to various sections of the lake 

during and after rainstorms via storm drains. This is a point source. 

2. Wind action: trash blown into the lake directly. This is a nonpoint source. 

3. Direct disposal: direct dumping or littering into the lake. This is a nonpoint source. 

Since the Echo Park Lake watershed includes residential areas, open space, parks, roads, and storm 

drains, both point and nonpoint sources contribute trash to the lake. 

6.8.4.1 Point Sources 

Based on reports from similar watersheds, the amount and type of trash transported is a function of the 

surrounding land use. The city of Long Beach recorded trash quantity collected at the mouth of the Los 

Angeles River; the results suggest total trash amount is linearly correlated with precipitation (Figure 6-14, 
Echo Park Lake TMDLs January 2011 

6-55

R

2=0.90, Signal Hill, 2006). A similar study found that the amount of gross pollutants entering the 

stormwater system is rainfall dependent but does not necessarily depend on the source (Walker and 

Wong, 1999). The amount of trash entering the stormwater system depends on the energy available to remobilize and transport deposited gross pollutants on street surfaces, rather than the amount of available 

gross pollutants deposited on street surfaces. Where gross pollutants exist, a clear relationship is 

established between the gross pollutant load in the stormwater system and the magnitude of the storm 

event. The limiting mechanism affecting the transport of gross pollutants, in the majority of cases, 

appears to be re-mobilization and transport processes (i.e., stormwater rates and velocities). 

Figure 6-14. Storm Debris Collection Summary for Long Beach (Signal Hill, 2006) 

In order to estimate trash generation rates, data from a comparable watershed was analyzed. 

The city of Calabasas completed a study on a Continuous Deflective Separation (CDS) unit installed to 

catch runoff from Calabasas Park Hills to Las Virgenes. The CDS unit is a hydrodynamic separator that 

uses vortex settling to remove sediment, trap debris and trash, and separate floatables such as oil and 

grease. It is assumed that this CDS unit prevented all trash from passing through. The calculated area 

drained by this CDS Unit is approximately 12.8 square miles. Regional Board staff estimated the 

waterbody’s urbanized area to be 0.10 square miles. The results of this clean-out, which represents 

approximately half of the 1998-1999 rainy season, were 2,000 gallons of sludgy water and a 64-gallon 

bag two-third full of plastic food wrappers. Part of the trash accumulated in this CDS unit for over half 

of the rainy season is assumed to have decomposed due to the absence of paper products. Since the CDS 

unit was cleaned out after slightly more than nine months of use, it was assumed that this 0.10 square 

mile urbanized area produced a volume of 64 gallons of trash. Therefore, 640 gallons of trash were 

generated per square mile per year. This estimate is used to determine trash loads. 

During the 1998/1999 and 1999/2000 rain seasons, a Litter Management Pilot Study (LMPS) was 

conducted by Caltrans to evaluate the effectiveness of several litter management practices in reducing 

litter discharged from Caltrans storm water conveyance systems. The LMPS employed four field study 

sites, each of which was measured with the amount of trash produced when separate BMPs were applied. 

The average total load for each site normalized by the total area of control catchments was 6,677 

gallons/mi2/year. Other trash generation rates and studies exist but the LMPS study is the most 

applicable to Echo Park Lake because of similar land use, population density, and average daily traffic 

conditions. Therefore, this analysis will use 6,677 gal/mi2/yr as the baseline estimate of trash for 

Caltrans roads. 
Echo Park Lake TMDLs January 2011

6-56

Table 6-36 shows the current estimated volume of trash deposited within each of the responsible 

jurisdictions, in gallons per year, assuming a trash generation rate of 6,677 gallons of uncompressed 

trash/mi2/year for Caltrans and a trash generation rate of 640 gallons of uncompressed trash per square 

mile per year for other jurisdictions. For responsible jurisdictions that are only partially located in the 

watershed, the square mileage indicated is for the portion in the watershed only. The current loads need 

to be reduced 100 percent to meet the TMDL target of zero trash.

Table 6-36. Echo Park Lake Estimated Point Source Trash Loads

Responsible Jurisdictions Point Source Area (mi

2

)

Current Point Source Trash 

Load (gal/year)

CA DOT (Caltrans) 0.022 150

City of Los Angeles 1.2 750

Note: 

For Caltrans: Current Point Source Trash Load (gal/yr) = Point Source Area (mi2) * 6,677 (gal/ mi2/yr). 

For all other jurisdictions: Current Point Source Trash Load (gal/yr) = Point Source Area (mi2) * 640 (gal/ mi2/yr)

6.8.4.2 Nonpoint Sources

Nonpoint source pollution is a source of trash in Echo Park Lake. Trash deposited in the lake from 

nonpoint sources is a function of transport via wind, wildlife, and overland flow and direct dumping. 

Few studies have evaluated the relationship between wind strength and movement of trash from land 

surfaces to a waterbody. Lighter trash with a sufficient surface area to be blown in the wind, such as 

plastic bags, beverage containers, and paper or plastic food containers, are easily lifted and carried to 

waterbodies. Also, overland flow carries trash from the shoreline to waterbodies. Transportation of 

pollutants from one location to another is determined by the energy of both wind and overland stormwater 

flow. 

Existing trash surrounding the lake is the fundamental cause of nonpoint source trash loading. Land use 

directly surrounding Echo Park Lake includes recreational areas. Visitors may intentionally or 

accidentally discard trash to grass or trails in the park, which initiate the journey of trash to waterbodies 

via wind or overland water flow. Varying uses of the park are responsible for different degrees of trash 

impairment. For example, areas with picnic tables generate more trash than parking lots. Visitation rates 

are also likely linked to the amount of trash from nonpoint sources.

Table 6-37 summarizes the nonpoint source area and current estimate of nonpoint source trash loads for 

responsible jurisdictions (see Figure 6-6 for an illustration of the park area surrounding the lake), 

assuming a trash generation rate of 640 gallons of uncompressed trash per square mile per year. The 

current loads need to be reduced 100 percent to meet the TMDL target of zero trash.

Table 6-37. Echo Park Lake Estimated Nonpoint Source Trash Loads

Responsible Jurisdictions

Nonpoint Source Area 

(Mile2)

Current Nonpoint Source 

Trash Loads (Gal/year)

City of Los Angeles 0.024 16

Note: Current Nonpoint Source Trash Load (gal/yr) = Nonpoint Source Area (mi2) * 640 (gal/ mi2/yr)
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6.8.5 Linkage Analysis

These TMDLs are based on numeric targets derived from narrative water quality objectives in the Los 

Angeles Basin Plan (LARWQCB, 1994) for floating materials and solid, suspended, or settleable 

materials. The narrative objectives state that waters shall not contain these materials in concentrations 

that cause nuisance or adversely affect beneficial uses. Since any amount of trash impairs beneficial uses, 

the loading capacity of Echo Park Lake is set to zero allowable trash. 

6.8.6 TMDL Summary

Both point sources and nonpoint sources are identified as sources of trash in Echo Park Lake. For point 

sources, water quality standards are attained by assigning waste load allocations (WLAs) to Permittees of 

the Los Angeles County Municipal Separate Storm Sewer System (MS4) Permit and Caltrans (hereinafter 

referred to as responsible jurisdictions); these WLAs will be implemented through permit requirements. 

For nonpoint sources, water quality standards are attained by assigning load allocations (LAs) to 

municipalities and agencies having jurisdictions over Echo Park Lake and its subwatershed. These LAs 

may be implemented through regulatory mechanisms that implement the State Board’s 2004 Nonpoint 

Source Policy such as conditional waivers, waste discharge requirements, or prohibitions. 

The TMDL of zero trash requires that current loads are reduced by 100 percent. Final WLAs and LAs are 

zero trash (Table 6-38). 

Table 6-38. Echo Park Lake Trash WLAs and LAs

Echo Park Lake Allocation

Trash WLA 0

Trash LA 0

6.8.6.1 Wasteload Allocations

The geographical boundary contributing to point sources is defined by watershed areas which contain 

conveyances discharging to the waterbodies of concern. Conveyances include, but are not limited to, 

natural and channelized tributaries, and stormwater drains and conveyances. 

Wasteload allocations (WLAs) are set to 0 (zero) allowable trash. 

The permits affected are:

 County of Los Angeles (includes all cities in Los Angeles County except Long Beach): Board 

Order 01-182 (as amended by Board Orders R4-2006-0074 and R4-2007-0042), CAS004001

 Caltrans: Order No 99-06-DWQ, CAS000003

 General Industrial Stormwater: Order No 97-03-DWQ, CAS000001

6.8.6.2 Load Allocations

Nonpoint source areas refer to locations where trash may be carried by overland flow, wildlife, or wind to 

waterbodies. Due to the transportation mechanism by wind, wildlife, and overland flow to relocate trash 

from land to waterbodies, the nonpoint source area may be smaller than the watershed. In addition, trash 

loadings frequently occur immediately around or directly into the lake making the load allocation a 

significant source of trash. According to the study by the city of Calabasas, the trash generation rate is 

640 gallons per square mile per year from nonpoint sources areas (including, but not limited to, schools, 
Echo Park Lake TMDLs January 2011

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commercial areas, residential areas, public services, road, and open space and parks areas). Current trash 

rates were calculated in the nonpoint source section.

Load allocations (LAs) for nonpoint sources are zero trash. Zero is defined as no allowable trash found in 

and on the lake, and along the shoreline. According to the Porter-Cologne Act, load allocations may be 

addressed by the conditional Waivers of WDRs, or WDRs. Responsible jurisdictions should monitor the 

trash quantity deposited in the vicinities of the waterbodies of concern as well as on the waterbody to 

comply with the load allocation.

The area adjacent to Echo Park Lake or defined as nonpoint sources includes parking lots, recreational 

areas, picnic areas, and walking paths. Assuming that trash within a reasonable distance from Echo Park 

Lake has a high potential to reach the waterbody, the nonpoint source jurisdiction is the city of Los 

Angeles. All load allocations are set to zero allowable trash.

6.8.6.3 Margin of Safety

A margin of safety (MOS) accounts for uncertainties in the TMDL analysis. The MOS can be expressed 

as an explicit mass load, or included implicitly in the WLAs and LAs that are allocated. Because this 

TMDL sets WLAs and LAs as zero trash, the TMDL includes an implicit MOS. Therefore, an explicit 

MOS is not necessary.

6.8.6.4 Critical Conditions/Seasonality

Critical conditions for Echo Park Lake are based on three conditions that correlate with loading 

conditions:

 Major storms

 Wind advisories issued by the National Weather Service

 High visitation – On weekends and holidays from May 15 to October 15. 

Critical conditions do not affect wasteload or load allocations because zero trash is a conservative target. 

However, implementation efforts should be heightened during critical conditions in order to ensure that

no trash enters the waterbody.

6.8.6.5 Future Growth

If any sources, currently assigned load allocations, are later determined to be point sources requiring 

NPDES permits, those load allocations are to be treated as wasteload allocations for purposes of 

determining appropriate water quality based effluent limitations pursuant to 40 CFR 122.44(d)(1).

6.9 IMPLEMENTATION RECOMMENDATIONS

Implementation measures may be developed in the future by the Regional Board through an 

implementation plan, NPDES permits, or non-point source enforcement. This section describes USEPA’s 

recommendations to the Regional Board as to the implementation procedures and regulatory mechanisms 

that could be used to provide reasonable assurances that water quality standards will be met. General 

information about various lake management strategies can be found in a USEPA document titled 

Managing Lakes and Reservoirs (EPA 841-B-01-006). Lake management options that can reduce 

pollutant loading to lakes include but are not limited to: increasing the volume of the lake that is aerated; 

installing hydroponic islands to remove nutrients; increasing flow volume or circulation in the lake; 

reducing stormwater discharges by improved infiltration; treating stormwater or supplemental water 
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inputs with a wetland system; alum treatment to immobilize nutrients in sediments; dredging in lake 

sediments; and/or fisheries management actions to reduce nutrient availability from sediments.

Additionally, responsible jurisdictions implementing these TMDLs are encouraged to utilize Los Angeles 

County’s Structural Best Management Practice (BMP) Prioritization Methodology which helps identify 

priority areas for constructing BMP projects. The tool is able to prioritize based on multiple pollutants. 

The pollutants that it can prioritize includes bacteria, nutrients, trash, metals and sediment. Reducing 

sediment loads would reduce OC pesticides and PCBs delivery to the lake in many instances. More 

information about this prioritization tool is available at: labmpmethod.org.

6.9.1 Nonpoint Sources and the Implementation of Load Allocations

Regional Board may regulate nonpoint pollutant sources through the authority contained in sections 

13263 and 13269 of the California Water Code, in conformance with the State Water Resources Control 

Board’s Nonpoint Source Implementation and Enforcement Policy. Additionally, South Coast Air 

Quality Management District has authority to regulate air emissions throughout the basin that affect air 

deposition. Load allocations are expressed in Table 6-8, Table 6-17, Table 6-26, Table 6-35, and 

Table 6-38 for nutrients, PCBs, chlordane, dieldrin, and trash, respectively. 

6.9.2 Point Sources and the Implementation of Wasteload Allocations 

Wasteload allocations apply to MS4 and Caltrans Stormwater permits as well as supplemental water 

additions. Wasteload allocations are expressed in Table 6-6, Table 6-7, Table 6-15, Table 6-24, 

Table 6-33, and Table 6-38 for individual and grouped nutrients, PCBs, chlordane, dieldrin, and trash,

respectively. The concentration and mass-based wasteload allocations will be incorporated into the 

Caltrans and Los Angeles County MS4 permits. 

6.9.3 Source Control Alternatives

Echo Park Lake has nutrient-related, chlordane, dieldrin, PCB, and trash impairments. There are some 

management strategies that would address multiple impairments (i.e., sediment removal BMPs in the 

watershed) while other pollutants require a more specific management plan. The City of Los Angeles 

Department of Recreation and Parks submitted a recommendation to develop the Echo Park Lake 

Rehabilitation plan to the Proposition O program funds in 2006 (CDM, 2006), developed the concept 

plan and presented it to the Prop O Citizens Oversight Committee for bond funding approval. BMP and 

restoration efforts associated with this plan will impact several of the Echo Park Lake impairments and 

initial modeling predicts that TMDL targets will be met upon its full implementation. An explicit goal of 

this project is to provide multiple environmental benefits by also enhancing open water, wetland, and 

nesting island habitat for native migratory waterfowl, turtles and gamefish. 

The objective of the Plan is to improve water quality in both Echo Park Lake and the Los Angeles River 

watershed. Funds were allocated to general tasks including: site investigation and preliminary studies, 

engineering design tasks, permitting costs, construction of structural improvements to the lake and storm 

drain system, implementation of water quality BMPs, habitat restoration, educational efforts regarding 

water quality improvements, and post-construction monitoring. Due to the wide range of components, the 

Plan is divided into four phases: pre-design, design, construction, and post-construction. Major lake 

improvements are summarized below; however, additional improvements are discussed in the Plan.

In-lake improvements, as part of the construction phase, will begin with draining the lake and removing 

contaminated soils. Fishes will also be removed. Once contaminated soils are properly disposed of 

offsite, an impermeable liner will be placed on the lake’s bottom to eliminate infiltration, thus conserving 

the potable water used to supplement water levels in the lake. Structural BMPs to the lake’s infrastructure 
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will include the installation of trash capture and pollution control devices at the city’s storm drain inlets. 

Sedimentation basins at all storm drains will be designed as stilling basins to enhance sedimentation and 

additional biological filters will trap pollutants, trash, and debris before stormwater flows into the lake. 

In-lake habitat and vegetation improvements will include lotus bed reconditioning as well as enhancement 

of the wetland and the lake’s edge. Finally, the Plan details specific BMPs to be implemented throughout 

the surrounding park area, including grass swales, infiltration strips, porous pavement, “smart” irrigation 

systems, and educational signage. 

Proposition O improvements to Echo Park Lake will assist with achieving local and regional water quality 

goals, including load reductions specific to the impairments addressed within these TMDLs. While there 

are some management strategies that would address multiple impairments (i.e., sediment removal BMPs

in the watershed), their differences warrant separate implementation and monitoring discussions.

6.9.3.1 Nutrient-Related Impairments

The Echo Park Lake Rehabilitation Plan identified a number of BMPs that may help prevent degradation 

of this waterbody due to nutrient loading associated with future land use changes. Several of the 

recommended BMPs would function as sediment removal devices, which may also result in decreased 

concentrations of nitrogen and phosphorus in the runoff water. The sediment removal BMPs proposed in 

the plan include:

 Hydrodynamic sediment and trash removal units within the city’s concrete stormdrain structure or 

at the forebay of the lake

 Sediment removal device at the county stormdrain outfall

 Sediment basins at stormdrain outfall locations

The plan also proposes BMPs that provide that provide filtration, infiltration, and vegetative uptake and 

these removal processes may reduce nutrient loads. These BMPs include:

 Lotus bed reconditioning

 Submerging of existing floating wetland islands

 Lake edge vegetation

 Grassy swales/infiltration strips

 Porous pavement

 New “smart” irrigation system

The rehabilitation plan also proposes educational signage and kiosks regarding the above improvements. 

In addition to these efforts, education of park maintenance staff regarding the proper placement, timing, 

and rates of fertilizer application will also result in reduced nutrient loading to the lake. Staff should be 

advised to follow product guidelines regarding fertilizer amounts and to spread fertilizer when the chance 

of heavy precipitation in the following days is low. Encouraging pet owners to properly dispose of pet 

wastes will also reduce nutrient loading associated with fecal material that may wash directly into the lake 

or into storm drains that eventually discharge to the lake. Discouraging feeding of birds at the lake will 

reduce nutrient loading associated with excessive bird populations. The NNE BATHTUB model 

indicated Additional Parkland Loading is present in Echo Park Lake. This lake is heavily frequented by 

bird feeders and the additional bird feces produced by bird feeding contributes to this load; loads linked to 

trash and associated food scraps would also be reduced.

In order to meet the fine particulate (PM2.5) and ozone (O3) national ambient air quality standards by their 

respective attainment dates of 2015 and 2024, the South Coast Air Quality Management District and the 
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California Air Resources Board have prepared an air quality management plan that commits to reducing 

nitrogen oxides (NOx, a precursor to both PM2.5 and ozone) by over 85 percent by 2024. These 

reductions will come largely from the control of mobile sources of air pollution such as trucks, buses, 

passenger vehicles, construction equipment, locomotives, and marine engines. These reductions in NOx 

emissions will result in reductions of ambient NOx levels and atmospheric deposition of nitrogen to the 

lake surface. 

6.9.3.2 Organochlorine Pesticides and PCB Impairments

The manufacture and use of chlordane, dieldrin, and PCBs are currently banned in the U.S. except for 

certain limited uses of PCBs authorized by USEPA. Therefore, no additional allowances for future 

growth are needed in the TMDLs. Source control BMPs and pollutant removal are the most suitable 

courses of action to reduce OC pesticides and PCBs in Echo Park Lake. The TMDL calculations 

performed for each pollutant (described above in their individual sections) indicated internal lake storage 

as the greatest contributing source and driving factor affecting fish tissue concentrations. Additionally, 

the watershed loads for chlordane and PCBs are less than one percent of the total loading that would be 

required to maintain the current sediment concentrations in the lake under steady-state conditions. 

Therefore, the most effective remedial actions and/or implementation efforts will focus on addressing the 

internal lake storage, such as capping or removal of contaminated lake sediments. As described above in 

Section 6.9.3, the Echo Park Lake Rehabilitation Plan proposes the draining of the lake, removal of 

sediments, and placement of an impermeable layer to address any residual contaminated soil. 

A thorough remedial design study should be conducted prior to implementing removal of lake sediments 

and impermeable layer placement for Echo Park Lake. When properly conducted, removal of 

contaminated lake sediments, or dredging, can be an effective remediation option. The object of sediment 

dredging is to eliminate the pollutants that have accumulated in sediments at the lake bottom. Dredging is 

optimal in waterbodies with known spatial distribution of contamination because sediment removal can 

focus on problem areas. However, no spatial pattern of pollutant contamination was apparent in Echo 

Park Lake. Removal of the contaminated sediments reduces the pollutants available to the in-lake cycling 

by discontinuing exposure to benthic organisms, water column loading, and consequent bioaccumulation 

in higher trophic level fish. Potential negative effects of dredging include increased turbidity and lowered 

dissolved oxygen concentrations in the short term, and disturbance to the benthic community and 

reactivation of buried sediment and any associated pollutants. These negative impacts could be avoided

through a plan that combines thorough removal of sediments and placement of an impermeable layer or 

cap. 

In some cases, sediment capping may be appropriate to sequester contaminated sediments below an 

uncontaminated layer of sediment, clay, gravel, or media material. Capping is effective in restricting the 

mobility of OC pesticides and PCBs; however, it is most useful in deep lakes and capping alone may not 

be a viable solution at Echo Park Lake. Capping of in-place sediments without removal should be 

restricted to areas with sediments that can support the weight of a capped layer, and to areas where 

hydrologic conditions of the waterbody will not disturb the cap. The combination of sediment removal 

and capping of any residuals could be an effective solution if properly designed.

The in-lake options for remediation are costly, but would be the only way to achieve full use support in a 

short timeframe. It is, however, also true that the OC pesticides and PCBs in question are no longer 

manufactured and will tend to decline in concentration due to dilution by clean sediment and natural 

attenuation. Natural attenuation includes the chemical, biological, and physical processes that degrade 

compounds, or remove them from lake sediments in contact with the food chain, and reduce the 

concentrations and bioavailability of contaminants. These processes occur naturally within the 

environment and do not require additional remediation efforts; however, the half-lives of OC pesticides 
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and PCBs in the environment are long, and natural attenuation often requires decades before observing 

significant improvement. 

Loading from the watershed can also be expected to decline over time due to natural attenuation. While 

reductions are called for in watershed loads, these loads are a small fraction of the historic loads already 

stored in the lakes. Limited sampling has not identified any hotspots of elevated loading under current 

conditions. It may, however, be necessary to further investigate potential sources of OC pesticide and 

PCBs loading in the watershed, such as active and abandoned industrial sites, waste disposal areas, former 

chemical storage areas, and other potential hotspots, if sediment concentration is found to be elevated 

after the planned dredging project.

6.9.3.3 Trash Impairment

WLA may be complied with via full capture systems, partial capture systems, nonstructural BMPs, or any 

other lawful method which meet the target of zero trash. USEPA recommends the installation of full 

capture systems throughout the watershed. The Linear Radial, Inclined Screen, Baffle Box, and Catch 

Basin Insert are examples of full capture systems that fulfill the criteria of capturing all trash greater than 

5 mm during flows less than the 1-year 1-hour storm. The Linear Radial utilizes a casing with louvers to 

serve as screens or mesh screen. Flows are routed through the louvers and into a vault. The Inclined 

Screen uses a wedge-wire screen with the slotting perpendicular or parallel to the direction of flow. This 

device is configured with an influent trough to allow solids to settle. The Baffle Box applies a twochamber concept: the first chamber utilizes an underflow weir to trap floatable solids, and the second 

chamber uses a bar rack to capture material. The catch basin has an opening cover screen which is a 

coarse mesh screen at street level that is paired with a catch basin insert, a 5 mm screen inside the catch 

basin which filters out smaller trash. USEPA recommends implementation plans be consistent with the 

Los Angeles River trash TMDL. A monitoring plan should be developed in order to understand the 

effectiveness of the implementation efforts. 

Similar devices to those described above were proposed in the Echo Park Lake Rehabilitation Plan. The 

plan proposes the installation of hydrodynamic units (either Continuous Deflective Separation (CDS) or 

Vortechnics units) which are estimated to capture 100 percent of floatables as well as provide sediment, 

nutrient, and other pollutant removal. These devices would be installed in the city’s concrete stormdrain 

structure or at the forebay of the lake, adjacent to the inlet structure. The Prop O recirculation system will 

also assist in removal of small pieces of trash.

LA may be complied with through the implementation of nonstructural BMPs or any other lawful 

methods which meet the target of zero trash. A minimum frequency of trash collection and assessment 

should be established at an interval that prevents trash from accumulating in deleterious amounts in 

between collections. Trash should be prevented by providing effective public education about littering 

impacts. Signs dissuading littering and wildlife feeding along roadways and around the lake are 

recommended. A city ban, tax, or incentive program reducing single-use plastic bags, Styrofoam 

containers, and other commonly discarded items which cannot decompose is recommended (Los Angeles 

County Department of Public Works, 2007). 

Echo Park’s grounds and facilities are maintained by the city of Los Angeles. Trash is currently collected 

and removed from the park every other day during typical conditions and daily during windy or rainy 

weather. USEPA recommends continuation and expansion of the current trash pickups by the city of Los 

Angeles, including the collection of small trash items, such as cigarette butts. 

The city of Los Angeles is also responsible for collection of trash in the lake. Currently a boat is used to 

remove large trash items from the lake. USEPA recommends a more frequent in-lake trash removal 

schedule to prevent the accumulation of small trash pieces.
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The prevention and removal of trash in Echo Park Lake will lead to enhanced aesthetics, improved water 

quality, and the protection of habitat. 

6.10 MONITORING RECOMMENDATIONS

Although estimates of the loading capacity and allocations are based on best available data and 

incorporate a MOS, these estimates may potentially need to be revised as additional data are obtained. 

The mass-based loading capacity will be affected by changes in flow volumes; therefore, loading

capacities may be reconsidered if significant volume reductions or additions occur. 

To provide reasonable assurances that the assigned allocations result in compliance with the chlorophyll 

a, fish tissue, and trash targets a commitment to continued monitoring and assessment is warranted. The 

purposes of such monitoring will be: 1) to evaluate the efficacy of control measures instituted to achieve 

the needed load reductions, 2) to document trends over time in algal densities and bloom frequencies, fish 

tissue organochlorine compounds concentrations and trash levels, and 3) to determine if the load 

reductions proposed for the TMDLs lead to attainment of standards. 

6.10.1 Nutrient Related Impairments

To assess compliance with the nutrient TMDLs, monitoring for nutrients and chlorophyll a should occur 

at least twice during the summer months and once in the winter. At a minimum, compliance monitoring 

should measure the following in-lake water quality parameters: ammonia, TKN or organic nitrogen, 

nitrate plus nitrite, orthophosphate, total phosphorus, total suspended solids, total dissolved solids and 

chlorophyll a. Measurements of the temperature, dissolved oxygen, pH and electrical conductivity should 

also be taken throughout the water column with a water quality probe along with Secchi depth 

measurement. All parameters must meet target levels at half the Secchi depth. DO and pH must meet 

target levels from the surface of the water to 0.3 meters above the lake bottom. Additionally, in order to 

accurately calculate compliance with wasteload allocations to the lake expressed in yearly loads, 

monitoring should include flow estimation or monitoring as well as the water quality concentration 

measurements. Wasteload allocations are assigned to stormwater inputs and supplemental water 

additions. These sources should be measured near the point where they enter the lakes twice a year for at 

minimum: ammonia, TKN or organic nitrogen, nitrate plus nitrite, orthophosphate, total phosphorus, total 

suspended solids and total dissolved solids. 

The nutrient-response analysis for Echo Park Lake indicates that existing levels of nitrogen and 

phosphorus loading are resulting in attainment of the summer average chlorophyll a target concentration 

of 20 μg/L. As an antidegradation measure, nitrogen and phosphorus TMDLs are allocated based on 

existing loading. As an example of concentrations that responsible jurisdictions may need to target in 

order to meet and comply with the mass-based WLAs and LAs, this discussion provides concentrations 

calculated based on existing flow volumes (a recalculation is needed if flow volumes change). Assuming 

flow volumes remain at existing levels (Table 6-5), the target concentrations of total phosphorus and total 

nitrogen that may be 0.58 mg-P/L and 4.5 mg-N/L for the Caltrans areas, and 0.71 mg-P/L and 

4.5 mg-N/L for the city of Los Angeles areas. Targeted concentrations in the supplemental water 

additions may be 0.12 mg-P/L and 1.13 mg-N/L assuming volumes remain at existing levels. Assuming 

average precipitation depths, the targeted concentration of nitrogen in precipitation may be 0.204 mg-N/L. 

The flows associated with the additional parkland sources are unknown, so LA concentrations cannot be 

estimated. As stated above, these concentrations are provided as guidelines; however, mass-based WLAs 

must be achieved.
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6.10.2 Organochlorine Pesticides and PCB Impairments

To assess compliance with the organochlorine compounds TMDLs, monitoring should include 

monitoring of fish tissue at least every three years as well as once yearly sediment and water column 

sampling. For the OC pesticides and PCBs TMDLs a demonstration that fish tissue targets have been met 

in any given year must at minimum include a composite sample of skin off fillets from at least five 

common carp each measuring at least 350 mm in length. At a minimum, compliance monitoring should 

measure the following in-lake water quality parameters: total suspended sediments, total PCBs, total 

chlordane and dieldrin; as well as the following in-lake sediment parameters: total organic carbon, total 

PCBs, total chlordane, and dieldrin. Environmentally relevant detection limits should be used (i.e.,

detection limits lower than applicable target), if available at a commercial laboratory. Measurements of 

the temperature, dissolved oxygen, pH and electrical conductivity should also be taken throughout the 

water column with a water quality probe along with Secchi depth measurement. Wasteload allocations 

are assigned to stormwater inputs and supplemental water additions. These sources should be measured 

near the point where they enter the lakes once a year during a wet weather event. Sampling should be 

designed to collect sufficient volumes of suspended solids to allow for the analysis of at minimum: total 

organic carbon, total suspended solids, total PCBs, total chlordane, and dieldrin. Measurements of the 

temperature, dissolved oxygen, pH and electrical conductivity should also be taken.

WLAs and LAs for each pollutant are assigned to the sediment-associated load from the watershed as 

well as the lake bottom sediments. The concentration-based WLAs and LAs are 2.10 μg/kg dry weight

for total chlordane, 1.77 μg/kg dry weight for total PCBs, and 0.80 μg/kg dry weight for dieldrin. The 

associated reductions from the watershed load needed to meet the WLAs are 74.7 percent for total 

chlordane, and 92.7 percent for total PCBs. A quantitative percent reduction cannot be calculated for 

dieldrin because all sediment samples are below detection limits (which are greater than the TMDL target 

concentration); however, the needed reduction appears to be on the order of 39 percent.

6.10.3 Trash Impairments

Responsible jurisdictions should monitor the trash quantity deposited in the vicinity of Echo Park Lake as 

well as on the waterbody to comply with the load allocation and to understand the effectiveness of various 

implementation efforts. Quarterly monitoring using the Rapid Trash Assessment Method is 

recommended. The trash TMDL target is zero trash; a 100 percent reduction is required.
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