REGISTRATION REVIEW

ECOLOGICAL RISK ASSESSMENT

PROBLEM FORMULATION FOR:

BORIC ACID SALTS

B(OH)3

PREPARED BY: 

Ron Dean, Biologist 

William P. Eckel, PhD, Senior Physical Scientist 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

APPROVED BY: 

Tom Bailey, Chief 

Environmental Risk Branch 2 

Environmental Fate and Effects Division 

Office of Pesticide Programs 

2
TABLE OF CONTENTS

STRESSOR SOURCE AND DISTRIBUTION ............................................................................ 4 

INTEGRATION OF AVAILABLE INFORMATION........................................................................ 4 

ECOLOGICAL EFFECTS........................................................................................................ 5 

Toxicity Studies.............................................................................................................. 5 

Toxicity to Avian Species........................................................................................... 6 

Birds, Chronic......................................................................................................... 8 

Toxicity to Mammalian Species ................................................................................. 8 

Mammals, Acute and Chronic ................................................................................ 8 

Toxicity to Benificial Insects...................................................................................... 9 

Toxicity to Aquatic Animals..................................................................................... 10 

Freshwater Fish, Acute ......................................................................................... 10 

Freshwater Fish, Acute ......................................................................................... 10 

Freshwater Invertebrates, Acute ........................................................................... 10 

Freshwater Invertebrates, Chronic ........................................................................ 11 

Estuarine and Marine Animals, Acute and Chronic ............................................. 11 

Toxicity to Plants...................................................................................................... 11 

EXPOSURE CHARACTERISTICS......................................................................................... 12 

Persistence and Mobility....................................................................................... 13 

Major Degradation Pathways and Degradates...................................................... 13 

Routes of Dissipation............................................................................................ 13 

CHARACTERISTICS OF ECOSYSTEMS POTENTIALLY AT RISK........................................... 13 

CONCEPTUAL MODEL ....................................................................................................... 14 

ANALYSIS PLAN OPTIONS................................................................................................. 17 

ANTICIPATED DATA NEEDS........................................................................................... 17 

LITERATURE CITED ........................................................................................................... 24 

List of Impaired Waters ............................................................................................. 25 

List of Approved TMDLs............................................................................................ 29 

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STRESSOR SOURCE AND DISTRIBUTION

Boric acid salts are registered as acaricides, algicides, fungicides, herbicides and 

insecticides. Most of the registered products are for indoor use. The multiple indoor and 

outdoor use products consist of dusts, wettable powders, liquids, granules, pellets, 

impregnated material, soluble concentrates/solids, bait solids and liquids and liquids 

ready-to-use. 

The highest labeled rate for boric acid salts is for Redzone Bait granular formulation, 

where applications of 45 lbs formulated product per acre (2.25 lbs a.i./A) may be applied 

at seven day intervals up to nine times a year for the control of Fire Ants (Solenopsis 

richteri) and Red Imported Fire Ants (Solenopsis invicta) in pastures, commercial 

nurseries, sod farms, home lawns, golf courses and commercial and recreational turf. 

This product is a bait formulation of corn grit and attractant oil. 

When dissolved in water, boric acid salts produce boric acid (H3BO3) and sodium ions. 

Therefore, boric acid will be treated as the chemical stressor for this assessment. The 

active moiety is boric acid salts, which causes insects’ water-repellent outer protective 

layer (exoskeleton) to lose its effectiveness, causing death by loss of body fluids. It also 

disrupts the protective membrane of fungal mycelia, sporangia, and spores, breaking it 

down and exposing these tissues to the drying effect of the atmosphere. Boric acid salts 

are also registered for use as herbicides. 

Boric acid salts include the following registered active ingredients. 

PC Code CAS Registry No. Chemical Name

011001 10043-35-3 Boric acid 

011102 1303-96-4 Borax (B4Na2O7•10H2O) 

011103 12280-03-4 Boron sodium oxide (B8Na2O13), tetrahydrate 

011104 7775-19-1 Boric acid, sodium salt 

011107 12008-41-2 Boron sodium oxide (B8Na2O13) 

011110 12179-04-3 Boron sodium oxideB4Na2O7), pentahydrate 

011112 1330-43-4 Boron sodium oxide (B4Na2O7) 

011111 11130-12-4 Sodium borate pentahydrate 

011002 1303-86-2 Boric oxide 

INTEGRATION OF AVAILABLE INFORMATION

The most recent ecological assessment for boric acid salts was done 7/17/08 for Redzone 

Bait granular formulation, for aerial applications of 45 lbs formulated product per acre 

(2.25 lbs a.i./A) applied at seven day intervals up to nine times a year for the control of 

Fire Ants (Solenopsis richteri) and Red Imported Fire Ants (Solenopsis invicta) in 

pastures, commercial nurseries, sod farms, home lawns, golf courses and commercial and 

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recreational turf. This application resulted in risk quotients (RQ’s) above the Agency’s 

level of concern (LOC) for federally listed and non-listed mammals. 

The 1993 RED decision concluded that the Agency’s “concerns regarding risks to birds, 

fish and wildlife species are minimal. Boric acid’s limited outdoor use patterns, low 

toxicity, and natural presence in terrestrial and aquatic environments are mitigating 

factors for any potential risk to nontarget organisms.” However, the application rate and 

method of Redzone Bait was not considered in that decision. 

ECOLOGICAL EFFECTS

Toxicity Studies 

Acute and chronic toxicity data from studies submitted by pesticide registrants along with 

the available open literature are used to evaluate the potential direct effects of boric acid 

salts to the aquatic and terrestrial receptors identified in this section. This includes 

toxicity data on the technical grade active ingredient, degradates, and when available, 

formulated products (e.g. “Six-Pack” studies). The open literature studies are identified 

through EPA’s ECOTOX database (http://cfpub.epa.gov/ecotox/), which employs a 

literature search engine for locating chemical toxicity data for aquatic life, terrestrial 

plants, and wildlife. The evaluation of both sources of data can also provide insight into 

the direct and indirect effects of boric acid salts on biotic communities from loss of 

species that are sensitive to the chemical and from changes in structure and functional 

characteristics of the affected communities. 

Table 1 provides a summary of the taxonomic groups and the surrogate species tested to 

help understand potential acute ecological effects of pesticides to these non-target 

taxonomic groups. In addition, the table provides a preliminary overview of the potential 

acute toxicity of boric acid salts by providing the acute toxicity classifications. 

Table 1 Test Species Evaluated for Assessing Potential Ecological Effects of 

Associated Acute Toxicity Classification 

Taxonomic Group Example(s) of Surrogate Species Acute Toxicity 

Classification 

Birds1 Mallard (Anas platyrhynchos) 

Bobwhite (Colinus virginianus) 

Practically non-toxic 

Mammals Laboratory rat (Rattus norvegicus) Moderately toxic 

Benificial Insects Honey bee (Apis mellifera) Practically non-toxic 

Freshwater fish2 Bluegill sunfish (Lepomis macrochirus) 

Rainbow trout (Onchorhynchus mykiss) 

Practically non-toxic 

Freshwater 

invertebrates 

Water flea (Daphnia magna) Practically non-toxic 

Estuarine/marine fish Sheepshead minnow (Cyprinodon 

variegatus) 

No data 

Estuarine/marine Mysid shrimp (Americamysis bahia) No data 

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invertebrates Eastern oyster (Crassostrea virginica) 

Terrestrial plants3 Monocots: corn (Zea mays) 

Dicots: soybean (Glycine max) 

No data 

Aquatic plants and 

algae 

Vascular: Duckweed (Lemna gibba) 

Nonvascular: Green algae (Selenastrum 

capricornutum) 

No data 

1

 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 2

 Freshwater fish may be surrogates for aquatic-phase amphibians. 3

 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of which 

one is soybeans. 

There are no submitted studies regarding the toxicity of boric acid salts to terrestrial 

vascular or aquatic vascular and non-vascular plants. Boron is an essential element in the 

diet of animals, and the metabolism of plants. Non excessive xposures may therefore be 

beneficial in many cases, rather than adverse. While natural concentrations of boron are 

essential for normal plant growth, an excess of boron is toxic to plants (WHO 1998). In 

many areas, there are naturally high levels of boron in the soil and water that would 

outweigh any potential exposure from boric acid use as a pesticide. According to 

ATSDR, the average concentration of boron in U.S. soil is 26 to 33 mg/kg, and the 

average surface water concentrations are about 0.1 mg/L (ATSDR, Sept. 2007. Draft 

Toxicological Profile, for Boron). 

Toxicity to Avian Species 

According to data submitted to OPP, boric acid salts are practically non-toxic to birds on 

an acute basis. Literature studies indicate that reproductive effects in birds may occur, 

but only at exposures of 250 ppm in the diet or higher. Effects on egg hatchability and 

spermatozoa production were also found. 

Birds, Acute

An acute oral toxicity study using the technical grade of the active ingredient (TGAI) is 

required to establish the toxicity of boric acid to birds. The preferred test species is either 

mallard duck (a waterfowl) or bobwhite quail (an upland gamebird). Boric Acid is 

considered practically nontoxic to avian species on an acute oral basis with an LD50 of 

>2150 mg ai/kg. 

No acute toxicity data for passerine species are available. Although the submitted avian 

acute data suggest that boric acid is practically non-toxic to the Bobwhite Quail, toxicity 

data for game birds may not reflect risks to passerine birds which have been identified to 

be more sensitive to pesticides in some cases than the Bobwhite Quail. In addition, 

because there are bait formulations for boric acid that are made from corn grit and oil, 

birds may be attracted to this bait and consume large quantities of it. Therefore, 

additional data are needed to accurately assess risks to these species. Acceptable avian 

acute oral toxicity values for boric acid salts are summarized in Table 2. 

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Table 2. Avian Acute Oral Toxicity 

Species 

LD50

(mg 

ai/kg ) 

Toxicity 

Category MRID No. Study 

Classification 

Mallard Duck > 2150 Practically 

nontoxic 

ACC254367 

Acceptable 

(No Mortalities 

Observed) 

Birds, Subacute

Two subacute dietary studies using the TGAI are required to establish the toxicity of 

boric acid to birds. The preferred test species are mallard duck and bobwhite quail. 

Boric acid salts exhibit a 5-Day LC50 of > 2510 ppm ai. Therefore it is considered 

practically nontoxic to avian species on a subacute dietary basis. Results of these tests 

are tabulated below in Table 3. 

Table 3. Avian Subacute Dietary Toxicity 

Species 

5-Day 

LC50

(ppm ai) 

Toxicity 

Category 

MRID No. Study 

Classification 

Mallard Duck > 5620 Practically 

nontoxic ACC254367 

Acceptable 

(No Mortalities 

Observed) 

Bobwhite Quail > 5620 Practically 

nontoxic ACC254367 

Acceptable 

(No Mortalities 

Observed) 

Mallard Duck > 10000 Practically 

nontoxic 

Not 

Reported/ 

Noles / 1984 

Acceptable 

(No Mortalities 

Observed) 

Bobwhite Quail > 10000 Practically 

nontoxic 

Not 

Reported/ 

Noles / 1987 

Acceptable 

(No Mortalities 

Observed) 

Bobwhite Quail > 2510 Practically 

nontoxic 

Not 

Reported/ 

Noles/ 1992 

Acceptable 

(No Mortalities 

Observed) 

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Birds, Chronic

Avian reproduction studies using the TGAI are required for boric acid salt because the 

birds may be subject to repeated or continuous exposure to boric acid salt due to its 

persistence, especially preceding or during the breeding season. 

Currently no reproductive toxicity studies have been submitted to the Agency and no 

acceptable studies are available from the ECOTOX database. 

Toxicity to Mammalian Species 

Clinical signs of acute toxicity observed following acute exposures include depression, 

ataxia and convulsions Toxicity values classifications for boric acid salts are summarized 

in Table 1. 

Mammals, Acute and Chronic

Based on the results of acute exposure studies, boric acid salt is classified as moderately 

toxic, with an LD50 in male rats of 4.5 g boric acid salts/kg (Weir and Fisher 1972). 

Clinical signs of toxicity observed following acute exposures include depression, ataxia 

and convulsions. 

In a two generation reproduction study conducted in mice, boric acid salt was 

administered throughout the study in the diet at levels of 0, 1000, 4500, or 9000 ppm (0, 

150, 675, or 1350 mg/kg). The parental LOAEL was 4500 ppm based on decreases in 

organ weights in both sexes. The reproductive LOAEL was also 4500 ppm based on 

decreased fertility and decreased pup weight. At this dose, the average number of days 

between litters increased after the second litter and the number of dams producing litters 

decreased significantly. At the highest dose tested, no litters were produced and the 

males in this group had a decrease in sperm concentration and motility when compared to 

controls. The NOAEL reported for this study was 1000 ppm for this study. 

In a reproduction study conducted in Sprague Dawley rats, boric acid salt was 

administered in the feed at doses of 0, 65, 154, or 515 mg/kg/day for three generations. 

The systemic and reproductive NOAELs were 154 mg/kg/day and the systemic and 

reproductive LOAELs were 515 mg/kg/day. At this dose level, there was a reported 

decrease in weight gain during the pre-mating period in both sexes and food efficiency 

was lower in females. The testes in males were atrophied and there was a reported 

decrease in the number of corpora lutea in females at the highest dose tested. 

Additionally, no litters were produced when high dose males were mated to high dose 

females. When high dose females were mated to control males, there was a reported 

decrease in the number of litters and pup survival was adversely affected. These toxicity 

values are reported below in Table 4. 

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Table 4. Mammalian Toxicity 

Species/ 

Study 

Duration 

% ai 

Test 

Type 

Toxicity 

Value 

Affected 

Endpoints 

MRID No/ 

Author / 

Year. 

Rat/ Acute 

Exposure Tech. Acute Oral 450 mg 

boric acid 

salts/kg 

Mortality. 5584/Weir 

and Fisher 

1972 

Mouse/Chronic 

Exposure Tech. 2 Generational 150 mg/kg 

NOAEL 

Decreased parental organ 

weight, fertility, and 

decreased pup weight 

5584 

Rat/Chronic 

Exposure Tech. 3- 

Generational 

154 

mg/kg/day 

NOAEL 

Decrease in weight gain 

during the pre-mating 

period in both sexes and 

food efficiency was lower 

in females. 

68882 

Toxicity to Benificial Insects 

Test results indicate that boric acid salt is relatively non-toxic to bees on an acute contact 

basis. Results of this test are tabulated below in Table 5. 

Table 5. Nontarget Benificial Insect Acute Contact Toxicity 

Species 

LD50 

(ug 

ai/bee) 

Toxicity 

Category 

MRID/ 

Document No. Study 

Classification 

Honey Bee 362.58 Practically 

nontoxic 40269201 Acceptable 

Although these results indicate that boric acid salts are relatively non-toxic to bees on an 

acute contact basis, boric acid is registered for use as an insecticide. Therefore, the 

Agency will consider risks to other terrestrial invertebrates. 

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Toxicity to Aquatic Animals 

Freshwater Fish, Acute

Two freshwater fish toxicity studies using the TGAI are required to establish the toxicity 

of boric acid salt to fish. The preferred test species are rainbow trout (a coldwater fish) 

and bluegill sunfish (a warmwater fish). A definitive LC50 endpoint value could not be 

determined. The highest concentration tested on the Rainbow Trout, was 1100 ppm ai, 

and exhibited no mortalities. Boric acid salts are therefore considered practically nontoxic to freshwater fish on an acute basis. Results of these tests are tabulated below in 

Table 6. 

Table 6. Freshwater Fish Acute Toxicity 

Species 

96-hour 

LC50 (ppm ai) Toxicity 

Category 

MRID/ 

Document 

No. 

Study 

Classification 

Bluegill sunfish > 1021 Practically 

nontoxic 

40594602 Acceptable 

Rainbow trout > 800 Practically 

nontoxic 

TN 2751 

Doc. No.: 

2047235/42 

Supplemental 

Rainbow trout > 1100 Practically 

nontoxic 

40594601 Acceptable 

Freshwater Fish, Chronic

There are no acceptable studies by which to assess chronic fish toxicity for boric acid 

salts. It can be assumed that fish are adapted to naturally-occurring boron levels in their 

local environments. Therefore, there is only a concern for water bodies with naturally 

low levels of boron because the fish inhabiting these waters are not selected to be 

resistant to boron, nor would they be expected to be acclimated to high levels of boron. 

Freshwater Invertebrates, Acute

A freshwater aquatic invertebrate toxicity test using the TGAI is required to establish the 

toxicity of boric acid salt to aquatic invertebrates. The preferred test species is Daphnia 

magna. The most sensitive EC50 endpoint, as exhibited by Daphnia magna, is 133 ppm 

ai, boric acid salt is considered practically nontoxic to aquatic invertebrates on an acute 

basis. Results of this test are tabulated below in Table 7. 

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Table 7. Freshwater Invertebrate Acute Toxicity 

Species 

48-hour 

EC50 (ppm 

ai) Toxicity 

Category 

MRID/ 

Document 

No. 

Study 

Classification 

Water flea 133 Practically 

nontoxic Doc No.: 

2024942 

Acceptable 

Water flea 226 Practically 

nontoxic 

Doc No.: 

2024942 Supplemental 

Water flea 

777 Practically 

nontoxic TN 2750 Supplemental 

Freshwater Invertebrates, Chronic

There are no acceptable studies by which to assess chronic invertebrate toxicity for boric 

acid salts. However, it can be assumed that invertebrates are adapted to naturallyoccurring boron levels in their local environments. Therefore, there is a concern for 

water bodies with naturally low levels of boron because the species inhabiting these 

waters are not selected to be resistant to boron, nor would they be expected to be 

acclimated to high levels of boron.. 

Estuarine and Marine Animals, Acute and Chronic

There are no acceptable studies by which to assess acute or chronic toxicity of boric acid 

salts to estuarine or marine fish or invertebrates. However, there is a high naturallyoccurring level of boron in seawater. It can be assumed that marine organisms are 

adapted to naturally-occurring boron levels. The contribution of pesticidal uses of boric 

acid is expected to be negligible. 

Toxicity to Plants 

Terrestrial Plants

There are no acceptable studies by which to assess the toxicity of boric acid salts to 

terrestrial plants. However, it is expected that literature data will be available to assess 

both adverse and beneficial effects of boron on plants. It is generally known that 

terrestrial plants differ in their tolerance of, and requirement for, boron. In many cases, 

crops are studied for the effects of boron deficiency. 

11
Aquatic Plants

There are no acceptable studies submitted to the agency by which to assess the toxicity of 

boric acid salts to aquatic vascular and non-vascular plants. There is a study in the open 

literature that suggests that Waterweed (Elodea Canadensis) and Watermillfoil 

(Myriophyllum alterniflorum) express an LD50 of 5.0 ppm (WHO 1998). However, this 

study has not been reviewed by the agency. This and other relevant data will be 

considered during the risk assessment. 

Incident Reports 

There are no reported incidents involving Boric Acid in EFED’s Ecological Incident 

Information System regarding boric acid salts. The absence of documented incidents 

does not necessarily mean that such incidents did not occur. Mortality incidents must be 

seen, reported, investigated, and submitted to the Agency in order to be recorded in the 

incident database. Incidents may not be noticed because the carcasses decayed, were 

removed by scavengers, or were in out-of-the-way or hard-to-see locations. Due to the 

voluntary nature of incident reporting, an incident may not be reported to appropriate 

authorities capable of investigating it. 

EXPOSURE CHARACTERISTICS

All boric acid salts yield boric acid upon contact with water. Therefore, boric acid will 

be treated as the chemical stressor for this assessment. Table 8 provides a list of boric 

acid’s chemical characteristics. 

Table 8 Nature of the Chemical Stressor 

Value Source 

Common name Boracic acid, 

ortho boric acid 

salts, borofax 

Chemical name Boric acid 

Pesticide type Inorganic salt 

Chemical class 

Merck Index, 1983 

CAS number 10043-35-3 

Empirical formula H3BO3

Molecular mass (g/mol) 61.84 

Vapor pressure Volatile with 

steam 

Merck Index, 1983 

Henry’s Law Constant (atmm3

/mol) 

Not calculated 

Solubility in water (g/L) 1 g/18 mL cold 

water 

Merck Index, 1983 

12
1 g/4 mL 

boiling water 

Log Kow Not applicable 

pKa (or pKb) pH of 0.1 molar 

solution: 5.1 

Merck Index, 1983 

Persistence and Mobility 

Boron acid salts dissolve in water to produce boric acid (H3BO3). Boric acid should 

persist indefinitely until absorbed and metabolized by a plant or animal. As an acid, 

boric acid will be present in the water column, and will be very mobile. 

Major Degradation Pathways and Degradates 

Boric acid is the stable form of boron in the environment, and is not expected to break 

down any further. Boric acid may act as a Lewis base and complex with an electron pair 

donor. 

Routes of Dissipation 

Boric acid dissipates by transport in surface or ground water. 

Clean Water Act: 

Some areas, such as the western US, have higher natural borate content in soil, and 

therefore in adjacent waters. In such areas, it is expected that the plants and animals 

naturally present are adapted to, or tolerant of, higher borate levels, and that less-tolerant 

organisms will not be present, or will find such areas to be marginal habitat. 

Certain water bodies have been identified under section 303(d) of the Clean Water Act by 

the USEPA Office of Water as requiring limits on borate concentration (Total Maximum 

Daily Load, TMDL). Use of Boric acid salts in these watersheds may be subject to 

regulation under the Clean Water Act (see Appendix C). An updated list of watersheds 

listed under section 303(d) will be obtained during the Analysis phase of the registration 

review. 

CHARACTERISTICS OF ECOSYSTEMS POTENTIALLY AT RISK

EFED files indicate that boric acid products have similiar chemical properties, use rates 

and patterns. Outdoor use patterns include: terrestrial food and feed crops, unspecified 

agricultural crops/soils, and orchards, terrestrial non-food crops, agricultural uncultivated 

areas, golf course turfs, airports, landing fields, recreational areas, refuse solid waste 

sites, and rights-of-way, outdoor residental uses, ornamentals lawns and turf, swimming 

pools, aquatic food crops, drainage ditchbanks, lakes/ponds/reservoirs, aquatic non-food 

industrial areas, sewage systems and drainage systems, forestry, and forest products 

(treated wood). 

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ASSESSMENT ENDPOINTS

Assessment endpoints are defined as “explicit expressions of the actual environmental 

value that is to be protected.” Defining an assessment endpoint involves two steps: 1) 

identifying the valued attributes of the environment that are considered to be at risk; and 

2) operationally defining the assessment endpoint in terms of an ecological entity (i.e., a 

community of fish and aquatic invertebrates) and its attributes (i.e., survival and 

reproduction). Therefore, selection of the assessment endpoints is based on valued 

entities (i.e., ecological receptors), the ecosystems potentially at risk, the migration 

pathways of pesticides, and the routes by which ecological receptors are exposed to 

pesticide-related contamination. The selection of clearly defined assessment endpoints is 

important because they provide direction and boundaries in the risk assessment for 

addressing risk management issues of concern. Changes to assessment endpoints are 

typically estimated from the available toxicity studies, which are used as the measures of 

effects to characterize potential ecological risks associated with exposure to a pesticide, 

such as boric acid salts. 

To estimate exposure concentrations, the ecological risk assessment considers application 

at the maximum rate to fields that have vulnerable soils. If multiple applications are 

allowed, the maximum amount per application and minimum interval between 

applications are used – provided that maximum total annual application amounts are also 

included in this configuration. Several EFED exposure models (e.g., GENEEC, PRZMEXAMS, T-REX) are used to estimate likely high-end exposure to boric acid salts. The 

most sensitive toxicity endpoints are used from surrogate test species to estimate 

treatment-related direct effects on acute mortality and chronic reproductive, growth and 

survival assessment endpoints. Toxicity tests are intended to determine effects of 

pesticide exposure on birds, mammals, fish, terrestrial and aquatic invertebrates, and 

plants. These tests include short-term acute, sub-acute, and reproduction studies and are 

typically arranged in a hierarchical or tiered system that progresses from basic laboratory 

tests to applied field studies. The toxicity studies are used to evaluate the potential of a 

pesticide to cause adverse effects, to determine whether further testing is required, and to 

determine the need for precautionary label statements to minimize the potential adverse 

effects to non-target animals and plants. 

CONCEPTUAL MODEL

In order for a chemical to pose an ecological risk, it must reach ecological receptors in 

biologically significant concentrations. An exposure pathway is the means by which a 

pesticide moves in the environment from a source to an ecological receptor. For an 

ecological exposure pathway to be complete, it must have a source, a release mechanism, 

an environmental transport medium, a point of exposure for ecological receptors, and a 

feasible route of exposure. 

14
The conceptual model (Figure 1) depicts the potential pathways for ecological risk 

associated with boric acid use. The conceptual model provides an overview of the 

expected exposure routes for organisms within the boric acid action area. For terrestrial 

organisms, the major route of exposure (aside from direct contact to insects from foliar 

applications) considered here is ingestion of food items such as grasses, other green 

vegetation, seeds, and insects that harbor boric acid residues as a result of direct 

application or drift. For aquatic organisms, the major routes of exposure are considered 

to be via the respiratory surface (gills) or the integument. Aquatic plants may be exposed 

via direct uptake and adsorption. Estimated exposure concentrations for all organisms 

are obtained through the use of several Agency exposure models. Note that only 

aerial/ground spray and chemigation applications are depicted here; hand spray (spot 

treatment) is expected to result in much less exposure. 

Only outdoor use sites will be considered in this assessment. The use of borax products 

in non-pesticide products (for example, in laundry products) is expected to dominate the 

exposure from indoor use and “down-the-drain” exposure via sewage treatment and 

discharge. 

15
 

Figure 2. Ecological conceptual diagram for boric acid salts 

RISK HYPOTHESIS

Based on an examination of the physical/chemical properties of boric acid salts, the fate 

and disposition in the environment, and mode of application, a conceptual model was 

developed that represents the possible relationships between the stressor, ecological 

receptors, and the assessment endpoints. For boric acid salts, the following ecological 

risk hypothesis is being employed for this baseline risk assessment: 

Boric acid salt, when used in accordance with its labels, results in 

potential adverse effects upon the survival, growth, and reproduction of 

non-target terrestrial and aquatic organisms. There are no data to assess 

the effects of boric acid exposure to passerine birds, estuarine/marine 

organisms or the chronic risks that boric acid may pose to aquatic 

invertebrates. There are also no acceptable data submitted to the Agency 

by which to evaluate risks boric acid salts may pose to terrestrial vascular 

or aquatic vascular and non-vascular plants. Due to the fact that the 

sensitivity to chemicals may vary greatly between groupings of taxa, and 

that the acute sensitivity of an organism may not accurately predict the 

chronic sensitivity, in most cases the Agency must make the assumption 

16
that there will be acute and chronic risks to species for which there are no 

data. 

ANALYSIS PLAN OPTIONS

In registration review, pesticide ecological risk assessments will follow the Agency’s 

Guidelines for Ecological Risk Assessment, will be in compliance with the paper titled 

“Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs, U.S. Environmental Protection Agency” (“Overview Document”) (January 

2004), and will be done in accordance with Section 7 of the Endangered Species Act. 

Results from aquatic and terrestrial exposure models (GENEEC 2, T-Rex) will be used to 

determine likely high-end exposure conditions resulting from boric acid use (and 

compared with results from previous documents). It is likely that only Tier 1 aquatic 

modeling (GENEEC2) will be used, since the applicability of the Tier 2 model (PRZMEXAMS) is questionable for an inorganic compound such as boric acid salts. These 

predicted exposure values will then be used to determine the possible environmental 

effects of boric acid use. 

If the planned ecological risk assessment indicates that boric acid exceeds the Agency’s 

Level of Concern for Listed species, either directly or indirectly, a preliminary “May 

Affect” determination will be made for the affected taxa (e.g., birds, mammals, fish, 

invertebrates, etc). A map of the boric acid use “footprint,” consisting of all land cover 

types for which the LOC is exceeded may be generated, along with a narrative 

description of the area outside the footprint where effects are expected to occur. These 

maps and narrative descriptions will be provided to the U.S. Fish and Wildlife Service 

and the National Marine Fisheries Service (the Services) for them to determine which 

listed species may be affected. The Agency will then consult with the Services, formally 

or informally, to refine the Effects Determination. 

ANTICIPATED DATA NEEDS

The Agency does foresee requiring additional ecological effects studies prior to 

conducting the planned assessments. Data gaps, uncertainties and potential paths forward 

for the assessment of boric acid are described below. 

17
Guideline Number: 850.2100

Study Title: Avian oral toxicity (Passerine species) 

Rationale for Requiring the Data 

Because there are bait formulations for boric acid that are made from corn grit and oil, 

birds may be attracted to this bait and consume large quantities of it over an extended 

period of time. No data for passerine species are available. Although the submitted avian acute 

data suggest that boric acid is practically non-toxic to the Bobwhite Quail, toxicity data for game 

birds may not reflect risks to passerine birds which have been identified to be more sensitive to 

pesticides in some cases than the Bobwhite Quail. Therefore, additional data are needed to 

accurately assess risks to these species. Specifically, data are required on one passerine species in 

addition to either one waterfowl species or one upland game bird species for terrestrial, aquatic, 

forestry, and residential outdoor uses. New CFR 158.630 guidelines now require that 

passerine species be tested for outdoor uses.

Practical Utility of the Data 

How will the data be used? 

The passerine acute toxicity data are needed for future regulatory decisions, and for endangered 

species assessments. The data will allow the Agency to better assess the risks to these organisms, 

including the likelihood of potential risks to endangered species, either by direct effects or by 

indirect effects such as reducing food sources to listed predators and scavengers. Results of this 

study would be used to calculate acute risks to passerine species from exposure to boric acid and to 

identify whether current labeling is appropriate and whether further mitigation is necessary. 

How could the data impact the Agency’s future decision-making? 

If the data indicate that boric acid poses a significant acute risk to upland game or passerine birds, 

the Agency may explore additional decision options to minimize the risk of boric acid to these 

species. If future endangered species risk assessments are performed without these data, the 

Agency would have to assume that boric acid "may affect" passerine birds directly and other 

endangered species indirectly through loss of prey. The lack of these data will limit the flexibility 

the Agency and registrants have in complying with the Endangered Species Act and could result in 

unnecessary use restrictions, and the use of boric acid may need to be restricted in areas where 

endangered species occur unless these data are provided. 

Guideline Number: 850.2300

Study Title: Avian reproductive toxicity 

Rationale for Requiring the Data

Although the submitted avian acute data suggest that boric acid is practically non-toxic to the 

Bobwhite Quail, Adverse effects on avian reproduction can occur at levels of exposure several 

magnitudes lower than those that can cause acutely toxic effects. Boric acid is known to exert toxic 

effects on the male reproductive system, specifically causing testicular atrophy. Definitive data for 

this effect in avian species are needed to quantitatively assess this risk. A pesticide’s properties 

are not adequate predictors of avian reproduction effects. Because there are bait formulations that 

these species may consume over a long period of time, there is a need to determine the possible 

chronic risks this may pose to avian species. Therefore, additional data are needed to accurately 

assess risks to these species. Specifically, data are required for terrestrial, aquatic, forestry, and 

residential outdoor uses. 

18
Practical Utility of the Data

How will the data be used? 

The avian toxicity data are needed for future regulatory decisions, and for endangered species 

assessments. The data will allow the Agency to better assess the risks to these organisms, 

including the likelihood of potential risks to endangered species, either by direct effects or by 

indirect effects such as reducing food sources to listed predators and scavengers. Results of this 

study would be used to calculate chronic risks to avian species from exposure to boric acid salts 

and to identify whether current labeling is appropriate and whether further mitigation is necessary.

How could the data impact the Agency’s future decision-making?

If the data indicate that boric acid salt poses a significant chronic risks to birds, the Agency may 

explore additional decision options to minimize the risk of boric acid salts to these species. If 

future endangered species risk assessments are performed without these data, the Agency would 

have to assume that boric acid salts "may affect" birds directly and other endangered species 

indirectly through loss of prey. The lack of these data will limit the flexibility the Agency and 

registrants have in complying with the Endangered Species Act and could result in unnecessary use 

restrictions, and the use of boric acid salts may need to be restricted in areas where endangered 

species occur unless these data are provided.

Guideline Number: 850.1400

Study Title: Fish Early-Life Stage Toxicity (freshwater)

Rationale for Requiring the Data

The requested data would allow EPA to refine its chronic risk (growth and reproduction) 

estimates for freshwater fish, and allow it to define an action area for endangered species. Risk 

mitigation strategies (e.g., determining maximum clethodim application rate that results in an RQ 

below the LOC) cannot be evaluated without these data.

Since the registration of boric acid salts, the Agency has worked to finalize its update to the data 

requirements in 40 CFR Part 158. These updated data requirements were promulgated in October 

2007. Now one freshwater fish early life stage study is required to support all terrestrial, aquatic, 

forestry, and residential turf use patterns. 

40 CFR Part 158 was revised to list the fish early-life stage and aquatic invertebrate life-cycle 

studies as separate requirements in the data table; then identify each test organism as a freshwater 

or saltwater species. For the freshwater fish early-life stage and freshwater invertebrate life-cycle 

data requirements, the Agency requires testing of one fish species and one aquatic invertebrate 

species, respectively, for the terrestrial, aquatic, forestry, and residential turf use patterns. 

Previously, the freshwater invertebrate life cycle and freshwater fish early life stage tests were 

combined under one data requirement with testing required of only the more sensitive species in 

acute studies. However, when a pesticide enters the aquatic environment, both groups of 

organisms are exposed. Moreover, acute sensitivity is not a reliable indicator of chronic 

sensitivity, particularly when looking across different groups of organisms, so chronic data are 

needed regardless of the results of acute testing.

This change was warranted because the relative sensitivity of fish and invertebrates can vary 

widely across chemicals. Previously, only the more sensitive of the two organisms, either fish or 

aquatic invertebrates, as determined by Tier I acute studies, was tested. However, since both 

organisms are exposed when a pesticide enters an aquatic environment and the acute sensitivity of 

an invertebrate may not accurately predict the chronic sensitivity in fish and vice versa, both 

19
species must now be tested for chronic effects. The Agency cannot make the assumption that a 

chemical is not chronically toxic at much lower concentrations than some ratio of the LC50 value 

would suggest.

Practical Utility of the Data

How will the data be used? 

These data are needed for a registration review decision and for an endangered species 

assessment, which will be conducted as part of that decision. The effects data would be used to 

determine the likelihood that the chronic risks can potentially impact aquatic communities, by 

direct effects on fish and their reproduction. By refining the assessment, the Agency would be 

able to determine the appropriate mitigation for clethodim.

How could the data impact the Agency’s future decision-making?

If future endangered species risk assessments are performed without these data, the Agency 

would have to assume that clethodim “may affect” endangered fish directly (and endangered 

species from other taxa indirectly). Thus, use of clethodim might need to be restricted in areas 

where endangered species could be exposed. The lack of these data will limit the flexibility the 

Agency and registrants have in coming into compliance with the Endangered Species Act and 

could result in use restrictions for clethodim which are unnecessarily severe.

Guideline Number: 850.1300

Study Title: Daphnid chronic toxicity

Rationale for Requiring the Data

Since the registration of boric acid salts, the Agency has worked to finalize its update to the data 

requirements in 40 CFR Part 158. These updated data requirements were promulgated in October 

2007. Now one freshwater invertebrate life-cycle study is required to support all terrestrial use 

patterns.

The Agency had conditionally required fish early-life stage and aquatic invertebrate life-cycle 

studies (guidelines 850.1300, 850.1350, and 850.1400) for terrestrial food and nonfood, aquatic 

food and nonfood, forestry, and domestic outdoor uses. These studies still are not required for 

greenhouse food and nonfood, and indoor uses. The Agency has made several revisions to clarify 

the applicability of the requirements.

The first is to list the fish early-life stage and aquatic invertebrate life-cycle studies as separate 

requirements in the data table; then identify each test organism as a freshwater or saltwater 

species. For the freshwater fish early-life stage and invertebrate life-cycle studies, the Agency 

changed the conditional requirement for terrestrial and aquatic (food crop and nonfood) and 

forestry uses to required, and changed the aquatic nonfood residential use to not required. 

Previously, the freshwater invertebrate life cycle and fish early life stage tests were conditionally 

required for terrestrial, aquatic (food crop and nonfood), and forestry uses. When promulgated in 

1984, one basis for the conditional nature of the requirements was that only one of the two tests 

was required, depending on whether fish or invertebrates were more sensitive in the acute studies. 

However, when a pesticide enters the aquatic environment, both groups of organisms are 

exposed. Moreover, acute sensitivity is not a reliable indicator of chronic sensitivity, particularly 

when looking across different groups of organisms, so chronic data are needed regardless of the 

results of acute testing. The change to ‘‘not required’’ for aquatic nonfood residential use is due 

to the fact that the previous ‘‘aquatic nonfood’’ use pattern is now split into aquatic nonfood 

outdoor and aquatic nonfood residential. As the latter represents a much smaller use pattern, the 

20
Agency has reduced or eliminated the data requirement for aquatic nonfood residential uses. In 

addition, the Agency now requires both of these tests for all turf uses including residential, since 

exposure varies. 

This change was warranted because the relative sensitivity of fish and invertebrates can vary 

widely across chemicals. Previously, only the more sensitive of the two organisms, either fish or 

aquatic invertebrates was tested. However, since both organisms are exposed when a pesticide 

enters an aquatic environment and the acute sensitivity of an invertebrate may not accurately 

predict the chronic sensitivity in fish and vice versa, both species must now be tested for chronic 

effects. The Agency cannot make the assumption that a chemical is not chronically toxic at much 

lower concentrations than some ratio of the LC50 value would suggest.

Practical Utility of the Data

How will the data be used?

The data will be used to estimate potential risks to freshwater aquatic invertebrates and to reduce 

uncertainties associated with the current ecological risk assessment.

How could the data impact the Agency's future decision-making?

 

Without these data, the Agency cannot determine the levels of boric acid salts that could result in 

adverse effects to freshwater aquatic invertebrates. The lack of these data will limit the flexibility 

the Agency and registrants have in coming into compliance with the Endangered Species Act, and 

could result in use restrictions for boric acid salts which may otherwise be avoided, or which are 

unnecessarily severe.

 

Guideline Number: 850.4100 

Study Title: Seedling emergence, Tier II 

Guideline Number: 850.4150 

Study Title: Vegetative vigor, Tier II 

Guideline Number: 850.4400 

Study Title: Aquatic plant toxicity test using Lemna spp; Tier II 

Guideline Number: 850.5400

Study Title: Algal toxicity, Tier II

Rationale for Requiring the Data 

No toxicity data are currently available to assess the risk of boric acid salts to terrestrial or aquatic 

plants. Plants form the basis of most habitats and significantly contribute to overall environmental 

quality, and therefore a solid understanding of the potential risks to plants is essential for sound 

environmental management. While boric acid salts is applied as a foliar treatment to cotton and 

has not been reported to damage this plant, there are no data to determine if boric acid salts is 

phytotoxic to other terrestrial or aquatic plant taxa. Therefore, tier I testing for both aquatic and 

terrestrial plants is needed. 

Since the boric acid salts RED was signed, the Agency has finalized its update to the data 

requirements in 40 CFR Part 158. In these updated data requirements, which were promulgated 

on October 26, 2007, Tier II seedling emergence (guideline 850.4100), Tier II vegetative vigor 

21
(guideline 850.4150) and aquatic plant growth (850.5400, 850.4400) studies are conditionally 

required for terrestrial uses for known phytotoxicants. Because boric acid salts are registered as 

herbicides, phytotoxicity is assumed and the Tier II teats are therefore required. Boric acid salt is 

registered for use on terrestrial crops, and therefore these data are required under the new 40 CFR 

Part 158 data requirements. 

Practical Utility of the Data 

How will the data be used? 

The data will be used to estimate potential risks to terrestrial and aquatic plants, including the 

likelihood of potential risks to endangered species, either by direct effects or by indirect effects, 

and to reduce uncertainties associated with the current ecological risk assessment. By refining the 

assessment, the Agency will be able to determine whether current labeling is appropriate and 

whether further mitigation is necessary. 

How could the data impact the Agency’s future decision-making?

These data, once submitted, will allow the Agency to characterize the risk of boric acid salts to 

terrestrial and aquatic ecosystems. Primary producers (i.e. plants) provide oxygen, food and 

habitat vital to ecological processes. Therefore, a solid understanding of the potential risks to 

plants is essential in order to assess the environmental risks the use of boric acid salts may pose. 

If the data indicate that boric acid salts poses significant risks to these plant species, the Agency 

may explore additional decision options to minimize the risks to these species. 

The lack of these data will limit the flexibility the Agency and registrants have in complying with 

the Endangered Species Act and could result in use restrictions for boric acid salts which may 

otherwise be avoided, or which are unnecessarily severe. 

The Agency will however conduct a search of the open literature to ensure that all best 

available science is utilized. The Agency uses the ECOTOX database as its mechanism 

for searching the open literature for ecological effects information. ECOTOX integrates 

three previously independent databases - AQUIRE, PHYTOTOX, and TERRETOX - into 

a system which includes toxicity data derived predominately from the peer-reviewed 

literature, for aquatic life, terrestrial plants, and terrestrial wildlife, respectively. 

OTHER INFORMATION NEEDS

There is specific information that will assist the Agency in refining the ecological risk 

assessment, including any species-specific effects determinations. The Agency is very 

much interested in obtaining the following information: 

1. confirmation on the following label information 

a. sites of application 

b. formulations 

c. application methods and equipment 

d. maximum application rates 

22
e. frequency of application, application intervals, and maximum number of 

applications per season 

f. geographic limitations on use 

2. use or potential use distribution (e.g., acreage and geographical distribution of 

relevant crops) 

3. use history 

4. median and 90th percentile reported use rates (lbs. a.i./acre) from usage data – 

national, state, and county 

5. application timing (date of first application and application intervals) by crop – 

national, state, and county 

6. sub-county crop location data 

7. usage/use information for non-agricultural uses (e.g., forestry, residential, rightsof-way) 

8. directly acquired county-level usage data (not derived from state level data) 

a. maximum reported use rate (lbs. a.i./acre) from usage data – county 

b. percent crop treated – county 

c. median and 90th percentile number of applications – county 

d. total pounds per year – county 

e. the year the pesticide was last used in the county/sub-county area 

f. the years in which the pesticide was applied in the county/sub-county area 

9. typical interval (days) 

10. state or local use restrictions 

11. ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian 

and mammalian mortalities) not already reported to the Agency 

12. monitoring data 

The analysis plan will be revisited and may be revised depending upon the data available 

in the open literature and the information submitted by the public in response to the 

opening of the Registration review docket. 

23
LITERATURE CITED

Flickinger, E.L., D.H. White, C.A. Mitchell, and T.G. Lamont. 1984. Monocrotophos 

and boric acid residues in birds as a result of misuse of organophosphates in 

Matagorda County, Texas. J. Assoc. Off. Anal. Chem. 67:827-828. 

U.S. Environmental Protection Agency. 1998. Guidelines for Ecological Risk 

Assessment. Risk Assessment Forum, Office of Research and Development, 

Washington, D.C. EPA/630/R-95/002F. April 1998. 

U.S. Environmental Protection Agency. 2000. Risk Characterization Handbook. 

Science Policy Council, U.S. Environmental Protection Agency, Washington, 

D.C. 20460. EPA 100-B-00-002. December 2000. 

U.S. Environmental Protection Agency. 2004. Overview of the Ecological Risk 

Assessment Process in the Office of Pesticide Programs, U.S. Environmental 

Protection Agency. Endangered and Threatened Species Effects Determinations. 

Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide 

Programs, Washington, D.C. 

USDA, Forest Service. 2006. Human health and ecological risk assessment for 

boric acid salts (Sporax) Final Report. Forest Health Protection, USDA 

Forest Service. Rosslyn Plaza Building C, Room 7129C 1601 North 

Kent StreetArlington, VA 22209 

WHO (World Health Organization). 1998. Environmental health Criteria. 

 Boron. Environmental Health Criteria 204. 

24
List of Impaired Waters 

Click here to see metadata for this report. 

Query Parameters: 

Cause of Impairment = BORON 

NOTE: Click on the underlined Waterbody Name for a detailed Listed Water 

Report. Click on the underlined "MAP 303(d)" literal for a map of the Listed 

Water. 

State Waterbody 

Name 

Map 

of 

Listed 

Water

State Basin 

Name Location Cyles Listed

AZ 

GILA RIVER, 

CENTENNIAL 

WASH -

GILLESPIE 

DAM

No 

Spatial 

Data 

 HUC: 15070101 2004 

AZ 

GILA RIVER, 

COYOTE 

WASH -

FORTUNA 

WASH

No 

Spatial 

Data 

 HUC: 15070201 2004 

CA 

CALLEGUAS 

CREEK REACH 

4 (WAS

REVOLON 

SLOUGH MAIN 

BRANCH: 

MUGU 

LAGOON TO 

CENTRAL 

AVENUE ON 

1998 303D 

LIST)

MAP 

303(d) LOS ANGELES 2002 

CA 

CALLEGUAS 

CREEK REACH 

7 (WAS 

ARROYO SIMI 

REACHES 1 

AND 2 ON 1998 

303D LIST)

MAP 

303(d) LOS ANGELES 2002 

25
CA 

CALLEGUAS 

CREEK REACH 

8 (WAS TAPO 

CANYON 

REACH 1)

MAP 

303(d) LOS ANGELES 2002 

CA CHOLAME 

CREEK

MAP 

303(d)

CENTRAL 

COAST 2002 

CA 

FOX 

BARRANCA 

(TRIBUTARY 

TO 

CALLEGUAS 

CREEK REACH 

6)

MAP 

303(d) LOS ANGELES 2002 

CA MUD SLOUGH MAP 

303(d)

CENTRAL 

VALLEY 2002, 1998 

CA 

ORCUTT 

SOLOMON 

CREEK

MAP 

303(d)

CENTRAL 

COAST 2002 

CA 

SALT SLOUGH 

(UPSTREAM 

FROM 

CONFLUENCE 

WITH SAN 

JOAQUIN 

RIVER)

MAP 

303(d)

CENTRAL 

VALLEY 2002 

CA 

SAN ANTONIO 

CREEK (SAN 

ANTONIO 

WATERSHED, 

RANCHO DEL 

LAS FLORES 

BRIDGE AT 

HWY 135 TO 

DOWNSTREAM 

AT RAILROAD 

BRIDGE)

MAP 

303(d)

CENTRAL 

COAST 2002 

CA 

SAN JOAQUIN 

RIVER (BEAR 

CREEK TO 

MUD SLOUGH)

MAP 

303(d)

CENTRAL 

VALLEY 2002 

CA SAN JOAQUIN 

RIVER 

MAP 

303(d)

CENTRAL 

VALLEY 2002 

26
(MENDOTA 

POOL TO 

BEAR CREEK)

CA 

SAN JOAQUIN 

RIVER 

(MERCED 

RIVER TO 

SOUTH DELTA 

BOUNDARY)

MAP 

303(d)

CENTRAL 

VALLEY 2002 

CA 

SAN JOAQUIN 

RIVER (MUD 

SLOUGH TO 

MERCED 

RIVER)

MAP 

303(d)

CENTRAL 

VALLEY 2002 

CA SAN LORENZO 

CREEK

MAP 

303(d)

CENTRAL 

COAST 2002 

IL MARKHAM 

CREEK

MAP 

303(d) UPPER ILLINOIS 2004, 

2002 

IL 

S. FK. 

SANGAMON 

RIVER

MAP 

303(d)

LOWER 

ILLINOIS 2004, 2002 

IL SALINE BR. MAP 

303(d) WABASH RIVER 2004, 

2002 

IL SANGAMON 

RIVER

MAP 

303(d)

LOWER 

ILLINOIS 2004, 2002 

IL SUGAR CREEK MAP 

303(d) 

2004, 

2002, 

1998 

IL SUGAR CREEK MAP 

303(d) 

2004, 

2002, 

1998 

KS ARKANSAS 

RIVER

No 

Spatial 

Data 

UPPER 

ARKANSAS 

STATION/SEGMENT: 

286_1 2002 

KS ARKANSAS 

RIVER

MAP 

303(d)

UPPER 

ARKANSAS 

STATION/SEGMENT: 

594_1 2002 

KS ARKANSAS 

RIVER

MAP 

303(d)

UPPER 

ARKANSAS 

STATION/SEGMENT: 

594_11 

2002, 

1998, 

1996 

KS ARKANSAS 

RIVER

No 

Spatial 

Data 

UPPER 

ARKANSAS 

STATION/SEGMENT: 

594_10 2002 

27
KS DOOLEYVILLE 

CREEK

MAP

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_8 2002 

KS GOOSE 

CREEK

MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_10 

2002, 

1998, 

1996 

KS 

NORTH FORK 

NINNESCAH 

RIVER

MAP

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_6 

2002, 

1998, 

1996 

KS 

NORTH FORK 

NINNESCAH 

RIVER

MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_5 

2002, 

1998, 

1996 

KS RED ROCK 

CREEK

MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_12 

2002, 

1998, 

1996 

KS SILVER CREEK MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_7 

2002, 

1998, 

1996 

KS UNNAMED 

STREAM

MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_289 2002 

KS WOLF CREEK MAP 

303(d)

LOWER 

ARKANSAS 

STATION/SEGMENT: 

525_9 2002 

NV HUMBOLDT 

RIVER

MAP 

303(d)

HUMBOLDT 

BASIN 

BATTLE MTN TO 

COMUS 

2004, 

2002 

NV HUMBOLDT 

RIVER

MAP 

303(d)

HUMBOLDT 

BASIN 

RODGERS DAM TO 

HUMBOLDT SINK 

2004, 

2002 

NV MAGGIE 

CREEK

MAP 

303(d) 

CONFLUENCE WITH 

JACK CREEK TO 

HUMBOLDT RIVER 

2002 

NV MUDDY RIVER MAP 

303(d)

COLORADO 

RIVER BASIN 

GLENDALE TO LAKE 

MEAD 

2004, 

2002 

NV STEAMBOAT 

CREEK

MAP 

303(d)

TRUCKEE 

RIVER BASIN 

SEC 33, T18N, R20E 

TO TRUCKEE RIVER 2002 

NV STILLWATER 

MARSH

MAP 

303(d)

CARSON RIVER 

BASIN 

AREA OF 

STILLWATER 

MARSH EAST OF 

WESTSIDE ROAD 

AND NORTH OF 

THE COMMUNITY 

OF STILLWATER 

2004, 

2002 

NV VIRGIN RIVER MAP 

303(d)

COLORADO 

RIVER BASIN 

STATELINE TO 

MESQUITE 

2004, 

2002 

28
MAP 

303(d) NV VIRGIN RIVER COLORADO 

RIVER BASIN 

MESQUITE TO LAKE 

MEAD 

2004, 

2002 

NV 

WEST 

WALKER 

RIVER

MAP 

303(d)

WALKER RIVER 

BASIN 

STATELINE TO 

WELLINGTON 

2004, 

2002 

UT PARIETTE 

DRAW

MAP 

303(d)

UINTA RIVER 

BASIN 

PARIETTE DRAW & 

TRIBS: FROM 

COFLUENCE WITH 

GREEN RIVER TO 

HEADWATERS 

2002, 

2000, 

1998 

UT SALT LAKE 

CANAL

No 

Spatial 

Data 

WEBER RIVER HEXCEL CORP.- SL 

OPERATIONS 2002 

UT UNNAMED 

DRY WASH

No 

Spatial 

Data 

CEDAR/BEAVER 

RIVER 

AMERICAN AZIDE 

CORPORATION 2002 

List of Approved TMDLs 

Click here to see metadata for this report. 

Query Parameters: 

Pollutant = BORON 

NOTE: Click on the underlined TMDL Document Name to see a detailed TMDL report. Click on th

underlined Listed Water Impairment Name to see applicable listed waters for the TMDL. EPA is in

process of collecting TMDL information from the states. Because these efforts are on-going, there

additional approved TMDLs that were not included in the listings below. 

State TMDL Document 

Name 

TMDL 

Pollutant

TMDL 

Establishment 

Date 

EPA Action 

Listed Water 

Cause of 

Impairment 

Cycles 

Listed 

CO 

APACHE CANYON 

COALBED 

METHANE TMDL

BORON DEC-03-2001 EPA 

APPROVED None Reported None Reported

CO FLORIDA RIVER BORON DEC-10-2001 EPA 

APPROVED AMMONIA 1996 

CO 

RALSTON CREEK -

COTTER 

CORPORATION 

SCHWARTZWALDER 

MINE

BORON SEP-23-2005 EPA 

APPROVED 

PLACEHOLDER 

TO PROVIDE 

LINKAGE FOR 

UNLISTED 

IMPAIRMENTS 

AND/OR 

UNLISTED 

WATERS

None 

Reported

29
BORON SEP-11-2000 EPA 

APPROVED KS ARKANSAS RIVER BORON 1998 

KS ARKANSAS RIVER BORON SEP-11-2000 EPA 

APPROVED BORON 1998 

KS ARKANSAS RIVER BORON SEP-11-2000 EPA 

APPROVED BORON 1998 

KS ARKANSAS RIVER BORON SEP-11-2000 EPA 

APPROVED BORON 1998 

KS ARKANSAS RIVER BORON SEP-11-2000 EPA 

APPROVED BORON 1998 

NV 

VIRGIN RIVER 

(STATELINE-L. 

MEAD)

BORON JAN-14-2003 EPA 

APPROVED BORON 1998, 

1996 

30