UNITED ST ATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON. DC 20460 

OFFICE OF CHEM ICAL SAFETY AN D POLLUTION PREVENTION 

PC Code: 128931 

DP Barcodc: D 416416, 420160, 420159, 

420352,421434,42 1723 

Date: March 24, 2016 

MEMORANDUM 

Subject: 

To: 

From: 

Through: 

Addendum to Dicamba Diglycolamine Salt (DGA) and its Degradate, 3,6-

dichlorosalicylic ac id (DCSA) Section 3 Risk Assessment: Refined Endangered Species 

Assessment for Proposed New Uses on Herbicide-Tolerant Soybean and Cotton in 16 

states (Arkansas, Illinois, Iowa, Indiana, Kansas, Louisiana, Minnesota, Mississippi, 

Missouri, Nebraska, orth Dakota, Ohio, Oklahoma, South Dakota, Tennessee, and 

Wisconsin). 

Grant Rowland, Risk Manager 

Kay Montague, Product Manager Team 23 

Dan Kenny, Branch Chief 

Herbicide Branch 

Registration Division (7505 P) 

Office of Pesticide Programs / 

Elizabeth Donovan, M.S., Biologist ~ ~/ ~; 2 

</ I~ Michael Wagman, M.S., Biologist ?VI.ft~ !:?'-I( /6 

Monica Wait, Risk Assessment Process Leader ~ \tJ~ ~ / 2-4-/l L:-

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

Office of Pesticide Programs 

Mark Corbin, Branch Chief 

Environmental Risk Branch 6 

Environmental Fate and Effects Division (7507P) 

Office of Pesticide Programs 

Prior to conducting this refined Endangered Species Assessment, the Environmental Fate and Effects 

Division (EFED) performed a screening level ecological risk assessment for a Federal action involving 

proposed new uses of the diglycolamine salt of dicamba (dicamba DGA) on dicamba herbicide-tolerant 

soybean on March 8, 201 1 (DP 378444); an amendment to the assessment vvas issued on May 20, 2014 

(DP 404138, 404806, 405887, 4 10802, and 41 1382). Concurrent with this refined Endangered Species 
2

Assessment, a Section 3 New Use dicamba DGA salt on dicamba-tolerant cotton screening-level 

assessment (DP 404823) and a subsequent addendum for the use of dicamba DGA on dicamba-tolerant 

soybean (DP 426789) that addresses multiple issues (risk to terrestrial invertebrates, spray drift buffers, 

runoff, and updated mammalian toxicological endpoints for parent dicamba and its degradate DCSA)

have been finalized. As a result of the analyses in the screening level risk assessments and the new 

addendum (DP 426789), potential direct risk concerns could not be excluded for:

• mammals (chronic, from the soybean use only, due to residues from dicamba’s metabolite, 

DCSA, rather than from parent dicamba); 

• birds (acute from parent dicamba for both soybean and cotton uses; chronic from DCSA residues 

only in soybean but not cotton), considered surrogates for reptiles, and terrestrial-phase 

amphibians; and

• terrestrial plants (soybean and cotton uses). 

In the screening level risk assessments, indirect effect risk concerns for all taxa were possible for any 

species that have dependencies (e.g., food, shelter, and habitat) on mammals, birds, reptiles, terrestrialphase amphibians, or terrestrial plants. Additionally, the screening level assessment showed that direct 

risk concerns were unlikely (i.e. levels of concern were not exceeded) for:

• mammals (acute) and (chronic—for the cotton use only);

• birds, reptiles, and terrestrial-phase amphibians (chronic from parent dicamba or DCSA 

degradate from use on cotton);

• terrestrial insects (acute and chronic);

• freshwater fish (acute and chronic);

• aquatic-phase amphibians (acute and chronic);

• estuarine/marine fish (acute and chronic);

• freshwater invertebrates (acute and chronic); estuarine/marine invertebrates (acute and chronic);

and 

• aquatic plants1

The screening assessment for dicamba DGA on dicamba-tolerant cotton (D404823) and the recent 

addendum to the screening level risk assessment for the use of dicamba DGA on dicamba-tolerant 

soybean (D426789) used updated terrestrial mammal endpoints for dicamba and its metabolite, DCSA. 

EPA has a specific process based on sound science that it follows when assessing risks to listed species 

for pesticides like dicamba that will be used on seeds that have been genetically modified to be tolerant to 

the pesticide. The Agency begins with a screening level assessment that includes a basic ecological risk 

assessment based on its 2004 Overview of the Ecological Risk Assessment Process document. [USEPA, 

2004, available at http://www.epa.gov/oppfead1/endanger/litstatus/riskasses.htm]. That assessment uses 

broad default assumptions to establish estimated environmental concentrations of particular pesticides. If 

the screening level assessment results in a determination that no levels of concern are exceeded EPA 

concludes its analysis. On the other hand, where the screening level assessment does not rule out potential 

effects (exceedances of the level of concern) based on the broad default assumptions, EPA then uses 

increasingly specific methods and exposure models to refine its estimated environmental exposures. At 

each screening step, EPA compares the more refined exposures to the toxicity of the pesticide active 

 1 The listed species LOC was exceeded for non-vascular aquatic plants, however there are no listed species of this 

taxa.
3

ingredient to determine whether the pesticide exceeds levels of concern established for listed aquatic and 

terrestrial species. EPA determines that there is “no effect” on listed species if, at any step in the 

screening level assessment, no levels of concern are exceeded. If, after performing all of the steps in the 

screening level assessment, a pesticide still exceeds the Agency’s levels of concern for listed species, 

EPA then conducts a species-specific refined assessment to make effects determinations for individual 

listed species. The refined assessment, unlike the screening level assessment, takes account of species’ 

habitats and behaviors to determine whether any listed species may be affected by use of the pesticide. 

The screening level ecological risk assessment generates a series of taxonomic (e.g., mammals, birds, 

fish, etc.) risk quotients (RQs) that are the ratio of estimated exposures to acute and chronic effects 

endpoints. These RQs are then compared to EPA established levels of concern (LOCs) to determine if 

risks to any taxonomic group are of concern. The LOCs address risks for both acute and chronic effects. 

Acute effects LOCs range from 0.05 for aquatic animals that are Federally-listed threatened or

endangered species (listed species) to 0.5 for aquatic non-listed animal species and 0.1 to 0.5 for 

terrestrial animals for listed and non-listed species. The LOC for chronic effects for all animal taxa (listed 

and non-listed) is 1. Plant risks are handled in a similar manner, but with different toxicity thresholds 

(NOAEC/EC05 and EC25, respectively) used in RQ calculation for listed and non-listed species and an 

LOC of 1 used to interpret the RQ. When a given taxonomic RQ exceeds either the acute or chronic LOC, 

a concern for direct toxic effects is identified for that particular taxon. If RQs fall below the LOC, a no 

effect determination is identified for the corresponding taxon.

The purpose of this document is to explain the refined risk assessment conducted for Federally-listed 

threatened or endangered (listed) species that could potentially be impacted by this pesticide registration. 

The refined assessment was conducted based on the 2004 Overview document, as discussed above. The 

assessment of risks to listed species posed by the use of Dicamba DGA has been conducted in phases 

covering a specific set of states, assessing risk to all the listed species covered in those states. This 

assessment covers the endangered species analysis for 16 states: Arkansas, Illinois, Iowa, Indiana, 

Kansas, Louisiana, Minnesota, Mississippi, Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South 

Dakota, Tennessee, and Wisconsin. Based on EFED’s LOCATES v.2.4.0 database and information from 

the U.S. Fish and Wildlife Service (USFWS), 183 species in the 16 states proposed for registration were 

identified as within the action area (at a preliminary county-wide level of resolution) associated with the 

new herbicide-tolerant soybean and cotton uses. Table 1 presents a summary of this assessment. 

Separate concurrent assessment phases cover the endangered species analysis for 7 states (D422305,

covering AL, GA, KY, MI, NC, SC, and TX) and 11 states (D425049, covering AZ, CO, DE, FL, MD, 

NM, NJ, NY, PA, VA and WV). 

EPA consulted U.S. Fish and Wildlife Service Recovery Plans to determine whether listed species in 

these states would be expected to occur in an action area encompassing the treated soybean and corn 

fields. The refined assessment was then conducted on those species that could not be excluded from the 

action area. EPA also consulted the recovery plans in the refined assessment for additional habitat 

information and incorporated species biological information regarding dietary items (used to model 

dicamba DGA residues in prey tissue) and body weight (used to determine food consumption rates and 

scale ecotoxicity data from the tested surrogate species, the bobwhite quail and rat, to the body weight of 

the listed species).

Table 1. Summary of species effects determinations and critical habitat modification

determinations for Federally listed threatened or endangered species in AR, IL, IA, 

IN, KS, LA, MN, MS, MO, NE, ND, OH, OK, SD, TN, and WI for dicamba DGA use

on genetically modified cotton and soybeans.
4

Species Effects Determination Comments

Spring Creek Bladderpod May Affect, Likely to 

Adversely Affect

Found in Wilson Co., TN

All other species (terrestrial and 

aquatic)

No Effect None

Critical Habitat Modification Determination Comments

All Critical Habitats No Modification None

Making an Effects Determination

The bullets below outline EFED’s process for making an effects determination for the Federal action:

• For listed individuals inside the action area but NOT part of an affected taxa NOR relying on the 

affected taxa for services (involving food, shelter, biological mediated resources necessary for 

survival/reproduction), use of a pesticide would be determined to have NO EFFECT.

• For listed individuals outside the action area, use of a pesticide would be determined to fall under NO 

EFFECT.

• Listed individuals inside the action area may either fall into the NO EFFECT or MAY AFFECT 

(LIKELY or NOT LIKELY TO ADVERSELY AFFECT) categories depending upon their specific 

biological needs, circumstances of exposure, etc.

• LIKELY or NOT LIKELY TO ADVERSELY AFFECT determinations are made using the 

following criteria:

o Insignificant - The level of the effect cannot be meaningfully related to a “take.”

o Highly Uncertain - The effect is highly unlikely to occur.

o Wholly beneficial - The effects are only good things.

Spray Drift Mitigation

EFED’s refined endangered species risk assessment took into account the spray drift mitigation language 

that was added to the most recent proposed label submitted by the registrant. An accounting of federallylisted threatened or endangered species within the 16 states (covered in this assessment) proposed for 

dicamba DGA use on genetically modified cotton and soybeans is included in Appendix 1 (183 species).

Specifically, the spray drift mitigation language on the M1691 Herbicide Supplemental labels for the use 

dicamba DGA salt on ROUNDUP READY 2 XTENDTM soybean and BOLLGARD II® XTENDFLEX 

cotton includes the following limitations:

species action 

NO EFFECT

NO EFFECT or

MAY AFFECT 

(LAA/NLAA)

MAY AFFECT
5

• Specifying the use of a nozzle (Tee Jet® TTI11004) with ASABE S-572 ultra-coarse and 

extremely coarse droplet spectra and a maximum operating pressure of 63 psi. 

• A maximum equipment ground speed of 15 miles per hour and ground boom height of 24 inches 

above the target pest or crop canopy.

• Restricting all applications when wind speeds are < 3 mph or > 15 mph and restricting 

applications when wind is blowing towards sensitive areas at > 10 mph. Maintaining use of a 

110 foot in-field buffer for a 0.5 lb a.i./A application (220 foot in-field buffer for a 1 lb a.i./A 

application) when the wind is blowing towards any areas that are not fields in crop cultivation, 

paved areas, or areas covered by buildings and other structures. 

• Applications done in low relative humidity conditions are to use equipment set to produce larger 

droplet spectra to compensate for evaporation. 

• Applications are not be conducted during temperature inversions.

• In order to prevent effects to non-target susceptible plants, the label also includes the following 

language: “do not apply under circumstances where spray drift may occur to food, forage or 

other plantings that might be damaged or the crops thereof rendered unfit for sale, use or 

consumption. Avoid contact of herbicide with foliage, green stems, exposed non-woody roots of 

crops, and desirable plants, including beans, cotton, flowers, fruit trees, grapes, ornamentals, 

peas, potato, soybean, sunflower, tobacco, tomato, and other broadleaf plants because severe 

injury or destruction may result, including plants in a greenhouse. Applicators are required to 

ensure that they are aware of the proximity to sensitive areas, and to avoid potential adverse 

effects from the off-target movement of M1691 Herbicide. The Applicator must survey the 

application site for neighboring sensitive areas prior to application. The applicator also should 

consult sensitive crop registries for locating sensitive areas where available.”

• Finally, in order to prevent unintended damage from the drift of M1691 Herbicide, the label says 

not to apply this product when the wind is blowing towards adjacent commercially grown 

sensitive crops. 

The incorporation of the spray drift mitigation measures into the product labeling as outlined above 

would result in exposure to dicamba DGA from spray drift at a level where effects are expected only 

within the confines of the treated field and so the action area is limited to the dicamba DGA treated field. 

Further, the incorporation of the “susceptible plants” spray drift mitigation language on the label is to 

avoid damage to these plants (including adjacent crops). Because the risk assessment interprets the 

threshold for plant damage concern to be based on the most sensitive plant species tested and the 

screening level ecological risk assessment has demonstrated that these plant effects endpoints constitute 

the most conservative terrestrial organism levels of effect, it is concluded that the “susceptible plants” 

requirement requires a level of drift mitigation that would also prevent less sensitive organisms from 

being exposed at levels of concern. Terrestrial species that are not expected to occur on treated fields 

under the provisions of the proposed label are not expected to be directly exposed to dicamba DGA, nor 

are their critical biologically mediated resources expected to be exposed to levels of the herbicide above 

any effects thresholds of concern. Additionally, as indicated in the screening level ecological risk 

assessments for cotton and soybean, no aquatic receptor taxa are of concern for drift or runoff exposure

(LOCs were not exceeded for aquatic taxa). Consequently, all but 10 of the listed species originally 

identified as potentially at-risk are determined to be given a “no effect” (NE) without further 

refinement because they are not expected to occur in an action area encompassing the treated 

soybean and cotton fields (Appendix 2). The remaining 10 species are assessed using the refinements 

set forth in the 2004 Overview document referred to earlier in this assessment.
6

Exposure through Runoff

The cotton screening-level risk assessment and the concurrently issued soybean addendum characterized 

risk following exposure to dicamba residues in runoff and found that the predicted concentrations from 

modeling were lower than the most sensitive taxa’s endpoint (soybean plant height). Combining the 

predictions of this modeling, the toxicological endpoints and that most of the off-site plant community 

would not experience foliar contact with dicamba DGA in runoff sheet flow, EFED concluded that all 

available lines of evidence supported a “no effects” determination for runoff exposure for off-field listed 

plants for the proposed labeled use of dicamba DGA. Additionally, rainfast mitigation on the label would 

also protect against the risk of exposure to listed species off the treated field.

In addition to the spray drift and runoff mitigation measures contained in the proposed labeling, EFED 

analyzed species-specific biology, dicamba-specific foliar residue data and dicamba application timing 

information in this refined endangered species assessment. An accounting of the federally-listed 

threatened or endangered species within the 16 states proposed for this registration showed 183 listed 

species as potentially at risk (direct or indirect effects) as a result of the screening-level assessment 

(Appendix 1). The spray drift mitigation label language cannot preclude listed species being exposed to 

dicamba DGA salt or DCSA residues on treated fields, should a listed species utilize such areas as part of 

its range and corresponding habitat. Of the 183 listed species within the 16 states (AR, IL, IN, IA, KS, 

LA, MN, MS, MO, NE, ND, OH, OK, SD, TN, WI) considered part of the proposed Federal decision, the 

following 10 species were reasonably expected to occur on soybean and cotton fields, which could 

potentially be treated with dicamba and therefore could not be assumed to be “no effect” solely on the 

basis of occurrence outside the action area: 

• gray wolf (Canis lupis)

• Indiana bat (Myotis sodalis) 

• Ozark bat (Corynorhinus townsendii ingens)

• Louisiana black bear (Ursus americanus luteolus)

• whooping crane (Grus americana)

• Mississippi sandhill crane (Grus canadensis pulla)

• lesser prairie-chicken (Tympanuchus pallidicinctus)

• gopher tortoise (Gopherus polyphemus)

• American burying beetle (Nicrophorus americanus)

• Spring Creek bladderpod (Lesquerella perforata) 

Therefore, species specific biological information (e.g., body size, dietary requirements, and seasonality) 

and dicamba DGA use patterns were considered in more depth to further refine the assessment and effects 

determinations. 

This assessment also uses the refined exposure values determined in the cotton screening level assessment 

and the concurrently issued addendum to the soybean screening level risk assessment documents 

compared to the initial exposure estimates from the soybean screening level assessment. This ESA 

assessment also evaluates chronic exposures from DCSA separately from the chronic exposure to parent 
7

dicamba. Dicamba exposure values were determined from the upper bound of the modeled T-REX run for 

exposures following spray applications based on the Kenaga nomogram modified by Fletcher et al

(1984), which is based on a large set of actual field residue data. Modeled dicamba exposure values were 

identical between the soybean addendum and the cotton screening level risk assessment (since the 

maximum application rates and minimum application intervals are the same). 

Similar modeling of DCSA residues, which are formed inside the tolerant-soybean and tolerant-cotton

plants through plant metabolism, is not feasible at this time due to a lack of sufficient data tracking DCSA 

residues in plant tissues over time to ascertain degradation rates. Therefore, in the soybean addendum and 

the cotton screening-level risk assessment, EFED used the maximum empirical measured DCSA residue 

concentrations in dicamba-tolerant soybean (61.1 mg/kg (ppm) DCSA in broadleaf plants and 0.440 ppm 

in soybean seeds) and cotton plant tissues (6.29 ppm DCSA in cotton gin byproducts and 0.27 ppm in 

undelinted cotton seed) to evaluate chronic exposures to DCSA for animals foraging on soybean and 

cotton plants. Residues in arthropods (as a dietary item for birds and mammals consuming insects that 

have consumed soybean/cotton tissues with DCSA residues) were assumed to follow the Kenaga 

nomogram relationship between broadleaf plants and arthropods for spray applications (i.e. arthropod 

concentrations estimated to be approximately 70% of the concentrations in broadleaf plant tissues or 42.5 

ppm DCSA in arthropods feeding on soybean plants and 4.4 ppm in arthropods feeding on cotton plants). 

The empirical residue data for cotton indicated that chronic exposures of birds and mammals to dicamba 

or DCSA in cotton tissues would not be above any levels of concern. Although the concurrently issued 

soybean addendum indicates that chronic risk to mammals and birds was only a concern from DCSA 

residues in plant/prey tissues and not from residues of parent dicamba, since the original soybean 

screening-level assessment (USEPA, 2011) indicated chronic risk to mammals, this assessment presents 

the estimated exposures and comparisons to threshold toxicity values for both dicamba and DCSA for 

mammals, but evaluates them separately since their chronic toxicity and exposure profiles differ greatly. 

For birds, following the conclusions of the screening level assessments and the soybean addendum, only 

acute risk from dicamba exposures and chronic risk from DCSA exposures is evaluated.

Critical Habitat Analysis 

In addition to the species-specific effects determinations, EFED also conducted a critical habitat 

modification analysis (Appendix 3) consistent with the Overview Document (USEPA, 2004) as discussed 

earlier in this refined assessment. The critical habitat modification analysis is based on an assessment of 

how dicamba DGA salt would affect the U.S. Fish and Wildlife or National Marine Fisheries Service (the 

Services) established principle constituent elements (PCE’s) of the designated habitat as well as how 

direct species effects outcomes would impact critical habitat’s present and future utility for promoting the 

conservation of a particular listed species.

The following text discusses the lines of evidence and processes that were used to make effects 

determinations for listed species identified as potentially at-risk in the screening level assessment.

Refined ecological risk assessment for the remaining species potentially exposed to dicamba

and DCSA residues

For the effects determinations for whooping crane, sandhill crane, lesser prairie chicken, gopher tortoise, 

American burying beetle, spring creek bladderpod, Indiana bat, Ozark bat, gray wolf and Louisiana bear,
8

a refined risk assessment approach was used to evaluate additional lines of evidence to determine whether 

the conservative generic assumptions in the screening risk assessment apply to a particular species of 

interest (e.g. the whooping crane). In the example of the whooping crane, the refined risk assessment 

investigated the impacts of more crane-specific data related to: 

1. Bird size (as the crane is larger than the 1000g large bird category used in the initial 

screen) 

2. Bird food consumption tailored to:

a. The true weight of the bird

b. Energy requirements of the crane

c. Improvement on the generic food intake model of the screen to assess energy content 

of the diet and the actual free living energy requirements of a bird the size of a crane

3. Toxicity endpoints were scaled from the weight of the tested surrogate species (bobwhite 

quail) to reflect the comparatively larger actual size of the whooping crane.

Using the whooping crane as the example to show how EPA made its effects determinations, EPA 

determined that the whooping crane could be feeding on arthropod prey in treated cotton and soybean 

fields during its migration from March to May. As stated above, for acute and chronic exposures to 

dicamba, EPA used the upper bound predicted concentrations of dicamba DGA salt found on arthropods

from T-REX modeling. For chronic exposures to DCSA residues, EPA used the maximum measured 

concentrations found in broadleaf plants, modified by the Kenaga relationship between broadleaf plants 

and arthropods. This prey analysis is consistent with the preliminary risk concerns identified in the 

screening assessment. This analysis is conservative as it assumes 1) that 100% of the crane’s food 

consumption comes from exposed arthropods and 2) the level of dicamba DGA residues assumed to be on 

these prey arthropods is based on the upper bound Kenaga residues expected for arthropods directly 

exposed to spray applications of dicamba DGA and for exposure to DCSA that residues in the arthropod 

prey item are based on the maximum measured values in broadleaf plant tissues modified by the Kenaga 

relationship between residues in arthropods and broadleaf plants following spray applications. EPA 

determined the field metabolic rate of the whooping crane through the use of a published peer reviewed 

allometric equation that relates bodyweight to energy requirements. From there the mass of prey 

consumed per day is determined by dividing the field metabolic rate (kcal/day) by the energy content of 

the arthropod prey and an assimilation factor that accounts for the ability of birds to absorb that energy 

from the diet. Values were obtained from a published peer reviewed EPA document produced by the 

Office of Research and Development for Agency-wide use in conducting ecological risk assessment 

(Wildlife Exposure Factors Handbook, USEPA, 1993). The mass of dicamba DGA in the insect diet is 

determined from the T-REX run found in the addendum to the soybean screening-level risk assessment

(USEPA, 2016a), issued concurrently with this risk assessment while the mass of DCSA in insect diet 

was assumed to be 42.5 ppm (70% of the maximum measured residues in soybean hay of 61.1 ppm). The 

mass of prey consumed per day is then multiplied by the mass of dicamba or DCSA in the insect diet to 

determine the mass of dicamba or DCSA in the crane’s daily diet in mg/day. Then the daily dose that the 

crane (considering its bodyweight) receives is determined by multiplying the mass of dicamba or DCSA 

in the daily diet of arthropods (assuming that is the only food item) times the mass of prey consumed per 

day divided by the bodyweight of the crane. Then EPA scaled the acute toxicity endpoint (based on the 

most sensitive tested surrogate bird species, bobwhite quail’s default weight of 178 grams) to the 

bodyweight of the whooping crane to determine the acute oral toxicity for the crane. For exposures to 
9

DCSA residues, the chronic toxicity endpoint for the mallard (the most sensitive tested species) was 

modified by the relationship between the chronic dicamba and DCSA endpoints for rats (a 17x 

difference). The acute RQ for dicamba exposures is then calculated by dividing the daily dose of dicamba 

from consuming arthropods by the acute oral toxicity endpoint while the chronic RQ is calculated by 

dividing the daily dose of DCSA by the chronic toxicity endpoint. In this case the acute RQ for dicamba 

was 0.03, which is below the endangered species level of concern of 0.1, while the chronic RQ for DCSA 

was 0.11, which is below the listed and non-listed species chronic LOC of 1.0. At this point, EPA was 

able to conclude that dicamba and its metabolite DCSA would not have a direct effect on the whooping 

crane. 

Birds

The screening-level assessments showed that birds could be at risk of mortality from acute exposures to 

dicamba DGA on treated fields, but chronic risk to dicamba was not expected as no chronic RQs 

exceeded the Agency’s LOC (1.0) for chronic risk (USEPA 2011. D378444, p. 15). The concurrently 

issued soybean addendum did indicate that chronic exposures to DCSA residues in soybean could be a 

concern, while the screening level cotton assessment indicated that chronic exposures to DCSA residues 

in cotton would not exceed the Agency’s LOC for chronic risk. Therefore, for listed species that could 

reasonably be expected to occur on treated soybean and cotton fields, EPA conducted a refined 

assessment for acute (dicamba only) and chronic (DCSA only, and only for soybean) exposures. Of the

bird species identified as potentially at acute risk in the sixteen states, three are reasonably expected to 

occur on treated soybean and cotton fields. Therefore, species specific biological information and 

dicamba DGA use patterns were considered in more depth to further refine the assessment and effects 

determinations for those species. 

Whooping crane

Dicamba Acute Effects Assessment

Whooping cranes migrate from Texas to Canada from March 25th to May 1st (Canadian Wildlife Service 

and USFWS, 2007). Whooping cranes are omnivorous and during migration may feed on a variety of 

foods including frogs, fish, plant tubers, crayfish, insects and agricultural grains. EFED considered the 

upper bound T-REX predicted concentrations of DGA expected to be found on arthropods as a 

conservative pesticide load in the prey base. This is considered a conservative approach as modeled 

residues in arthropods are higher than for the other likely dietary items and 100% of the crane’s diet 

would be considered to consist of exposed arthropods receiving the upper bound Kenaga nomogram 

dicamba residues from the spray application. Alternative terrestrial vertebrate prey and agricultural grains 

are expected to have lower residues than those predicted for arthropods. A biologically representative

refinement to the screening assessment follows: 

Field metabolic rate kcal/day = 1.146(5826)0.749 = 757.6 kcal/day (USEPA 1993, body weight 

Dunning 1984)

Mass of prey consumed per day = 757.6 kcal/day/(1.7 kcal/gX0.72 AE) = 619 g/day

Mass of DGA in insect diet 102.99 mg/kg-bw from T-REX run
10

Mass of DGA in daily diet mg = 619 g/day X 102.99 mg DGA/kg bird prey X 0.001 = 63.75

mg/day

Daily dose in crane = 63.75 mg DGA/day/5.826 kg = 10.94 mg/kg-bw/day

Scaling the acute toxicity endpoint by bodyweight (per T-REX methodology), the acute oral 

toxicity value for the crane is:

Crane LD50 mg/kg-bw = 188 mg/kg-bw (5826/178)(1.15-1) = 317.25mg/kg-bw

RQ for daily acute exposure for three applications, peak exposure number: RQ = 10.94/317.25 = 

0.03.

An RQ of 0.03 does not exceed the acute LOC of 0.1; consequently a “no effect” determination 

is concluded for the whooping crane.

DCSA Assessment for Whooping Crane consuming prey that had previously consumed soybean forage

EFED considered DCSA residues in arthropods to be the maximum measured DCSA residues from 

broadleaf plants, modified by the Kenaga nomogram relationship between broadleaf plant and arthropods 

as a conservative pesticide load in the prey base. This is considered a conservative approach as the 

estimated residues in arthropods are higher than for the other likely dietary items and 100% of the crane’s 

diet would be considered to consist of exposed arthropods feeding on dicamba-tolerant soybean plants 

that had the highest measured DCSA residues. Alternative terrestrial vertebrate prey and agricultural 

grains are expected to have lower residues than those predicted for arthropods. A biologically 

representative refinement to the screening assessment follows: 

Field metabolic rate kcal/day = 1.146(5826)0.749 = 757.6 kcal/day (USEPA 1993, body weight 

Dunning 1984)

Mass of prey consumed per day = 757.6 kcal/day/(1.7 kcal/gX0.72 AE) = 619 g/day

Mass of DCSA in insect diet 42.5 mg/kg-bw (conservative assumption of Kenaga nomogram 

relationship between arthropod residues and broadleaf plant tissue residues based on 61.1 mg/kg 

maximum value from empirical data for soybean forage)

Mass of DCSA in daily diet mg = 619 g/day X 42.5 mg DCSA/kg bird prey X 0.001 = 26.31

mg/day

Daily dose in crane = 26.31 mg DCSA/day/5.826 kg = 4.52 mg/kg-bw/day

Avian Chronic Endpoint of 695 mg/kg-diet (from mallard duck study for parent dicamba) 

modified by ratio of parent dicamba to metabolite DCSA from chronic rat studies (17x) results in 

Avian chronic NOAEC of 40.88 mg/kg-diet.

RQ for chronic exposure: RQ = 4.52/40.88 = 0.11
11

An RQ of 0.11 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the whooping crane.

Mississippi sandhill crane 

Sandhill cranes are known to feed on farms nearby the Mississippi Sandhill Crane National Wildlife 

Refuge that they inhabit (USFWS, 1991). Cranes feed on adult and larval insects, earthworms, crayfish, 

small reptiles, amphibians, roots, tubers, seeds, nuts, fruits and leaves. EFED considered the upper bound 

T-REX predicted concentrations of DGA expected to be found on arthropods as a conservative pesticide 

load in the prey base. This is considered a conservative approach as modeled residues in arthropods are 

higher than for the other likely dietary items and 100% of the crane’s diet would be considered to consist 

of exposed arthropods receiving the upper bound Kenaga nomogram dicamba residues from the spray 

application. Alternative terrestrial vertebrate prey are expected to have lower residues than those 

predicted for arthropods. A biologically representative refinement to the screening assessment follows: 

Field metabolic rate kcal/day = 1.146(2500)0.749 = 402.01 kcal/day (USEPA 1993, body weight 

Dunning 1984)

Mass of prey consumed per day = 402.01 kcal/day/(1.7 kcal/gX0.72 AE) = 328.44 g/day

Mass of DGA in insect diet 102.99 mg/kg-ww from T-REX run

Mass of DGA in daily diet mg = 328.44 g/day X 102.99 mg DGA/kg bird prey X 0.001 = 33.82

mg/day

Daily dose in crane = 33.82 mg DGA/day/2.5 kg = 13.53 mg/kg-bw/day

Scaling the acute toxicity endpoint by bodyweight (per T-REX methodology), the acute oral 

toxicity value for the crane is:

Crane LD50 mg/kg-bw = 188 mg/kg-bw (2500/178)(1.15-1) = 279.44 mg/kg-bw

RQ for daily acute exposure for three applications, peak exposure number: RQ = 13.53/279.44 = 

0.05.

An RQ of 0.05 is less than the acute LOC of 0.1; consequently a “no effect” determination is 

concluded for the Mississippi sandhill crane.

DCSA Assessment for Mississippi sandhill crane consuming prey that had previously fed on soybean 

forage

EFED considered DCSA residues in arthropods to be the maximum measured DCSA residues from 

broadleaf plants, modified by the Kenaga nomogram relationship between broadleaf plant and arthropods 

as a conservative pesticide load in the prey base. This is considered a conservative approach as the 

estimated residues in arthropods are higher than for the other likely dietary items and 100% of the crane’s 

diet would be considered to consist of exposed arthropods feeding on dicamba-tolerant soybean plants 
12

that had the highest measured DCSA residues. Alternative terrestrial vertebrate prey and agricultural 

grains are expected to have lower residues than those predicted for arthropods. A biologically 

representative refinement to the screening assessment follows: 

Field metabolic rate kcal/day = 1.146(2500)0.749 = 402.01 kcal/day (USEPA 1993, body weight 

Dunning 1984)

Mass of prey consumed per day = 402.01 kcal/day/(1.7 kcal/gX0.72 AE) = 328.44 g/day

Mass of DCSA in insect diet 42.5 mg/kg-bw (conservative assumption of Kenaga nomogram 

relationship between arthropod residues and broadleaf plant tissue residues based on 61.1 mg/kg 

maximum value from empirical data for soybean forage)

Mass of DCSA in daily diet mg = 328.44 g/day X 42.5 mg DCSA/kg bird prey X 0.001 = 13.96

mg/day

Daily dose in crane = 13.96 mg DGA/day/2.5 kg = 5.58 mg/kg-bw/day

Avian Chronic Endpoint of 695 mg/kg-diet (from mallard duck study for parent dicamba) 

modified by ratio of parent dicamba to metabolite DCSA from chronic rat studies (17x) results in 

Avian chronic NOAEC of 40.88 mg/kg-diet.

RQ for chronic exposure: = 5.58/40.88 = 0.14.

An RQ of 0.14 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Mississippi sandhill crane

Lesser prairie chicken 

The lesser prairie chicken makes use of agricultural fields at specific times of the year. However, as 

explained below, all available lines of evidence indicate the use of cotton and soybean fields is limited 

temporally and that the agricultural field is not an ideal habitat for the species because conversion of 

rangelands to cropland has reduced lesser prairie-chicken populations greatly since the early 1900’s 

(Giesen 1998). An analysis of exposure potential for dicamba DGA use and lesser prairie chickens 

focused on the seasonal use of soybean and cotton fields by the birds as well as the likely food 

consumption during those periods.

Available information suggests that the birds do not use agricultural fields during the nesting and rearing 

cycle. Nesting lesser prairie chickens have been observed to establish nest sites deep within native prairie 

habitat and similar grass land that affords adequate cover and an understory that allows the young to 

move. Within these areas, nesting sites are observed to be situated far from edge areas (Jamison, 2000 

and Hagen et al. 2007). A review of nesting and brood rearing habitat studies indicates that hens nest in 

tall, residual grasses or under shrubs in native pasture avoiding shortgrass habitats and cultivated fields 

and transition to habitats for rearing brood that can be described as areas with abundant bare ground and 

approximately 25% canopy cover of shrubs, forbs, or grasses <30 cm in height (Jamison, 2000). In 

Jamison’s review of almost a dozen studies of nesting and brood rearing habitat, cotton and soy fields are 

not included as habitat used by the birds. Similarly, spring and summer foraging habitat has been 
13

summarized as including grasses and forbs less than 80 cm in height (Jamison, 2000). In all studies of 

spring and summer habitat there is no inclusion of cotton or soybean as a cover type utilized by the birds 

during nesting, brood rearing or foraging.

In contrast to the spring and summer months, the lesser prairie chicken in Finney County of southwestern 

Kansas has been observed commonly foraging in agricultural fields such as harvested fields of irrigated 

corn during fall and winter (Jamison, 2000) and this pattern has been confirmed by a radiotelemetry study 

(Salter et al. 2005). Rob and Schroeder (2005) report similar use of soybean fields by the birds as a fall 

and winter source of seed and Jamison (2000) cited 17 studies reporting the use of sorghum, corn and 

other grain fields as fall and winter foraging habitat in areas adjacent to prairie chicken grassland habitat. 

This utilization of cropland during the fall and winter months for the present waste grain is further 

supported by Jamison et al. (2002) in their review of 25 habitat studies for the lesser prairie chicken 

(summarized in Appendix 5). Despite cropland comprising a cover type in many of these studies, 

observations of its actual use are confined to the fall and winter months and consumption of waste grain. 

The available information indicates that the lesser prairie chicken is attracted to corn and soybean fields in 

the fall and winter months, where the birds exploit waste seed as an important over-wintering food source.

Based on the reports of over two dozen studies spanning multiple sites across the lesser prairie chicken 

established range, it is reasonable to expect that utilization of cotton and soybean by lesser prairie 

chickens occurs during the fall and winter months and is associated with the consumption of waste grain 

and seed in the fields. However, it is unlikely, given the toxic gossypol content of cotton seed, that the 

plant provides similar resources as corn and soybean for the bird. This is supported by the position of 

Timmer (2012) which states that cotton is not considered habitat for this species. Consequently, the 

exposure refinement for the labeled dicamba DGA product use on soybean and cotton should focus on the 

consumption of soybean seeds. This may still be considered conservative as 100% of the chicken’s diet 

would be considered to consist of exposed seed receiving the upper bound Kenaga nomogram dicamba 

residues from the spray application. A biologically representative refinement to the screening assessment 

follows: 

Field metabolic rate kcal/day = 1.146(730)0.749 = 159.89 kcal/day (USEPA 1993, body weight The 

Birds of North America, No. 364, 1998)

Mass of seed consumed per day = 159.89 kcal/day/(4.6 kcal/gX0.59 AE) = 58.91 g/day

Mass of DGA in seed diet 16.43 mg/kg-ww from T-REX run

Mass of DGA in daily diet mg = 58.91 g/day X 16.43 mg DGA/kg bird prey X 0.001 = 0.97 

mg/day

Daily dose in chicken = 0.97 mg DGA/day/0.73 kg = 1.33 mg/kg-bw/day

Scaling the acute toxicity endpoint by bodyweight (per T-REX methodology), the acute oral 

toxicity value for the chicken is:

Chicken LD50 mg/kg-bw = 188 mg/kg-bw (737/178)(1.15-1) = 232.32 mg/kg-bw
14

RQ for daily acute exposure for three applications, peak exposure number: RQ = 1.33/232.66 = 

0.01.

An RQ of 0.01 does not exceed the acute LOC of 0.1; consequently EPA makes a “no effect” 

determination for the lesser prairie chicken.

DCSA Assessment for lesser prairie chicken consuming soybean seeds

As above, the exposure for DCSA residues in soybean and cotton should focus on the consumption of 

soybean seeds. This may still be considered conservative as 100% of the chicken’s diet would be 

considered to consist of exposed seed receiving maximum measured residues in soybean seed. A 

biologically representative refinement to the screening assessment follows: 

Field metabolic rate kcal/day = 1.146(730)0.749 = 159.89 kcal/day (USEPA 1993, body weight The 

Birds of North America, No. 364, 1998)

Mass of seed consumed per day = 159.89 kcal/day/(4.6 kcal/gX0.59 AE) = 58.91 g/day

Mass of DCSA in seed diet 0.44 mg/kg-ww (max residues from empirical data on dicambatolerant soybean seed).

Mass of DCSA in daily diet mg = 58.91 g/day X 0.44 mg DCSA/kg bird prey X 0.001 = 0.026 

mg/day

Daily dose in chicken = 0.026 mg DCSA/day/0.73 kg = 0.036 mg/kg-bw/day

Avian Chronic Endpoint of 695 mg/kg-diet (from mallard duck study for parent dicamba) 

modified by ratio of parent dicamba to metabolite DCSA from chronic rat studies (34x) results in 

Avian chronic NOAEC of 40.88 mg/kg-diet.

RQ for chronic exposure for three applications, peak exposure number: RQ = 0.036/40.88 = 

<0.01.

An RQ of <0.01 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the lesser prairie chicken.

Reptiles and amphibians

Using birds as a surrogate for reptiles and terrestrial-phase amphibians, consistent with the Overview 

document (USEPA, 2004), the screening level assessment suggests that reptiles and terrestrial-phase 

amphibians could be at risk of effects from acute exposures to dicamba DGA or chronic exposures to 

DCSA on treated fields. Of the reptile and amphibian species identified as potentially at risk in the sixteen 

states, one reptile is reasonably expected to occur on treated soybean and cotton fields. Therefore, species 

specific biological information and dicamba DGA use patterns were considered in more depth to further 

refine the assessment and effects determinations for that species. 
15

Gopher tortoise 

The gopher tortoise inhabits droughty, deep sand ridges, xeric communities, originally longleaf pinescrub oak, and may also be found along fence rows, field edges, power lines, and in pastures (USFWS, 

1990). The tortoise feeds on plant material, such as leaves and grass. EFED considers the maximum TREX predicted concentrations of DGA expected to be found on short grass as a conservative pesticide 

load in the dietary items. This is considered conservative as it assumes 100% of the tortoise’s diet is 

exposed short grass (for which modeled T-REX residues are higher than any other dietary item) receiving 

the upper bound Kenaga nomogram dicamba residues from the spray application. A biologically 

representative refinement to the screening assessment follows:

Field metabolic rate kcal/day = 0.019(4500)0.841 = 22.44 kcal/day (USEPA 1993)

Mass of soybean plants consumed per day = 22.44 kcal/day/(1.3 kcal/gX0.47 AE) = 36.73 g/day

Mass of DGA in short grass diet 262.94 mg/kg-ww from T-REX run

Mass of DGA in daily diet mg = 36.73 g/day X 262.94 mg DGA/kg tortoise prey X 0.001 = 9.66

mg/day

Daily dose in tortoise = 9.66 mg DGA/day/4.5 kg = 2.15 mg/kg-bw/day

Appropriate scaling factors are not available for reptiles and amphibians so the acute toxicity 

value for the bobwhite quail (most sensitive avian species for which acute data are available)

serves as a surrogate (USEPA, 2004) toxicity value for the tortoise:

Tortoise LD50 mg/kg-bw = 188 mg/kg-bw

RQ for daily acute exposure for three applications, peak exposure number: RQ = 2.15/188 = 

0.01.

An RQ of 0.01 less than the acute LOC of 0.1; consequently a “no effect” determination is 

concluded for the gopher tortoise.

DCSA Assessment for gopher tortoise consuming soybean forage

As above, the tortoise feeds on plant material, such as leaves and grass. EFED considers the maximum 

measured DCSA residues in soybean tissue as a conservative pesticide load in the dietary items. This is 

considered conservative as it assumes 100% of the tortoise’s diet is exposed soybean leaves/stems, which 

would have the highest DCSA residues. A biologically representative refinement to the screening 

assessment follows:

Field metabolic rate kcal/day = 0.019(4500)0.841 = 22.44 kcal/day (USEPA 1993)

Mass of soybean plants consumed per day = 22.44 kcal/day/(0.63 kcal/gX0.47 AE) = 75.79 g/day

Mass of DCSA in soybean forage (broadleaf plant) diet 61.1 mg/kg-ww from max residues from 

empirical data on dicamba-tolerant soybean forage)
16

Mass of DCSA in daily diet mg = 75.79 g/day X 61.1 mg DCSA/kg tortoise prey X 0.001 = 4.63

mg/day

Daily dose in tortoise = 4.63 mg DCSA/day/4.5 kg = 1.03 mg/kg-bw/day

Avian Chronic Endpoint of 695 mg/kg-diet (from mallard duck (surrogate for reptiles) for parent 

dicamba) modified by ratio of parent dicamba to metabolite DCSA from chronic rat studies (34x) 

results in Avian chronic NOAEC of 40.88 mg/kg-diet.

RQ for chronic exposure: RQ = 1.03/40.88 = 0.03.

An RQ of 0.03 less than the chronic LOC of 1.0; consequently a “no effect” determination is 

concluded for the gopher tortoise.

Terrestrial Invertebrates

The screening-level risk assessments (USEPA, 2011 D378444 and USEPA, 2016b D404823) did not 

identify risk concerns for terrestrial invertebrates. Additional analyses in the first addendum to the 

soybean assessment (USEPA, 2014. D404138+) and the subsequent addendum issued concurrently with 

this ESA assessment (USEPA, 2016a) indicate that using a screening approach and given the available 

empirical toxicological data for terrestrial invertebrates showing that dicamba is practically non-toxic to 

honey bees, acute contact (from exposure to direct sprays of dicamba) and acute dietary (from exposure to 

dicamba residues in pollen and nectar) risks are not anticipated (i.e. acute oral and dietary exposures were 

below LOCs) to arthropods under the proposed use patterns for dicamba on tolerant soybean and cotton. 

Though the chronic toxicity of dicamba to adult and larval honey bees is more uncertain, EPA’s analysis 

from the concurrent soybean addendum and cotton assessment using chronic data for other invertebrates 

(i.e. daphnids) also indicates that chronic toxicity to honey bees and other terrestrial invertebrates is 

anticipated to be low. No other data has been submitted to the Agency for dicamba’s toxicity to other 

arthropods. 

No data is available for the acute or chronic toxicity of dicamba’s degradate DCSA to honey bees or other 

pollinators. Although EFED used the toxicity differential between the chronic mammalian studies with 

dicamba and DCSA to estimate a chronic endpoint for avian organisms, such an approach is not 

considered appropriate for terrestrial organisms given the greater differences in species biology between 

arthropod taxa compared to birds and mammals. However, based on the available data including the low 

DCSA residues measured in dicamba-tolerant seeds (max measured residue of 0.440 ppm), exposures to 

honey bees and other pollinators from DCSA residues in pollen and nectar of dicamba-tolerant soybean 

are anticipated to be low. 

Despite the addendum and screening-level conclusions that direct risk from dicamba DGA to terrestrial 

invertebrates is not anticipated, EPA investigated whether there were any arthropod species on treated 

soybean and cotton fields that might be indirectly impacted by the effect of dicamba on plants on the 

treated field. One arthropod is reasonably expected to occur on treated soybean and cotton fields. 

Therefore, species specific habitat information and dicamba DGA use patterns were considered in more 

depth to further refine the assessment and effects determinations for that species. 
17

American burying beetle

Habitat use and dependencies were explored to determine if any effects on plants would indirectly affect 

the burying beetle. Except where noted, the information was sourced from the Recovery Plan for the 

species (USFWS, 1991). The American burying beetle is a carnivorous species. Adults feed on a variety 

of carrion as well as live insects. The larvae are reared on cached (buried) carrion. Consequently, any 

effect of dicamba DGA would be mediated through the availability of vegetative cover for the species 

because direct toxic effects are not expected, and plants do not constitute a necessary food component. 

Variable habitat and wide soil types make its habitat difficult to describe in anything other than broad 

terms.

The species exhibits broad vegetation tolerances (from large mowed and grazed fields to dense shrub 

thickets), though natural habitat may be mature forests. The species has been recorded in grassland, old 

field shrubland, and hardwood forests. For example, the Block Island population (Rhode Island) occurs 

on glacial moraine dominated by maritime scrub-shrub community. Plant species include bayberry, 

shadbush, goldenrod, and various non-native plants. Oklahoma habitats vary from deciduous oak-hickory 

and coniferous forests atop ridges or hillsides to deciduous riparian corridors and pasturelands on valley 

floors. 

Based on the available data, there are no direct toxicological effects to the burying beetle. Likely, the 

only potential mechanism for an indirect effect from dicamba would be a reduction in cover provided by 

plants. The Recovery Plan (USFWS 1991) indicates that vegetative structure and soil types are unlikely 

to be limiting factors for the burying beetle given its broad historical geographic range. Furthermore, the 

apparent persistence of the beetle on Block Island suggests broad vegetation (landscape) tolerances. 

Given that applications of dicamba DGA will occur when the crop is intact, the field is expected to 

maintain sufficient vegetative cover for the burying beetle. Consequently, a “no effect” determination 

is concluded for the American burying beetle.

Terrestrial Plants

The screening level risk assessment showed that dicot plant species, but not monocots, would be at risk of 

adverse effects from dicamba applications. Of the terrestrial plant species identified as potentially at risk 

in the sixteen states, one plant species is reasonably expected to occur on treated soybean and cotton 

fields.

Spring Creek Bladderpod

Dicamba is highly toxic to broadleaf plant species (most sensitive NOAEC of 0.000261 lbs a.i./A for nontolerant soybean) and given a maximum single application rate of 1.0 lbs a.i./A, it is assumed that any 

dicots on the field at the time of application would be considered to be at risk. The Spring Creek 

bladderpod (a dicot in the Brassicaceae family), is found in northern Wilson County, Tennessee in the 

watersheds of Spring Creek, Bartons Creek, and Cedar Creek. It is located primarily in the floodplain, in 

agricultural fields, as well as pastures, glades, and disturbed areas. It is found mainly on newly disturbed 

sites and requires some degree of annual disturbance to complete its lifecycle (USFWS 2006).

This species is a winter annual that “germinates between September and early October, overwinters as a 

small rosette of leaves, and fully develops and flowers the following spring. Full sun is required for 
18

optimum growth. Flowering usually occurs in March and April. The fruit splits open upon maturity in 

late April and early May, and the enclosed seeds are dispersed and lie dormant until autumn,” when the 

cycle starts over again (USFWS, 2006). “If conditions are not suitable for germination the following fall, 

the seeds can remain dormant (but viable) for several years” (USFWS 1996).

It is likely that the species is in flowering stage when dicamba DGA is applied to soybean and cotton 

fields in the early season. Consequently, EPA makes a “may effect, likely to adversely affect” 

determination for the Spring Creek bladderpod.

Mammals

The screening-level assessments indicated that acute risk to mammals was not expected as no acute RQs 

exceeded the Agency’s LOC (0.1) for acute risk (USEPA 2011. D378444, p. 15). However, the soybean 

screening-level assessment (USEPA, 2011) indicated that mammals could be at reproductive risk from 

chronic exposures to dicamba DGA on treated fields, though the cotton screening level and concurrently 

issued soybean addendum (USEPA, 2016a and USEPA, 2016b) indicated that chronic exposures to 

dicamba DGA would be below the chronic LOC (1.0). This difference is due to soybean screening level 

risk assessment’s use of a chronic endpoint from the rat 2-generation study (MRID 43137101), of 45 

mg/kg-bw for the NOAEL, based on decreased pup weight at 136 mg/kg-bw compared to the concurrent 

controls. HED recently reanalyzed the data from this study (USEPA, 2016c; D431873) in comparison to 

the historical control database range and determined that the NOAEL and LOAEL should be raised to 136 

and 450 mg/kg-bw, respectively, as pup weights in each generation in the 136 mg/kg-bw treatment group 

were within the historical control range and above the historical control mean for the F1, F2A and F2B 

generations. Therefore, the cotton screening level risk assessment, the concurrently issued soybean 

addendum and this refined endangered species risk assessment use this revised NOAEL for dicamba 

DGA salt. 

The concurrently issued soybean addendum did indicate that chronic exposures to dicamba’s metabolite, 

DCSA, residues in soybean could be a concern, while the screening level cotton assessment indicated that 

chronic exposures to DCSA residues in cotton would not exceed the Agency’s LOC for chronic risk. 

Therefore, EPA only conducted a refined assessment for chronic exposures to DCSA in soybeans for 

listed species that could reasonably be expected to occur on treated soybean fields.

Of the mammalian species identified as potentially at risk in the sixteen states, four are reasonably 

expected to occur on treated soybean fields. Species specific biological information and dicamba DGA 

use patterns were considered in more depth to further refine the assessment and effects determinations for 

the four species potentially expected to occur on treated soybean fields. 

Gray Wolf

According the USFWS Recovery Plan (USFWS 1982), gray wolves are habitat generalists that live 

throughout the northern hemisphere. Gray wolves are a carnivorous species that typically feed on 

ungulate species, such as deer. While not likely to feed on agricultural fields themselves, the primary prey 

species of the gray wolf may be expected to feed on plant material within the field during the period of

applications. Based on this information, it is reasonable to conclude that the gray wolf may be exposed to 

dicamba DGA residues in prey. A biologically representative modification to the screening assessment 
19

follows:

The first step in the refinement process is to calculate dicamba DGA residues in the prey species. Using 

the conservative assumptions that the prey species is represented by a 1000 g mammal that feeds 

exclusively on exposed short grass receiving the upper bound Kenaga residues from the spray application 

of dicamba, EFED calculated the residues based on the following allometric equations (USEPA, 1993): 

1000 g mammal prey ingestion rate (dry) = 0.621(1000)0.564 =30.56 g /day

1000 g mammal prey ingestion rate (wet) = 30.56/0.2 = 152.8 g/day

Dicamba DGA residue in prey eating short grass from T-REX = 262.94 mg dicamba DGA/kgfood (ww) x 0.1528 kg food/kg-bw = 40.17 mg/kg-bw/day

The next step is to calculate the expected daily dose for a typical 17.7 kg (17700 g) gray wolf, the 

adjusted NOAEL value and the chronic dose-based RQ for the gray wolf based on the following 

allometric equations: 

Food Intake (wet) = (0.235(17700)0.822)/(1-0.69)/1000 = 2.35 kg wet/day

Dose-based EEC in wolf eating small mammal= 40.17 mg/kg wet x 2.35/(17700/1000) = 5.33

mg/kg-bw/day

Adjusted NOAEL = 136 mg/kg-bw (350/17700)(0.25) = 51.00 mg/kw-bw

Chronic Dose-Based RQ = 5.33/51.00 = 0.10

An RQ of 0.10 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Gray Wolf.

DCSA Assessment for Gray Wolf consuming prey that had previously consumed soybean forage

The first step in the refinement process is to calculate DCSA residues in the prey species. Using 

the assumption that the prey species is represented by a 1000 g mammal and the conservative 

assumptions that the prey animal feeds exclusively on exposed soybean forage containing the 

maximum measured residues of 61.1 ppm, EFED calculated the residues based on the following 

allometric equations (USEPA, 1993): 

1000 g mammal prey ingestion rate (dry) = 0.621(1000)0.564 =30.56 g /day

1000 g mammal prey ingestion rate (wet) = 30.56/0.2 = 152.8 g/day

DCSA residue in prey eating soybean forage/hay 61.1 mg DCSA/kg-food (ww) x 0.1528 kg 

food/kg-bw = 9.34 mg/kg-bw/day

The next step is to calculate the expected daily dose for a typical 17.7 kg (17700 g) gray wolf, the 

adjusted NOAEL value and the chronic dose-based RQ for the gray wolf based on the following 

allometric equations: 

Food Intake (wet) = (0.235(17700)0.822)/(1-0.69)/1000 = 2.35 kg wet/day
20

Dose-based EEC in wolf eating small mammal= 9.47 mg/kg wet x 2.35/(17700/1000) = 1.24

mg/kg-bw/day

Adjusted NOAEL = 8 mg/kg-bw (350/17700)(0.25) = 3.00 mg/kw-bw

Chronic Dose-Based RQ = 1.25/3.00 = 0.41

An RQ of 0.41 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Gray Wolf.

Indiana Bat 

The USFWS Recovery Plan (USFWS 2007) states that most Indiana bat maternity colonies have been 

found in agricultural areas with fragmented forests. According to the Recovery Plan there are some 

235,000 individual bats within the hibernacula of the states subject to the proposed Federal action. The 

Recovery Plan also indicates that the sex ratio of males to females is roughly equal. Therefore, there are 

approximately 117,500 female bats within the hibernacula that are found in the states in this proposed 

Federal action.

While bats may be associated with forested areas proximal to agricultural land, data on the extent and 

possibility of foraging over agricultural fields is limited. The Recovery Plan states that observations of 

light-tagged animals and bats marked with reflective bands indicate that Indiana bats typically forage in 

closed to semi-open forested habitats and forest edges and that radio-tracking studies of adult males, adult 

females, and juveniles consistently indicate that foraging occurs preferentially in wooded areas, although 

type of forest varies with individual studies. The Recovery Plan states that Indiana bats hunt primarily 

around, not within, the canopy of trees, but they occasionally descend to sub-canopy and shrub layers. 

However, the Recovery Plan also states that Indiana bats have been caught, observed, and radio-tracked 

foraging in open habitats; analyses of habitats used by radio-tracked adult females while foraging versus 

those habitats available for foraging have been performed in two states. 

In Illinois, floodplain forest was the most preferred habitat, followed by ponds, old fields, row crops, 

upland woods, and pastures. In Indiana, woodlands were used more often than areas of agriculture, lowdensity residential housing, and open water, and this latter group of habitats was used more than pastures, 

parkland, and heavily urbanized sites. Old fields and agricultural areas seemed important in both studies, 

but bats likely were foraging most often along forest-field edges, rather than in the interior of fields, 

although errors inherent in determining the position of a rapidly moving animal through telemetry made it 

impossible to verify this. The Recovery Plan remarks that visual observations suggest that foraging over 

open fields or bodies of water, more than 50 m (150 ft) from a forest edge, does occur, although less 

commonly than in forested sites or along edges. The Recovery Plan places feeding within agriculturally 

managed areas of lesser significance than forested areas and their immediate edges. 

The Recovery Plan reports that in Illinois, 67 percent of the land near one colony was agricultural, and in 

Michigan, land cover consisted of 55 percent agricultural land. Recovery Plan discussion of available 

proportions of different land covers encompassing foraging habitat are limited, but the available literature 

suggests that foraging in agricultural lands relative to other habitats is variable with study. Sparks et al. 

(2005), in radio-tracking bats in Indiana, found that the number of telemetry observations of foraging was 

closely associated with the availability of agricultural land within the home range of the species and 

accounted for approximately 35 percent of observations. In contrast, Murray and Kurta (2004) radio-
21

tracked Indiana bats in Michigan and found that, despite the study area being over 60 percent agricultural 

land, the habitats frequented by 12 of the 13 monitored bats was forest land. It should be noted that exact 

frequencies could not be established because triangulation of individual observation points precluded 

exact locations in different cover types with any confidence. Menzel et al. (2005) radio-tracked bats in 

Illinois and found that bats foraged significantly closer to forest roads and riparian habitats than 

agricultural lands. A ranking of the foraging use of habitats suggested the following order of preference 

by bats in this study: roads> forests> riparian areas> grasslands>agricultural lands. 

The Recovery Plan indicates that the prey base for the Indiana bat consists primarily of flying insects, 

with only a very small amount of spiders (presumably ballooning individuals) included in the diet. Four 

orders of insects contribute most to the diet: Coleoptera, Diptera, Lepidoptera, and Trichoptera. The 

Recovery Plan concludes that the diet of Indiana bats, to a large degree, may reflect availability of 

preferred types of insects within the foraging areas that the bats happen to be using, again suggesting that 

they are selective opportunists. 

Given the above information, it is reasonable to conclude that Indiana bats make use of agricultural land 

as a source of prey and can reasonably be expected to roost in patches of fragmented forest that are 

adjacent to cotton and soybean fields. They are opportunistic foragers and are expected to forage over 

many different land covers, including agricultural land, on a broad range of insects/arthropods. A survey 

of insect populations in agricultural fields reveals a variety of flying, foliage and ground dwelling 

invertebrates comprising a large number of taxonomic groups that could provide on-field prey sources for 

bats foraging over these areas. However, the extent of foraging over agricultural land is expected to be 

less than the degree of foraging around the canopies of forested areas.

Initial screening level risk assessment results for the Indiana bat were refined to account for the bat’s 

biology and contained the conservative assumption that bats would feed exclusively on exposed

insects/arthropods having received the upper bound Kenaga residues from the spray application of 

dicamba. 

Field metabolic rate kcal/day = 0.6167(5.4)0.862= 2.64 kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Indiana bat)

Mass of prey consumed per day = 2.64 kcal/day /( 1.7 kcal/g ww X 0.87AE)= 1.78 g/day

Mass of DGA in insect diet 102.99 mg/kg-ww from T-REX run

Mass of DGA in daily diet = 1.78 g/day X 102.99 mg DGA/kg-ww mammal prey X 0.001 = 0.18 

mg/day

Daily dose in bat = 0.18 mg DGA/day/0.0054 = 33.95 mg/kg-bw/day

Indiana Bat NOAEL mg/kg-bw/day = 136 mg/kg-bw (350/5.4)

(0.25) = 385.88 mg/kg-bw

RQ for chronic exposure for three applications, peak exposure number: RQ = 33.95/385.88 = 

0.09.

An RQ of 0.09 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Indiana Bat.
22

DCSA Assessment for Indiana bat consuming prey that had previously consumed soybean forage

Initial screening level risk assessment results for the Indiana bat were refined to account for the bat’s 

biology and contained the conservative assumption that bats would feed exclusively on exposed

insects/arthropods feeding on dicamba-tolerant soybean plant tissues that had the highest measured DCSA 

residues.

Field metabolic rate kcal/day = 0.6167(5.4)0.862= 2.64 kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Indiana bat)

Mass of prey consumed per day = 2.64 kcal/day /( 1.7 kcal/g ww X 0.87AE)= 1.78 g/day

Mass of DCSA in insect diet 42.5 mg/kg-ww (conservative assumption of Kenaga nomogram 

relationship between arthropod residues and broadleaf plant tissue residues based on 61.1 mg/kg 

maximum value from empirical data for soybean forage)

Mass of DCSA in daily diet = 1.78 g/day X 42.5 mg DCSA/kg-ww insect prey X 0.001 = 0.076

mg/day

Daily dose in bat = 0.076 mg DCSA /day/0.0054 kg = 14.01 mg/kg-bw/day

Indiana Bat NOAEL mg/kg-bw/day = 8 mg/kg-bw (350/5.4)(0.25) = 22.70 mg/kg-bw

RQ for chronic exposure: RQ = 8.00/22.70 = 0.62

An RQ of 0.62 does not exceeds the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Indiana Bat.

Ozark Bat 

The Ozark big-eared bat inhabits caves and cliffs that can be found in large blocks of forest to small forest 

tracts interspersed with open areas. Land use of surrounding areas does not appear to influence location of 

occupied maternity caves and hibernacula. The Recovery Plan (USFWS, 1995) indicates that the prey 

base for the Ozark bat consists primarily of lepidopterans and that edge habitat between forested and open 

areas is the preferred foraging area. Open areas allow for easy foraging because bats are not obstructed 

by branches while pursuing prey and are able to discriminate insects at greater distances. Based on this 

information, the Ozark bat cannot be precluded from foraging on agricultural fields. 

Initial screening level risk assessment results for the Ozark bat were refined to account for the bat’s 

biology and contained the conservative assumption that bats would feed exclusively on exposed insects 

having received the upper bound Kenaga residues from the spray application of dicamba. 

Field metabolic rate kcal/day = 0.6167(7.0)0.862= 3.30kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Ozark bat)

Mass of prey consumed per day = 3.30 kcal/day /( 1.7 kcal/g ww X 0.87AE)= 2.23 g/day

Mass of DGA in insect diet 102.99 mg/kg-ww from T-REX run
23

Mass of DGA in daily diet = 2.23 g/day X 102.99 mg DGA/kg-ww mammal prey X 0.001 = 0.23

mg/day

Daily dose in bat = 0.23 mg DGA/day/0.007 = 32.81 mg/kg-bw/day

Ozark Bat NOAEL mg/kg-bw/day = 136 mg/kg-bw (350/7.0)(0.25) = 361.64 mg/kg-bw

RQ for chronic exposure for three applications, peak exposure number: RQ = 32.81/361.64 = 

0.09.

An RQ of 0.09 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Ozark Bat.

DCSA Assessment for Ozark Bat consuming prey that had previously consumed soybean forage

Initial screening level risk assessment results for the Ozark bat were refined to account for the bat’s 

biology and contained the conservative assumption that bats would feed exclusively on exposed

insects/arthropods feeding on dicamba-tolerant soybean plant tissues that had the highest measured DCSA 

residues.

Field metabolic rate kcal/day = 0.6167(7.0)0.862= 3.30kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Ozark bat)

Mass of prey consumed per day = 3.30 kcal/day /( 1.7 kcal/g ww X 0.87AE)= 2.23 g/day

Mass of DCSA in insect diet 42.5 mg/kg-ww (conservative assumption of Kenaga nomogram 

relationship between arthropod residues and broadleaf plant tissue residues based on 61.1 mg/kg 

maximum value from empirical data for soybean forage)

Mass of DCSA in daily diet = 2.23 g/day X 42.5 mg DCSA/kg-ww mammal prey X 0.001 = 

0.095 mg/day

Daily dose in bat = 0.095 mg DCSA/day/0.007 = 13.54 mg/kg-bw/day

Ozark Bat NOAEL mg/kg-bw/day = 8 mg/kg-bw (350/7.0)(0.25) = 21.27 mg/kg-bw

RQ for chronic exposure for three applications, peak exposure number: RQ = 13.54/21.27 = 0.64

An RQ of 0.64 does not exceed the chronic LOC of 1.0; consequently a “no effect” 

determination is concluded for the Ozark Bat.

Louisiana Black Bear 

The Louisiana black bear inhabits bottomland hardwood forest communities, brackish and freshwater 

marshes, salt domes, wooded spoil levees along canals and bayous, and agricultural fields. Remoteness is 

an important spatial feature based on forest tract size and presence of roads (US FWS Recovery Plan, 

1995). The Recovery Plan further describes black bears as opportunistic omnivores with their diet being 
24

determined by food availability and season. Diet includes: grasses, sedges, invertebrates (primarily 

beetles, grubs, and insects), carrion, garbage, and agricultural crops (including grain from soybean and 

corn, but consumption of cotton plant parts is unlikely). Personal communication with Deborah Fuller of 

the USFWS (Fuller 2015) indicates that, by analogy to North Carolina black bears, Louisiana black bears 

can be expected to feed on cotton boll pests as well as grubs in the fields. The other potential attractive 

food source in these fields would be soybean grain. On the basis of this information and the expectation 

that the modeled residues on arthropods (111.14 mg dicamba DGA/kg) would be much higher than 

modeled residues in soybean pods or seeds (17.74 mg dicamba DGA/kg), a refinement of the screening 

level assessment for the bear was initiated to reflect the conservative assumptions of exclusive 

consumption of exposed terrestrial invertebrates having received the upper bound Kenaga residues from 

the dicamba application in a treated field: 

Field metabolic rate kcal/day = 0.800(92000)

0.813= 8682.59 kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Louisiana black bear)

Mass of prey consumed per day = 8682.59 kcal/day /(1.7 kcal/g ww X 0.87 AE)= 5870.58 g/day

Mass of DGA in terrestrial invertebrate diet 102.99 mg/kg-ww from T-REX run

Mass of DGA in daily diet = 5870.58 g/day X 102.99 mg DGA/kg-ww mammal prey X 0.001 = 

604.61 mg/day

Daily dose in bear = 604.61 mg DGA/day/92 kg = 6.57 mg/kg-bw/day

Louisiana Black Bear NOAEL mg/kg-bw/day = 136 mg/kg-bw (350/92000)(0.25) = 33.78 mg/kgbw

RQ for chronic exposure for three applications, peak exposure number: RQ = 6.57/33.78 = 0.19.

A chronic RQ of 0.19 does not exceed the chronic LOC of 1.0. Consequently a “no effect” 

determination is concluded for the Louisiana black bear.

DCSA Assessment for Louisiana Black Bear consuming prey that had previously consumed 

soybean forage

The screening level risk assessment found that DCSA residues in arthropods in cotton fields 

(based on the empirical residues in broadleaf plant tissues and extrapolated via the Kenaga 

nomogram to residues in arthropods) would not exceed any chronic levels of concern for 

mammals. The analysis of the Louisiana Black Bear’s recovery plan described above indicates 

that in soybean fields, the attractive food source in these fields would be soybean grain (seeds). 

On the basis of this information, the refinement of the soybean screening level assessment was 

initiated to reflect the conservative assumption of exclusive consumption of exposed soybean 

grain containing the maximum measured DCSA residues. 

Field metabolic rate kcal/day = 0.800(92000)0.813= 8682.59 kcal/day (USEPA 1993, body weight 

reflects screening assumption for the Louisiana black bear)
25

Mass of soybean seeds consumed per day = 8682.59 kcal/day /(0.51 kcal/g ww X 0.85 AE0.43)= 

20029.0 g/day

Mass of DCSA in seed diet 0.440 mg/kg-ww (conservative assumption using the maximum value 

from empirical data for soybean seeds)

Mass of DCSA in daily diet = 20029 g/day X 0.44 mg DCSA/kg-ww mammal prey X 0.001 = 

8.88 mg/day

Daily dose in bear =8.8 mg DCSA/day/92 kg = 0.10 mg/kg-bw/day

Louisiana Black Bear NOAEL mg/kg-bw/day = 8 mg/kg-bw (350/92000)(0.25) = 1.99 mg/kg-bw

RQ for chronic exposure for three applications, peak exposure number: RQ = 0.10/1.99 = 0.05

A chronic RQ of 0.05 does not exceed the chronic LOC of 1.0. Consequently a “no effect” 

determination is concluded for the Louisiana black bear.

References

Benson, J.F. 2005. Ecology and Conservation of Louisiana Black bears in the Tensas River Basin and 

Reintroduced Populations (Masters Thesis). Louisiana State University and Agricultural and Mechanical 

College.

Benson, J.F. and M.J. Chamberlain 2006. Food Habits of Louisiana Black Bears (Ursus americanus 

luteolus) in Two Subpopulations of the Tensas River Basin. The American Midland Naturalist 

156(1):118-127.

Canadian Wildlife Service and U.S. Fish and Wildlife Service. 2007. International Recovery Plan for the 

Whooping Crane. Ottawa: Recover of Nationally Endangered Wildlife (RENEW), and U.S. Fish and 

Wildlife Service, Albuquerque, New Mexico. 162 pp. 

http://ecos.fws.gov/docs/recovery_plan/070604_v4.pdf

Dunning, J.B. 1984. Body weights of 686 species of North American birds. Western Bird Banding 

Association Monograph 1.

Giesen, K. M. 1998. Lesser prairie-chicken (Tympanuchus pallidicinctus). In The birds of North America, 

No. 364 (A. Poole and F. Gill, editors). The Birds of North America, Inc., Philadelphia, Pennsylvania.

Hagen, C.A., J. C. Pitman, R.J. Robel, T.M. Loughin, and R.D. Applegate. 2007. Niche Partitioning by 

Lesser Prairie-chicken Tympanuchus pallidicinctus and Ring-necked Pheasant Phasianus colchicus in 

Southwestern Kansas. Wildlife Biology 13:34-41. 

Jamison, B. E., J. A. Dechant, D. H. Johnson, L. D. Igl, C. M. Goldade, and B. R. Euliss. 2002. Effects of 

management practices on grassland birds: Lesser Prairie-Chicken. Northern Prairie Wildlife Research 

Center, Jamestown, ND. 29 pages.

Jamison, B. E. 2000. Lesser prairie-chicken chick survival, adult survival, and habitat selection and 

movements of males in fragmented rangelands of southwestern Kansas. M.S. Thesis, Kansas State 

University, Manhattan.
26

Jimenez, N. 1994. Crop Residue Study with Dicamba Formulations on Grass Forage and Hay: Final 

Report: Lab Project Number: 480068: 128: DP/301489. Unpublished study prepared by ChemAlysis Inc. 

MRID 43370701.

NAFTA, 2015 .Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media. 

NAFTA Technical Working Group on Pesticides. 

http://www.epa.gov/oppfead1/international/naftatwg/guidance/degradation-kin.pdf

Robb, L.A. and M.A. Schroeder. 2005. Lesser Prairie-chicken. (Tympanuchus pallidicinctus): A 

Technical Conservation Assessment. Prepared for the USDA Forest Service, Rocky Mountain Region, 

Species Conservation Project. http://www.fs.fed.us/r2/projects/scp/assessments/lesserprairiechicken.pdf

Salter, G.C., R.J Robel, and K.E. Kemp. 2005. Lesser Prairie-chicken Use of Harvested Corn Fields 

during Fall and Winter in Southwestern Kansas. The Prairie Naturalist 37: 1-9.

United States Environmental Protection Agency (USEPA). 1993. Wildlife Exposure Factors Handbook 

EPA/600/R-93/187a, Office of Research and Development, Washington, DC.

USEPA, 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 Pesticide Programs, Office of Prevention, Pesticides and Toxic Substances. Washington, D.C. 

January 23, 2004.

USEPA, 2011. Ecological Risk Assessment for Dicamba and its Degradate, 3,6-dichlorosalicylic acid 

(DCSA), for the Proposed New Use on Dicamba-Tolerant Soybean (MON 87708). DP Barcode: 378444. 

Environmental Fate and Effects Division, Office of Pesticide Programs, Office of Chemical Safety and 

Pollution Prevention. March 8, 2011, Washington, D.C. 

USEPA, 2013. Addendum to the Environmental Fate and Ecological Risk Assessment for the Section 3 

New Use of Dicamba-Tolerant Soybean. DP Barcodes: 404138, 404806, 405887, 410802, 411382. 

Environmental Fate and Effects Division, Office of Pesticide Programs, Office of Chemical Safety and 

Pollution Prevention. May 20, 2013, Washington, D.C. 

USEPA, 2016a. Dicamba DGA: Second Addendum to the Environmental Fate and Ecological Risk 

Assessment for Dicamba DGA salt and its Degradate, 3,6-dichlorosalicylic acid (DCSA) for the Section 3 

New Use on Dicamba-Tolerant Soybean. D426789. Environmental Fate and Effects Division, Office of 

Pesticide Programs, Office of Chemical Safety and Pollution Prevention. Washington, DC. March 24, 

2016

USEPA, 2016b. Ecological Risk Assessment for Dicamba DGA Salt and its Degradate, 3,6-

dichlorosalicylic acid (DCSA), for the Proposed New Use on Dicamba-Tolerant Cotton (MON 87701). 

DP Barcodes: 404823. Environmental Fate and Effects Division, Office of Pesticide Programs, Office of 

Chemical Safety and Pollution Prevention. Washington, DC. March 24, 2016.

USEPA, 2016c. 3,6-Diclorosalicyclic acid (DCSA): Benchmark Dose Analysis of a Reproduction 

Study. Health Effects Division. Office of Pesticide Programs, Washington D.C. March, 2, 2016. 

D431873.
27

USEPA, 2016d. Dicamba and Dicamba BAPMA salt: Human-Health Risk Assessment for Proposed 

Section 3 New Uses on Dicamba. DP Barcodes: D378366, D402514, D402551, D404917 and D421306. 

Health Effects Division, Office of Pesticide Programs, Office of Chemical Safety and Pollution 

Prevention. Washington, DC. March, 2016

USEPA, 2016e. Addendum to Dicamba Diglycolamine (DGA) Salt and its Degradate, 3,6-

dichlorosalicylic acid (DCSA) Section 3 Risk Assessment: Refined Endangered Species Assessment for 

Proposed New Uses on Herbicide-Tolerant Cotton and Soybean in 7 U.S. States (Alabama, Georgia, 

Kentucky, Michigan, North Carolina, South Carolina, and Texas). D422305. Environmental Fate and 

Effects Division, Office of Pesticide Programs, Office of Chemical Safety and Pollution Prevention. 

Washington, DC. March 24, 2016

USEPA, 2016f. Addendum to Dicamba Diglycolamine Salt (DGA) and its Degradate, 3,6-

dichlorosalicylic acid (DCSA) Section 3 Risk Assessment: Refined Endangered Species Assessment for 

Proposed New Uses on Herbicide-Tolerant Soybean and Cotton in in 11 U.S. States: (Arizona, Colorado, 

Delaware, Florida, Maryland, New Mexico, New Jersey, New York, Pennsylvania, Virginia and West 

Virginia). D425049. Environmental Fate and Effects Division, Office of Pesticide Programs, Office of 

Chemical Safety and Pollution Prevention. Washington, DC. March 24, 2016

United States Fish and Wildlife Service (USFWS). 1982. Mexican Wolf Recovery Plan. U.S. Fish and 

Wildlife Service, Albuquerque, New Mexico. 103 pp. URL: 

http://ecos.fws.gov/docs/recovery_plan/820915_1.pdf

USFWS. 1990. Gopher Tortoise Recovery Plan. U.S. Fish and Wildlife Service, Jackson, Mississippi. 28 

pp. URL: http://ecos.fws.gov/docs/recovery_plan/901226.pdf

United States Fish and Wildlife Service (USFWS). 1991. American Burying Beetle (Nicrophorus 

americanus) Recovery Plan. U.S. Fish and Wildlife Service, Region 5. 81 pp. URL: 

http://ecos.fws.gov/docs/recovery_plan/910927.pdf

USFWS, 1991. Mississippi Sandhill Crane Recovery Plan. U.S. Fish and Wildlife Service, Atlanta, 

Georgia. 42 pp. URL: http://ecos.fws.gov/docs/recovery_plan/910906.pdf

USFWS, 1995. Louisiana Black Bear (Ursus americanus luteolus) Recovery Plan. U.S. Fish and 

Wildlife Service, Southeast Region. Atlanta, Georgia. URL: 

http://ecos.fws.gov/docs/recovery_plan/950927.pdf

USFWS, 1995. Ozark Big-Eared Bat Revised Recover Plan. U.S. Fish and Wildlife Service, Region 2. 

Tulsa, Oklahoma. URL: http://ecos.fws.gov/docs/recovery_plan/950328b.pdf

USFWS, 1996. Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for 

Lesquerella perforata (Spring Creek Bladderpod). Federal Register 61(247): 67493—67497. URL: 

http://ecos.fws.gov/docs/federal_register/fr3029.pdf

USFWS, 1996. Determination of Endangered Status for Lesquerella perforata (Spring Creek bladderpod), 

Final Rule. Federal Register 61(247): 67493-67497. URL: 

http://ecos.fws.gov/docs/federal_register/fr3029.pdf.

USFWS, 2006. Recovery Plan for Lesquerella perforata (Spring Creek Bladderpod). Atlanta, Georgia. 

23 pp. URL: http://ecos.fws.gov/docs/recovery_plan/spring%20creek%20bladderpod%20rp.pdf
28

USFWS, 2007. Indiana Bat (Myotis sodalis) Draft Recovery Plan: First Revision. U.S. Fish and Wildlife 

Service, Region 3. Fort Snelling, Minnesota. URL: http://ecos.fws.gov/docs/recovery_plan/070416.pdf
29

Appendix 1

Threatened and Endangered Species in Arkansas, Illinois, Iowa, Indiana, Kansas, Louisiana, 

Minnesota, Mississippi, Missouri, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, 

Tennessee, and Wisconsin. 

Animals

1. Acornshell, southern (Epioblasma othcaloogensis)

2. Amphipod, Illinois cave (Gammarus acherondytes)

3. Bat, gray (Myotis grisescens)

4. Bat, Indiana (Myotis sodalis)

5. Bat, Ozark Big-Eared (Corynorhinus (=plecotus) townsendii ingens)

6. Bean, Cumberland (pearlymussel) Populations (Villosa trabalis)

7. Bean, purple (Villosa perpurpurea)

8. Bean, rayed (Villosa fabalis)

9. Bear, Louisiana Black (Ursus americanus luteolus)

10. Beatle, American Burying (Nicrophorus americanus)

11. Blossom, green (pearlymussel) (Epioblasma torulosa gubernaculum)

12. Blossom, tubercled (pearlymussel) (Epioblasma torulosa torulosa)

13. Blossom, turgid (pearlymussel) (Epioblasma turgidula)

14. Blossom, yellow (pearlymussel) (Epioblasma florentina florentina)

15. Butterfly, Karner blue (Lycaeides melissa samuelis)

16. Butterfly, Mitchell's satyr (Neonympha mitchellii mitchellii)

17. Catspaw, white (pearlymussel) (Epioblasma obliquata perobliqua)

18. Cavefish, Ozark (Amblyopsis rosae)

19. Cavesnail, Tumbling Creek (Antrobia culveri)

20. Chicken, Lesser-Prairie (Tympanuchus pallidicinctus) 

21. Chub, slender (Erimystax cahni)

22. Chub, spotfin (Erimonax monachus)

23. Clubshell (Pleurobema clava)

24. Clubshell, black (Pleurobema curtum)

25. Clubshell, ovate (Pleurobema perovatum)

26. Clubshell, southern (Pleurobema decisum)

27. Combshell, Cumberlandian (Epioblasma brevidens)

28. Combshell, southern (Epioblasma penita)

29. Combshell, upland (Epioblasma metastriata)

30. Crane, Mississippi Sandhill (Grus canadensis pulla)

31. Crane, Whooping (Grus americana)

32. Crayfish, cave (Cambarus aculabrum)

33. Crayfish, cave (Cambarus zophonastes)

34. Crayfish, Nashville (Orconectes shoupi)

35. Dace, blackside (Phoxinus cumberlandensis)

36. Dace, Laurel (Chrosomus saylori)

37. Darter, amber (Percina antesella)

38. Darter, bayou (Etheostoma rubrum)

39. Darter, bluemask (=jewel) (Etheostoma sp.)

40. Darter, boulder (Etheostoma wapiti)

41. Darter, Cumberland (Etheostoma susanae)

42. Darter, duskytail (Etheostoma percnurum)
30

43. Darter, leopard (Percina pantherina)

44. Darter, Niangua (Etheostoma nianguae)

45. Darter, slackwater (Etheostoma boschungi)

46. Darter, snail Entire (Percina tanasi)

47. Darter, yellowcheek (Etheostoma moorei)

48. Dragonfly, Hine's emerald (Somatochlora hineana)

49. Elktoe, Appalachian (Alasmidonta raveneliana)

50. Elktoe, Cumberland (Alasmidonta atropurpurea)

51. Fanshell (Cyprogenia stegaria)

52. Fatmucket, Arkansas (Lampsilis powellii)

53. Ferret, black-footed (Mustela nigripes)

54. Frog, dusky gopher (Rana sevosa)

55. Heelsplitter, Alabama (=inflated) (Potamilus inflatus)

56. Hellbender, Ozark (Cryptobranchus alleganiensis bishopi)

57. Higgins eye (pearlymussel) (Lampsilis higginsii)

58. Kidneyshell, fluted (Ptychobranchus subtentum)

59. Kidneyshell, triangular (Ptychobranchus greenii)

60. Lampmussel, Alabama (Lampsilis virescens)

61. Lilliput, pale (pearlymussel) (Toxolasma cylindrellus)

62. Logperch, Conasauga (Percina jenkinsi)

63. Lynx, Canada (Lynx canadensis)

64. Madtom, chucky (Noturus crypticus)

65. Madtom, Neosho Entire (Noturus placidus)

66. Madtom, pygmy (Noturus stanauli)

67. Madtom, Scioto (Noturus trautmani)

68. Madtom, smoky (Noturus baileyi)

69. Madtom, yellowfin (Noturus flavipinnis)

70. Manatee, West Indian (Trichechus manatus)

71. Mapleleaf, winged (Quadrula fragosa)

72. Marstonia, royal (snail) (Pyrgulopsis ogmorhaphe)

73. Moccasinshell, Alabama (Medionidus acutissimus)

74. Moccasinshell, Coosa (Medionidus parvulus)

75. Monkeyface, Appalachian (pearlymussel) (Quadrula sparsa)

76. Monkeyface, Cumberland (pearlymussel) (Quadrula intermedia)

77. Mucket, Neosho (Lampsilis rafinesqueana)

78. Mucket, orangenacre (Lampsilis perovalis)

79. Mucket, pink (pearlymussel) Entire (Lampsilis abrupta)

80. Mussel, oyster (Epioblasma capsaeformis)

81. Mussel, scaleshell (Leptodea leptodon)

82. Mussel, sheepnose (Plethobasus cyphyus)

83. Mussel, snuffbox (Epioblasma triquetra)

84. Pearlshell, Louisiana (Margaritifera hembeli)

85. Pearlymussel, birdwing (Lemiox rimosus)

86. Pearlymussel, cracking (Hemistena lata)

87. Pearlymussel, Curtis (Epioblasma florentina curtisii)

88. Pearlymussel, dromedary (Dromus dromas)

89. Pearlymussel, littlewing (Pegias fabula)

90. Pearlymussel, Slabside (Pleuronaia dolabelloides)

91. Pigtoe, Cumberland (Pleurobema gibberum)

92. Pigtoe, finerayed (Fusconaia cuneolus)

93. Pigtoe, flat (Pleurobema marshalli)
31

94. Pigtoe, Georgia (Pleurobema hanleyianum)

95. Pigtoe, rough (Pleurobema plenum)

96. Pigtoe, shiny (Fusconaia cor)

97. Pigtoe, southern (Pleurobema georgianum)

98. Pimpleback, orangefoot (pearlymussel) (Plethobasus cooperianus)

99. Plover, piping except Great Lakes watershed (Charadrius melodus)

100. Plover, piping Great Lakes watershed (Charadrius melodus)

101. Pocketbook, fat (Potamilus capax)

102. Pocketbook, Ouachita rock (Arkansia wheeleri)

103. Pocketbook, speckled (Lampsilis streckeri)

104. Purple Cat's paw (=Purple Cat's paw pearlymussel) (Epioblasma obliquata obliquata)

105. Rabbitsfoot (Quadrula cylindrica cylindrica)

106. Rabbitsfoot, rough (Quadrula cylindrica strigillata)

107. Riffleshell, northern (Epioblasma torulosa rangiana)

108. Riffleshell, tan (Epioblasma florentina walkeri (=E. walkeri))

109. Ring pink (mussel) (Obovaria retusa)

110. Riversnail, Anthony's (Athearnia anthonyi)

111. Sawfish, smalltooth TX, FL (Pristis pectinata)

112. Sculpin, grotto (Cottus sp.)

113. Sea turtle, green (Chelonia mydas)

114. Sea turtle, hawksbill (Eretmochelys imbricata)

115. Sea turtle, Kemp's ridley (Lepidochelys kempii)

116. Sea turtle, leatherback (Dermochelys coriacea)

117. Sea turtle, loggerhead Northwest Atlantic DPS (Caretta caretta)

118. Shiner, Arkansas River (Notropis girardi)

119. Shiner, blue (Cyprinella caerulea)

120. Shiner, Topeka (Notropis topeka (=tristis))

121. Snail, Iowa Pleistocene (Discus macclintocki)

122. Snail, painted snake coiled forest (Anguispira picta)

123. Snake, copperbelly water (Nerodia erythrogaster neglecta)

124. Spectaclecase (mussel) (Cumberlandia monodonta)

125. Spider, spruce-fir moss (Microhexura montivaga)

126. Squirrel, Carolina northern flying (Glaucomys sabrinus coloratus)

127. Stirrupshell (Quadrula stapes)

128. Sturgeon, gulf (Acipenser oxyrinchus desotoi)

129. Sturgeon, pallid (Scaphirhynchus albus)

130. Tern, least interior pop. (Sterna antillarum)

131. Tiger beetle, Salt Creek (Cicindela nevadica lincolniana)

132. Tortoise, gopher (Gopherus polyphemus)

133. Turtle, ringed map (Graptemys oculifera)

134. Turtle, yellow-blotched map (Graptemys flavimaculata)

135. Vireo, black-capped (Vireo atricapilla)

136. Warbler, Kirtland’s (Setophaga kirtlandii)

137. Wartyback, white (pearlymussel) (Plethobasus cicatricosus)

138. Whale, finback (Balaenoptera physalus)

139. Whale, humpback (Megaptera novaeangliae)

140. Wolf, gray (Canis lupus)

141. Woodpecker, red-cockaded (Picoides borealis)

Plants

142. Aster, decurrent false (Boltonia decurrens)
32

143. Aster, Ruth's golden (Pityopsis ruthii)

144. Avens, spreading (Geum radiatum)

145. bladderpod, Missouri (Physaria filiformis)

146. Bladderpod, Spring Creek (Lesquerella perforata)

147. Bluet, Roan Mountain (Hedyotis purpurea var. montana)

148. Bush-clover, prairie (Lespedeza leptostachya)

149. Butterfly plant, Colorado (Gaura neomexicana var. coloradensis)

150. Chaffseed, American (Schwalbea americana)

151. Clover, running buffalo (Trifolium stoloniferum)

152. Daisy, Lakeside (Hymenoxys herbacea)

153. Fern, American hart's-tongue (Asplenium scolopendrium var. americanum)

154. Geocarpon minimum (No common name)

155. Goldenrod, Blue Ridge (Solidago spithamaea)

156. Goldenrod, Short’s (Solidago shortii)

157. Grass, Tennessee yellow-eyed (Xyris tennesseensis)

158. Ground-plum, Guthrie's (=Pyne's) (Astragalus bibullatus)

159. Harperella (Ptilimnium nodosum)

160. Iris, dwarf lake (Iris lacustris)

161. Ladies'-tresses, Ute (Spiranthes diluvialis)

162. Lichen, rock gnome (Gymnoderma lineare)

163. Lily, Minnesota dwarf trout (Erythronium propullans)

164. Locoweed, Fassett's (Oxytropis campestris var. chartacea)

165. Milkweed, Mead's (Asclepias meadii)

166. Monkshood, northern wild (Aconitum noveboracense)

167. Orchid, eastern prairie fringed (Platanthera leucophaea)

168. Orchid, western prairie fringed (Platanthera praeclara)

169. Penstemon, blowout (Penstemon haydenii)

170. Pitcher-plant, green (Sarracenia oreophila)

171. Pogonia, small whorled (Isotria medeoloides)

172. Pondberry (Lindera melissifolia)

173. Potato-bean, Price's (Apios priceana)

174. Prairie-clover, leafy (Dalea foliosa)

175. Quillwort, Louisiana (Isoetes louisianensis)

176. Rock-cress, Braun's (Arabis perstellata)

177. Rosemary, Cumberland (Conradina verticillata)

178. Roseroot, Leedy's (Rhodiola integrifolia ssp. leedyi)

179. Sandwort, Cumberland (Arenaria cumberlandensis)

180. Skullcap, large-flowered (Scutellaria montana)

181. Sneezeweed, Virginia (Helenium virginicum)

182. Spiraea, Virginia (Spiraea virginiana)

183. Thistle, Pitcher's (Cirsium pitcheri)
33

Appendix 2

Listed Species Rationale for NO Effects When Action Area is Limited to Treated Agricultural Field 

– Accounting for Spray Drift and Runoff Mitigation Labeling Restrictions

The spray drift (in-field buffer) and rainfast mitigations discussed in the cotton section 3 ecological risk 

assessment (D404823), the concurrently issued soybean addendum (D426789) and the beginning of this 

assessment are anticipated to restrict dicamba and DCSA residues above any threshold toxicity values to 

the agricultural field. Therefore, the following table describes the habitat and rationale for all listed 

species that were determined to not use cotton and soybean fields or resources that may overlap with the 

dicamba DGA uses.

Species Habitat Rationale Source 

Animals

Acornshell, 

southern 

(Epioblasma 

othcaloogensis)

The southern acornshell 

is historically restricted 

to shoals in small rivers 

to small streams above 

the Fall Line. It was 

found on stable 

sand/gravel/cobble 

substrate in moderate to 

swift currents (US FWS 

2000, p. 57).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. 2000. Recovery 

Plan for Mobile River Basin 

Aquatic Ecosystem. 

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Amphipod, 

Illinois cave 

(Gammarus 

acherondytes)

The Illinois cave 

amphipod lives in 

streams primarily in the 

dark zone of caves in 

parts of the Salem 

Plateau of Illinois. 

Little is known of the 

biology and habitat 

requirements of this 

species although it has 

been collected in 

mainstream gravel 

riffles, smaller tributary 

streams, rimstone pools, 

and from streams with 

silt overlying bedrock. 

As a group, amphipods 

require cool water 

temperatures and are 

intolerant of wide 

ranges in temperature 

(US FWS 2002)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2002. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/020920.pdf
34

Species Habitat Rationale Source 

Bat, gray 

(Myotis 

grisescens)

Gray bats are year 

round cave dwellers, 

although they may also 

use mines. They 

hibernate from as late 

as November 10 to late 

March or early April. 

At other times, they 

forage from late 

afternoon through early 

morning within 12-20 

miles of their caves, 

most often within 4 

miles of their caves. 

Foraging habitat is 

strongly correlated with 

open waters (rivers, 

lakes, reservoirs) (US 

FWS, 2009, pp. 6-7). 

Historically, rivers near 

caves provided both 

foraging habitat and 

riparian tree vegetation 

that provided cover. 

Small lakes and 

reservoirs where cover 

is not too distant also 

provide foraging 

habitat. Bats will 

opportunistically forage 

in riparian and upland 

areas, particularly when 

migrating (US FWS, 

1982. pp. 6-7).

The proposed dicamba 

DGA uses are not 

expected to encompass 

caves or the forest/open 

water areas where bats 

forage.

USFWS. 1982. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/820701.pdf

USFWS. 2009. 5-Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc2625.pdf
35

Species Habitat Rationale Source 

Bean, 

Cumberland 

(pearlymussel) 

(Villosa 

trabalis)

Restricted

typically to tributary 

streams of the upper 

reaches of the 

Tennessee and 

Cumberland Rivers. 

This species is most 

often found associated 

with clean, fast flowing 

water in stable 

substrate, which 

contains relatively firm 

rubble, gravel, and sand 

swept-free from 

siltation. Typically, V. 

trabalis is found buried 

in shallow riffle and 

shoal areas, often 

located under large 

rocks that must be 

removed by hand to 

inspect the habitat 

underneath. Ideal 

habitat conditions are 

difficult to find; much 

of the historical habitat 

for the species has 

likely been degraded 

and may be incapable 

of currently harboring 

the species (US FWS 

2010, p. 7).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2010. 5 Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc3244.pdf

Bean, purple 

(Villosa 

perpurpurea)

Inhabits small 

headwater streams 

(Neves 1991) to 

medium-sized rivers

(Gordon 1991). It is 

found in moderate to 

fast-flowing riffles with 

sand, gravel, and cobble 

substrates (Neves 1991) 

and rarely occurs in 

deep pools or slack 

water (Ahlstedt 1991a). 

It is sometimes found 

out of the main current 

adjacent to waterwillow beds and under 

flat rocks (Ahlstedt 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040524.pdf
36

Species Habitat Rationale Source 

1991a, Gordon 1991) 

(US FWS 2004, p. 19). 

Bean, rayed 

(Villosa fabalis)

The rayed bean is 

generally known from 

smaller, headwater 

creeks, but occurrence 

records exist from 

larger rivers 

(Cummings and Mayer 

1992, p. 142; Parmalee 

and Bogan 1998, p. 

244). They are usually 

found in or near shoal 

or riffle (short, shallow 

length of stream where 

the stream flows more 

rapidly) areas, and in 

the shallow, wavewashed areas of glacial 

lakes, including Lake 

Erie (West et al. 2000, 

p. 253). In Lake Erie, 

the species is generally 

associated with islands 

in the western portion 

of the lake. Preferred 

substrates typically 

include gravel and sand. 

The rayed bean is 

oftentimes found 

among vegetation 

(water willow (Justicia 

americana) and water 

milfoil (Myriophyllum 

sp.)) in and adjacent to 

riffles and shoals 

(Watters 1988b, p. 15; 

West et al. 2000, p. 

253) (US FWS 2012, p. 

8633).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS 2012 - Federal 

Register Determination of 

Endangered Status.

http://www.gpo.gov/fdsys/pk

g/FR-2012-02-14/pdf/2012-

2940.pdf

Blossom, green 

(pearlymussel) 

(Epioblasma 

torulosa 

gubernaculum)

Cumberlandian 

freshwater mussels are 

most often observed in 

clean, fast-flowing 

water in substrates that 

contain relatively firm 

rubble, gravel, and sand 

substrates swept free 

from siltation. The 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/060228.pdf

USFWS. 2007. 5 Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc1961.pdf
37

Species Habitat Rationale Source 

mussels are usually 

found buried in the 

substrate in shallow 

riffle and shoal areas 

(US FWS 1984, p. 5) 

The last known record 

for the green-blossom 

pearly mussel was a 

live individual collected 

in 1982 (US FWS 2007, 

p. 7). 

Blossom, 

tubercled 

(pearlymussel) 

(Epioblasma 

torulosa 

torulosa)

Occurs only in 

headwater tributaries of 

the Tennessee River 

(US FWS 1985, p. 11). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1985. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/850125.pdf

Blossom, turgid 

(pearlymussel) 

(Epioblasma 

turgidula)

The last known 

collection of the turgidblossom pearly mussel 

was a fresh-dead 

specimen found in the 

Duck River, Tennessee, 

in 1965 (US FWS 2007, 

p. 7) 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2007. 5 Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc1961.pdf

Blossom, 

yellow 

(pearlymussel) 

(Epioblasma 

florentina 

florentina)

The last known 

specimen of the yellowblossom pearly mussel 

was recorded in the 

Little Tennessee River 

and Citico Creek, 

Tennessee in 1967 (US 

FWS 2007, p. 7) 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2007. 5 Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc1961.pdf

Butterfly, 

Karner blue 

(Lycaeides 

melissa 

samuelis)

Habitat is successional 

areas with wild lupines, 

such as open areas in 

and near forest stands, 

along with old fields, 

highway and powerline 

rights-of-way, and 

remnant barrens and 

savannas, having a 

broken or scattered tree 

or tall shrub canopy 

(US FWS, 2003. pp.28-

30)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

successional areas with 

lupines or other 

wildflowers.

USFWS. 2003. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/030919.pdf
38

Species Habitat Rationale Source 

Butterfly, 

Mitchell's satyr 

(Neonympha 

mitchellii 

mitchellii)

Mitchell’s satyr habitat 

is best characterized as 

a sedge-dominated fen 

community; Known 

habitats are all 

peatlands but range 

along a continuum from 

prairie/bog fen to sedge 

meadow/swamp. 

However, certain 

attributes at each site 

remain fairly constant. 

All historical and active 

habitats have a 

herbaceous community 

which is dominated by 

sedges, usually Carex 

stricta, with scattered 

deciduous and/or 

coniferous trees, most 

often L. laricina or 

Juniperus virginiana 

(red cedar) (US FWS 

1998, pp. 11-12). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

wetlands or areas with 

sedge communities. 

USFWS 1998. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/980402.pdf

Catspaw, white 

(pearlymussel) 

(Epioblasma 

obliquata 

perobliqua)

The white cat’s paw 

pearly mussel is 

currently known to exist 

in only a 3-mile portion 

of Fish Creek in 

Williams County in 

northwest Ohio. 

Museum records 

indicate that it 

historically occurred in 

Indiana in the Wabash, 

White, Tippecanoe, 

Maumee, and St. Joseph 

rivers, and Ohio in the 

Maumee and St. Joseph 

Rivers and Fish Creek. 

It was last observed in 

1999 (US FWS, 2009, 

p. 7). The Recovery 

Plan indicates that the 

habitat is unclear but 

appears to be riffle run 

reaches of small to 

moderately large rivers 

(US FWS, 1990, p. 16).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1990. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/900125.pdf
39

Species Habitat Rationale Source 

Cavefish, Ozark 

(Amblyopsis 

rosae)

Cavefish occur in 

groundwater habitats 

(the Springfield Plateau 

Aquifer) within Boone 

and Burlington 

Formation limestones, 

especially in cave 

streams with chert 

rubble substrate, and 

occasionally in wells 

and sinkholes, and even 

in the soil phreatic zone 

(Poulson, 1961, 1963; 

USFWS, 1986). Woods 

and Inger (1957) 

suggest cavefish 

dispersal occurs 

through phreatic cave 

passages. Noltie and 

Wicks (2001) suggests 

that due to shale 

geologic confining 

units, Ozark cavefish 

are distributed in near 

surface and epikarst 

habitats (US FWS 

2011).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS 2011. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc3850.pdf

Cavesnail, 

Tumbling Creek 

(Antrobia 

culveri)

Troglobitic creek -

Tumbling Creek ranges 

from 0.014 to 2.8 cubic 

meters per second (~ 

0.5 to 100 cubic ft. per 

second); the mean 

annual flow is between 

0.08 to 0.14 cubic 

meters per second (~ 3 

to 5 cubic feet per 

second). The stream 

contains many chert 

pebbles which have 

been highly polished by 

natural abrasion within 

the cave...The land 

surface above the cave 

includes a variety of 

woodland and glade 

natural communities as 

well as pastures and/or 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2003. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/030922a.pdf
40

Species Habitat Rationale Source 

open fields. (US FWS 

2003, p. 10).

Chub, slender 

(Erimystax 

cahni)

The slender chub is 

restricted to the upper 

Tennessee River 

drainage in Tennessee 

and Virginia (US FWS 

2014, p. 6)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2014. 5 Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4357.pdf

Chub, spotfin 

(Erimonax 

monachus)

The species is an 

insectivore, feeding 

diurnally presumably 

by both sight and taste 

in benthic areas of slow 

to swift current over 

various substrates with 

little siltation. Streams 

may range from 15-60 

m in width and, where 

occupied, 0.3-10.0 m in 

depth. Water 

temperature in their 

summer habitat usually 

reaches greater than 

20°C, and submerged 

macrophytes are usually 

absent, occasionally 

common. The species 

has been observed 

associated with sand, 

gravel, rubble, boulder, 

and bedrock substrates 

(Jenkins and Burkhead, 

1982) (US FWS 1983, 

p. 15). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1983. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/831121.pdf

Clubshell 

(Pleurobema 

clava)

Clubshell is generally 

found in clean, coarse 

sand and gravel in runs, 

often just downstream 

of a riffle, and cannot 

tolerate mud or 

slackwater conditions 

(USFWS, 1994).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1994. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/940921.pdf

Clubshell, black 

(Pleurobema 

curtum)

This species inhabits 

the Tombigbee River, 

which is a major 

western tributary of the 

Mobile Basin. It is 

characterized by an 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/891114e.pdf
41

Species Habitat Rationale Source 

increasing number of 

sand and gravel shoals 

and decreasing channel 

size (US FWS, 1989, p. 

1)

Clubshell, ovate 

(Pleurobema 

perovatum)

Sand/gravel shoals and 

runs of small rivers and 

large streams (US FWS 

2000, p. 56)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Clubshell, 

southern 

(Pleurobema 

decisum)

Sand/gravel shoals and 

runs of small rivers and 

large streams (US FWS 

2000, p. 58)

The proposed dicamba

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Combshell, 

Cumberlandian 

(Epioblasma 

brevidens)

This species inhabits 

medium-sized streams 

to large rivers on shoals 

and riffles in coarse, 

sand, gravel, cobble, 

and boulders. It is not 

associated with small 

stream habitats and 

tends not to extend as 

far upstream in 

tributaries (US FWS 

2004, p. 18). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040524.pdf

Combshell, 

southern 

(Epioblasma 

penita)

This species inhabits 

the Tombigbee River, 

which is a major 

western tributary of the 

Mobile Basin. It is 

characterized by an 

increasing number of 

sand and gravel shoals 

and decreasing channel 

size (US FWS, 1989, p. 

1)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/891114e.pdf

Combshell, 

upland 

(Epioblasma 

metastriata)

Restricted to shoals in 

rivers and large streams 

above the Fall Line. It 

was found on stable 

sand/gravel/cobble 

substrate in moderate to 

swift currents (US 

FWS, 2000, p. 61)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Five Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc4153.pdf
42

Species Habitat Rationale Source 

Crayfish, cave 

(Cambarus 

aculabrum)

This species inhabits 

troglobitic Stream -

Along the walls of 

pools or along stream 

edges. They can be 

found on silt, gravel, 

rubble and bedrock, or 

even hiding underneath 

trash, such as an old 

discarded boot.; Logan 

Cave, Bear Hollow 

Cave, Elm Springs, and 

Old Pendergrass (US 

FWS 2013, p. 7).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. 2013. Five Year 

Recovery. 

http://ecos.fws.gov/docs/five_

year_review/doc4153.pdf

Crayfish, Cave 

(Cambarus 

zophonastes)

This species inhabits 

troglobitic stream -

muddy stream bottoms, 

cave stream walls, and 

other in-stream habitats; 

found in Hell Creek, 

Nesbitt Spring: 

groundwater upwelling 

in Town Branch... 

approximately 40 miles 

northwest of the other 

known sites, which are 

found near one another, 

suggesting a much 

wider subterranean 

distribution of the 

species. (6)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. Hell Creek Cave 

Crayfish 5-Year Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4153.pdf

Crayfish, 

Nashville 

(Orconectes 

shoupi)

Much of the stream 

bank where this species 

occurs is vegetated with 

trees and shrubs 

(Bouchard 1976). The 

Nashville crayfish has 

been found in a wide 

range of environments 

including gravel and 

cobble runs, pools with 

up to 10 centimeters 

(cm) of settled 

sediment, and under 

slabrocks and other 

cover (the largest 

crayfish are usually 

under cover) (USFWS 

1989). The species is 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/890208.pdf
43

Species Habitat Rationale Source 

highly photosensitive 

and is usually found 

under cover during the 

day (Bouchard 1976). 

Canopy cover appears 

important, as O’Bara et 

al. (1985) reported that 

all sites they sampled 

had canopy cover of 60 

to 90 percent. The 

species has been found 

in small pools where 

the flow was 

intermittent (Stark 

1986, Miller and 

Hartfield 1985). Gravelcobble substrate 

provides good cover for 

juveniles (Stark 1986, 

Miller and Hartfield 

1985). Females seek out 

large slabrocks when 

they are carrying eggs 

and young. These 

secluded places are also 

needed for molting 

(USFWS 1989). 

Dace, blackside 

(Phoxinus 

cumberlandensi

s)

This species inhabits 

cool, small, upland 

streams with moderate 

flows. The fish is 

generally associated 

with undercut stream 

banks and large rocks, 

and it is usually found 

within well-vegetated 

watersheds with good 

riparian vegetation (US 

FWS 1988, p. 6). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1988. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/880817.pdf

Dace, Laurel 

(Chrosomus 

saylori)

This species has most 

often been collected 

from pools or slow runs 

from undercut banks or 

beneath slab-rock 

boulders, typically in 

first or second order, 

clear, cool, streams. 

Substrates typically 

consist of a mixture of 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Designated 

Critical Habitat. 

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24468.pdf
44

Species Habitat Rationale Source 

cobble, rubble, and 

boulders, and the 

streams tend to have a 

dense riparian zone 

consisting largely of 

mountain laural (US 

FWS, 2012, p. 63606)

Darter, amber 

(Percina 

antesella)

This species inhabits 

gentle riffle areas over 

sand, gravel, and cobble 

substrates. Aquatic 

vegetation that develops 

in riffles provides 

habitat for feeding and 

cover (US FWS, 1986, 

p. 6). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1986. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/860620.pdf

Darter, bayou 

(Etheostoma 

rubrum)

The portion of Bayou 

Pierre System serving 

as habitat for this 

species is a meandering 

stream with stable 

gravel riffles or 

sandstone exposures 

(US FWS, 1990, p. 3). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1990. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/900710.pdf

Darter, 

bluemask 

(=jewel) 

(Etheostoma 

sp.)

This species inhabits 

slow to moderate 

current over clean sand 

and fine gravel at 

depths of 4 to 20 

inches; it typically 

occurs just downstream 

of riffles or along the 

margins of pools and 

runs (US FWS, 1997, 

Executive Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1997. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/970725.pdf

Darter, boulder 

(Etheostoma 

wapiti)

This species inhabits 

warm-water riverine 

environments and has 

been found only in 

moderate to fast current 

over boulder/slab rock 

substrate in water over 

2 feet deep (US FWS, 

1989, p. 2). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/890727.pdf

Darter, 

Cumberland 

(Etheostoma 

susanae)

This species inhabits 

pools or shallow runs of 

low to moderate 

gradient sections of 

streams with stable 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Designated 

Critical Habitat. 
45

Species Habitat Rationale Source 

sand, silt, or sandcovered bedrock 

substrates (US FWS, 

2012, p. 63605). 

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24468.pdf

Darter, 

duskytail 

(Etheostoma 

percnurum)

This species inhabits 

rocky areas in gently 

flowing shallow pools 

and runs in large creeks 

and moderately large 

rivers in the Tennessee 

and Cumberland River 

Systems (US FWS, 

1994, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1994. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/duskytaildarter_RP

.pdf

Darter, leopard 

(Percina 

pantherina)

The leopard darter 

typically inhabits pools 

having predominantly 

rubble and boulder 

substrates with current 

velocities less than 48 

centimeters/second 

(Jones 1984, Lechner et 

al. 1987). Preferred 

water depths are 

generally 20-102 cm 

(Jones et al. 1984; 

James 1989), although 

joint Service/U.S. 

Forest Service surveys 

over the past 10 years 

have observed leopard 

darters from depths 

over 4.0 meters; large to 

intermediate streams 

having relatively steep 

grade (US FWS 2012, 

p. 12).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4107.2.12%2

0with%20signautres.pdf

Darter, Niangua 

(Etheostoma 

nianguae)

Medium sized streams 

of the Salem Plateau, of 

order 3, 4, and 5, 

having gradients of 3 to 

21 feet/mile, elevation 

of stream bed =550-

1050 ft, moderately 

clear upland creeks 

draining hilly 

topography underlain 

by bedrocks consisting 

principally of chertThe proposed dicamba

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/890717.pdf
46

Species Habitat Rationale Source 

bearing dolomites (US 

FWS 1989, pp. 9-10). 

Darter, 

slackwater 

(Etheostoma 

boschungi)

Nonbreeding habitat is 

small to moderately 

large streams. The 

current is usually slow, 

and under normal 

conditions, the flow 

ranges from still to 0.34 

m/sec. In small streams, 

the darters show no 

position preference; 

however, in large 

streams they seem to 

confine themselves to 

near the banks or to 

undercuts in the banks. 

They also occur on 

gravel infiltrated with 

silt, on silt and mud, or 

in a combination of 

these. The breeding 

habitat is seepage water 

in open fields and 

woods (US FWS, 1984, 

pp. 7-8).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840308.pdf

Darter, snail 

(Percina tanasi)

This species occupies 

seven of nine tributaries 

of the upper Tennessee 

River in Alabama, 

Georgia and Tennessee 

(US FWS, 2013, p. 10). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4136.pdf

Darter, 

yellowcheek 

(Etheostoma 

moorei)

Devil’s, Middle, South, 

and Archey forks of the 

Little Red River in 

Cleburne, Searcy, 

Stone, and Van Buren 

Counties... primarily 

within the Boston 

Mountains 

subdivision of the 

Ozark Plateau. Inhabits 

high-gradient headwater 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS 2012. Federal 

Register Notice: Designation 

of Critical Habitat.

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24468.pdf
47

Species Habitat Rationale Source 

tributaries with clear 

water; permanent flow; 

moderate to strong 

riffles; and gravel, 

cobble, and boulder 

substrates (Robison and 

Buchanan 1988, p. 429) 

(US FWS 2012, p. 

63605).

Dragonfly, 

Hine's emerald 

(Somatochlora 

hineana)

The hine’s emerald 

dragonfly occupies 

grass marshes and 

sedge meadows fed 

primarily by water from 

a mineral source or 

fens. Two important 

characteristics of the 

habitat appear to be 

groundwater-fed, 

shallow water slowly 

flowing through 

vegetation, and 

underlying dolomitic or 

limestone bedrock. 

Parts of the aquatic 

channels are typically 

covered by vegetation 

such as cattails or 

sedges. Soils can range 

from organic muck to 

mineral soils like marl. 

Two other important 

components are areas of 

open vegetation for 

foraging and forests, 

trees or shrubs that 

provide shaded areas 

for perching or 

roosting. Nearby 

adjacent forests may be 

deciduous (Illinois) or 

conifer (Wisconsin and 

Michigan).

Larvae are usually 

found in small flowing 

streamlets within cattail 

marshes, sedge 

meadows, and 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

grass marshes, sedge 

meadows, forested areas, 

or other habitat where 

the Hine’s emerald 

dragonfly is expected to 

be found.

USFWS. 2001. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/010927.pdf
48

Species Habitat Rationale Source 

hummocks. Places with 

silt, leaf litter, and 

decaying grasses as a 

substrate are often used 

(US FWS, 2001, p. 15-

16.).

Critical Habitat of 

26,531 acres have been 

designated in Michigan, 

Illinois, Wisconsin, and 

Missouri. Almost half 

of this is Mackinac 

County, MI.

Elktoe, 

Appalachian 

(Alasmidonta 

raveneliana)

This species has been 

reported from relatively 

shallow medium-sized 

creeks and rivers with 

cool, well-oxygenated, 

and moderate- to fastflowing water. It has 

been observed in 

gravelly substrata, often 

mixed with cobble and 

boulders; in cracks in 

bedrock; and 

occasionally in 

relatively silt-free, 

coarse, sandy substrata 

(US FWS, 1996, 

Executive Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1996. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/960826.pdf

Elktoe, 

Cumberland 

(Alasmidonta 

atropurpurea)

This species inhabits 

medium-sized rivers 

and may extend into 

headwater streams 

where it is often the 

only mussel present 

(Gordon and Layzer 

1989, Gordon 1991). 

Gordon and Layzer 

(1989) reported that the 

species appears to be 

most abundant in flats, 

which were described 

as shallow pool areas 

lacking the bottom 

contour development of 

typical pools, with sand 

and scattered 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040524.pdf
49

Species Habitat Rationale Source 

cobble/boulder 

material, relatively 

shallow depths, and 

slow (almost 

imperceptible) currents. 

They also report the 

species from swifter 

currents and in areas 

with mud, sand, and 

gravel substrates (US 

FWS, 2004, p. 18). 

Fanshell 

(Cyprogenia 

stegaria)

The fanshell inhabits 

gravel substrates in 

medium to large rivers 

of the Ohio River basin 

(US FWS, 1991, 

Executive Summary).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1991. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/910709.pdf

fatmucket, 

Arkansas 

(Lampsilis 

powellii)

Four microhabitat types 

that include: 1) long 

pools with cobble and 

rock as primary 

substrate types, 2) 

backwater areas 

downstream of 

peninsulas or islands 

covered with water 

willow (Justicia 

americana) and with 

cobble and sand as the 

dominant substrate, 3) 

slow moving pools 

upstream from water 

willow islands with 

sand, gravel, and cobble 

substrate, and 4) 

overflow, secondary 

channel pools, and 

tributary confluence 

areas with sand, cobble, 

and some rock substrate 

(US FWS 2013, p. 5)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Five Year 

Review. 

http://www.gpo.gov/fdsys/pk

g/FR-2011-09-27/pdf/2011-

24046.pdf

Ferret, blackfooted (Mustela 

nigripes)

The black-footed ferret 

relies on prairie dog 

colonies for both food 

and shelter.

The proposed dicamba 

DGA uses are not 

expected to overlap with 

prairie dog colonies. 

USFWS. 2008. 5-Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc2364.pdf

Frog, dusky 

gopher (Rana 

sevosa)

Upland sandy habitats 

(forest dominated by 

longleaf pine (Pinus 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

USFWS. 2011. Federal 

Register Notice: Designation 

of Critical Habitat.
50

Species Habitat Rationale Source 

palustris)), wetlands 

(ephemeral ponds) 

embedded within the 

forest ...Adults and 

subadults spend the 

majority of their lives 

underground (in gopher 

tortoise (Gopherus 

polyphemus) and 

mammal burrows and 

holes under old 

stumps)...During the 

breeding season, 

Mississippi gopher 

frogs leave their 

subterranean retreats in 

the uplands and migrate 

to their breeding sites 

during rains associated 

with passing cold 

fronts. Breeding sites 

are ephemeral 

(seasonally flooded) 

isolated ponds (not 

connected to other 

water bodies) located in 

the uplands. Both 

forested uplands and 

isolated wetlands (see 

further discussion of 

isolated wetlands in 

‘‘Sites for Breeding, 

Reproduction, and 

Rearing of Offspring’’ 

section) are needed to 

provide space for 

individual and 

population growth and 

normal behavior. (US 

FWS 2011, p. 59777-

59778)

forested areas, wetlands, 

or ephemeral isolated 

ponds. 

http://www.gpo.gov/fdsys/pk

g/FR-2011-09-27/pdf/2011-

24046.pdf
51

Species Habitat Rationale Source 

Heelsplitter, 

Alabama 

(=inflated) 

(Potamilus 

inflatus)

This species prefers a 

soft, stable substrate in 

slow to moderate 

currents. It has been 

found in sand, mud, silt 

and sandy-gravel, but 

not in large or armored 

gravel (US FWS, 1993, 

Executive Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1993. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/930413.pdf

Hellbender, 

Ozark 

(Cryptobranchu

s alleganiensis 

bishopi)

Cool, clear streams and 

rivers with many large 

rocks...small 

hellbenders hide 

beneath large rocks and 

also small stones in 

gravel beds. Adults

spend most of their life 

under large, flat rocks; 

typically limestone or 

dolomite [rocks], and in 

moderate to deep (less 

than 3 to 9.8 feet (less 

than 1 to 3 meters)), 

rocky, fast-flowing 

streams in the Ozark 

Plateau (Johnson 2000, 

p. 42; Fobes and 

Wilkinson 1995, pp. 5–

7). In spring-fed 

streams, Ozark 

Hellbenders will often 

concentrate downstream 

of the spring, where 

there is little water 

temperature change 

throughout the year (US 

FWS 2011, p. 61956).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2011. Federal 

Register Notice: Listing 

Document.

http://www.gpo.gov/fdsys/pk

g/FR-2011-10-06/pdf/2011-

25690.pdf

Higgins eye 

(pearlymussel) 

(Lampsilis 

higginsii)

The higgins eye 

pearlymussel is 

characterized as an 

inhabitant of large 

rivers with loose 

substrates and low 

velocities. Many of the 

largest populations are 

in the Mississippi 

River, and all are in its 

upper drainage (US 

FWS, 2004, p. 7-8). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040714.pdf
52

Species Habitat Rationale Source 

Kidneyshell, 

fluted 

(Ptychobranchu

s subtentum)

Associated with the 

Cumberland and 

Tennessee River 

drainages. Generally 

live embedded in the 

bottom of stable 

streams and other 

bodies of water, and 

within riffle areas of 

sufficient current 

velocities to remove 

finer sediments and 

provide well 

oxygenated waters (US 

FWS, 2013, p. 59560)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Federal 

Register Notice: Designation 

of Critical Habitat. 

http://www.gpo.gov/fdsys/pk

g/FR-2013-09-26/pdf/2013-

23357.pdf

Kidneyshell, 

triangular 

(Ptychobranchu

s greenii)

Sand/gravel shoals and 

runs of small rivers and 

large streams (US FWS 

2000, p. 60)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/850702.pdf

Lampmussel, 

Alabama 

(Lampsilis 

virescens)

This species inhabits 

sand and gravel 

substrates in small to 

medium sized streams 

(US FWS, 1985, p. 9). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1985. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/850702.pdf

Lilliput, pale 

(pearlymussel) 

(Toxolasma 

cylindrellus)

This species is observed 

in clean, fast-flowing 

water in substrates that 

contain relatively firm 

rubble, gravel, and sand 

substrates swept free 

from siltation. These 

mussels are usually 

found buried in the 

substrate in shallow 

riffle and shoal areas 

(US FWS, 1984, p. 5). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840822.pdf

Logperch, 

Conasauga 

(Percina 

jenkinsi)

This species has been 

collected in deep shuts 

and flowing pools with 

clear, clean gravel and 

mixed rubble substrates 

in areas with moderate 

to swift currents (US 

FWS, 1986, p. 8).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1986. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/860620.pdf
53

Species Habitat Rationale Source 

Lynx, Canada

(Lynx 

canadensis)

PCE: Boreal forest 

landscapes with large 

populations of 

snowshoe hares. 

Distribution and 

abundance of prey and 

microclimate influence 

movement, hunting 

behavior, and den and 

resting site locations. 

Areas with dense cover. 

The proposed dicamba 

DGA uses are not 

expected to overlap with

boreal forests. The 

lynx’s prey, snowshoe 

hares, also do not 

overlap with the 

proposed dicamba DGA 

use sites.

USFWS. 2014. Federal 

Register Notice: Designation 

of Critical Habitat

http://www.gpo.gov/fdsys/pk

g/FR-2014-09-12/pdf/2014-

21013.pdf

Madtom, 

chucky Entire 

(Noturus 

crypticus)

This species has been 

found in stream runs 

with slow to moderate 

current over pea gravel, 

cobble, or slab-rock 

boulder substrates (US 

FWS, 2012, p. 63606)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Designation 

of Critical Habitat. 

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24468.pdf

Madtom, 

Neosho 

(Noturus

placidus)

Benthic species inhabits 

shallow gravel 

substrates. The species 

remains primarily 

inactive and hidden in 

bottom substrate during 

the day, and comes out 

at night to forage for 

aquatic invertebrates 

(Moss 1981). The 

majority of Neosho 

madtom collections are 

from areas with gravel 

substrates, primarily 

gravel in the size range 

of 0.5 to 2.5 inches (12 

– 64 mm) in diameter. 

Most collections are 

made in the Spring and 

Neosho Rivers in 

shallow water, 

generally less than three 

feet deep (<1 m). 

Within these systems, 

no significant 

differences in madtom 

preferences for depth, 

velocity, and substrate 

size were found but 

gravel riffles with 

currents of one to four 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4140.pdf
54

Species Habitat Rationale Source 

feet per second (<1.25 

m/sec.) are preferred by 

adults (Moss 1981; 

Fuselier and Edds 1994; 

Wildhaber et al. 2000a) 

(US FWS 2013, pp. 6).

Madtom, 

pygmy (Noturus 

stanauli)

This species inhabits 

shallow shoals, where 

the current is moderate 

to strong and where 

there is pea-sized gravel 

or fine sand substrates, 

in moderately large 

rivers of the Tennessee 

River system (US FWS, 

1994, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1994. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/940927a.pdf

Madtom, Scioto 

(Noturus 

trautmani)

Only 18 individuals 

have ever been 

collected, all found 

along one stretch of Big 

Darby Creek in Ohio 

(US FWS, 2009, p. 4). 

The scioto madtom 

prefers stream riffles of 

moderate current over 

gravel bottoms with 

high quality water that 

is free of suspended 

sediments. The riffle 

habitat where the 18 

individual were 

collected was 

comprised of glacial 

cobble, gravel, sand, 

and silt substrate with 

some large boulders 

(US FWS, 2009, p. 5).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2009. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc3057.pdf

Madtom, smoky 

(Noturus 

baileyi)

This species is 

restricted to Citico 

Creek, primarily within 

the Cherokee National 

Forest, Monroe County, 

Tennessee (US FWS, 

1985,p. 1)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1985. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/060313b.pdf
55

Species Habitat Rationale Source 

Madtom, 

yellowfin 

(Noturus 

flavipinnis)

This species prefers 

pool habitats beneath 

cobble and small 

boulder substrates 

(Miller 2011). The 

strongest habitat models 

identified preferred 

pools for yellowfin 

madtoms as greater than 

40 meters in length with 

gravel being the main 

substrate beneath cover 

rocks (Miller 2011). 

(US FWS, 2012, p. 16).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4146.pdf

Manatee, West 

Indian 

(Trichechus 

manatus)

This species lives in 

freshwater, brackish 

and marine habitats (US 

FWS, 2001, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. 2001. Recovery 

Plan- Third Revision. 

http://ecos.fws.gov/docs/reco

very_plan/011030.pdf

Mapleleaf, 

winged 

(Quadrula 

fragosa)

The general habitat is 

poorly known, although 

it has been 

characterized as a large 

stream species. It has 

been collected on mud, 

mud-covered gravel, 

and gravel substrates. 

In its current location in 

the St. Croix River, it 

occurs in riffles with 

clean gravel, sand, or 

rubbles substrates and 

fast current. It was not 

found in a natural 

impoundment of the 

river (US FWS, 1997, 

p. 5-6). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1997. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/970625.pdf

Marstonia, royal 

(snail) 

(Pyrgulopsis 

ogmorhaphe)

This species is found in 

Blue Spring, which is in 

the water supply for the 

town of Jasper, 

Tennessee, and 

downstream to the State 

Highway 64 bridge (US 

FWS, 1995, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1995. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/950811.pdf
56

Species Habitat Rationale Source 

Moccasinshell, 

Alabama 

(Medionidus 

acutissimus)

Inhabits 

sand/gravel/cobble 

shoals with moderate to 

strong currents in 

streams and small 

rivers. (US FWS 2000, 

p. 51)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Moccasinshell, 

Coosa 

(Medionidus 

parvulus)

Inhabits 

sand/gravel/cobble 

shoals with moderate to 

strong currents in 

streams and small 

rivers. (US FWS 2000, 

p. 52)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Monkeyface, 

Appalachian 

(pearlymussel) 

(Quadrula 

sparsa)

This species is most 

often observed in cleanfast-flowing water in 

substrates that contain 

relatively firm rubble, 

gravel, and sand 

substrates swept free 

from siltation. These 

mussels are usually 

found buried in the 

substrate in shallow 

riffle and shoal areas 

(US FWS, 1984, p. 7).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/840709.pdf

Monkeyface, 

Cumberland 

(pearlymussel) 

(Quadrula 

intermedia)

This species is most 

often observed in cleanfast-flowing water in 

substrates that contain 

relatively firm rubble, 

gravel, and sand 

substrates swept free 

from siltation. These 

mussels are usually 

found buried in the 

substrate in shallow 

riffle and shoal areas 

(US FWS, 1984, p. 9). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/840709b.pdf

Mucket, Neosho 

(Lampsilis 

rafinesqueana)

The Neosho mucket is 

associated with shallow 

riffles and runs 

comprising gravel 

substrate and moderate 

to swift currents. The 

species is most often 

found in areas with 

swift current, but in 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Proposed 

Listing Document.

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24151.pdf
57

Species Habitat Rationale Source 

Shoal Creek and the 

Illinois River it prefers 

near-shore areas or 

areas out of the main 

current (Oesch 1984, p. 

221; Obermeyer 2000, 

pp. 15–16) (US FWS 

2012, p. 63443). 

Mucket, 

orangenacre 

(Lampsilis 

perovalis)

Currently restricted to 

high quality stream and 

small river habitat, the 

species is found on 

stable 

sand/gravel/cobble 

substrate in moderate to 

swift currents (US FWS 

2000, p. 55)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Mucket, pink 

(pearlymussel) 

(Lampsilis 

abrupta)

The pink mucket may 

still exist in stretches of 

the lower Ohio River 

(US FWS, 1985, p. 10).

The pink mucket habitat 

is large rivers at least 60 

feet wide, where it 

occurs at depths up to 

25 feet deep. Currents 

are typically moderate 

to fast and substrates 

range from silt to 

boulders, rubble, gravel, 

and sand (US FWS, 

1985, p. 11). The 

species seems to have 

adapted to living in 

impounded waters, at 

least in the upper 

reaches where the water 

is flowing (US FWS, 

1985, p. 10).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1985. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/pink%20mucket%

20rp.pdf

Mussel, oyster 

(Epioblasma 

capsaeformis)

This species is 

generally adapted to 

live in the gravel shoals 

of free-flowing rivers 

and streams (US FWS, 

2004, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040524.pdf
58

Species Habitat Rationale Source 

Mussel, 

scaleshell 

(Leptodea 

leptodon)

The scaleshell habitat is 

composed of riffles and 

runs in medium to large 

rivers with low to 

medium gradients and 

slow to moderate 

velocity of current. It 

inhabits a variety of 

substrates from gravel 

to mud, but riffles are 

primarily stable (US 

FWS, 2010, p.18).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/100407_v2.pdf

Mussel, 

sheepnose 

(Plethobasus 

cyphyus)

The sheepnose is a 

larger-stream species 

occurring primarily in 

shallow shoal habitats 

with moderate to swift 

currents over coarse 

sand and gravel. 

Habitats with sheepnose 

may also have mud, 

cobble, and boulders. 

Sheepnose in larger 

rivers may occur at 

depths exceeding 6 m 

(US FWS, 2012, p 

14916).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Final Rule. 

http://www.gpo.gov/fdsys/pk

g/FR-2012-03-13/pdf/2012-

5603.pdf

Mussel, 

snuffbox 

(Epioblasma 

triquetra)

The habitat is described 

as swift currents and 

riffles, and shoals and 

wave-washed shores of 

lakes over gravel and 

sand with occasional 

cobble and boulders. 

They generally burrow 

deep into the substrate 

(US FWS, 2010, p 

67554). This 

constitutes a wide 

diversity of habitats. 

However, they do not 

occur in impounded 

areas or reservoirs 

(except tailwaters) (US 

FWS, 2012, p 8652).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2010. Federal 

Register Notice: Listing.

http://www.gpo.gov/fdsys/pk

g/FR-2010-11-02/pdf/2010-

27413.pdf#page=2

USFWS. 2012. Federal 

Register Notice: Final Rule.

http://www.gpo.gov/fdsys/pk

g/FR-2012-02-14/pdf/2012-

2940.pdf
59

Species Habitat Rationale Source 

Pearlshell, 

Louisiana 

(Margaritifera 

hembeli)

Specific habitat 

requirements are not 

known. This species 

apparently requires a 

free-flowing stream 

(US FWS, 1990, 

Executive Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with

rivers, streams, creeks, 

or other water bodies.

USFWS. 1990. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/901203.pdf

Pearlymussel, 

birdwing 

(Lemiox 

rimosus)

This species is most 

often observed in clean 

fast-flowing water in 

substrates that contain 

relatively firm rubble, 

gravel and sand 

substrates swept free 

from siltation. It is 

usually found buried in 

the substrate in shallow 

riffle and shoal areas 

(US FWS, 1984, p. 6). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/060206a.pdf

Pearlymussel, 

cracking 

(Hemistena 

lata)

The cracking 

pearlymussel has 

undergone a substantial 

range reduction. It was 

historically distributed 

in the Ohio, 

Cumberland, and 

Tennessee River 

systems. The species 

has been extirpated 

throughout much of its 

range. It was last 

collected from Mussel 

Shoals, an 85 km reach 

of the Tennessee River 

in Alabama, prior to 

1925 and is presumed 

to be extirpated from 

the shoal. It is presently 

known to survive at 

only a few shoals in the 

Clinch and Powell 

Rivers in Tennessee and 

Virginia, and it has 

likely been reduced to 

only three viable 

populations in these 

systems. The species 

possibly survives in the 

Green River, Kentucky, 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

http://ecos.fws.gov/docs/life_

histories/F01X.html
60

Species Habitat Rationale Source 

and below Pickwick 

Reservoir in the 

Tennessee River, 

Tennessee as well 

Pearlymussel, 

Curtis 

(Epioblasma 

florentina 

curtisii)

The Curtis’ 

pearlymussel has not 

been seen alive in over 

a decade. Limited to 

stream segments that 

are transitional between 

headwater and lowland 

streams reaches -

shallow stable riffles 

(US FWS 2010, p. 3, 

7).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2010. Five Year 

Review. 

http://ecos.fws.gov/docs/reco

very_plan/840709c.pdf

Pearlymussel, 

dromedary 

(Dromus 

dromas)

This species is most 

often observed in clean, 

fast-flowing water in 

substrates that contain 

relatively firm rubble, 

gravel and sand 

substrates swept free 

from siltation. These 

mussels are usually 

found buried in the 

substrate in shallow 

riffle and shoal areas 

(US FWS, 1984, p. 8). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840709c.pdf

Pearlymussel, 

littlewing 

(Pegias fabula)

This species inhabits 

small to medium, low 

turbidity, cool-water, 

high to moderate 

gradient streams in the 

Cumberland and 

Tennessee River basins 

(US FWS, 1989, p. 5).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/890922.pdf

Pearlymussel, 

Slabside 

(Pleuronaia 

dolabelloides)

Associated with the 

Cumberland and 

Tennessee River 

drainages. Generally 

live embedded in the 

bottom of stable 

streams and other 

bodies of water, and 

within riffle areas of 

sufficient current 

velocities to remove 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Federal 

Register Notice: Designation 

of Critical Habitat. 

http://www.gpo.gov/fdsys/pk

g/FR-2013-09-26/pdf/2013-

23357.pdf
61

Species Habitat Rationale Source 

finer sediments and 

provide well 

oxygenated waters (US 

FWS, 2013, p. 59560)

Pigtoe, 

Cumberland 

(Pleurobema 

gibberum)

This species inhabits 

medium-sized rivers 

with fast-flowing water 

in areas with 

predominately gravel, 

sand and cobble 

substratum (US FWS, 

1992, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1992. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/920813.pdf

Pigtoe, 

finerayed 

(Fusconaia 

cuneolus)

This species is typically 

a riffle species that 

inhabits ford and shoal 

areas in free-flowing 

streams of moderate 

gradient (US FWS, 

1984, p. 7). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/fine%20rayed%20r

ecov%20plan.pdf

Pigtoe, flat 

(Pleurobema 

marshalli)

Habitat is the 

Tombigbee River, 

characterized by an 

increasing number of 

sand and gravel shoals 

and decreasing channel 

size in the upper 

portions (US FWS, 

1989). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/891114e.pdf

Pigtoe, Georgia 

(Pleurobema 

hanleyianum)

This species requires 

flowing water, stable 

stream channels with 

minimal sediment and 

algae growth, and 

adequate water quality. 

It also requires a host 

fish, which is currently 

unknown (US FWS, 

2013, Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Draft 

Recovery Plan. 

http://ecos.fws.gov/docs/reco

very_plan/Hartfield%20and%

20Powell%202013%20Draft

%20Three%20Mollusks%20

RP%20062813.pdf

Pigtoe, rough 

(Pleurobema 

plenum)

The rough pigtoe 

habitat is medium to 

large rivers, 60 feet or 

wider, in sand and 

gravel substrates. Very 

limited collection 

information suggests it 

occurs below spillways, 

in transition zones, and 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840806.pdf
62

Species Habitat Rationale Source 

in sand and gravel 

substrates (US FWS, 

1984, p. 8).

Pigtoe, shiny 

Entire 

(Fusconaia cor)

This species is typically 

a riffle species, found 

along fords and shoals 

of clear, moderate to 

fast-flowing streams 

and rivers with stable 

substrate. It does not 

inhabit deep pools or 

impounded areas. This 

species is usually found 

well-buried in the 

substrate during most of 

the year and is more 

readily visible in early 

summer (US FWS, 

1984, p. 8). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840709d.pdf

Pigtoe, southern 

(Pleurobema 

georgianum)

Sand/gravel shoals and 

runs of small rivers and 

large streams (US FWS 

2000, p. 59)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2000. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/001117.pdf

Pimpleback, 

orangefoot 

(pearlymussel) 

(Plethobasus 

cooperianus)

The 1984 Recovery 

Plan indicated that the 

orange-foot pimpleback 

was known from the 

Tennessee, 

Cumberland, and lower 

Ohio Rivers (US FWS, 

1984. p. 2). The habitat 

is described as medium 

to large rivers in sand 

and gravel substrates. 

In the Ohio River it was 

collected from 15-29 

feet depths, but may 

have lived in shallower 

riffles (US FWS, 1984, 

p. 6).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840930b.pdf
63

Species Habitat Rationale Source 

Plover, piping 

except Great 

Lakes 

watershed 

(Charadrius 

melodus)

The northern Great 

Plains DPS of the 

piping plover utilizes 

four types of habitats 

for breeding: alkali 

lakes and wetlands, 

inland lakes (Lake of 

the Woods), reservoirs, 

and rivers. Most 

breeding occurs along

alkali lakes and 

wetlands, where nesting 

sites are generally wide, 

gravelly, salt encrusted 

beaches with minimal 

vegetation. At inland 

lakes, they use barren to 

sparsely vegetated 

islands, beaches, and 

peninsulas. Sparsely 

vegetated sandbars and 

reservoir shorelines are 

preferred in riverine 

systems (US FWS, 

2002, p. 57640).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

shorelines, beaches, and 

sandbars of rivers and 

alkali wetlands. 

USFWS. 2002. Federal 

Register Notice.

http://ecos.fws.gov/docs/feder

al_register/fr3943.pdf

Plover, piping 

Great Lakes 

watershed 

(Charadrius 

melodus)

The breeding habitat of 

the Great Lakes DPS of 

the piping plover is well 

defined by the Critical 

Habitat designation. 

Critical Habitat for this 

DPS consists of 

approximately 200 

miles of Great Lakes 

shoreline (extending 

1640 ft inland) in 26 

counties in Minnesota, 

Wisconsin, Michigan, 

Illinois, Indiana, Ohio, 

Pennsylvania, and New 

York. Additional 

Critical Habitat for 

wintering populations 

of this DPS are in the 

southeastern United 

States and other areas 

that are outside the 

scope of this analysis 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

sparsely vegetated sandy 

shorelines or islands of 

the Great Lakes.

USFWS. 2009. 5-Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc3009.pdf

USFWS. 2000. Federal 

Register Notice

http://ecos.fws.gov/docs/feder

al_register/fr3648.pdf
64

Species Habitat Rationale Source 

(USFWS, 2000; 

USFWS, 2009, p.2).

Pocketbook, fat 

(Potamilus 

capax)

The fat pocketbook is a 

large river species 

requiring flowing water 

and a stable substrate, 

which can vary widely 

but is most likely a 

mixture of sand, silt and 

clay. It occurs in water 

from a few inches deep 

to at least 8 feet. 

Habitat includes 

drainage ditches. (US 

FWS, 1989, p. 6). 

Populations have been 

found in larger rivers in 

the Ohio River system, 

and it may occur as 

deep as 20 feet (US 

FWS, 2012, p. 7-8). It 

can also tolerate periods 

of high suspended 

sediments (US FWS, 

2012, p. 11).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/891114c.pdf

USFWS. 2012. Five Year 

Review.

http://ecos.fws.gov/docs/reco

very_plan/891114c.pdf

Pocketbook, 

Ouachita rock 

(Arkansia 

wheeleri)

This species inhabits 

pools, backwaters, and 

side channels of rivers 

and large creeks in or 

near the southern slope 

of the Ouachita Uplift. 

This species occupies 

stable substrates 

containing gravel, sand, 

and other materials (US 

FWS, 2004. Executive 

Summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/040602.pdf
65

Species Habitat Rationale Source 

Pocketbook, 

speckled 

(Lampsilis 

streckeri)

Specific habitat 

requirements are not 

known. The species is 

found in coarse to 

muddy sand in depths 

up to 0.4 meters (1.3 

feet) with a constant 

flow of water. The 

occurrence in areas of 

constant water flow 

suggests a requirement 

for well-oxygenated 

conditions (US FWS 

1992, p. 3).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1992. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/920102.pdf

Purple Cat's 

paw (=Purple 

Cat's paw 

pearlymussel) 

(Epioblasma 

obliquata 

obliquata)

Inhabits boulder to 

sandy substrates in 

large rivers of the Ohio 

River basin (US FWS 

1992, Executive 

summary). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1992. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/920310.pdf

Rabbitsfoot 

(Quadrula 

cylindrica 

cylindrica)

Primarily an inhabitant 

of small to medium 

sized streams and some 

larger rivers. It usually 

occurs in shallow water 

areas along the bank 

and adjacent runs and 

shoals with reduced 

water velocity. They 

have been reported in 

deep water runs up to 

12 feet depth. "Bottom 

substrates generally 

include gravel and 

sand" (US FWS, 2012, 

p. 63446).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice.

http://www.gpo.gov/fdsys/pk

g/FR-2012-10-16/pdf/2012-

24151.pdf

Rabbitsfoot, 

rough 

(Quadrula 

cylindrica 

strigillata)

Inhabits medium-sized 

to large rivers in 

moderate to swift 

current but often exists 

in areas close to, but not 

in, the swiftest current 

(Gordon 1991). It is 

reported to live in silt, 

sand, gravel, or cobble 

in eddies at the edge of 

midstream currents and 

may be associated with 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

FWS. 2004. Recovery Plan.

http://ecos.fws.gov/docs/reco

very_plan/040524.pdf
66

Species Habitat Rationale Source 

macrophyte beds 

(Yeager and Neves 

1986, Gordon 1991). 

The rough

rabbitsfoot seldom 

burrows; it generally 

lies on its side on the 

stream bottom (Neves,

pers. comm., 2003) (US 

FWS 2004, p. 19). 

Riffleshell, 

northern 

(Epioblasma 

torulosa 

rangiana)

The habitat of the 

riffleshell occurs in 

packed sand and gravel 

in riffles and runs, and 

also in the western 

basin of Lake Erie 

where there is sufficient 

wave action to produce 

continuously moving 

water (US FWS, 1994, 

p. 18). FWS further 

describes the habitat as 

medium to large rivers 

where they are often 

associated with high 

water velocities, 

although they have also 

been documented in 

Lake Erie and in deep 

more slow-flowing 

rivers down to 20 feet 

(US FWS, 2009. p. 9).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1994. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/940921.pdf

USFWS. 2009. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc3284.pdf

Riffleshell, tan 

(Epioblasma 

florentina 

walkeri (=E. 

walkeri))

This species inhabits 

streams described as 

shallow and turbid with 

numerous riffles and 

substrate consisting of 

loose rocks and gravel 

bars with an abundance 

of water willow (US 

FWS, 1984. P, 7). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/tan%20riffleshell%

20rp.pdf

Ring pink 

(mussel) 

(Obovaria 

retusa)

This species inhabits 

gravel and sandy 

substrates in large rivers 

of the Ohio River basin 

(US FWS, 1991). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1991. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/910325.pdf
67

Species Habitat Rationale Source 

Riversnail, 

Anthony's 

(Athearnia 

anthonyi)

This species is typically 

found in large streams 

on large submerged 

objects (e.g., rocks and 

logs) or gravelly 

substrata in relatively 

shallow, moderately to 

fast-flowing water (US 

FWS, 1997). 

The proposed dicamba 

DGA uses are not 

expected to overlap with

rivers, streams, creeks, 

or other water bodies.

USFWS. 1997. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/970813.pdf

Sawfish, 

smalltooth 

(Pristis 

pectinata)

Smalltooth sawfish are 

tropical marine and 

estuarine fish that have 

the northwestern 

terminus of their 

Atlantic range in the 

waters of the eastern 

United States. In the 

United States, 

smalltooth sawfish are 

generally a shallow 

water fish of inshore 

bars, mangrove edges, 

and seagrass beds, but 

are occasionally found 

in deeper coastal 

waters. (US FWS 

NMFS, NOAA 2001, p. 

19416)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

NMFS, NOAA. 2001.

Federal Register Notice: 

Proposed Endangered Status 

for a DPS of Smalltooth 

Sawfish.

http://ecos.fws.gov/docs/feder

al_register/fr3741.pdf

Sea turtle, green 

(Chelonia 

mydas)

Green turtles are 

primarily restricted to 

tropical and subtropical 

waters. In U.S. Atlantic 

and Gulf of Mexico 

waters, green turtles are 

found from

Massachusetts to Texas 

and in the U.S. Virgin 

Islands and Puerto 

Rico...Seagrasses are 

the principal dietary 

component of juvenile 

and adult green turtles 

throughout the Wider 

Caribbean region 

(Bjorndal, 1995). 

(NMFS, NOAA 1998, 

p. 46694)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

NMFS, NOAA. 1998. 

Federal Register Notice: 

Designated critical habitat.

http://ecos.fws.gov/docs/feder

al_register/fr3295.pdf
68

Species Habitat Rationale Source 

Sculpin, grotto 

(Cottus sp.)

Grotto sculpin occupy 

cave streams, 

resurgences (also 

known as ‘‘spring 

branches’’) (Vandike 

1985, p. 10), springs, 

and surface streams 

(Adams 2012, pers. 

comm.; Adams et al. 

2013, pp. 491–493; 

Burr et al. 2001, p. 

284). They occupy 

pools and riffles with 

moderate flows and 

variable depths (4 to 33 

centimeters (cm) (1.6 to 

13 in)) (Burr et al. 

2001, p. 284). Although 

grotto sculpin have 

been documented to 

occur over a variety of 

substrates (for example, 

silt, gravel, cobble, rock 

rubble, and bedrock), 

the presence of cobble 

or pebble is necessary 

for spawning (Burr et 

al. 2001, p. 284; Adams 

et al. unpub. data; 

Adams et al. 2013, pp. 

491–492) (US FWS 

2013, p. 58928).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2013. Federal 

Register Notice: Designation 

of Critical Habitat (58938)

http://www.gpo.gov/fdsys/pk

g/FR-2013-09-25/pdf/2013-

23182.pdf

Sea turtle, 

hawksbill 

(Eretmochelys 

imbricata)

The hawksbill turtle 

occurs in tropical and 

subtropical waters of 

the Atlantic, Pacific, 

and Indian Oceans. 

Coral reefs, like those 

found in the waters 

surrounding Mona and 

Monito Islands, are 

widely recognized as 

the primary foraging 

habitat of juvenile, 

subadult, and adult 

hawksbill turtles. This 

habitat association is 

directly related to the 

species’ highly specific 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

NMFS, NOAA. 1998. 

Federal Register Notice: 

Designated critical habitat. 

http://ecos.fws.gov/docs/feder

al_register/fr3295.pdf
69

Species Habitat Rationale Source 

diet of sponges 

(Meylan, 1988). 

Hawksbills depend on 

coral reefs for food and 

shelter; therefore, the 

condition of reefs 

directly affects the 

hawksbill’s well-being. 

(NMFS, NOAA 1998, 

p. 46695)

Sea turtle, 

Kemp's ridley 

(Lepidochelys 

kempii)

This life history pattern 

is characterized by three 

basic ecosystem zones: 

(1) Terrestrial zone 

(supralittoral) - the 

nesting beach where 

both oviposition and 

embryonic development 

occur; (2) Neritic zone -

the nearshore (including 

bays and sounds) 

marine environment 

(from the surface to the 

sea floor) where water 

depths do not exceed 

200 meters, including 

the continental shelf; 

and (3) Oceanic zone -

the vast open ocean 

environment (from the 

surface to the sea floor) 

where water depths are 

greater than 200 meters. 

(NMFS, NOAA 2011, 

p. I-8)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

NMFS, NOAA. 2011. Binational recovery plan for the 

kemp's ridley sea turtle.

http://ecos.fws.gov/docs/reco

very_plan/090116.pdf
70

Species Habitat Rationale Source 

Sea turtle, 

leatherback 

(Dermochelys 

coriacea)

Leatherbacks are able to 

take advantage of a 

wide variety of marine 

ecosystems (reviewed 

by Saba 2013; see 

NOAA large marine 

ecosystem website: 

http://www.lme.noaa.go

v/). Within these 

ecosystems, various 

oceanic features such as 

water temperature, 

downwelling, Ekman 

upwelling, sea surface 

height, chlorophyll-a 

concentration, and 

mesoscale eddies affect 

the presence of 

leatherbacks (Bailey et 

al. 2013; Benson et al. 

2011). The physical 

characteristics observed 

within these marine 

ecosystems also affect 

the distribution and 

abundance of 

leatherback prey 

(reviewed by Saba 

2013). (NFMS, NOAA 

2013, p. 20-22).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

NMFS, NOAA. 2013. Five 

Year Review. 

http://ecos.fws.gov/docs/reco

very_plan/090116.pdf

Sea turtle, 

loggerhead 

Northwest 

Atlantic DPS 

(Caretta caretta)

The three basic 

ecosystems in which 

loggerheads live are 

the: 

1. Terrestrial zone 

(supralittoral) - the 

nesting beach where 

both oviposition (egg 

laying) and embryonic 

development and 

hatching occur. 

2. Neritic zone - the 

nearshore marine 

environment (from the 

surface to the sea floor) 

where water depths do 

not exceed 200 meters. 

The neritic zone 

generally includes the 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

NMFS. NOAA. 2009. 

Recovery Plan. 

http://ecos.fws.gov/docs/reco

very_plan/090116.pdf
71

Species Habitat Rationale Source 

continental shelf, but in 

areas where the 

continental shelf is very 

narrow or nonexistent, 

the neritic zone 

conventionally extends 

to areas where water 

depths are less than 200 

meters. 

3. Oceanic zone - the 

vast open ocean 

environment (from the 

surface to the sea floor) 

where water depths are 

greater than 200 meters. 

(NMFS, NOAA 2009, 

p. I-20)

Shiner, 

Arkansas River 

(Notropis 

girardi)

Wilde et al. (2000) 

found no obvious 

selection for or 

avoidance of any 

particular habitat type 

(i.e., main channel, side 

channel, backwaters, 

and pools) by Arkansas 

River shiner. Arkansas 

River shiners did tend 

to select side channels 

and backwaters slightly 

more than expected 

based on the availability 

of these habitats (Wilde 

et al. 2000). Likewise, 

they appeared to make 

no obvious selection 

for, or avoidance of, 

any particular substrate 

type. Substrates (i.e., 

the river bed) in the 

Canadian River in New 

Mexico and Texas were 

predominantly sand, 

however, the Arkansas 

River shiner was 

observed to occur over 

silt slightly more than 

expected based on the 

availability of this 

substrate (Wilde et al. 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. 2005. Federal 

Register Notice: Designation 

of Critical Habitat. 

http://ecos.fws.gov/docs/reco

very_plan/950830.pdf
72

Species Habitat Rationale Source 

2000) ; preferred habitat 

for the Arkansas River 

shiner is the mainstem 

of larger plains rivers... 

historically inhabited 

the main channels of 

wide, shallow, sandybottomed rivers and 

larger streams of the 

Arkansas River basin 

(Gilbert 1980). Adults 

are uncommon in quiet 

pools or backwaters 

lacking streamflow, and 

almost never occurred 

in habitats having deep 

water and bottoms of 

mud or stone (Cross 

1967) (US FWS 2005). 

Shiner, blue 

(Cyprinella 

caerulea)

The blue shiner 

primarily occupies 

second to fourth order, 

moderate gradient 

streams within the 

Ridge and Valley and 

Piedmont physiographic 

provinces of Alabama, 

Georgia, and Tennessee 

(Smith-Vaniz 1968, 

Ramsey 1976, Krotzer 

1984, Ramsey and 

Pierson 1986, Pierson 

and Krotzer 1987, 

Mayden 1989, Pierson 

et al. 1989, Boschung 

1992, Etnier and 

Starnes 1993, Dobson 

1994). Most watersheds 

where it is found are 

predominately forested, 

and agriculture and 

urban development are 

minimal. For example 

in Alabama, land cover 

in the Choccolocco 

watershed is 66 percent 

forest, 20 percent 

pasture, and 13 percent 

agriculture...It prefers a 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

US FWS. 1995. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/950830.pdf
73

Species Habitat Rationale Source 

sand or sand and gravel 

substrate sometimes 

with cobble, low to 

moderate velocity 

current, and a depth of 

about 0.15 to 1 meters 

(0.5 to 3 feet) (Gilbert 

et al. 1979; Krotzer 

1984, Pierson and 

Krotzer 1987, Dobson 

1994) (US FWS 1995, 

p. 3-4)

Shiner, Topeka 

(Notropis 

topeka 

(=tristis))

Topeka shiners are 

typically found in 

small, low order, prairie 

streams with good 

water quality, relatively 

cool temperatures, and 

low fish diversity. 

Although Topeka 

shiners can tolerate a 

range of water 

temperatures, cooler, 

spring-maintained 

systems are considered 

optimal. These streams 

generally maintain 

perennial flow but may 

become intermittent 

during summer or 

periods of drought, as 

long as there are refuge 

areas in headwaters 

springs or main 

channels of larger 

streams that do not 

provide adequate yearround habitat. While 

headwaters, oxbows 

and side channels 

provide the typical 

habitat, mainstem 

streams provide for 

dispersal as well as for 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2004. Federal 

Register Notice: Designation 

of Critical Habitat. 

http://ecos.fws.gov/docs/five_

year_review/doc2585.pdf
74

Species Habitat Rationale Source 

drought refuge. The 

shiner is very often 

associated with 

groundwater 

discharges. Substrates 

are typically clean 

gravel, cobble, or sand, 

but may include 

bedrock and clay 

hardpan covered by a 

thin layer of silt, or 

coarse sand overlain by 

silt and detritus. 

Spawning is often over 

native sunfish nests (US 

FWS, 2004, pp, 44743-

4).

Snail, Iowa 

Pleistocene 

(Discus 

macclintocki)

The Iowa Pleistocene 

snail only occurs on 

high quality algific 

(cold producing) talus 

slopes with 

temperatures ranging 

from 35-45 degrees 

Fahrenheit. Air flows 

through fractured 

bedrock, over frozen 

groundwater, and outvents on steep slopes to 

create a cold 

microclimate. These 

are talus covered slopes 

with thin soil that 

makes them extremely 

fragile and sensitive to 

disturbance, and 

irreplaceable. This 

habitat is known only to 

occur in the "driftless 

area" that overlaps 

where the states of 

Illinois, Iowa, 

Minnesota, and 

Wisconsin come 

together (US FWS, 

2009, p. 11). All 

known areas are northfacing slopes, and the 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

algific talus slopes. 

USFWS. 1984. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/840322.pdf

USFWS. 2009. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc2585.pdf
75

Species Habitat Rationale Source 

ground temperature 

seldom exceeds 50 

degrees Fahrenheit even 

in the hottest summers 

(US FWS, 1984, p. 5).

Snail, painted 

snake coiled 

forest 

(Anguispira 

picta)

This species is limited 

to Buck Creek Cove. It 

is found only in 

limestone outcrops in 

parts of the cove with 

good cover. The slopes 

of the cove are very 

steep with crock 

outcrops and sheer 

cliffs at intervals along 

both sides of the creek 

(US FWS, 1982). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

creeks or stone outcrops 

along creeks. 

USFWS. 1982. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/060206.pdf

Snake, 

copperbelly 

water (Nerodia 

erythrogaster 

neglecta)

Copperbellies are 

generally affiliated with 

wetlands and prefer 

shallow wetlands, such 

as shrub-scrub wetlands 

dominated by

buttonbush 

(Cephalanthus 

occidentalis), emergent 

wetlands, or the 

margins of palustrine 

open water wetlands.

Buttonbrush swamps 

are used as basking 

areas. Areas frequented 

by copperbellies 

generally have an open 

canopy, shallow water, 

and short dense 

vegetation. Uplands are 

also important. (US 

FWS, 2008, p. 17-18).

Critical Habitat has not 

been designated for the 

snake because of 

concerns related to 

illegal collection (US 

FWS, 2008. p. 20).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

wetlands. 

USFWS. 2008. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/081223.pdf
76

Species Habitat Rationale Source 

Spectaclecase 

(mussel) 

(Cumberlandia 

monodonta)

The spectaclecase 

generally inhabits large 

rivers where it occurs in 

microhabitats sheltered 

from the main force of 

current. It occurs in a 

variety of substrates 

from mud and sand to 

gravel, cobble, and 

boulders in relatively 

shallow riffles and 

shoals with a slow to 

swift current. It is 

most often found in 

firm mud between large 

rocks in quiet water 

very near the interface 

with swift currents (US 

FWS, 2012, p 14916).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2012. Federal 

Register Notice: Final Rule.

http://www.gpo.gov/fdsys/pk

g/FR-2012-03-13/pdf/2012-

5603.pdf

Spider, sprucefir moss 

(Microhexura 

montivaga)

Typical habitat appears 

to be associated with 

moist, well-drained 

moss mats growing on 

rocks and boulders in 

well-shaded situations 

in mature highelevation conifer forests 

dominated by Fraser fir, 

Abiesfraseri, often with 

scattered red spruce, 

Picea rubens. (US FWS 

1998, p. iii)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

high-elevation conifer 

forests. 

US FWS, 1998, Recovery 

Plan. 

http://www.gpo.gov/fdsys/pk

g/FR-2011-09-27/pdf/2011-

24046.pdf

Squirrel, 

Carolina 

northern flying 

(Glaucomys 

sabrinus 

coloratus)

Species composition of 

the occupied forest may 

vary in different 

locations, some 

combination of 

hardwoods and conifers 

(particularly spruce and 

fir) appears essential to 

support these 

animals...Food sources 

for the Carolina 

northern flying squirrel 

include fungi, lichens, 

staminate cones, 

insects, and other 

animal matter (US FWS 

1990, p. 6-7)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

hardwood and conifer 

forests. 

USFWS. 1990. Recovery 

Plan for Appalachian

Northern Flying Squirrels. 

United States Fish and 

Wildlife Service. 
77

Species Habitat Rationale Source 

Stirrupshell 

(Quadrula 

stapes)

Habitat is the 

Tombigbee River, 

characterized by an 

increasing number of 

sand and gravel shoals 

and decreasing channel 

size in the upper 

portions (US FWS, 

1989). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1989. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/891114e.pdf

Sturgeon, gulf 

(Acipenser 

oxyrinchus 

desotoi)

The Gulf sturgeon is an 

Anadromous fish which 

migrates from salt water 

into large coastal rivers 

to spawn and spend the 

warm months. The 

majority of its life is 

spent in fresh water (US 

FWS, 1995). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1995. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/950922.pdf

Sturgeon, pallid 

(Scaphirhynchu

s albus)

Habitat is the bottom in 

swift waters of large, 

turbid, free-flowing 

rivers, often over sand 

substrates, but other 

substrates include at 

least gravel and rock. 

Sloughs, chutes, and 

side channels that 

transition from 

floodplain to the main 

channels are apparently 

important as spawning, 

nursery, and feeding 

areas. Within the 

subject states, this 

habitat occurs in the 

Mississippi and 

Missouri rivers (US 

FWS, 1993, pp 6-7). 

Within this habitat, they 

tend to select main 

channel habitats in the 

Mississippi River, and 

main channel habitats 

with islands or sand 

bars in the upper 

Missouri River (US 

FWS, 2007. p. 8). They 

do not typically occur 

in impounded areas due 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 2014. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/Pallid%20Sturgeon

%20Recovery%20Plan%20Fi

rst%20Revision%20signed%

20version%20012914_3.pdf

USFWS. 2007. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc1059.pdf
78

Species Habitat Rationale Source 

to lower flows and 

other hydrologic 

factors, nor where 

channel stabilization 

has reduced channel 

meandering and access 

to floodplain areas (US 

FWS, 2007, p. 38).

Tern, least 

interior pop. 

(Sterna 

antillarum)

Species is a piscivore, 

feeding in shallow 

waters of rivers, 

streams (USFWS, 1990, 

p. 20). Beaches, sand 

pits, sandbars, islands 

and peninsulas are the 

principal breeding 

habitats of coastal areas 

and nesting can be close 

to water but is usually 

between the dune 

environment and the 

high tide line. 

Vegetation at coastal 

nesting areas is sparse, 

scattered and short. 

Riverine nesting areas 

are sparsely vegetated 

sand and gravel bars 

within a wide 

unobstructed river 

channel, or salt flats 

along lake shorelines. 

Nesting occurs along 

river banks (US FWS, 

1990, p. 20).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

riparian areas, including 

coastal areas. 

USFWS. 1990. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/900919a.pdf
79

Species Habitat Rationale Source 

Tiger beetle, 

Salt Creek 

(Cicindela 

nevadica 

lincolniana)

Very specific habitat 

requirements and 

occurs in saline 

wetlands—on exposed 

saline mud flats or 

along mud banks of 

streams and seeps that 

contain salt deposits 

and are sparsely 

vegetated (Carter 1989; 

Spomer and Higley 

1993; LaGrange 1997; 

Spomer et al. 2004a). 

Larvae have been found 

only on moist salt flats 

and salt-encrusted 

banks of Little Salt 

Creek in northern 

Lancaster County 

(Spomer et al. 2004a) 

and saline wetlands 

associated with Rock 

Creek in the southern 

margin of Saunders 

County. Salt Creek tiger 

beetles require open, 

barren salt flat areas 

(US FWS 2009, p. 2).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

wetlands. 

US FWS, 2009, Recovery 

Outline for the Salt Creek 

tiger beetle (2)

Turtle, ringed 

map 

(Graptemys 

oculifera)

Rivers and adjacent 

white sand beaches with 

basking sites (brush, 

logs debris) (USACE)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers or beaches.

USACE. Ringed Map Turtle 

Species Profile. US Army 

Corps of Engineers, Engineer 

Research and Development 

Center, Environmental 

Laboratory. 

Turtle, yellowblotched map 

(Graptemys 

flavimaculata)

Rivers and large creeks, 

prefers moderate 

currents, abundant 

basking sites, and 

sandbars (US FWS 

1993, p. 2)

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies 

and their associated 

beaches.

USFWS. 1993. Recovery 

Plan for the Yellow-blotched 

Map Turtle. United States 

Fish and Wildlife Service

Vireo, blackcapped (Vireo 

atricapilla)

This species is an 

insect-eating, migratory 

songbird. They arrive in 

Texas from mid-March 

to mid-April, while 

those in Oklahoma 

arrive approximately 10 

days later. Breeding 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

shrublands associated 

with rocky gullies, edges 

of ravines, or eroded 

slopes. 

USFWS. 2007. Five Year

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc1073.pdf 

USFWS. 1991. Recovery 

Plan. 
80

Species Habitat Rationale Source 

habitat is quite variable 

across its range, but is 

generally shrublands 

with a distinctive 

patchy structure. The 

shrub vegetation is 

mostly deciduous and 

generally extends from 

the ground to about six 

feet above ground and 

covers about 30 to 60% 

of the total area. Open 

grassland separates the 

clumps of shrubs. (US 

FWS 2007, p. 7) 

From Oklahoma 

through most of Texas, 

this type of vegetational 

configuration occurs 

most frequently on 

rocky substrates with 

shallow soils, in rocky 

gullies, on edges of 

ravines, and on eroded 

slopes. (US FWS 1991, 

p. 20)

http://ecos.fws.gov/docs/reco

very_plan/910930h.pdf 

Kirtland's 

Warbler 

(Setophaga 

kirtlandii)

Kirtland's warblers 

generally occupy jack 

pine stands that are 5-

23 years old and at least 

30 acres in size. Stands 

with less than 20% 

canopy over are rarely 

used for nesting. 

Occupied stands usually 

occur on dry, 

excessively drained and 

nutrient poor glacial 

outwash sands. They 

are structurally 

homogenous with trees 

ranging from 1.7-5.0 m 

in height (US FWS, 

2012, p. 24). Species is 

migratory and mobile 

species and breeding 

areas are found in 

Wisconsin.

The proposed dicamba 

DGA salt uses are not 

expected to overlap with 

jack pine stands.

USFWS. 2012. 5-Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc4045.pdf
81

Species Habitat Rationale Source 

Wartyback, 

white 

(pearlymussel) 

(Plethobasus 

cicatricosus)

The white wartyback 

has undergone a 

substantial range 

reduction and is 

considered to be 

possibly extinct. It was 

historically distributed 

in the Wabash, Ohio, 

Kanawha, Cumberland, 

Holston, and Tennessee 

Rivers of the Ohio, 

Cumberland, and 

Tennessee River 

systems; however, no 

live specimens have 

been recovered from 

these drainages since 

the early 1900s). The 

white wartyback may 

still exist in a short 

reach of the Tennessee 

River below Pickwick 

Dam. No living 

populations have been 

found in numerous 

surveys conducted in 

the Tennessee River 

since the 1960s; 

however, fresh dead 

specimens were 

collected in 1979 and 

1982 below Pickwick 

Dam near Savannah, 

Tennessee. If this 

species still exists, the 

viability of remaining 

populations is 

extremely threatened 

The white wartyback is 

a riffle species that is 

typically found in large 

rivers in gravel 

substrates.

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

USFWS, 1984, Recovery 

Plan White Warty-backed 

Pearlymussel

http://ecos.fws.gov/docs/reco

very_plan/060313h.pdf

http://ecos.fws.gov/docs/life_

histories/F00M.html

Whale, finback 

(Balaenoptera 

physalus)

Fin whales are found in 

deep, offshore waters of 

all major oceans, 

primarily in temperate 

to polar latitudes, and 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

http://www.nmfs.noaa.gov/pr/

species/mammals/cetaceans/fi

nwhale.htm
82

Species Habitat Rationale Source 

less commonly in the 

tropics. They occur 

year-round in a wide 

range of latitudes and 

longitudes, but the 

density of individuals in 

any one area changes 

seasonally.

Whale, 

humpback 

(Megaptera 

novaeangliae)

During migration, 

humpbacks stay near 

the surface of the ocean.

While feeding and 

calving, humpbacks 

prefer shallow waters. 

During calving, 

humpbacks are usually 

found in the warmest 

waters available at that 

latitude. Calving 

grounds are commonly 

near offshore reef 

systems, islands, or 

continental shores.

Humpback feeding 

grounds are in cold, 

productive coastal 

waters. 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

coastal waters.

http://www.nmfs.noaa.gov/pr/

species/mammals/cetaceans/h

umpbackwhale.htm

Woodpecker, 

red-cockaded 

Entire (Picoides 

borealis)

Habitat: Forest, 

Savannah (open pine 

woodlands and 

savannahs with large 

old pines) (US FWS 

2003, p. x)

Habitat size (home 

range): 116 – 357 acres 

(US FWS 2003, p. 49)

Proposed dicamba DGA 

uses are not expected to 

overlap with forest or 

savannah. 

USFWS. 2003. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/030320_2.pdf

Plants

Aster, decurrent 

false (Boltonia 

decurrens)

The natural habitat of 

the aster was the shores 

of lakes and the banks 

of streams including the 

Illinois River. It 

appears to require 

abundant light. It 

presently grows in such 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

the shores of 

lakes/streams or other 

floodplain habitats 

where the aster may 

occur. 

USFWS. 1990. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/900928c.pdf

USFWS. 2012. 5-YearReview.
83

Species Habitat Rationale Source 

habitats but is more 

common in disturbed 

lowland areas where it 

appears to be dependent 

on human activity for 

survival (US FWS, 

1990, p. 3). It occupies 

unimpounded 

floodplain habitats 

along the Illinois River 

system; the plant relies 

on periodic flood pulses 

to maintain populations 

and suitable habitat (US 

FWS, 2012, p. 7).

http://ecos.fws.gov/docs/five_

year_review/doc4044.pdf

Aster, Ruth's 

golden 

(Pityopsis 

ruthii)

This species grows only 

in the cracks or crevices 

found in phyllite or 

graywacke boulders 

along the banks of or 

within the Ocoee and 

Hiwassee Rivers (US 

FWS, 1992).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers. 

USFWS. 1992. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/920611.pdf

Avens, 

spreading 

(Geum 

radiatum)

This species grows in 

full sun on the shallow 

acidic soils of highelevation cliffs, rocky 

outcrops, steep slopes, 

and on gravelly talus 

(US FWS, 1993).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

high-elevation cliffs, 

rocky outcrops, steep 

slopes or gravelly talus. 

USFWS. 1993. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/930428.pdf

bladderpod, 

Missouri 

(Physaria 

filiformis)

This species grows in 

shallow soils on 

limestone glades and 

outcrops in pastures and 

rarely in rocky open 

woods. Grows in 

shallowest soils with 

other annuals where 

bare soil occurs and few 

perennials are present. 

Burlington limestone of 

Mississippian age (US 

FWS, 1998).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

pasture outcrops and 

rocky open wooded 

areas. 

USFWS. 1998. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/880407.pdf

Bluet, Roan 

Mountain 

(Hedyotis 

purpurea var. 

montana)

This species grows in 

shallow soils and 

crevices of cliffs and 

outcrops and on thin 

rocky soils of grassy 

balds (US FWS, 1996). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

cliffs and outcrops. 

USFWS. 1996. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/960513.pdf
84

Species Habitat Rationale Source 

Bush-clover, 

prairie 

(Lespedeza 

leptostachya)

The prairie bush clover 

occurs on both 

undisturbed and 

disturbed sites over 

sandy, loam, or gravelly 

soils included at the 

thin margins near rock 

outcrops. Sites may 

have been previously 

mowed, burned or 

grazed (US FWS, 1988, 

p. 7-8).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

prairies.

USFWS. 1988. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/881006.pdf

Butterfly plant, 

Colorado 

(Gaura 

neomexicana 

var. 

coloradensis)

This species requires 

early- to midsuccession riparian 

habitat. It commonly 

occurs in habitat types 

that are usually 

intermediate in 

moisture between wet, 

streamside communities 

dominated by sedges, 

rushes, and cattails, and 

dry, upland short-grass 

prairie. Typically, 

Colorado butterfly plant 

habitat is open, without 

dense or overgrown 

vegetation (US FWS, 

2010). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

riparian habitat or 

upland prairies. 

USFWS. 2010. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/Colorado%20Butte

rfly%20Plant%20Recovery%

20Outline_Final_May%2020

10.pdf

Chaffseed, 

American 

(Schwalbea 

americana)

Habitats described as 

pine flatwoods, firemaintained savannas, 

ecotonal areas between 

peaty wetlands and 

xeric sandy soils, and 

other open grass-sedge 

systems (US FWS, 

1995).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

pine flatwoods, firemaintained savannas,

wetland or sedge 

dominated systems. 

USFWS. 1995. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/950929c.pdf

Clover, running 

buffalo 

(Trifolium 

stoloniferum)

Running buffalo clover 

occurs in mesic habitats 

of partial to filtered 

sunlight, where there is 

a prolonged pattern of 

moderate periodic 

disturbance, such as 

mowing, trampling, or 

grazing. It is most 

often found in regions 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

mesic habitats where the 

clover is expected to be 

found. 

USFWS. 2007. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/070627.pdf
85

Species Habitat Rationale Source 

underlain with 

limestone or other 

calcareous bedrock. 

Specific habitats 

include mesic 

woodlands, savannahs, 

floodplains, stream 

banks, sandbars, grazed 

woodlots, mowed paths 

(e.g. cemeteries, parks), 

old logging roads, jeep 

trails, ATV trails, skid 

trails, mowed wildlife 

openings within mature 

forest, and steep 

ravines. It has been 

suggested that the 

original habitat may 

have been open woods 

or savannah, and bison 

herbivory on associated 

species may have kept 

the habitats open (US 

FWS, 2007, p. 12.).

Daisy, Lakeside 

(Hymenoxys 

herbacea)

Although historical 

habitats include 

outcrops of dolomite or 

limestone bedrock, dry, 

gravelly prairies on 

terraces or hills 

associated with major 

river systems, rocky 

shores, sandy fields and 

alvars, the Lakeside 

daisy in the U. S. is 

now restricted to dry, 

thin-soiled, degraded 

prairies in which 

limestone or dolomite 

bedrock is at or near the 

surface. Habitats are 

alkaline, seasonally wet 

in spring and fall, and 

are moderately to 

extremely droughty in 

summer. Typically, 

habitats have little 

topographic relief, are 

relatively open at the 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

quarries and dry prairies.

USFWS. 1990. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/900919b.pdf
86

Species Habitat Rationale Source 

ground surface, and 

vegetation density and 

diversity are relatively 

low. Within these 

habitats, lakeside daisy 

occurs in open patches 

of ground, occupies the 

dry to mesic portions of 

the soil moisture 

continuum and has a 

highly aggregated 

distribution. This 

species is either absent 

or infrequently found in 

shaded or densely 

vegetated areas (US 

FWS, 1990, pp. 20-21).

Fern, American 

hart's-tongue 

(Asplenium 

scolopendrium 

var. 

americanum)

Early successional 

habitats Northern 

populations occur in 

forests of secondary 

growth where canopy 

openings are abundant. 

New York populations 

occur in conifer forests. 

Bryophyte beds are an 

important substrate.

The proposed dicamba 

DGA uses are not 

expected to overlap early 

successional forests, 

conifer forests or 

bryophyte beds where 

the species is found.

http://ecos.fws.gov/docs/reco

very_plan/930915.pdf

Geocarpon 

minimum (No 

common name)

This species grows on 

sandstone glades and 

outcrops as well as 

bare, sparsely vegetated 

areas where the soil 

contains relatively large 

amounts of magnesium 

and sodium salts (US 

FWS, 1993). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

the sandstone glades and 

outcrops where this 

species is expected to be 

found. 

USFWS. 1993. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/930726.pdf

Goldenrod, 

Blue Ridge 

(Solidago 

spithamaea)

This species grows on 

rock outcrops and 

vertical to near vertical 

cliffs in southern 

Appalachians of 

western North Carolina 

and extreme eastern 

TN. Rocky summits 

and cliffs usually 

appear as smaller-scale 

patchy habitats 

embedded in larger 

forest consisting of 

The proposed dicamba

DGA uses are not 

expected to overlap with 

rock outcrops and 

vertical cliffs. 

USFWS. 1987. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/blueridge%20gold

enrod%20rp.pdf
87

Species Habitat Rationale Source 

spruce-fir or northern 

hardwoods or 

occasionally high 

elevation red oak forest 

(US FWS, 1987). 

Goldenrod, 

Short’s 

(Solidago 

shortii)

The habitat of Short's 

goldenrod is open areas 

in full sun or partial 

shade. Known 

occurrences are in 

limestone cedar glades, 

open eroded areas, 

edges, of open oakhickory woods, cedar 

thickets, pastures, old 

fields, power line 

rights-of-way and rock 

ledges along rights-ofway. Cedar glades and 

woodland edges appear 

to be the natural habitat. 

Short's goldenrod was 

known historically and 

currently only from 

Kentucky when the 

Recovery Plan was 

written in 1988 (US 

FWS, pp. 3-4). An 

Indiana occurrence was 

located in 2001 along 

the Blue River in 

riparian habitat (US 

FWS, 2007, p. 6).

The proposed dicamba 

DGA salt uses are not 

expected to overlap with 

glades, woodland edges, 

pastures, or other habitat 

favorable for goldenrod 

growth.

USFWS. 1988. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/shortsgrodRP.pdf

USFWS. 2007. 5-Year 

Review.

http://ecos.fws.gov/docs/five_

year_review/doc1609.pdf

Grass, 

Tennessee 

yellow-eyed 

(Xyris 

tennesseensis)

Xyris tennessensis is a 

rare perennial monocot 

that is an obligate 

wetland plant that 

prefers relatively high 

pH seeps and 

streambanks. An 

Obligate wetland plant 

that is restricted to 

calcareous seeps, fens, 

and spring runs (US 

FWS, 2014). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

wetlands. 

USFWS. 2014. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc4360.pdf

Ground-plum, 

Guthrie's 

(=Pyne's) 

This species is endemic 

to cedar glades (US 

FWS, 2011). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

cedar glades. 

USFWS. 2011. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/20110722b_Pynes
88

Species Habitat Rationale Source 

(Astragalus 

bibullatus)

%20ground%20plum_RP_fin

al_1.pdf

Harperella 

(Ptilimnium 

nodosum)

Harperella is known 

from only two locations 

in North Carolina. One 

population occurs in the 

Tar River in Granville 

County. Another 

population was 

reintroduced to the 

Deep River recently 

after the original 

population known from 

that area disappeared. 

This population occurs 

in Chatham County, but 

the river serves as the 

divide between 

Chatham and Lee 

counties (US FWS, 

1991). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

river habitats. 

USFWS. 1991. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/910305b.pdf

Iris, dwarf lake 

(Iris lacustris)

The dwarf lake iris 

grows along the 

northern shorelines of 

lakes Michigan and 

Huron in Wisconsin, 

Michigan and Ontario, 

Canada. It typically 

occurs in shallow soil 

over moist calcareous 

sands, gravel and beach 

rubble. Sunlight is one 

of the most critical 

factors to the growth 

and reproduction of the 

species and partly 

shaded or sheltered 

forest edges are optimal 

for sexual reproduction. 

Some form of 

disturbance is also 

required to maintain the 

forest openings that 

provide these partial 

shade conditions. The 

species is most often 

associated with 

shoreline coniferous 

forests dominated by 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

shoreline coniferous 

forests.

USFWS. 2013. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/

DLI%20RP%20FINAL%20A

UG2013_1.pdf
89

Species Habitat Rationale Source 

northern white cedar 

and balsam fir. The 

principal limiting factor 

for dwarf lake iris is the 

availability of this 

suitable shoreline 

habitat (US FWS, 2013, 

pp. 6-7).

Ladies'-tresses, 

Ute (Spiranthes 

diluvialis)

Occurs in relatively low 

elevation riparian, 

spring, and lakeside 

wetland meadows. 

Endemic to mois soils 

in mesic or wet 

meadows near springs, 

lakes, or perrenial 

streams. Occur 

primarily in areas where 

the vegetation is 

relatively open and not 

overly dense or 

overgrown, but some 

populations are found in 

riparian woodlands. 

Observed to be shadeintolerant (US FWS, 

1995). 

Occurs in relatively low 

elevation riparian, 

spring, and lakeside 

wetland meadows. 

Endemic to moist soils 

in mesic or wet 

meadows near springs, 

lakes, or perennial 

streams. Occur 

primarily in areas where 

the vegetation is 

relatively open and not 

overly dense or 

overgrown, but some 

populations als found in 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

riverine, spring, or 

lakeside wet meadows. 

USFWS. 1995. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/950921.pdf

USFWS. Species Profile 

Page. 

http://ecos.fws.gov/speciesPr

ofile/profile/speciesProfile.act

ion?spcode=Q2WA
90

Species Habitat Rationale Source 

riparian woodlands. 

Observed to be shadeintolerant (US FWS, 

Species Profile Page).

Lichen, rock 

gnome 

(Gymnoderma 

lineare)

Rock gnome lichen is 

primarily limited to 

vertical rock faces 

where seepage water 

from forest soils above 

flows during (and only 

during) very wet times. 

It appears the species 

needs a moderate 

amount of light, but that 

it cannot tolerate highintensity solar radiation. 

It does well on moist, 

generally open, sites, 

with northern 

exposures, but needs at 

least partial canopy 

coverage where the 

aspect is southern or 

western

Rock gnome lichen is 

known from the 

Southern Appalachian 

Mountains of North 

Carolina and South 

Carolina, Tennessee, 

and Georgia, in areas of 

high humidity, either at 

high elevations, where 

it is frequently bathed 

in fog, or in deep 

gorges at lower 

elevations.

The proposed dicamba 

DGA uses are not 

expected to overlap with 

high elevation vertical 

rock faces where the 

species occurs.

http://www.fws.gov/raleigh/s

pecies/es_rock_gnome_lichen

.html

Lily, Minnesota 

dwarf trout 

(Erythronium 

propullans)

The Minnesota dwarf 

trout lily is most 

commonly found in the 

lower parts of wooded 

north-facing slopes, and 

on adjacent floodplains. 

Sites are associated 

either with streams or 

abandoned stream 

channels, dominated by 

deciduous trees. It may 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

woodlands or 

floodplains. 

USFWS. 1987. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/060309c.pdf
91

Species Habitat Rationale Source 

be intolerant of shade 

(US FWS, 1987). 

Locoweed, 

Fassett's 

(Oxytropis 

campestris var. 

chartacea)

Fassett’s locoweed 

grows along the 

shorelines of small, 

landlocked, hardwater 

lakes where the bedrock 

is overlain by sandy 

glacial drift. Nearly all 

lakes with historical 

populations of the 

species are less than 15 

ha in size and occur at 

approximately 350 m 

elevation. Dependent 

upon groundwater 

seepage for their water 

supply, most are 

shallow (maximum 

depth of a few meters) 

and subject to frequent, 

large fluctuations in 

water level. 

Fassett’s locoweed is 

found along the lakes 

on open shoreline and, 

to a lesser extent, on 

higher ground under the 

partial shade of adjacent 

vegetation. I t grows on 

gentle, sandgravel 

slopes and is absent 

from flat, low, mucky 

shorelines dominated 

by cattails and 

bulrushes. Because of 

periodic fluctuations in 

lake levels, the amount 

of exposed, open 

shoreline varies, from 

being virtually 

nonexistent during 

times of high water, to 

about 30 m wide when 

the water level is low. 

In all cases, Fassett’s 

locoweed occurs in 

areas which are 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

the shorelines of lakes.

USFWS. 1991. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/910329.pdf
92

Species Habitat Rationale Source 

completely exposed to 

sunlight or receive only 

partial shade from other 

species. (US FWS, 

1991, pp.4-5).

Milkweed, 

Mead's 

(Asclepias 

meadii)

Mead’s milkweed 

occurs primarily in 

tallgrass prairie with a 

late successional bunchgrass structure, but also 

occurs in hay meadows 

and in thin soil glades 

or barrens. This plant is 

essentially restricted to 

sites that have never 

been plowed and only 

lightly grazed, and hay 

meadows that are 

cropped annually for 

hay (US FWS, 2003, p. 

9).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

tallgrass prairies, hay 

meadows, or thing soil 

glades or barrens.

USFWS. 2003. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/030922b.pdf

Monkshood, 

northern wild 

(Aconitum 

noveboracense)

Typical habitat is 

shaded to partially 

shaded cliffs and talus 

slopes or in New York, 

also occurs in semishaded seepage springs 

at high elevation 

headwaters. Various 

bedrock types from 

sandstones to dolomite 

and others act as 

substrates. All habitats 

have a cold soil 

environment associated 

with active and 

continuous cold air

drainage or cold ground 

water flowage out of 

the nearby bedrock. 

Typically cliff and talus 

slope populations are 

associated with 

openings or caves, often 

ice-filled, through 

which the cold air 

emanates (US FWS, 

1983, p. 18-20).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

cliffsides, rockfalls at 

cliff bases or springs 

associated with cold air 

or water.

USFWS. 1983. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/830923.pdf
93

Species Habitat Rationale Source 

Orchid, eastern 

prairie fringed 

(Platanthera 

leucophaea)

The eastern prairie 

fringed orchid occurs in 

a wide variety of 

habitats, from mesic 

prairie to wetland 

communities such as 

sedge meadows, marsh 

edges and even fens and 

sphagnum bogs. It 

requires full sunlight for 

optimum growth and 

flowering, which 

restricts it to grass- and 

sedge-dominated plant 

communities. The 

substrate of the sites 

where it occurs ranges 

from more or less 

neutral to mildly 

calcareous, typically 

glacial soils. It is often 

early successional, but 

can be maintained in 

mid- to late 

successional wetlands 

that remain open and 

sunny (US FWS, 1999, 

pp. 6-7).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

grass or sedgedominated plant 

communities.

USFWS. 1999. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/990929.pdf

Orchid, western 

prairie fringed 

(Platanthera 

praeclara)

The western prairiefringed orchid occurs 

primarily in tall grass 

prairies dominated by 

bluestem grass and in 

sedge meadows that are 

seasonally wet (US 

FWS, 1996, p. 6). They 

also may occur in 

successional 

communities such as 

borrow pits, old fields, 

and roadside ditches 

(US FWS, 1996, p. 4).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

prairie, meadow areas, 

roadside ditches, borrow 

pits or abandoned fields.

USFWS. 1996. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/960930a.pdf

Penstemon, 

blowout 

(Penstemon 

haydenii)

This species grows in 

depressions in the 

topography caused by 

wind erosion. 

Vegetation associated 

with blowouts is 

distinctly different than 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

sandy slough slopes or 

dunes. 

USFWS. 1992. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/920717.pdf
94

Species Habitat Rationale Source 

vegetation associated 

with adjacent, noneroding areas.

In Wyoming, blowout 

penstemon is found 

primarily on the rim 

and lee slopes of 

blowouts, or the rim 

and steep faces of sandy 

slough slopes. 

These deposits are 

found at the base of 

mountains or ridges, 

which represent 

topographic barriers. 

Shifting sand dunes are 

prevented from 

becoming fully 

stabilized and 

overgrown because of 

wind and gravity. 

The dunes may be 60 to 

120 feet high (US FWS, 

1992). 

Pitcher-plant, 

green 

(Sarracenia 

oreophila)

Habitats for this species 

can be generally 

grouped into two types: 

stream banks 

(considered ephemeral) 

and upland bogs. 

Upland bogs, fire 

dependent, range from 

open to forested, 

underlain by semiimpervious clay layers 

(US FWS, 1994). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

stream banks or upland 

bogs. 

USFWS. 1994. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/941212.pdf

Pogonia, small 

whorled (Isotria 

medeoloides)

The small whorled 

pogonia occurs on 

upland sites in mixeddeciduous or mixed 

deciduous/coniferous 

forests that are 

generally in second- or 

third-growth 

successional stages. It 

occurs on both fairly 

young and maturing 

forest stands. Most 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

mixed 

deciduous/coniferous 

forests.

USFWS. 1992. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/921113b.pdf
95

Species Habitat Rationale Source 

occurrences include 

sparse to moderate 

ground cover in the 

species’ microhabitat, a 

relatively open 

understory canopy, and 

proximity to features 

that create long 

persisting breaks in the 

forest canopy. Soils at 

most sites are highly 

acidic and nutrient 

poor, with moderately 

high soil moisture 

values. Light 

availability could be a 

limiting factor for this 

species. The one 

Illinois site is unusual 

in being on a dry, steep, 

thinly forested slope 

atop a vertical 

sandstone bluff. The 

one Ohio site is along 

the Ohio River in a 

typical Appalachiantype forest association 

(US FWS, 1992, pp. 

23-24).

Pondberry 

(Lindera 

melissifolia)

Associated with 

seasonally flooded 

wetlands. Found on 

wet edges of sandy 

sinks, ponds, and 

swampy depressions. 

Shade tolerant (US 

FWS, 1993). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

wetlands. 

USFWS. 1993. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/930923a.pdf

Potato-bean, 

Price's (Apios 

priceana)

Found in open forests 

along the edges of 

forests, creeks, and 

rivers (US FWS, 1993, 

p. executive summary).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

forests, or water bodies.

USFWS. 1993. Recovery 

Plan

http://ecos.fws.gov/docs/reco

very_plan/930210.pdf

Prairie-clover, 

leafy (Dalea 

foliosa)

Leafy prairie-clover is 

found only in open 

limestone cedar glades, 

limestone barrens, and 

dolomite prairies which 

have shallow, silt to 

silty clay loam soils 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

prairies or areas with 

visible bedrock.

USFWS. 1996. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/900919b.pdf
96

Species Habitat Rationale Source 

over flat and often 

highly fractured, 

horizontally bedded 

limestone or dolomite 

with frequent expanses 

of exposed bedrock at 

surface. Elevations are 

typically between 550 

and 700 feet. These 

habitats experience high 

surface and soil 

temperatures, generally 

have low soil moisture 

but are wet in the spring 

and fall and become 

droughty in summer. 

The distribution of 

glade, barren, and dry 

to wet dolomite prairie 

at any particular site 

varies and leads to a 

mosaic of soils and

their associated plant 

communities (USFWS, 

1996, p.13).

Quillwort, 

Louisiana 

(Isoetes 

louisianensis)

This species grows in 

sandy soils and gravel 

bars in or near shallow 

blackwater streams and 

overflow channels in 

riparian woodland. 

bayhead forests of fine 

flatwoods and upland 

longleaf pine (US FWS, 

1996). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

streams, overflow 

channels, or riparian 

woodlands. 

USFWS. 1996. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/960930b.pdf

Rock-cress, 

Braun's (Arabis 

perstellata)

Braun’s rockcress 

occurs on the slopes of 

calcareous mesophytic 

and sub-xeric forest 

types. The occurrence 

of this species does not 

appear to be limited to a 

particular slope aspect, 

elevation, or moisture 

regime within the slope 

forests. It is, however, 

sun intolerant and 

always occurs in at least 

partial shade. The 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

calcareous mesophytic 

and sub-xeric forested 

systems. 

USFWS. 1997. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/970722.pdf
97

Species Habitat Rationale Source 

largest and most 

vigorous populations 

occur on moist mid- to 

upper slope sites. Plants 

are often found around 

rock outcrops, protected 

sites on the downslope 

side of tree bases, and 

sites of natural 

disturbance, such as 

talus slopes and animal 

trails. It is rarely found 

growing among the

Leaf litter and 

herbaceous cover of the 

forest floor (US FWS, 

1997). 

Rosemary, 

Cumberland 

(Conradina 

verticillata)

This species is found on 

rocky river bars 

composed of unsorted 

boulders, cobbles, 

gravel and sand, with 

the largest populations 

occurring in open, 

washed-out areas near 

the centers of these 

bars. The essential 

habitat requirements of 

this species are: open to 

barely shaded sites; 

moderately deep, sandy, 

well-drained soils with 

no visible organic 

matter; periodic 

forceful flooding to 

maintain openness; 

topographic features to 

enhance sand 

deposition; and, 

perhaps, periods of 

inundation of at least 

two weeks to induce 

rooting at the lower 

nodes (pg. 8) (US FWS, 

2011). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers. 

USFWS. 2011. Five Year 

Review. 

http://ecos.fws.gov/docs/five_

year_review/doc3629.pdf

Roseroot, 

Leedy's 

(Rhodiola 

New York populations 

occur on cliffs along the 

western shore of Seneca 

lake. In Minnesota, 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

cliffs. 

USFWS. 1998. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/980925.pdf
98

Species Habitat Rationale Source 

integrifolia ssp. 

leedyi)

populations occur on

moderate cliffs, which 

are cooled by air exiting 

underground passages 

in the karst topography 

(US FWS, 1998).

Sandwort, 

Cumberland 

(Arenaria 

cumberlandensi

s)

This species is 

restricted to sandstone 

rock houses, ledges, and 

solution pockets on 

sandstone rock faces; 

The species is found on 

the sandy floors of rock 

houses, in solution 

pockets on the face of 

sandstone cliffs, and on 

ledges beneath 

overhanging sandstone 

(pg. 4) (US FWS, 

1996). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

sandstone rock houses, 

ledges, or rock faces. 

USFWS. 1996. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/960620.pdf

Skullcap, largeflowered 

(Scutellaria 

montana)

This species occurs in 

slope, ravine, and 

stream-bottom forests 

in northwestern Georgia 

and adjacent 

southeastern Tennessee. 

Habitat loss and lack of 

information on 

appropriate 

management are the 

factors limiting the 

number of viable 

populations (US FWS, 

1996). 

The proposed dicamba 

DGA uses are not 

expected to overlap with 

ravine and streambottom forests. 

USFWS. 1996. Recovery 

Plan. 

http://ecos.fws.gov/docs/reco

very_plan/960515.pdf

Sneezeweed, 

Virginia 

(Helenium 

virginicum)

Seasonal wetlands, sink 

hole ponds varying 

from forest settings to 

farm pond margins.

The proposed dicamba 

DGA uses are not 

expected to overlap sink 

hole ponds and seasonal 

wetlands.

http://ecos.fws.gov/docs/reco

very_plan/001002.pdf
99

Species Habitat Rationale Source 

Spiraea, 

Virginia 

(Spiraea 

virginiana)

Spiraea virginiana is 

found along the banks 

of high gradient 

sections of second and 

third order streams, or 

on meander scrolls and 

point bars, natural 

levees, and other 

braided features of 

lower reaches (often 

near the stream mouth). 

The habitat is in oftdisturbed early 

successional areas. 

Occasional flood 

scouring reduces 

shading and seems to be 

essential, although the 

spiraea can tolerate 

some overstory growth 

(US FWS, 1992, pp.17-

18.).

The proposed dicamba 

DGA uses are not 

expected to overlap with 

rivers, streams, creeks, 

or other water bodies.

USFWS. 1992. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/921113a.pdf

Thistle, 

Pitcher's 

(Cirsium 

pitcheri)

It occurs on nonforested sand dunes of 

several types (grassland 

dunes, simple linear 

beach foredunes, 

continuous and 

discontinuous dune 

complexes), sand 

beaches, and sandy 

blowouts, primarily 

occurring around the 

Great Lakes (US FWS, 

2002, p. 23-27).

The proposed dicamba

DGA uses are not 

expected to overlap with 

sand dunes, sand 

beaches, or sandy 

blowouts.

USFWS. 2002. Recovery 

Plan.

http://ecos.fws.gov/docs/reco

very_plan/020920b.pdf
100

Appendix 3. Designated Critical Habitat Modification Determinations

In addition to the species-specific effects determinations, EFED also conducted a critical habitat 

modification analysis consistent with the Overview Document (USEPA, 2004) as discussed earlier in this 

refined assessment. The critical habitat modification analysis is based on an assessment of how dicamba 

DGA salt would affect the U.S. Fish and Wildlife or National Marine Fisheries Service (the Services) 

established principle constituent elements (PCE’s) of the designated habitat as well as how direct species 

effects outcomes would impact critical habitat’s present and future utility for promoting the conservation 

of a particular listed species. The Agency will conclude ‘modification’ of designated critical habitat if the 

range of designated critical habitat co-occurs with the states subject to the Federal action and one or more 

of the following conditions exist:

1. The available Services’ information indicates that cotton or soybean fields are habitat for the 

species and there is a “may affect” determination for the species associated with exposure to Dicamba 

DGA salt or its degradate DCSA, as labeled.

2. The available Services’ information indicates that the species uses cotton or soybean fields and 

one or more effects on taxonomic groups predicted for dicamba DGA salt or its degradate DCSA, on 

cotton or soybean fields would modify one or more of the designated PCEs.

If the above conditions are not met, EPA concludes ‘no modification.’

Results of Analysis

Of the 183 listed species within the 16 states there are 173 species identified in the effects determinations 

as not using cotton or soybean fields and 10 species using these fields. Critical habitats have been 

designated for 59 of the 183 species. Fifty-three species with critical habitat were judged to not use 

cotton or soybean fields and so the critical habitat determination for these was no modification. The 

remaining 6 species with critical habitat designations were assumed to use cotton or soybean fields and so 

the previous listed species effects determinations were consulted to ascertain if any were determined to be 

at risk for direct adverse effects. None of the species were determined to be at risk for direct adverse 

effects, so the PCE’s listed in the Services’ critical habitat designations were consulted to determine if, in 

light of the screening assessment risk findings, they would be impacted by on-field exposure to dicamba 

DGA salt. For all but one of these species, the PCE’s are not relatable to agricultural fields and so a 

determination of no modification has been made for these 5 species. 

The only species using cotton or soybean fields and with critical habitat PCE’s relatable to agricultural 

fields was the whooping crane, for which agricultural fields were discussed as providing waste grain as a 

potential food source for migratory cranes. The potential pathway for applications of dicamba DGA salt 

to affect this PCE is by making grain potentially toxic to the birds. Because there is unlikely to be any 

edible waste grain remaining following cotton harvesting, it is unlikely that the proposed dicamba DGA 

salt use on cotton could affect this PCE. However, the proposed use on soybean could affect this PCE by 

making waste soybean grain potentially toxic.

The Health Effect Division summarized available soybean grain residues of dicamba in the Human Health 

Risk Assessment for the Registration Eligibility Decision for Dicamba and Associated Salts (DP317703). 

Based on the soybean trials results, maximum residues of dicamba were 0.04 ppm in hay, 0.097 ppm in 

forage, and 8.13 ppm in seed 6-8 days post treatment (MRIDs 43814101 and 44089307). These measured 

values were used to set the tolerance value of 10 ppm for soybean seeds. The measured residues are not 
101

reasonably expected to be at a level raising a concern for direct effects to the whooping crane because the 

direct effects assessment for this species (presented on pages 9-10 of this assessment) did not establish a 

concern for residues in other dietary items at much higher (~ 1 order of magnitude) concentrations than 

would occur at the maximum measured residues in seed or if residues were present even at the tolerance 

level of 10.0 ppm. Because this analysis shows no direct effects of dicamba at levels that would be 

expected in the fields as waste grain, an indirect effect, there is no modification of critical habitat. 

Similarly, measured DCSA residues in waste soybean grain (0.44 ppm) would be well below the 

estimated DCSA concentrations in arthropods (42.5 ppm) used in the direct effects assessment for this

species (pp 9-10). Therefore, whooping crane critical habitat within the 16 states would not be modified.

Summary of Determinations for Critical Habitat

The Agency has determined that the proposed labeled use of dicamba DGA salt on cotton and soybeans 

will not modify designated critical habitat for the 59 species for which such habitats have been 

designated in AR, IL, IN, IA, KS, LA, MN, MS, MO, NE, ND, OH, OK, SD, TN, and WI.

Summary of listed species identified as not being on agricultural fields with and without critical habitat 

designations for the first 16 states assessed for dicamba DGA salt

Critical Habitat Designation Species Name

Species with Critical Habitat 

Designations (53 Species)2

Bean, Purple (Villosa perpurpurea)

Butterfly Plant, Colorado (Gaura neomexicana var.

coloradensis)

Butterfly, Karner Blue (Lycaeides melissa samuelis)

Cavesnail, Tumbling Creek (Antrobia culveri)

Chub, Slender (Erimystax cahni) 

Chub, Spotfin (Erimonax monachus)

Clubshell, Ovate (Pleurobema perovatum)

Clubshell, Southern (Pleurobema decisum)

Combshell, Cumberlandian (Epioblasma brevidens)

Combshell, Upland (Epioblasma metastriata)

Dace, Laurel (Chrosomus saylori)

Darter, Amber (Percina antesella)

Darter, Cumberland (Etheostoma susanae)

Darter, Leopard (Percina pantherina)

Darter, Niangua (Etheostoma nianguae)

Darter, Slackwater (Etheostoma boschungi)

Darter, Snail (Percina tanasi)

Darter, Yellowcheek (Etheostoma moorei)

Dragonfly, Hine's Emerald (Somatochlora hineana)

Elktoe, Appalachian (Alasmidonta raveneliana)

Elktoe, Cumberland (Alasmidonta atropurpurea)

Frog, Dusky Gopher (Rana sevosa)

Kidneyshell, Fluted (Ptychobranchus subtentum)

Kidneyshell, Triangular (Ptychobranchus greenii)

Logperch, Conasauga (Percina jenkinsi)

Lynx, Canada (Lynx canadensis)

 2 Critical habitat designation status determined using U.S. Fish & Wildlife Service’s Environmental Conservation 

Online System (ECOS) species profiles. 
102

Critical Habitat Designation Species Name

Madtom, Chucky (Noturus crypticus)

Madtom, Smoky (Noturus baileyi)

Madtom, Yellowfin (Noturus flavipinnis)

Manatee, West Indian (Trichechus manatus)

Moccasinshell, Alabama (Medionidus acutissimus)

Moccasinshell, Coosa (Medionidus parvulus)

Mucket, Neosho (Lampsilis rafinesqueana)

Mucket, Orangenacre (Lampsilis perovalis)

Mussel, Oyster (Epioblasma capsaeformis)

Pearlymussel, Slabside (Pleuronaia dolabelloides)

Pigtoe, Georgia (Pleurobema hanleyianum)

Pigtoe, Southern (Pleurobema georgianum)

Plover, Piping (Great Lakes DPS, Northern Great Plains DPS) 

(Charadrius melodus) 

Rabbitsfoot (Quadrula cylindrica cylindrica) 

Rabbitsfoot, Rough (Quadrula cylindrica strigillata)

Rock-Cress, Braun's (Arabis perstellata)

Sculpin, Grotto (Cottus sp.)

Sea Turtle, Green (Chelonia mydas)

Sea Turtle, Hawksbill (Eretmochelys imbricata)

Sea Turtle, Kemp's Ridley (Lepidochelys kempii)

Sea Turtle, Leatherback (Dermochelys coriacea)

Sea Turtle, Loggerhead Northwest Atlantic DPS (Caretta 

caretta)

Shiner, Arkansas River (Notropis girardi)

Shiner, Topeka (Notropis topeka (=tristis))

Spruce-Fir Moss Spider (Microhexura montivaga)

Sturgeon, Gulf (Acipenser oxyrinchus desotoi)

Tiger Beetle, Salt Creek (Cicindela nevadica lincolniana) 

Species without Critical Habitat 

Designations (123 species)

Acornshell, Southern (Epioblasma othcaloogensis)

Amphipod, Illinois Cave (Gammarus acherondytes) 

Aster, Decurrent False (Boltonia decurrens)

Aster, Ruth's Golden (Pityopsis ruthii)

Avens, Spreading (Geum radiatum)

Bat, Gray (Myotis grisescens)

Bean, Cumberland (pearlymussel) (Villosa trabalis)

Bladderpod, Missouri (Physaria filiformis)

Blossom, Green (pearlymussel) (Epioblasma torulosa 

gubernaculum)

Blossom, Tubercled (pearlymussel) (Epioblasma torulosa 

torulosa)

Blossom, Turgid (pearlymussel) (Epioblasma turgidula)

Blossom, Yellow (pearlymussel) (Epioblasma florentina 

florentina)

Bluet, Roan Mountain (Hedyotis purpurea var. montana)

Bush-Clover, Prairie (Lespedeza leptostachya)

Butterfly, Mitchell's Satyr (Neonympha mitchellii mitchellii) 

Catspaw , White (Epioblasma obliquata perobliqua) 
103

Critical Habitat Designation Species Name

Cavefish, Ozark (Amblyopsis rosae)

Chaffseed, American (Schwalbea americana)

Clover, Running Buffalo (Trifolium stoloniferum)

Clubshell (Pleurobema clava) 

Clubshell, Black (Pleurobema curtum)

Combshell, Southern (Epioblasma penita)

Crayfish, Cave (Cambarus aculabrum)

Crayfish, Cave (Cambarus zophonastes) 

Crayfish, Nashville (Orconectes shoupi) 

Dace, Blackside (Phoxinus cumberlandensis)

Daisy, Lakeside (Hymenoxys acaulis var. glabra (herbacea)) 

Darter, Bayou (Etheostoma rubrum)

Darter, Bluemask (=jewel) (Etheostoma sp.)

Darter, Boulder (Etheostoma wapiti)

Darter, Duskytail (Etheostoma percnurum)

Disc, Iowa Pleistocene (Discus macclintocki) 

Fanshell (Cyprogenia stegaria) 

Fatmucket, Arkansas (Lampsilis powellii)

Fern, American Hart's-Tongue (Asplenium scolopendrium var. 

americanum)

Ferret, Black-Footed (Mustela nigripes)

Geocarpon minimum (No common name)

Goldenrod, Blue Ridge (Solidago spithamaea)

Goldenrod, Short's (Solidago shortii) 

Grass, Tennessee Yellow-Eyed (Xyris tennesseensis)

Ground-Plum, Guthrie's (=Pyne's) (Astragalus bibullatus)

Harperella (Ptilimnium nodosum)

Heelsplitter, Alabama (=inflated) (Potamilus inflatus)

Hellbender, Ozark (Cryptobranchus alleganiensis bishopi)

Higgins Eye Pearlymussel (Lampsilis higginsii) 

Iris, Dwarf Lake (Iris lacustris) 

Lampmussel, Alabama (Lampsilis virescens)

Lichen, Rock Gnome (Gymnoderma lineare)

Lilliput, Pale (pearlymussel) (Toxolasma cylindrellus)

Lily, Minnesota Dwarf Trout (Erythronium propullans)

Locoweed , Fassett's (Oxytropis campestris var. chartacea) 

Madtom, Neosho (Noturus placidus)

Madtom, Pygmy (Noturus stanauli)

Madtom, Scioto (Noturus trautmani) 

Marstonia, Royal (snail) (Pyrgulopsis ogmorhaphe)

Milkweed, Mead's (Asclepias meadii) 

Monkeyface, Appalachian (pearlymussel) (Quadrula sparsa)

Monkeyface, Cumberland (pearlymussel) (Quadrula 

intermedia)

Monkshood, Northern Wild (Aconitum novoboarense) 

Mucket, Pink (pearlymussel) (Lampsilis abrupta)

Mussel, Mapleleaf Winged (Quadrula fragosa) 

Mussel, Scaleshell (Leptodea leptodon) 
104

Critical Habitat Designation Species Name

Mussel, Sheepnose (Plethobasus cyphyus)

Mussel, Snuffbox (Epioblasma triquetra) 

Orchid , Western Prairie White-fringed (Platanthera 

praeclara) 

Orchid, Eastern Prairie White-fringed (Platanthera 

leucophaea) 

Pearlshell, Louisiana (Margaritifera hembeli)

Pearlymussel, Birdwing (Lemiox rimosus)

Pearlymussel, Cracking (Hemistena lata)

Pearlymussel, Curtis (Epioblasma florentina curtisii)

Pearlymussel, Dromedary (Dromus dromas)

Pearlymussel, Fat Pocketbook (Potamilus capax) 

Pearlymussel, Littlewing (Pegias fabula)

Penstemon, Blowout (Penstemon haydenii)

Pigtoe, Cumberland (Pleurobema gibberum)

Pigtoe, Finerayed (Fusconaia cuneolus)

Pigtoe, Flat (Pleurobema marshalli)

Pigtoe, Rough (Pleurobema plenum) 

Pigtoe, Shiny (Fusconaia cor)

Pimpleback, Orangefoot (Plethobasus cooperianus) 

Pitcher-Plant, Green (Sarracenia oreophila)

Pocketbook, Ouachita Rock (Arkansia wheeleri)

Pocketbook, Speckled (Lampsilis streckeri)

Pogonia, Small Whorled (Isotria medeoloides) 

Pondberry (Lindera melissifolia)

Potato-Bean, Price's (Apios priceana)

Prairie-Clover, Leafy (Dalea foliosa) 

Purple Cat's Paw (Epioblasma obliquata obliquata) 

Quillwort, Louisiana (Isoetes louisianensis)

Rayed Bean (Vilosa fabalis) 

Riffleshell, Northern (Epioblasma torulosa rangiana) 

Riffleshell, Tan (Epioblasma florentina walkeri (=E. walkeri))

Ring Pink (mussel) (Obovaria retusa)

Riversnail, Anthony's (Athearnia anthonyi)

Rosemary, Cumberland (Conradina verticillata)

Roseroot, Leedy's (Rhodiola integrifolia ssp. leedyi)

Sandwort, Cumberland (Arenaria cumberlandensis)

Sawfish, Smalltooth (Pristis pectinata)

Shiner, Blue (Cyprinella caerulea)

Skullcap, Large-Flowered (Scutellaria montana)

Snail, Painted Snake Coiled Forest (Anguispira picta)

Sneezeweed, Virginia (Helenium virginicum)

Spectaclecase Mussel (Cumberlandia monodonta) 

Spiraea, Virginia (Spiraea virginiana) 

Squirrel, Carolina Northern Flying (Glaucomys sabrinus 

coloratus)

Stirrupshell (Quadrula stapes)

Sturgeon, Pallid (Scaphirhynchus albus)
105

Critical Habitat Designation Species Name

Tern, Least (Sterna antillarum) 

Thistle, Pitcher's (Cirsium pitcheri) 

Turtle, Ringed Map (Graptemys oculifera)

Turtle, Yellow-Blotched Map (Graptemys flavimaculata)

Ute, Ladies'-Tresses, (Spiranthes diluvialis)

Vireo, Black-Capped (Vireo atricapilla)

Warbler, Kirtland's (Dendroica kirtlandii) 

Wartyback, White (pearlymussel) (Plethobasus cicatricosus)

Watersnake, Northern Copperbelly (Nerodia erythrogaster 

neglecta) 

Whale, Finback (Balaenoptera physalus)

Whale, Humpback (Megaptera novaeangliae)

Woodpecker, Red-Cockaded (Picoides borealis)

Summary of listed species identified as being on agricultural fields with and without critical habitat 

designations for the first 16 states assessed for dicamba DGA salt:

Species Name Primary Constituent Elements (PCE) Source

Species with Critical Habitat Designations (6 Species)3

Bat, Indiana 

(Myotis sodalis)

PCE: Shelter during winter hibernation.

Critical habitat designations are either mines or caves.

http://ecos.fws.gov/doc

s/federal_register/fr161

.pdf

http://ecos.fws.gov/doc

s/federal_register/fr83.

pdf

Bat, Ozark 

(Corynorhinus 

townsendii ingens) 

PCE: Not specified.

Critical habitat designations are caves.

http://ecos.fws.gov/doc

s/federal_register/fr171

.pdf

Bear, Louisiana 

Black 

(Ursus 

americanus 

luteolus)

PCE: Habitat components that provide: 

(i) Breeding habitat (i.e., within or contiguous to the 

home range of females in a core breeding population) 

consisting of hardwood forest areas having a diversity

of age class and species and containing sources of hard 

mast (acorns and nuts) produced by such species as 

mature oaks, hickories, and pecan, and that may 

include one or more of the following:

(A) Areas containing soft mast provided by a diversity 

of plant species, including, but not limited to, 

blackberry, grape, mulberry, sassafras, paw paw, etc., 

occurring primarily in forest openings, on spoil banks, 

and in areas adjacent to forested habitat.

(B) Areas within forested habitat providing protein 

sources consisting of beetles and other colonial insects 

found in rotting and decaying wood found on the forest 

floor.

http://www.gpo.gov/fds

ys/pkg/FR-2009-03-

10/pdf/E9-

4536.pdf#page=1

 3 Critical habitat designation status determined using U.S. Fish & Wildlife Service’s Environmental Conservation 

Online System (ECOS) species profiles. 
106

Species Name Primary Constituent Elements (PCE) Source

(C) Grasses and sedges found in forest openings, on 

spoil banks with open canopies, and in vegetated areas 

adjacent to forested habitats.

(D) Secure areas for reproduction, winter dormancy, 

day bedding, and escape. These include areas with den 

trees (e.g., bald cypress, overcup oak, American 

sycamore, etc.); areas with a thick understory, shrubscrub habitat,

openings along spoil banks, vegetated areas adjacent to 

forests, or any vegetation that provides cover, limits 

visibility, slows foot travel, or creates noise when 

traversed; early successional forests (0 to 12 years) 

with an open canopy and dense understory of shrubs, 

vines, and saplings; or areas with vegetation such as 

palmetto, greenbriars, blackberry, dewberry, and 

downed trees.

(ii) Corridors consisting of:

(A) Habitat patches 12 acres (5 hectares) or greater in 

size; or

(B) Forested areas greater than 150 feet (46 meters) 

wide along waterways and sloughs and having a 

diversity of plant species and age-classes of sufficient 

area, quality, and configuration, as described in 

paragraph (2)(i) of this entry, to provide dispersal 

habitat between breeding populations to maintain 

genetic variability and promote stable or increasing 

populations, and to provide habitat supporting safe 

movement, foraging, and denning.

Crane, Mississippi 

Sandhill 

(Grus canadensis 

pulla)

PCE: Not specified. http://ecos.fws.gov/doc

s/federal_register/fr150

.pdf

Crane, Whooping 

(Grus Americana)

PCE: All areas proposed in this rule would provide 

food, water, and other nutritional or physiological 

needs of the whooping crane during spring or fall 

migration. (1) Insects, crayfish, frogs, small fish, and 

other small animals as well as some aquatic vegetation 

and some cereal crops in adjacent croplands appear to 

be major items taken during the migration period. 

Consumption of some cereal crops in adjacent 

croplands during migration period. (2) Require an open 

expanse for nightly rooting, especially sand and gravel 

bars or very shallow water in rivers and lakes. (3) 

Whooping cranes are territorial and require several 

acres of undisturbed wetlands. (4) Potential nesting 

habitat.

http://ecos.fws.gov/doc

s/federal_register/fr237

.pdf

http://ecos.fws.gov/doc

s/federal_register/fr214

.pdf

Wolf, Gray 

(Canis lupis)

PCE: Not specified. http://ecos.fws.gov/doc

s/federal_register/fr186

.pdf
107

Species Name Primary Constituent Elements (PCE) Source

Species without critical habitat designations (4 species)

Beetle, American 

burying

(Nicrophorus 

americanus)

No critical habitat rules have been published. n/a

Bladderpod, 

Spring Creek 

(Lesquerella 

perforata)4

No critical habitat rules have been published. n/a

Prairie-chicken, 

Lesser 

(Tympanuchus 

pallidicinctus)

No critical habitat rules have been published. n/a

Tortoise, Gopher 

(Gopherus 

polyphemus)

No critical habitat rules have been published. n/a

 4 Bold text indicates assessed species with “may effect, likely to adversely affect” determination.
108

Appendix 4. Foliar Half-Life Calculations

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

0.5 lb/A application

DMA+ 

Salt

FL 0 71 SFO 8.98

FL 7 35

FL 14 26

FL 28 11

FL 56 0.53

GA 0 78 TR IORE 2.89

GA 7 10

GA 14 7.1

GA 28 1.5

GA 56 0.3

IN 0 69 TR IORE 8.46

IN 7 15

IN 14 16

IN 28 4.6

IN 56 3

KS 0 81 TR IORE 6.16

KS 7 25

KS 14 11

KS 28 6.5

KS 56 2.5

MI 0 27 TR IORE 4.69

MI 7 6.9

MI 14 3

MI 28 1

MI 56 0.8

MO 0 20 SFO 7.03

MO 7 10

MO 14 4.2

MO 28 2.6

MO 56 1.8

NE 0 28 SFO 5.13

NE 7 12

NE 14 2.7
109

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

NE 28 1.3

NE 56 0.64

OK 1 0 41 SFO 2.98

OK 1 7 8

OK 1 14 1.7

OK 1 28 0.79

OK 1 56 0.75

OK 2 0 61 TR IORE 5.58

OK 2 7 15

OK 2 14 11

OK 2 28 1.8

OK 2 56 1.2

OR 0 31 TR IORE 1.14

OR 7 2

OR 14 3.6

OR 28 3.7

OR 56 1.3

TN 0 20 TR IORE 3.18

TN 7 2.2

TN 14 2.5

TN 28 0.71

TN 56 0.74

TX 0 35 SFO 4.42

TX 7 11

TX 14 4.5

TX 28 1.9

TX 56 3.2

WI 0 39 TR IORE 4.3

WI 7 9

WI 14 4.3

WI 28 1

WI 56 0.74

DGA+ 

Salt

GA 0 55 TR IORE 3.18

GA 7 6.3

GA 14 7.7

GA 28 1.1
110

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

GA 56 0.21

MO 0 22

MO 7 10

MO 14 5.8

MO 28 5.9

MO 56 1.4

OK 1 0 32 TR IORE 1.84

OK 1 7 2.6

OK 1 14 2.8

OK 1 28 1.3

OK 1 56 0.34

OR 0 20 SFO 3.77

OR 7 1.6

OR 14 8

OR 28 2.2

OR 56 0.59

WI 0 45 TR IORE 2.53

WI 7 5.5

WI 14 2.4

WI 28 1.2

WI 56 0.45

Na+ Salt GA 0 57 SFO 6.9

GA 7 41

GA 14 4.3

GA 28 1.4

GA 56 1

MO 0 25 TR IORE 11

MO 7 9.3

MO 14 6.6

MO 28 3.4

MO 56 0.92

OK 1 0 23 TR IORE 7.23

OK 1 7 9.2

OK 1 14 4.1

OK 1 28 2.4

OK 1 56 0.33
111

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

OR 0 29 TR IORE 2.84

OR 7 3.5

OR 14 5.5

OR 28 2.8

OR 56 3.3

WI 0 42 TR IORE 2.67

WI 7 5.2

WI 14 3.1

WI 28 0.68

WI 56 0.38

DMA+ 

Salt

FL 0 76 SFO 12.3

FL 7 36

FL 14 38

FL 28 19

FL 56 1.6

GA 0 87 TR IORE 4.08

GA 7 18

GA 14 8.1

GA 28 4.3

GA 56 0.4

IN 0 102

IN 7 306

IN 14 48

IN 28 16

IN 56 2.6

KS 0 49 TR IORE 12.1

KS 7 28

KS 14 18

KS 28 8.6

KS 56 2.4

MI 0 44 TR IORE 4.75

MI 7 11

MI 14 3.7

MI 28 3.1

MI 56 1.2

MO 0 42 TR IORE 6.93
112

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

MO 7 5.7

MO 14 5.8

MO 28 4.5

MO 56 2.2

NE 0 54 TR IORE 3.84

NE 7 12

NE 14 4.5

NE 28 1.4

NE 56 0.74

OK 1 0 47 SFO 5.02

OK 1 7 20

OK 1 14 4

OK 1 28 1.7

OK 1 56 0.36

OK 2 0 101 TR IORE 5.77

OK 2 7 30

OK 2 14 15

OK 2 28 6.8

OK 2 56 0.88

OR 0 11 SFO 35.2

OR 7 5.6

OR 14 3.2

OR 28 7.7

OR 56 2.9

TN 0 5

TN 7 5.9

TN 14 3.5

TN 28 3.2

TN 56 0.96

TX 0 77 TR IORE 6.67

TX 7 21

TX 14 11

TX 28 6.9

TX 56 2.9

WI 0 571 TR IORE 1.11

WI 7 21
113

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

WI 14 4.2

WI 28 4.1

WI 56 0.82

DGA+ 

Salt

FL 0 65 TR IORE 4.38

FL 7 14

FL 14 8.5

FL 28 1.8

FL 56 0.069

MI 0 29 TR IORE 17.3

MI 7 9.7

MI 14 9.8

MI 28 3.3

MI 56 2.7

NE 0 36 TR IORE 5.92

NE 7 14

NE 14 6

NE 28 2.1

NE 56 0.078

OK 2 0 9.1 SFO 28.9

OK 2 7 5.3

OK 2 14 4.1

OK 2 28 5.3

OK 2 56 2.2

TX 0 99 SFO 2.83

TX 7 18

TX 14 2.5

TX 28 4.6

TX 56 0.81

Na+ Salt FL 0 60 TR IORE 4.81

FL 7 18

FL 14 7.1

FL 28 2.5

FL 56 0.26

MO 0 51 TR IORE 8.43

MO 7 7.1

MO 14 8.9
114

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

MO 28 4.3

MO 56 3.4

OK 1 0 62 SFO 7

OK 1 7 29

OK 1 14 7.8

OK 1 28 21

OK 1 56 0.93

OR 0 14 SFO 14.9

OR 7 7.2

OR 14 4.1

OR 28 6

OR 56 2.3

WI 0 110 SFO 2.89

WI 7 21

WI 14 1.2

WI 28 1.4

WI 56 0.4

1.0 lb/A application

Dicamba 

acid

FL 0 120 TR IORE 10.3

FL 7 33

FL 14 26

FL 28 19

FL 56 0.72

GA 0 88 TR IORE 4.18

GA 7 21

GA 14 8.6

GA 28 3

GA 56 0.46

IN 0 116 TR IORE 9.81

IN 7 41

IN 14 27

IN 28 17

IN 56 1.4

KS 0 116 TR IORE 9.37

KS 7 30

KS 14 24
115

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

KS 28 14

KS 56 3.4

MI 0 75 SFO 4.74

MI 7 29

MI 14 6.5

MI 28 3.3

MI 56 1.6

MO 0 53 TR IORE 14.8

MO 7 25

MO 14 14

MO 28 11

MO 56 3.6

NE 0 34 SFO 5.36

NE 7 15

NE 14 3.9

NE 28 1.6

NE 56 0.8

OK 1 0 81 TR IORE 2.74

OK 1 7 10

OK 1 14 6.8

OK 1 28 1.2

OK 1 56 0.88

OK 2 0 119 TR IORE 5.25

OK 2 7 30

OK 2 14 17

OK 2 28 6.3

OK 2 56 1.1

OR 0 43 SFO 3.37

OR 7 5.1

OR 14 12

OR 28 7.4

OR 56 3

TN 0 78 TR IORE 1.87

TN 7 7.4

TN 14 2.4

TN 28 2.5
116

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

TN 56 1.6

TX 0 84 SFO 4.06

TX 7 25

TX 14 8

TX 28 2.6

TX 56 3.1

WI 0 64 TR IORE 5.15

WI 7 16

WI 14 9.5

WI 28 2.5

WI 56 0.9

2.0 lb/A application

DMA+ 

Salt

FL 0 206 SFO 11.5

FL 7 163

FL 14 81

FL 28 35

FL 56 1.6

FL 0 487 TR IORE 9.75

FL 7 155

FL 14 138

FL 28 53

FL 56 4.6

GA 0 251 TR IORE 4.49

GA 7 52

GA 14 36

GA 28 6.6

GA 56 0.51

GA 0 310 TR IORE 4.28

GA 7 63

GA 14 39

GA 28 10

GA 56 0.58

IN 0 240 SFO 10.2

IN 7 131

IN 14 83

IN 28 57
117

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

IN 56 5

IN 0 477 SFO 7.17

IN 7 67

IN 14 220

IN 28 110

IN 56 6.1

KS 0 273 TR IORE 4.82

KS 7 50

KS 14 35

KS 28 18

KS 56 4.6

KS 0 245 TR IORE 8.84

KS 7 72

KS 14 49

KS 28 28

KS 56 8.1

MI 0 96 SFO 8.56

MI 7 85

MI 14 15

MI 28 3.8

MI 56 1.8

MI 0 202 SFO 3.53

MI 7 54

MI 14 6.3

MI 28 8.2

MI 56 2.1

MO 0 82 SFO 16.4

MO 7 57

MO 14 34

MO 28 33

MO 56 8

MO 0 136 SFO 9.85

MO 7 63

MO 14 47

MO 28 33

MO 56 14
118

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

NE 0 115 SFO 3.91

NE 7 35

NE 14 6.4

NE 28 2.8

NE 56 2.1

NE 0 227 TR IORE 2.49

NE 7 26

NE 14 15

NE 28 6.5

NE 56 2.2

OK 1 0 131 TR IORE 3.64

OK 1 7 18

OK 1 14 18

OK 1 28 2.5

OK 1 56 2.3

OK 1 0 174 TR IORE 5.75

OK 1 7 64

OK 1 14 28

OK 1 28 7

OK 1 56 5.5

OK 2 0 138 SFO 8.69

OK 2 7 53

OK 2 14 64

OK 2 28 12

OK 2 56 2.6

OK 2 0 412 TR IORE 4.98

OK 2 7 77

OK 2 14 57

OK 2 28 26

OK 2 56 6.3

OR 0 71 SFO 5.52

OR 7 16

OR 14 23

OR 28 12

OR 56 4.9

OR 0 33
119

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

OR 7 28

OR 14 32

OR 28 44

OR 56 19

TN 0 99 TR IORE 1.22

TN 7 7.9

TN 14 4.1

TN 28 5.5

TN 56 2

TN 0 82 TR IORE 4.09

TN 7 12

TN 14 8.8

TN 28 5.5

TN 56 2.4

TX 0 64 SFO 12.3

TX 7 78

TX 14 19

TX 28 6.3

TX 56 9

TX 0 346 SFO 4.64

TX 7 120

TX 14 39

TX 28 28

TX 56 5.5

WI 0 98 SFO 4.59

WI 7 35

WI 14 10

WI 28 3.8

WI 56 2.6

WI 0 116 SFO 10.5

WI 7 138

WI 14 14

WI 28 16

WI 56 4

DGA+ 

Salt

GA 0 244 TR IORE 3.55

GA 7 45
120

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

GA 14 22

GA 28 5.2

GA 56 0.42

GA 0 509 TR IORE 2.64

GA 7 61

GA 14 39

GA 28 12

GA 56 1

MO 0 75 SFO 19.3

MO 7 79

MO 14 52

MO 28 23

MO 56 10

MO 0 132 TR IORE 23.3

MO 7 38

MO 14 48

MO 28 23

MO 56 6.8

OK 1 0 123 SFO 3.03

OK 1 7 24

OK 1 14 6.2

OK 1 28 8.6

OK 1 56 2.4

OK 1 0 231 SFO 6.19

OK 1 7 126

OK 1 14 30

OK 1 28 7.5

OK 1 56 0.92

OR 0 69 SFO 4.23

OR 7 8

OR 14 24

OR 28 18

OR 56 2.6

OR 0 49

OR 7 29

OR 14 27
121

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

OR 28 37

OR 56 12

WI 0 98 TR IORE 5.24

WI 7 27

WI 14 13

WI 28 5.1

WI 56 1.6

WI 0 287 SFO 3.17

WI 7 64

WI 14 8

WI 28 15

WI 56 2.7

Na+ Salt GA 0 358

GA 7 8.2

GA 14 47

GA 28 6.4

GA 56 0.17

GA 0 559 TR IORE 2.39

GA 7 62

GA 14 36

GA 28 9.3

GA 56 0.1

MO 0 92 SFO 11.2

MO 7 54

MO 14 28

MO 28 28

MO 56 7.3

MO 0 134 SFO 7.61

MO 7 39

MO 14 56

MO 28 17

MO 56 15

OK 1 0 131 TR IORE 9.49

OK 1 7 28

OK 1 14 28

OK 1 28 14
122

Table A4-1. Foliar half-life values calculated from residue data as presented in the HED 

review of Jimenez 1994 (MRID 43370701; DP Barcode 207649). 

Dicamba 

Salt

Sample 

Location

Post 

Treatment 

Measurement 

Interval (d)

Residue 

Value

Best Fit Equation (based on 

Degradation Kinetics 

Guidance1)

Foliar 

HalfLife (d)

OK 1 56 4.7

OK 1 0 206 SFO 4.75

OK 1 7 71

OK 1 14 31

OK 1 28 3

OK 1 56 3.9

OR 0 94 TR IORE 8.24

OR 7 9.4

OR 14 16

OR 28 15

OR 56 1

OR 0 44 SFO 43.7

OR 7 38

OR 14 11

OR 28 50

OR 56 7.7

WI 0 99 TR IORE 4.41

WI 7 19

WI 14 13

WI 28 3.9

WI 56 0.72

WI 0 342 TR IORE 2.83

WI 7 45

WI 14 23

WI 28 14

WI 56 1.4

Mean 7.272828

Standard Deviation 6.580145

n 99

Maximum 43.7

Minimum 1.11

Upper 90% CI on the mean 8.360618

1 2012 Memorandum from the Fate Tech Team: Release of NAFTA Guidance for Evaluating and 

Calculating Degradation Kinetics in Environmental Media. 
123

Appendix 5. Lesser Prairie-Chicken habitat characteristics identified by Jamison et al. (2002).

Study Location(s) Habitat(s) Studied Species-Specific Habitat Characteristics

1 New Mexico Cropland, idle, 

shinnery oak (Quercus 

havardii) pasture, 

shortgrass pasture, 

tame pasture

Hens with broods preferred shinnery oak pasture 

over cropland, fallow cropland, shortgrass, and 

tame pastures; broods used sites characterized by 

25% canopy cover of vegetation, canopy height of 

about 30 cm, 24-39% basal composition of shrubs,

47-60% grasses, and 13-26% basal composition of 

forbs; adults used grain sorghum fields during 

autumn and winter

2 Kansas Cropland, sand 

sagebrush (Artemisia 

filifolia) pasture

Nested in sand sagebrush pasture and foraged in 

cropland during winter

3 Oklahoma Burned shinnery oak 

pasture, burned tame 

pasture, shinnery oak 

pasture

Continued to display at a lek in burned pasture; 

males relocated from an unburned lek to a 

historical site in a burned weeping lovegrass 

(Eragrostis curvula) pasture and initiated display 

at a new site in burned shinnery oak/bluestem 

(Andropogon) pasture

4 Oklahoma Sand sagebrush 

pasture, shinnery oak 

pasture

Densities of birds in shinnery oak pasture were 

positively correlated with grass cover and grass 

frequency along transects, and with percent of 

grassland cover types identified from satellite 

imagery; in sand sagebrush pasture, numbers of 

birds were positively correlated with percent cover 

of shrubs and grass frequency along transects, but 

were not associated with percentages of cover 

types identified from satellite imagery

5 Oklahoma Cropland, mixed-grass 

pasture, sand 

sagebrush pasture, 

shinnery oak pasture

Nested in residual grasses and shinnery oak; raised 

broods in shinnery oak thickets; foraged in 

cropland (food plots) during winter

6 Texas Honey mesquite 

(Prosopis 

glandulosa)/shortgrass 

pasture, shinnery oak 

pasture

Preferred pastures dominated by shinnery oak and 

sand bluestem (Andropogon hallii); avoided honey 

mesquite/shortgrass areas; nested more 

successfully in residual sand bluestem than in 

other vegetation types; selected nest sites with 

north or northeast aspects, more litter and less bare 

ground than elsewhere in the habitat, and taller 

vegetation than the average vegetation height 

within 3 m; broods preferred shinnery oak/sand 

bluestem pasture and avoided mesquite/shortgrass 

habitat; broods foraged at sites with a minimum 

vegetation height of 24 cm and lower grass 
124

Study Location(s) Habitat(s) Studied Species-Specific Habitat Characteristics

abundance and greater shrub abundance than 

generally was available

7 Oklahoma Cropland, native 

pasture

Displayed on sparsely vegetated, flat-topped 

ridges overlooking expansive areas of native 

pasture and on slightly raised knolls that provided 

unobstructed views of broad valleys

8 Oklahoma Sand sagebrush 

pasture, shinnery oak 

pasture

More individuals were encountered in phenoxy 

herbicide-treated shinnery oak and phenoxy 

herbicide-treated sand sagebrush pastures than in 

untreated habitats of the same types

9 Colorado Sand sagebrush 

pasture

Nested among taller grasses (36 vs. 27 cm), forbs 

(21 vs. 16 cm), and shrubs (48 vs. 38 cm), and 

denser vegetation (32 vs. 20 cm) compared to 

areas within 5 m; nested mostly under sand 

sagebrush and yucca (Yucca glauca); at 29 nest 

sites, tallest vegetation averaged 51 cm, sand 

sagebrush plant density was 3471 plants/ha, sand 

sagebrush cover was 7.2%, grass cover was 

29.4%, forb cover was 1.4%, and bare ground was 

69.5%

10 Texas Shinnery oak/sand 

sagebrush pasture

Selected untreated shinnery oak pastures for 

nesting over tebuthiuron-treated pastures of the

same type; eight of 10 females that were captured 

in tebuthiuron-treated areas later nested in 

untreated shinnery oak; 13 nests were in residual 

grasses with 42% overhead cover, average plant 

height of 45 cm, and average visual obstruction of 

61-80% in the first 33 cm above ground; 

vegetation was dominated by purple three-awn 

(Aristida purpurea) at nine nest sites, little 

bluestem (Schizachyrium scoparium) at three 

nests, and sand bluestem at one nest

11 Colorado Cropland, mixed-grass 

pasture, sand 

sagebrush pasture

Males displayed at lek sites on slightly elevated 

terrain or on level flats; foraged in cropland during 

winter

12 Texas Cropland, sand 

sagebrush pasture, 

shinnery oak pasture

Used pastures vegetated by sand sagebrush, 

chickasaw plum (Prunus angustifolia), fragrant 

sumac (Rhusaromatica var. trilobata), shinnery 

oak, sand bluestem, little bluestem, sand lovegrass 

(Eragrostis trichodes), sand dropseed (Sporobolus 

cryptandrus), thin paspalum (Paspalum 

setaceum), switchgrass (Panicum virgatum), 

Indiangrass (Sorghastrum nutans), and various 

forbs; foraged in cropland during winter
125

Study Location(s) Habitat(s) Studied Species-Specific Habitat Characteristics

13 Kansas Cropland, sand 

sagebrush pasture

Males preferred habitats vegetated by sand 

sagebrush, blue grama (Bouteloua gracilis), 

sideoats grama (Bouteloua curtipendula), 

paspalum (Paspalum sp.), bluestem, western 

ragweed (Ambrosia psilostachya), sunflowers 

(Helianthus spp.), Russian-thistle (Salsola 

iberica), prickly pear (Opuntia sp.), and yucca and 

used cultivated fields, tallgrass and CRP, and 

other grassland habitats less than expected; 

median sizes of areas used by males were 12-140 

ha in April and May, 77-144 ha from June through 

September, and 229-409 ha in October and 

November

14 Oklahoma Sand 

sagebrush/mixedgrass pasture

Displayed in areas dominated by buffalograss; 

raised broods in areas with 22.8% sand sagebrush 

and 15.7% western ragweed; foraged in mixedgrass, rested among shrubs, and nested in residual 

grasses; broods also used shrubs; on a year-round 

basis, foraged mostly in grass, especially mixedgrass 25-80 cm in height; tallgrass, shortgrass, and 

shrub vegetation were used equally; sixweeks 

fescue (Festuca octoflora) and fragrant sumac 

were important food items; during spring, used 

shrubs <80 cm tall; used grasses and forbs 25-80 

cm in height during summer, and grasses 25-80 

cm tall during autumn; in winter, used tallgrass 

(specific heights of tallgrass species were not 

given)

15 New Mexico Cropland, shinnery 

oak/sand sagebrush 

pasture

Used pastures vegetated by shinnery oak, 

bluestem grasses, sand sagebrush, sunflower, 

honey mesquite, plum, yucca, dropseed, black 

grama (Bouteloua eriopoda), blue grama, and 

sideoats grama; foraged in grain sorghum and corn 

fields from fall through spring

16 New Mexico, 

Oklahoma, 

Texas

Cropland, shinnery 

oak pasture, shinnery 

oak/little bluestem 

pasture

Annual rates of habitat change were greater 

around leks with declining populations than at leks 

with stable populations (1.14% vs. 0.21% 

annually)

17 New Mexico Shinnery oak pasture, 

shortgrass pasture

Displayed on oil pads and in native pasture

18 New Mexico Cropland, oldfield, 

shinnery oak pasture, 

shortgrass pasture, 

tame pasture

Nested in shinnery oak habitats with little 

bluestem, sand bluestem, and purple three-awn; 

avoided weeping lovegrass, cultivated, oldfield, 

and shortgrass habitats
126

Study Location(s) Habitat(s) Studied Species-Specific Habitat Characteristics

19 New Mexico, 

Texas

Shinnery oak/sand 

sagebrush pasture

Occurred in similar densities in tebuthiurontreated and untreated shinnery oak pastures

20 New Mexico Shinnery oak pasture, 

shortgrass pasture

Nested in shinnery oak habitats dominated by sand 

bluestem; vegetation was taller at 10 successful 

than 26 unsuccessful nests (67 vs. 35 cm); percent 

composition of shrubs was similar at successful 

and unsuccessful nests (basal composition 31-

66%); 22 autumn foraging sites were 63% grasses 

and 37% shrubs, 50 winter sites were 59% grasses 

and 41% shrubs (forbs were rare); broods foraged 

in 25-cm tall shinnery oak and three-awn (Aristida

sp.), bare ground at 12 sites averaged 63%, basal 

composition of vegetation was 43% grass, 42% 

shrubs, and 15% forbs; daily movements of 40 

prenesting females were 390 m/day within 231-ha 

ranges; 12 nesting hens moved 250 m/day, and 

ranges averaged 92 ha; three hens with broods 

moved an average of 280 m/day within 119-ha 

ranges; movements of 19 females without broods 

was 220 m/day within 73-ha ranges

22 New Mexico Shinnery oak/sand 

sagebrush pasture

Hens generally used habitats with large unstable 

sand dunes, abundant shinnery oak, low grass 

cover, and low structural density; nested in sand 

sagebrush, residual grasses, and shinnery oak; five 

of eight nests were under sand sagebrush, two 

nests were in purple three-awn, and one nest was 

in shinnery oak; visual obstruction and canopy 

cover of sand sagebrush were significantly higher 

at nest sites than in surrounding habitat (specific 

values for visual obstruction, canopy cover, and 

canopy height were not given)

23 Texas Cropland, oldfield, 

shinnery oak pasture, 

shortgrass pasture, 

tame pasture

Prenesting and nesting hens preferred shinnery 

oak habitat characterized by rolling dunes and 

dominated primarily by shinnery oak, habitat 

dominated by little bluestem and sand bluestem, or 

habitat dominated by three-awn and shinnery oak; 

canopy coverage of grasses within 3 m of nest 

sites was 3.1-13.2%, shrub canopy was 21.4-

28.3%, and canopy coverage of all vegetation was 

31.4-38.4%; nests in grasses were more successful 

(4 of 5 successful) than those under shrubs (3 of 

10 successful)

24 New Mexico Cropland, oldfield, 

shinnery oak pasture, 

shortgrass pasture, 

tame pasture

Prenesting and nesting hens preferred shinnery 

oak habitat characterized by rolling dunes and 

dominated primarily by shinnery oak, habitat 

dominated by little bluestem and sand bluestem, or 
127

Study Location(s) Habitat(s) Studied Species-Specific Habitat Characteristics

habitat dominated by three-awn and shinnery oak;

canopy coverage of grasses within 3 m of nest 

sites was 3.1-13.2%, shrub canopy was 21.4-

28.3%, and canopy coverage of all vegetation was 

31.4-38.4%; nests in grasses were more successful 

(4 of 5 successful) than those under shrubs (3 of 

10 successful)

25 New Mexico, 

Oklahoma, 

Texas

Cropland, shinnery 

oak pasture, shinnery 

oak/little bluestem 

pasture

Populations stabilized or increased in landscapes 

(7238-ha areas) in which low-density shrubland 

composed 79.% of the total area and declined in 

landscapes with 43.2% low-density shrubland; 

total shrubland composed 81.9% around leks that 

did not decline and 63.4% of the landscape around 

declining leks; declined in areas where landscapes 

were unstable (e.g., experienced frequent changes 

from one landcover to another); population trends 

were positively correlated with loss of total 

shrubland