Federal Register / Vol. 82, No. 188 / Friday, September 29, 2017 / Proposed Rules 45551 

cloud, or other file sharing system). For 

additional submission methods, the full 

EPA public comment policy, 

information about CBI or multimedia 

submissions, and general guidance on 

making effective comments, please visit 

https://www2.epa.gov/dockets/ 

commenting-epa-dockets. 

FOR FURTHER INFORMATION CONTACT: 

Heather Hamilton, Air Planning and 

Development Branch, U.S. 

Environmental Protection Agency, 

Region 7, 11201 Renner Boulevard, 

Lenexa, KS 66219 at (913) 551–7039, or 

by email at hamilton.heather@epa.gov. 

SUPPLEMENTARY INFORMATION: This 

document proposes to take direct final 

action on Iowa’s infrastructure SIP 

submissions for the 2010 SO2 NAAQS. 

We have published a direct final rule 

approving the State’s SIP revision (s) in 

the ‘‘Rules and Regulations’’ section of 

this issue of the Federal Register, 

because we view this as a 

noncontroversial action and anticipate 

no relevant adverse comment. We have 

explained our reasons for this action in 

the preamble to the direct final rule. A 

detailed Technical Support Document 

(TSD) is included in this rulemaking 

docket to address the following: A 

description of Clean Air Act section 

110(a)(1) and (2) infrastructure SIPs; the 

applicable elements under sections 

110(a)(1) and (2); EPA’s approach to the 

review of infrastructure SIP 

submissions, and EPA’s evaluation of 

how Iowa addressed the relevant 

elements of sections 110(a)(1) and (2). If 

we receive no adverse comment, we will 

not take further action on this proposed 

rule. If we receive adverse comment, we 

will withdraw the direct final rule and 

it will not take effect. We would address 

all public comments in any subsequent 

final rule based on this proposed rule. 

We do not intend to institute a second 

comment period on this action. Any 

parties interested in commenting must 

do so at this time. For further 

information, please see the information 

provided in the ADDRESSES section of 

this document. 

List of Subjects in 40 CFR Part 52 

Environmental protection, Air 

pollution control, Incorporation by 

reference, Intergovernmental relations, 

Sulfur dioxide, Reporting and 

recordkeeping requirements. 

Dated: September 20, 2017. 

Cathy Stepp, 

Acting Regional Administrator, Region 7. 

[FR Doc. 2017–20965 Filed 9–28–17; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[Docket No. FWS–R5–ES–2016–0030; 

4500030113] 

RIN 1018–BB50 

Endangered and Threatened Wildlife 

and Plants; Withdrawal of the 

Proposed Rule to List Kenk’s 

Amphipod 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Proposed rule; withdrawal. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), withdraw the 

proposed rule to list the Kenk’s 

amphipod (Stygobromus kenki), an 

invertebrate from the District of 

Columbia, Maryland, and Virginia as an 

endangered species under the 

Endangered Species Act (Act) as 

amended. This withdrawal is based on 

our conclusion that the threats to the 

species as identified in the proposed 

rule are not as significant as we 

previously determined and the 

proposed listing is not warranted. We 

base this conclusion on our analysis of 

new information concerning the results 

of new surveys, current and future 

threats, and conservation efforts. We 

find the best scientific and commercial 

data available indicate that the Kenk’s 

amphipod does not meet the statutory 

definitions of an endangered or 

threatened species. Therefore, we are 

withdrawing our proposed rule to list 

the Kenk’s amphipod as an endangered 

species. 

DATES: The proposed rule that 

published on September 30, 2016 (81 FR 

67270), is withdrawn on September 29, 

2017. 

ADDRESSES: The withdrawal of our 

proposed rule and supplementary 

documents are available on the Internet 

at http://www.regulations.gov at Docket 

No. FWS–R5–ES–2016–0030, and at 

https://www.fws.gov/chesapeakebay/. 

Comments and materials we received, as 

well as supporting documentation we 

used in the preparation of this 

withdrawal, are available for public 

inspection by appointment, during 

normal business hours at: U.S. Fish and 

Wildlife Service, Chesapeake Bay Field 

Office, 177 Admiral Cochrane Drive, 

Annapolis, MD 21401, by telephone 

410–573–4577 or by facsimile 410–269– 

0832. 

FOR FURTHER INFORMATION CONTACT: 

Genevieve LaRouche, Field Supervisor, 

U.S. Fish and Wildlife Service, 

Chesapeake Bay Field Office, 177 

Admiral Cochrane Drive, Annapolis, 

MD 21401, by telephone 410–573–4577 

or by facsimile 410–269–0832. Persons 

who use a telecommunications device 

for the deaf (TDD) may call the Federal 

Relay Service at 800–877–8339. 

SUPPLEMENTARY INFORMATION: 

Executive Summary 

Why we need to publish this 

document. Under the Endangered 

Species Act (Act), if a species is 

determined to be an endangered or 

threatened species throughout all or a 

significant portion of its range, we are 

required to promptly publish a proposal 

in the Federal Register and make a 

determination on our proposal within 1 

year. On September 30, 2016, we issued 

a proposed rule to add the Kenk’s 

amphipod as an endangered species to 

the List of Endangered and Threatened 

Wildlife in title 50 of the Code of 

Federal Regulations (50 CFR 17.11(h)). 

Our proposal was based on threats due 

to poor water quality, erosion, and 

sedimentation resulting from urban 

runoff at the Maryland and the District 

of Columbia locations and the effects of 

small population size and climate 

change at all known locations (81 FR 

67270). This document withdraws our 

proposed rule to list the Kenk’s 

amphipod as an endangered species 

under the Act because we have now 

determined that the threats to the 

species are not as significant as we 

previously determined and additional 

populations have been discovered in 

Virginia with threats that will be 

reduced or eliminated through 

conservation measures; therefore, listing 

is not warranted. 

The basis for our action. Under 

section 4(a)(1) of the Act, we can 

determine that a species is an 

endangered or threatened species based 

on any of five factors: (A) The present 

or threatened destruction, modification, 

or curtailment of its habitat or range; (B) 

Overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) Disease or predation; (D) 

The inadequacy of existing regulatory 

mechanisms; or (E) Other natural or 

manmade factors affecting its continued 

existence. We have determined that the 

threats to the Kenk’s amphipod are not 

as significant and the species is more 

widely distributed than we previously 

determined and that listing is not 

warranted. Therefore, this document 

withdraws our proposed rule to list the 

Kenk’s amphipod as an endangered 

species under the Act. 

Peer review and public comment. We 

sought comments from five independent 

specialists to ensure that our 


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designation is based on scientifically 

sound data, assumptions, and analyses. 

We invited these peer reviewers to 

comment on our listing proposal and 

received comments from all five. We 

also considered all comments and 

information received during the 

comment period. 

Background 

Previous Federal Actions 

Please refer to the proposed listing 

rule for the Kenk’s amphipod (81 FR 

67270; September 30, 2016) for a 

detailed description of previous Federal 

actions concerning this species. 

On June 7, 2017, the Department of 

Defense, U.S. Army Garrison, Fort A.P. 

Hill, finalized their revised Integrated 

Natural Resources Management Plan 

(INRMP) to include conservation 

measures for the Kenk’s amphipod (Fort 

A.P. Hill 2017, pp. 5, 8, 8–56, 9–1– 

9–4, 9–31–9–34; Andersen 2017a, pers. 

comm.; Andersen 2017b pers. comm.). 

Species Description 

Please refer to the proposed listing 

rule for the Kenk’s amphipod (81 FR 

67270; September 30, 2016) for a 

detailed summary of species’ 

information; however, we note key 

pieces of updated information below. 

The Kenk’s amphipod (Stygobromus 

kenki) is a moderately small 

subterranean crustacean, growing to a 

maximum length of approximately 0.22 

inches (in) (5.5 millimeters (mm)), that 

can co-occur with other amphipods, 

such as the Potomac ground water 

amphipod (S. tenuis potomacus), Hay’s 

spring amphipod (S. hayi), Tidewater 

amphipod (S. indentatus), and 

Rappahannock spring amphipod (S. 

foliatus). Subterranean species like the 

Kenk’s amphipod may live for 4 to 6 

years, or even longer (Foltz and Jepson 

2009, p. 2; Culver 2016, pers. comm.). 

Accurate identification of the Kenk’s 

amphipod can occur only when a 

specimen is removed from the seepage 

spring site (hereafter referred 

interchangeably as seepage spring, seep, 

spring, or site depending upon the 

reference), and preserved in alcohol or 

other fixing agent for identification by a 

species expert who removes legs and 

other appendages from the specimen for 

microscopic examination. This 

identification method is the best 

scientific method available. Because the 

laboratory identification results in 

mortality, and the species co-occurs in 

at least one site with the federally listed 

Hay’s spring amphipod, the Service has 

been judicious in limiting the frequency 

and number of specimens removed from 

known sites. 

Habitat 

Amphipods of the genus Stygobromus 

occur in ground water and ground 

water-related habitats (e.g., caves, seeps, 

small springs, wells, interstices, and, 

rarely, deep ground water lakes). The 

Kenk’s amphipod is found in wooded 

areas where ground water emerges to 

form seepage springs (Holsinger 1978, p. 

39). More specifically, Culver and Pipan 

(2014, pp. 22–23) refer to this habitat as 

the hypotelminorheic. 

Hypotelminorheic is described as 

habitats: (1) With a perched aquifer fed 

by subsurface water that creates a 

persistent wet spot; (2) underlain by a 

clay or other impermeable layer 

typically 5 to 50 centimeters (cm) (2 to 

20 in) below the surface; and (3) rich in 

organic matter compared with other 

aquatic subterranean habitats. The water 

supplying the springs infiltrates to the 

ground water from precipitation and 

runoff into the catchment (e.g., recharge 

or drainage) areas. The water exits these 

habitats at seepage springs. The shading, 

hydrology, and organic matter found in 

these woodlands are considered 

important factors in maintaining 

suitable habitat (i.e., for feeding, 

breeding, and sheltering) for the species. 

Springs known to currently support 

the Kenk’s amphipod are found in 

forested areas with moderate to steep 

slopes, adjacent to streams, and 

overlying the Wissahickon geologic 

formation in the Piedmont of Maryland 

and the District of Columbia and in the 

Calvert formation just above the 

Nanjemoy formation in the upper 

Coastal Plain of Virginia. The Kenk’s 

amphipod has been found in the dead 

leaves or fine sediment submerged in 

the waters of its seepage spring outflows 

(Holsinger 1978, p. 130). The species 

will move between the surface and 

subterranean portions of the spring 

habitat, but it is unknown when or how 

often that movement occurs (Kavanaugh 

2009, p. 3). 

Our previous understanding of 

seepage springs drainage areas was that 

these springs typically drain an area of 

less than 10,000 square meters (2.5 acres 

(ac); 1 hectare (ha)). The Service 

contracted with the Maryland 

Geological Survey to delineate the 

recharge areas of the six Kenk’s 

amphipod’s seepage spring sites in 

Maryland and the District of Columbia 

(Burnt Mill Spring #6, East Spring, 

Kennedy Street Spring, Sherrill Drive 

Spring, Coquelin Run Spring, and 

Holsinger Spring) (Staley 2016, pp. 1– 

46; Staley 2017, pers. comm.). In 

addition, the Maryland Geological 

Survey conducted electrical resistivity 

surveying to determine elevations of 

bedrock or clay that may be perching 

the water table, and to detect elevation 

of the water table of three of the 

Washington metropolitan area seepage 

springs (Burnt Mill Spring #6, East 

Spring, and Kennedy Street Spring) 

(Staley 2016, pp. 1–46). The surface 

watershed area of the springs ranged 

from the largest area of 22,055 square 

meters (m2) (237,402 square feet (ft2) 

(Holsinger Spring) to the smallest of 

2,345 m2 (25,241 ft2) (East Spring) 

(Staley 2016, pp. 1–46; Staley 2017, 

pers. comm.). 

However, these watershed boundary 

calculations do not accurately reflect the 

extent and magnitude of the subsurface 

ground water flow to the springs, since 

fracture zones in the bedrock underlying 

the saturated zones may extend a 

spring’s ground water source beyond the 

surface watershed boundaries. The 

saturated zones supplying water to these 

springs appear to extend to a depth of 

10 meters (m) (32.8 ft) or more at 

locations near each of these springs 

(Staley 2016, pp. 1–46); they are 

underlain by bedrock or dense saprolite 

(material derived from weathered 

bedrock). This finding suggests that at 

some locations the ground water source 

for these seepage springs may not be as 

shallow as described by Culver and 

Chestnut (2006, p. 2), and could be 

influenced by a larger area than the 

surface catchment area. This finding 

may also mean that the Kenk’s 

amphipod could be present at times in 

deeper subsurface water or in fractured 

portions of bedrock. 

Distribution and Relative Abundance 

Current Known Range and Distribution 

The Kenk’s amphipod has been 

documented from a total of 13 seepage 

spring sites: East Spring, Holsinger 

Spring, Sherrill Drive Spring and 

Kennedy Street Spring in Rock Creek 

Park, managed by the National Park 

Service (NPS), in the District of 

Columbia; Coquelin Run Spring 

(privately owned) and Burnt Mill Spring 

#6 (county owned) in Montgomery 

County, MD; Upper Mill #2, Mill #4, 

Mill #5, Mill Creek #56, Mill Creek #58, 

and Mount Creek #2 on the U.S. Army 

Garrison’s Fort A.P. Hill, in Caroline 

County, VA; and Voorhees Nature 

Preserve (owned by The Nature 

Conservancy (TNC)) in Westmoreland 

County, VA (see figure 1). While we 

focus our analysis on the Kenk’s 

amphipod’s known sites, we consider it 

likely that additional springs supporting 

the species could be found in Virginia 

because a survey of only a small portion 

of the potential suitable habitat outside 

of Fort A.P. Hill resulted in the 


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discovery of the Voorhees Nature 

Preserve site. Surveyors had access to 

only publicly owned lands; potential 

suitable habitat also occurs on private 

land. In Virginia, 77 springs inside Fort 

A.P. Hill and 22 springs outside of Fort 

A.P. Hill in 3 counties (Caroline, King 

George, and Westmoreland) were 

surveyed. Two new sites were found on 

Fort A.P. Hill in 2017 (Mill Creek #56 

and #58) with more intensive surveys. 

In Maryland, no new Kenk’s amphipod 

sites were located during more 

widespread surveys of suitable habitat 

on publicly owned lands (129 springs in 

5 counties (Anne Arundel, Prince 

George’s, Charles, Calvert, and St. 

Mary’s) in 2017. 

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BILLING CODE 4333–15–C 


asabaliauskas on DSKBBXCHB2PROD with PROPOSALSEP29SE17.000</GPH>

Montgomery County 

0 5 10 20 

Miles 

N 

A 

Figure 1. Distribution of the 13 known Kenk's amphipod seep sites in 2017. Due to 

scale, some sites are obscured by the symbols of others. 
Federal Register / Vol. 82, No. 188 / Friday, September 29, 2017 / Proposed Rules 45555 

Relative Abundance 

There are no reliable total population 

numbers for Kenk’s amphipod sites due 

to sampling difficulties (e.g., flow 

conditions) and the lack of information 

on the portion of the population that 

may remain in the springs’ ground water 

supply (Feller 2005, p. 10). However, 

because surveying in the Washington 

metropolitan area has been conducted 

using systematic and consistent 

methodology over many years, often by 

the same individuals, the numbers of 

Kenk’s amphipod individuals observed 

and the number of conducted surveys 

required to find the species are 

considered to be the best available data 

and provide a reliable indication of the 

species’ relative abundance. 

The species is typically found in 

small numbers and then only when 

ground water levels are high and springs 

are flowing freely, conditions that cause 

the Kenk’s amphipod to be transported 

to the surface. These conditions 

typically occur during the spring 

season, except during especially dry 

years. Given the small size of the 

shallow ground water aquifers 

supporting the sites occupied by this 

species, and the known characteristics 

of subterranean invertebrates, it is 

probable that each of the Kenk’s 

amphipod populations has always been 

small (Hutchins and Culver 2008, 

pp. 3–6). 

Although specimens were not 

collected and identified to the species 

level, Stygobromus sp., including some 

in the right size range for the Kenk’s 

amphipod, were observed during site 

reconnaissance visits between 2004 and 

2012 in several of the known Kenk’s 

amphipod Washington metropolitan 

area spring habitats (Yeaman 2012, pers. 

comm.). In addition, visual inspections 

during this same time period indicated 

that most of the sites continued to 

appear to be suitable habitat, leading us 

to conclude that the Kenk’s amphipod 

was extant at least at Burnt Mill Spring 

#6, Kennedy Street Spring, and East 

Spring (Feller 2015, pers. comm.). 

However, actual identifications of 

specimens collected during surveys 

conducted in 2015 and 2016 (Feller 

2016b, pers. comm.) did not result in 

Kenk’s amphipod being found (see 

below). 

Prior to 2015, all Kenk’s amphipod 

specimens were discovered on the first 

or second survey conducted at all 

known sites. In 2015 and 2016, the 

Kenk’s amphipod was confirmed at only 

one of the Washington metropolitan 

area spring sites, Coquelin Run Spring, 

despite all of the sites being sampled 

multiple times during these 2 years (see 

table 1 below) (Feller 2016b, pers. 

comm.; Feller 2016c, pers. comm.). 

Additionally, an environmental DNA 

(eDNA) study was conducted in 2016 

(Niemiller et al. 2016, pp. 1–7) for 

several amphipod species, including the 

Kenk’s amphipod, to determine 

potential presence of the species in 

springs in the Rock Creek watershed. 

Individual Kenk’s amphipods were 

collected from Fort A.P. Hill for DNA 

sequencing since no individuals could 

be found in the Washington 

metropolitan area at the time (spring/ 

summer 2016) comparative samples 

were required for the study (Niemiller et 

al. 2016, p. 2). Water tested in the 

Washington metropolitan area did not 

detect the Kenk’s amphipod eDNA 

(Niemiller et al. 2016, p. 6). However, 

we cannot conclude that Kenk’s 

amphipods were absent at those sites. 

The abundance of the Kenk’s amphipod 

may not be high enough in the springs 

to amplify DNA in the water samples, or 

the DNA from the Fort A.P. Hill animals 

may be different enough from the 

Washington metropolitan area animals 

to not be detected in the Rock Creek 

water samples. Therefore, it is unclear 

without additional survey effort 

whether the species may be extirpated 

at Burnt Mill Spring #6, Kennedy Street 

Spring, and East Spring, although the 

best available data show a decrease in 

observed individuals at these sites (see 

table 1). 

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Table 1. S Its for the Kenk' hi nod 

1960s 1990s 2000 to2006 

Site N arne (owner) 

1966 1967 1968 1994 1995 2000 2001 2003 2004 2005 2006 201

East Spring (NPS) 1 of 1 5 of 5 1 of 1 0 of2* 0 of 1 * 0 of 1 2 of3 N/A N/A N/A N/A N/A 

(3) (3 to 21) (1) (1 and 2) 

Holsinger Spring (NPS) N/A 

1 of 1 

N/A N/A N/A N/A N/A 0 of 1 N/A N/A N/A N/A 

(24) 

Sherrill Drive Spring N/A N/A N/A 0 of 1 1 of2 0 of I 1 of2 0 of 1 N/A N/A N/A N/A 

(NPS) (3) (1) 

Kennedy Street Spring N/A N/A N/A N/A N/A N/A 1 of2 0 of 1 N/A N/A N/A N/A 

(NPS) (1) 

Coquelin Run Spring 1 of 1 1 of 1 

N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 

(Private) (2) (2) 

Burnt Mill Spring #6 N/A N/A N/A N/A N/A N/A N/A N/A N/A 1 of 1 0 of 1 N/A 

(County Park) (5) 

Upper Mill Creek #2 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 1 of 

(DoD) (1

Mill Creek #4 (DoD) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 1 of

(1

Mill Creek #5 (DoD) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 2 of

(4

Mill Creek #56 (DoD) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 

Mill Creek #59 (DoD) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 

Mount Creek #2 (DoD) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 2 of

(1

Voorhees Nature 

Preserve (TNC) N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 

*Individuals in the size range of the Kenk's amphipod were observed but not collected for verification (Feller 1997). The first pair of numbers (e.g., 

of site visits where the species was detected compared to the total number of site visits that year. The numbers in parenthesis"()" are the total n

collected. TheN/ A indicates no surveys were conducted at the site in that year. 
Federal Register / Vol. 82, No. 188 / Friday, September 29, 2017 / Proposed Rules 45557 

Summary of Comments and 

Recommendations 

In the proposed rule published on 

September 30, 2016 (81 FR 67270), we 

requested that all interested parties 

submit written comments on the 

proposal by November 29, 2016. We 

also contacted appropriate Federal and 

State agencies, scientific experts and 

organizations, and other interested 

parties and invited them to comment on 

the proposal. A newspaper notice 

inviting general public comment was 

published in USA Today on October 5, 

2016. We did not receive any requests 

for a public hearing. 

During the 60-day public comment 

period (September 30, 2016, to 

November 29, 2016), we received public 

comments from 10 individuals or 

organizations. Of these, seven were from 

individuals, including five peer 

reviewers, one was from a Federal 

agency, and two were from 

nongovernmental organizations (NGOs). 

All the commenters were generally 

supportive of the proposed listing, but 

only 8 of the 10 provided substantive 

information. All substantive information 

provided during the comment period is 

summarized below and has either been 

incorporated directly into this final 

determination or is addressed in the 

response to comments below. 

Comments From Peer Reviewers 

(1) Comment: Two peer reviewers 

agree with us that few if any studies 

exist that specifically examine critical 

thresholds for flow, water permanence, 

nutrient or contaminant loading, or the 

tolerance of close relatives of the Kenk’s 

amphipod to pollutants and toxicants. 

One of the reviewers suggests that 

additional studies conducted on the 

basic biology and population size of the 

Kenk’s amphipod would be helpful, 

noting that the more common and 

widespread Potomac ground water 

amphipod could be used as a surrogate 

species. 

Our Response: The Act requires that 

the Service make listing determinations 

based solely on the best scientific and 

commercial data available. When we 

published the proposed rule on 

September 30, 2016 (81 FR 67270), we 

relied on the best quantitative and 

qualitative data available at that time to 

assess the Kenk’s amphipod’s status. 

(2) Comment: One peer reviewer 

states that the proposed listing 

underestimates the potential effect due 

to urbanization stress for the 

Washington metropolitan area 

populations, given the species’ isolated 

populations. More specifically, this 

reviewer indicates that our analysis 

contained insufficient discussion of 

increased conductivity (salinity) and 

that the risk from potential sewage 

leakage may have been underestimated, 

in part because we did not consider 

that, in addition to increasing 

conductivity and nutrient loading, 

sewage leaks include ‘‘pharmaceuticals, 

personal care products, and home-use 

chemicals that even at very low levels 

can disrupt endocrine and immune 

systems.’’ Another peer reviewer 

provided additional references on 

several studies in the Rock Creek 

watershed showing the occurrence of 

pesticides, organic wastewater 

compounds, and metals in surface water 

and bed sediment that may be related to 

the degradation of habitat (Anderson et 

al. 2002; Miller et al. 2006; Koterba et 

al. 2010; Phelan and Miller 2010). 

Our Response: See the Factor A 

section below addressing Water Quality/ 

Quantity Degradation Due to Chronic 

Pollution of Urban/Suburban Runoff for 

added discussion regarding the effects 

of conductivity and the presence of 

pharmaceuticals, personal care 

products, and home-use chemicals from 

sewer leaks. Additional references on 

several studies in the Rock Creek 

watershed showing the occurrence of 

pesticides, organic wastewater 

compounds, and metals in surface water 

and bed sediment that may be related to 

the degradation of habitat were also 

added to the final determination. 

(3) Comment: One peer reviewer 

states that existing regulatory 

mechanisms are inadequate to address 

issues related to Factor A and that this 

is largely because many of the recharge 

areas for the seepage springs in the 

Washington metropolitan area extend 

outside the jurisdiction of Federal 

agencies. 

Our Response: Many of these seepage 

springs have recharge areas extending 

into private lands where Federal 

agencies have little jurisdiction. While 

the existing regulatory mechanisms do 

not fully ameliorate the stressors 

affecting the species’ sites in the 

Washington metropolitan area, we have 

concluded that those stressors do not 

rise to the level of the species being 

warranted for listing as an endangered 

or threatened species (See the Summary 

of Factor A and Kenk’s Amphipod 

Determination of Status Throughout All 

of Its Range sections below). 

(4) Comment: One peer reviewer 

states that the proposed rule 

underestimates the potential threat of 

warming of the shallow ground water 

habitats supporting this amphipod 

‘‘because the impacts of pollutants on 

Kenk’s amphipod may likely be 

compounded by even a slight increase 

in water temperature due to a potential 

increase of uptake of pollutants in 

concert with increased metabolic 

activities.’’ 

Our Response: We have included 

additional language in the final 

determination indicating the effects of 

increased water temperature on the 

uptake and metabolism of pollutants— 

see Factor E, Effects of Climate Change. 

(5) Comment: Two peer reviewers 

comment on the threat of small 

population dynamics and indicate that 

the proposed rule was missing a 

discussion about metapopulation 

structure. One reviewer states that the 

assumption of small population size and 

genetic isolation among Kenk’s 

amphipod populations is untested and 

that some analyses of DNA sequence 

information will shed light on the 

species’ metapopulation structure and 

the potential for migration of 

individuals among sites. The second 

reviewer states that many animal and 

plant species exist in low population 

numbers, but possess adequate levels of 

genetic diversity to maintain their 

populations. This reviewer also states 

that because the species’ ability to move 

between sites is considered low or 

perhaps nonexistent in the opinion of 

species experts, as discussed in the 

proposed rule, the Kenk’s amphipod 

may represent isolated populations with 

little potential for either recolonization 

or colonization of suitable habitat. 

Our Response: While we agree that 

the assumption of small population size 

and genetic isolation among Kenk’s 

amphipod populations is untested, the 

best available data indicate that the 

effect of small population dynamics 

may be contributing to the species’ 

viability, particularly in the Washington 

metropolitan area. Additionally, it is 

difficult to study the DNA sequences of 

Kenk’s amphipods at any sites other 

than Fort A.P. Hill sites, given the 

paucity of individuals collected and the 

preservation method used to store the 

collected individuals. 

Comments From the Public 

(6) Comment: One commenter 

considers the discussion of stressors 

incomplete because it does not include 

the ‘‘mounting circumstantial evidence 

that seep-inhabiting Stygobromus are 

susceptible to changes in the forest 

canopy and understory.’’ This 

commenter also suggests that the 

species’ very shallow ground water sites 

are in some ways more connected to the 

forest floor than to base-level streams. 

Our Response: We have added an 

assessment of potential activities that 

could change the forest canopy and 

understory in Factor A under Other 


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Habitat Considerations. This issue was 

not mentioned in the proposed rule 

because it had not been identified as 

occurring at any of the known Kenk’s 

amphipod sites. 

(7) Comment: One commenter, 

familiar with the management of Fort 

A.P. Hill, provided additional 

information about the identity of two 

springs, the level of stressors/threats to 

the Kenk’s amphipod at the installation, 

and how the species would be 

addressed under the Sikes Act. 

Our Response: We have revised the 

final determination, as appropriate, to 

reflect these comments. The Service 

appreciates the cooperation of the Army 

and looks forward to working with them 

to protect this species and its habitat on 

Fort A.P. Hill. 

(8) Comment: One commenter 

indicates that a number of projects pose 

threats to the species such that the 

species warrants listing and that 

reinitiation of conferencing under 

section 7(a)(4) of the Act is appropriate. 

This commenter provides multiple 

documents supporting their position; 

however, only one document was new 

information—the final report on the 

Stygobromus eDNA study. 

Our Response: Section 7 consultations 

under the Act are outside the scope of 

this final listing determination. 

However, to the extent that it is relevant 

here, we note that we completed the 

appropriate level of consultation on the 

projects and concluded that there would 

be no effect to the Kenk’s amphipod or 

its habitat. All of the commenter’s 

supporting information, with the 

exception of their proposed rule 

comment letter and the new eDNA 

report referenced above, were included 

in our earlier consultations. Our 

subsequent review of the eDNA report, 

as part of the analysis for this final 

listing determination, finds that the 

report provides no evidence to support 

the commenter’s position because no 

Kenk’s amphipod DNA was detected in 

any of the action areas related to the 

consultations. 

(9) Comment: One commenter states 

that susceptibility of Kenk’s amphipod 

sites to destruction by hikers on social 

trails near the seeps should be more 

fully discussed. The commenter also 

indicated that the NPS has taken no 

affirmative, proactive steps to divert 

hikers and other recreational traffic 

away from these seeps. 

Our Response: There is no evidence 

that the occasional use of social trails 

has had any effect on the Kenk’s 

amphipod or caused any disturbance to 

the seep habitat. While the NPS has not 

found a practical way to close most 

social trails, they have taken steps to 

prevent designated trails from being 

built in areas that could affect the Hay’s 

Spring or Kenk’s amphipods. 

(10) Comment: One commenter raises 

concerns with the Service’s and NPS’s 

compliance with section 7 of the Act 

and with NPS’s implementation of Rock 

Creek Enabling Legislation. 

Our Response: The Service and NPS 

have met our respective section 7 

regulatory obligations for the Hay’s 

Spring and Kenk’s amphipods (see the 

Water Quality/Quantity Degradation 

Due to Chronic Pollution of Urban/ 

Suburban Runoff section of the 

proposed rule (81 FR 67270, September 

30, 2016) and the Candidate Notices of 

Review (75 FR 69222, November 10, 

2010; 76 FR 66370, October 26, 2011; 77 

FR 69994, November 21, 2012; 78 FR 

70104, November 22, 2013; 79 FR 

72450, December 5, 2014; 80 FR 80584, 

December 24, 2015). 

(11) Comment: One commenter 

indicates that the proposed rule should 

more fully discuss agencies’ failure to 

clean up water pollution in the Rock 

Creek watershed, specifically citing 

NPS’s use of pesticides and the District 

of Columbia government’s and NPS’s 

use of road salt in the watershed. 

Our Response: We analyzed the use of 

pesticides in Rock Creek Park and 

determined that dimilin, which can be 

toxic to crustaceans, is not being used 

in the park. Other pesticides that may be 

toxic to amphipods are used on the 

Rock Creek Park Golf Course, but 

because the golf course is not within the 

recharge areas for the seepage springs 

known to support the Kenk’s amphipod, 

this activity is not considered a stressor 

for the species. The NPS has limited or 

discontinued the use of road salts at 

some locations, including Sherrill Drive, 

Ross Drive, Morrow Drive, and Ridge 

Road, where this practice might be a 

problem for the Hay’s Spring or Kenk’s 

amphipods (Bartolomeo 2017, pers. 

comm.). The use of road salts may affect 

one or more locations and we have 

added additional discussion on this 

topic in the final listing determination 

(see Factor A, Water Quality/Quantity 

Degradation Due to Chronic Pollution of 

Urban/Suburban Runoff). 

(12) Comment: One commenter 

questioned the rationale behind being 

able to collect up to 10 specimens for 

scientific collection. 

Our Response: The majority of 

amphipods collected at sites are the 

more common species, S. tenuis. 

However, the Service has allowed larger 

numbers to be collected during 2016 

surveys in the Washington metropolitan 

area because none of the specimens of 

appropriate size collected in the 2015 

surveys have been identified to be the 

Kenk’s amphipod. These protocols are 

followed to minimize effects to the 

species. Because the occurrence of 

subterranean invertebrates at spring 

emergence sites likely represents only a 

portion of the actual underground 

population, the Service has considered 

the collecting procedures (Feller 1997, 

p. 2) to be nondetrimental to the 

populations. 

Summary of Changes From the 

Proposed Rule 

Based upon our review of the public 

comments, comments from other 

Federal and State agencies, peer review 

comments, and new relevant 

information that has become available 

since the publication of the proposal, 

we have reevaluated our proposed 

listing rule and made changes as 

appropriate. This document differs from 

the proposal in the following ways: 

(1) Based on our analyses of the 

potential threats to the Kenk’s 

amphipod and additional survey data 

obtained in 2017, we have determined 

that the species no longer meets the 

definition of a threatened or an 

endangered species. This document 

withdraws our proposed rule as 

published on September 30, 2016 (81 FR 

67270). 

(2) We have added a discussion of 

Ongoing and Future Conservation 

Efforts below. Fort A.P. Hill’s INRMP 

(Fort A.P. Hill 2017, entire) is discussed 

in this section. 

(3) We have incorporated: (a) A more 

detailed impervious cover analysis 

using the Watershed Boundary Dataset 

(U.S. Geological Survey (USGS) 2014a, 

entire) and the 2011 National Land 

Cover Dataset (USGS 2014b, entire); (b) 

reference to an eDNA study conducted 

in 2016 (Niemiller et al. 2016, pp. 1–7); 

(c) reference to a hydrogeology electrical 

resistivity study conducted in 2016 that 

improves our understanding of the 

surface catchment area and the 

subsurface area surrounding the Kenk’s 

amphipod sites (Staley 2016, pp. 1–46); 

(d) water quality sampling results 

conducted in 2016 and 2017 by the 

Service; and (e) results from suitable 

habitat surveys conducted in 2017. 

Ongoing and Future Conservation 

Efforts 

Below we review conservation efforts 

for the Kenk’s amphipod, including 

those in Fort A.P. Hill’s recently revised 

INRMP. In our proposed rule, we 

described the conservation efforts that 

are already occurring or were planned to 

occur in the Washington metropolitan 

area; and there are no changes to this 

information based on peer review and 

public comments. We have also 


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completed an analysis of the newly 

initiated conservation efforts at Fort 

A.P. Hill pursuant to our Policy for 

Evaluation of Conservation Efforts 

When Making Listing Decisions (PECE) 

(68 FR 15100, March 28, 2003). 

Based on information provided in our 

proposed rule, Fort A.P. Hill revised its 

existing INRMP in 2017 to include the 

Kenk’s amphipod and established 

conservation measures (i.e., expanded 

buffer areas) to address the identified 

threats (Fort A.P. Hill 2017, p. 9–32). 

The INRMP includes the most recent 

Kenk’s amphipod survey information 

and establishes conservation areas that 

will be managed with limited surface 

disturbance and avoidance buffers (Fort 

A.P. Hill 2017, pp. 9–32 to 9–34), as 

further described below. In addition, 

Fort A.P. Hill has agreed to include 

expanded buffer areas around any future 

new locations of the species. The 

INRMP will be revised as part of the 

next annual review process to reflect 

that continued implementation of 

buffers would be subject to mission 

requirements (Andersen 2017b, pers. 

comm.). The INRMP is comprehensively 

updated every 5 years, with review and 

minor amendments occurring annually. 

More significant updates will occur if 

and when new biological information 

becomes available or if Fort A.P. Hill’s 

mission requirements change. The 

expanded buffer areas for the Kenk’s 

amphipod designated in the INRMP are 

designed to maintain the species’ 

redundancy, resiliency, and 

representation on Fort A.P. Hill, thus 

significantly contributing to the species’ 

viability (see table 3 and the Cumulative 

Effects section below). 

Fort A.P. Hill consists of 76,000 acres 

(30,756 ha) of land with 65,000 acres 

(26,304 ha) of forest (Fort A.P. Hill 2017, 

p. 2–1). The mission of the base is to 

ensure soldiers are fully prepared to 

fight and win the Nation’s wars (Fort 

A.P. Hill 2017, p. 12–2). Currently, 98 

percent of the base is undeveloped 

operational training lands. Training 

occurs year round for both active and 

reserve troops of the different branches 

of the military (Fort A.P. Hill 2017, pp. 

2–2 to 2–3). 

Management buffers are established 

around Kenk’s amphipod seeps to 

ensure the integrity of surficial habitats 

and water quality from potential 

impacts associated with land 

disturbance activities. Buffers are site 

specific and are determined based on 

the size of the seep area, surrounding 

terrain, hydrology, and contiguity of 

surrounding habitats. The buffer areas 

for each seep generally exceed 200 ft 

(0.06 kilometers (km)) all around, 

ranging in size from 1 to 6 acres (0.40 

to 2.43 ha) (average buffer area is 

approximately 2.3 acres (0.93 ha)). 

These buffers are also complemented by 

protections afforded to each site by 

adjacent wetlands and the undulating 

terrain of the surrounding landscape 

that provide additional habitat 

protections from disturbance activities. 

Within the buffers, land-disturbing 

activities (e.g., construction, land 

management (including pesticide 

application)) and ground-waterdisturbing activities (e.g., drilling wells) 

are prohibited unless Fort A.P. Hill 

coordinates with the Service to 

determine ways to minimize impacts to 

the Kenk’s amphipod (Fort A.P. Hill 

2017, pp. 9–32 to 9–33). 

All mounted military training 

maneuvers (i.e., those using tracked and 

wheeled vehicles) are restricted to 

established roads and designated open 

areas throughout the installation, and all 

tactical and nontactical vehicles must 

also use established stream crossings. 

Dismounted military maneuvers (i.e., 

those on foot) occur throughout the 

installation, including the training areas 

where Kenk’s amphipod seeps occur. 

Kenk’s amphipod seeps occur in the 

most undeveloped portion of the 

installation surrounded by an 

abundance of natural habitats 

characterized by rolling and often steep 

terrain. The seeps themselves where the 

Kenk’s amphipod has been found 

represent an exceptionally small 

fraction (0.00005 percent) of the training 

lands and are typically less often used 

for military training than other areas 

due to their isolated nature. Soldiers are 

precluded from bivouacking (i.e., 

camping) or digging within the buffer 

areas. Maps denoting the location of 

Kenk’s amphipod buffer areas are 

provided to Range Operations for the 

scheduling and coordination of training 

activities in these areas. No military 

training operations occur in Kenk’s 

amphipod seep areas or buffers that use 

petroleum operations (e.g., transport, 

storage, and handling) or chemical 

training (Fort A.P. Hill 2017, p. 9–33). 

Dirt and gravel trails are the primary 

transportation routes throughout the 

training areas where Kenk’s amphipod 

seeps can be found. Tactical and 

nontactical vehicle traffic on these trails 

is intermittent and is typically of low 

duration and intensity. The trails do not 

get chemically treated in the winter 

months nor are these trails designated 

for or used as transportation routes for 

industrial hazardous materials (i.e., 

tanker trucks). Routine recurring 

maintenance activities regularly 

conducted on installation trails include 

tree limbing, surface grading, 

application of surface material and 

surface and ditch stabilization. These 

types of maintenance activities occur as 

needed on these already established 

trails within the buffers to ensure safe 

access to military lands. Stabilization 

activities are the only type of 

maintenance activity that requires the 

application of erosion and sediment 

control procedures. Where stabilization 

of trails is required within Kenk’s 

amphipod buffers, stabilization efforts 

shall be in compliance with Virginia 

Erosion and Sediment Control 

procedures (VDEQ 1992). Of the six 

known Kenk’s amphipod sites, only two 

have trails within them, and these trails 

constitute only 1.8 mi (2.89 km) (0.3 

percent of total trail miles), half of 

which is closed to through traffic. Trail 

maintenance activities are anticipated to 

occur on trails within Kenk’s amphipod 

buffers less than once every 5 years. 

Large-scale trail improvements (e.g., 

culvert installation/replacement, trail 

widening) within Kenk’s amphipod 

buffers would require discussion with 

the Service to minimize impacts to the 

species and its habitat (Fort A.P. Hill 

2017, pp. 9–32 to–9–33). 

At Fort A.P. Hill, forest management 

activities, including timber harvest and 

controlled burns, occur throughout 

much of the facility, including areas 

along Mill Creek and Mount Creek 

supporting Kenk’s amphipod sites. No 

land-disturbance activities such as 

forest management or vegetation/habitat 

management will be conducted within 

established buffers without discussion 

with the Service. The seeps also occur 

in the non-live-fire portion of the base, 

meaning that wildfires are significantly 

less of a threat to the species or its 

habitat because no live rounds are used 

in those areas that can serve as ignition 

sources (Applegate 2016, pers. comm.). 

Additionally, when prescribed burns are 

used in areas adjacent to the seeps, Fort 

A.P. Hill will keep fire out of the buffers 

to the extent practicable. If a fire entered 

a buffer, Fort A.P. Hill would document 

any impacts to the buffers and the seeps 

(Andersen 2017c, pers. comm.). 

Recreational activities are allowed 

within Kenk’s amphipod buffer areas 

because installation regulations provide 

sufficient protections to ensure the 

conservation of the species. Hunting is 

the only recreational activity authorized 

in areas where three of the known 

Kenk’s amphipod sites occur. However, 

strict hunting regulations severely limit 

the numbers of hunters allowed in an 

area at any given time and restrict the 

timing and duration for hunting. 

Consequently, Fort A.P. Hill is only 

available for hunting less than 16 

percent of the year. The Kenk’s 

amphipod sites are unlikely to 


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experience adverse effects from hunting 

given: The limited availability of the 

Fort A.P. Hill landscape to hunting by 

the public in general; regulations 

prohibiting hunters from camping, 

digging, or using any motorized 

transportation (e.g., all-terrain vehicles, 

utility-terrain vehicles); that the Kenk’s 

amphipod buffers and seep areas 

represent an exceptionally small 

amount (0.014 percent and 0.00005 

percent) of the huntable areas of Fort 

A.P. Hill, respectively; and seeps and 

streams are typically avoided by hunters 

due to the difficulty in traversing them 

and the adjacent slopes. Fort A.P. Hill 

has offered public hunting opportunities 

for decades, and there has not been any 

evidence of adverse impacts observed at 

any stream, seep, or wetland to date, 

including the known Kenk’s amphipod 

sites (Fort A.P. Hill 2017, p. 9–34). 

Fort A.P. Hill has agreed to continued 

commitment to the conservation 

measures (buffers) identified in the 2017 

INRMP regardless of the Kenk’s 

amphipod Federal listing status, 

pending any currently unknown change 

in mission requirements (Andersen 

2017a, pers. comm.). However, should 

the species not warrant listing under the 

Act, some monitoring efforts for the 

species could be reduced (Andersen 

2017a, pers. comm.; Andersen 2017b 

pers. comm.). 

Based on past and current primary 

uses of the base (forest management, 

recreational use, and military 

maneuvers), the acreage of the base, the 

limited area occupied by the species, 

including the buffers, and the habitat 

characteristics (mature forest on steep or 

rolling topography, and often adjacent 

to wetland areas), and the location of 

the seep sites (e.g., on isolated areas of 

the base), the Service concludes that 

there is a low risk of sites being 

adversely affected even if mission 

requirements changed. 

The INRMP would result in the 

protection of 6 out of the 13 (46 percent) 

known Kenk’s amphipod locations. 

PECE Analysis 

The purpose of PECE is to ensure 

consistent and adequate evaluation of 

recently formalized conservation efforts 

when making listing decisions. The 

policy provides guidance on how to 

evaluate conservation efforts that have 

not yet been implemented or have not 

yet demonstrated effectiveness. The 

evaluation focuses on the certainty that 

the conservation efforts will be 

implemented and the certainty that the 

conservation efforts will be effective. 

The policy presents nine criteria for 

evaluating the certainty of 

implementation and six criteria for 

evaluating the certainty of effectiveness 

for conservation efforts. The certainty of 

implementation and the effectiveness of 

a formalized conservation effort may 

also depend on species-specific, habitatspecific, location-specific, and effortspecific factors. These criteria are not 

considered comprehensive evaluation 

criteria; we consider all appropriate 

factors in evaluating formalized 

conservation efforts. The specific 

circumstances will also determine the 

amount of information necessary to 

satisfy these criteria. 

To consider that a formalized 

conservation effort contributes to 

forming a basis for not listing a species, 

or listing a species as threatened rather 

than endangered, we must find that the 

conservation effort is sufficiently certain 

to be (1) implemented, and (2) effective, 

so as to have contributed to the 

elimination or adequate reduction of 

one or more threats to the species 

identified through the section 4(a)(1) 

analysis. The elimination or adequate 

reduction of section 4(a)(1) threats may 

lead to a determination that the species 

does not meet the definition of 

threatened or endangered, or is 

threatened rather than endangered. An 

agreement or plan may contain 

numerous conservation efforts, not all of 

which are sufficiently certain to be 

implemented and effective. Those 

conservation efforts that are not 

sufficiently certain to be implemented 

and effective cannot contribute to a 

determination that listing is 

unnecessary, or a determination to list 

as threatened rather than endangered. 

Regardless of the adoption of a 

conservation agreement or plan, 

however, if the best available scientific 

and commercial data indicate that the 

species meets the definition of an 

‘‘endangered species’’ or a ‘‘threatened 

species’’ on the day of the listing 

decision, then we must proceed with 

appropriate rulemaking activity under 

section 4 of the Act. Further, it is 

important to note that a conservation 

plan is not required to have absolute 

certainty of implementation and 

effectiveness in order to contribute to a 

listing determination. Rather, we need 

to be certain that the conservation 

efforts will be implemented and 

effective such that the threats to the 

species are reduced or eliminated. 

Using the criteria in PECE (68 FR 

15100, March 28, 2003), we evaluated 

the certainty of implementation (for 

those measures not already 

implemented) and effectiveness of 

conservation measures in the 2017 Fort 

A.P. Hill INRMP pertaining to the 

Kenk’s amphipod. We determined that 

the measures will be effective at 

eliminating or reducing threats to the 

species because they protect currently 

occupied, and any future occupied, 

seeps and their catchment areas from 

removal of forest canopy and the effects 

of poor water quality, erosion, and 

sedimentation, by instituting on-theground protections to better manage and 

regulate disturbance in the species’ 

occupied habitat. For example, two of 

the sites are in an area where timber 

harvest and prescribed burns were 

scheduled to occur within the next 5 

years, but will not be subjected to those 

management actions, pending any 

currently unknown change in mission 

requirements, due to the expanded 

buffer areas implemented around the 

Kenk’s amphipod sites (see below). 

We have a high degree of certainty 

that the measures will be implemented 

because Fort A.P. Hill has a track record 

of being good environmental stewards 

for the past 76 years since the base was 

established, and, more specifically, a 

track record of implementing 

conservation measures for federally 

listed species and species of concern 

since 1997 through their INRMPs. For 

example, Fort A.P. Hill has effectively 

implemented conservation measures 

specified in their INRMP for the 

Rappahannock spring amphipod 

(Stygobromus foliatus), a Department of 

Defense species at risk, including 

surveying its population and 

implementing avoidance buffers from 

ground-disturbing activities on the 

installation. In addition, during the 

spring of 2017, Fort A.P. Hill allowed 

access to its facility for amphipod 

surveys in potential suitable habitat. 

New conservation measures are 

prescribed by the 2017 INRMP for the 

Kenk’s amphipod and are already being 

implemented, including expanded 

buffer areas. The 2017 INRMP has 

sufficient monitoring and reporting 

requirements to ensure that the 

conservation measures we deem 

necessary are implemented as planned, 

and are effective at removing threats to 

the Kenk’s amphipod and its habitat. As 

specified above, the INRMP may be 

modified to reflect changes in mission 

requirements. Despite this provision, we 

believe that the site conditions at Fort 

A.P. Hill will continue to be adequate to 

conserve the Kenk’s amphipod, and Fort 

A.P. Hill will discuss with the Service 

any changes in mission requirements 

that would affect the Kenk’s amphipod 

and its habitat. 

Collaboration between the Service, 

Fort A.P. Hill, and Virginia Department 

of Game & Inland Fisheries previously 

occurred during development of the 

INRMP and continues to occur via 

discussions pertaining to 


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implementation throughout the year 

that are documented through electronic 

mail correspondence and telephone 

calls (Hoskin 2017, pers. comm.). This 

ongoing coordination and collaboration 

ensures that the conservation measures 

identified in the INRMP for all Federal 

and State listed species and species of 

concern are implemented. Based on Fort 

A.P. Hill’s implementation of previous 

conservation efforts as specified in its 

INRMP, we have a high level of 

certainty that the conservation measures 

in the 2017 INRMP will be implemented 

and effective, and thus they can be 

considered as part of the basis for our 

final listing determination for the 

Kenk’s amphipod. Our detailed PECE 

analysis is available for review at http:// 

www.regulations.gov and https://

www.fws.gov/chesapeakebay/. 

Summary of Biological Status and 

Threats 

Please refer to the proposed listing 

rule for the Kenk’s amphipod (81 FR 

67270; September 30, 2016) for a 

detailed description of the factors 

affecting the species, which are 

summarized and updated as appropriate 

below. 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Water Quality/Quantity Degradation 

Due to Chronic Pollution of Urban/ 

Suburban Runoff 

Habitat modification, in the form of 

degraded water quality and quantity, is 

one of the primary drivers of Kenk’s 

amphipod viability. While the species’ 

specific tolerances to parameters 

affecting water quality and quantity is 

not yet known, we do know that the 

Kenk’s amphipod is at increased risk to 

parameters that negatively affect water 

quality and quantity because these 

freshwater amphipods spend their 

entire life cycle in water and are, 

therefore, continually exposed to 

changes in the aquatic habitat. Water 

quality degradation of ground water at 

spring sites located in the Washington 

metropolitan area has been previously 

cited as a top concern in several studies 

and reports (Feller 1997, pp. 12–13; 

Culver and Sereg 2004, p. 13; Feller 

2005, p. 9; Hutchins and Culver 2008, 

p. 6; Kavanaugh 2009, p. 60; Culver et 

al. 2012, p. 37; Culver and Pipan 2014, 

p. 219). 

The amount of forested buffer 

surrounding the seep influences the 

species’ vulnerability and exposure to 

negative effects, and the smaller the 

buffer, the greater the risk of exposure. 

Buffer distance is important because the 

buffer helps filter sediment and other 

contaminants from the surface water 

entering the catchment areas and, 

therefore, the ground water that 

supports the Kenk’s amphipod. The 

Washington metropolitan area 

amphipod sites have narrow riparian 

buffers (94 ft to 1,000 ft) (29 m to 305 

m) separating them from the 

surrounding urban landscape. This 

urban land is characterized by 

impervious surface cover, which 

includes paved roads, sidewalks, 

parking lots, and buildings (Sexton et al. 

2013, p. 42). 

An impervious cover analysis was 

conducted by the Service within the 

watersheds occupied by the Kenk’s 

amphipod. 

We calculated the overall average 

value (percentage) for each watershed 

identified. We also identified three 

categories of impervious cover: (1) 0 

percent impervious cover, (2) 1 to 15 

percent impervious cover, and (3) 

greater than (>) 15 percent impervious 

cover. For each watershed, we then 

calculated the percentage of area that 

fell into each of these three categories. 

These percentages are presented in 

Table 2. 

TABLE 2—IMPERVIOUS COVER ESTIMATES

Amphipod species 

(total number of sites) Watershed 

Number of 

amphipod 

sites 

Categories of impervious cover (IC) percentage Average 

impervious 

cover (IC) 

percentage 0% IC 1–15% IC >15% IC 

Stygobromus kenki (12) ...... Lower Rock Creek ............. 5 17 24 59 83 

Northwest Branch ............... 1 28 27 45 72 

Mount Creek ....................... 1 92 6 2 8 

Mill Creek ........................... 3 93 5 2 7 

* Vorhees Nature Preserve was not evaluated. 

The four watersheds within the 

Kenk’s amphipod’s range have overall 

impervious cover estimates ranging 

from approximately 7 percent (Mill 

Creek in Virginia) to 83 percent (Lower 

Rock Creek in the District of Columbia 

and Montgomery County, MD). 

Although the data for this level of the 

impervious cover analysis were derived 

using the finest scale hydrologic units 

available in the National Land Cover 

dataset, they do not reference the exact 

location of the Kenk’s amphipod spring 

sites in relation to the location of 

impervious cover within the watersheds 

because the spring sites and their 

catchment areas are at a smaller scale. 

Additionally, because the data are from 

2011, there could be more impervious 

cover present than indicated in our 

analysis. However, by looking at aerial 

photographs from 1988 and 2014 of the 

areas surrounding the spring sites in the 

Washington metropolitan area, there has 

been little change in the amount of 

development; therefore, we determined 

that the estimates of impervious cover 

derived from the 2011 dataset are 

sufficiently accurate for our analysis. 

To provide a general indication of 

how much impervious cover may be 

influencing surface water quality at 

individual sites, we created maps with 

the individual sites included within the 

impervious cover data layers (see 

Supplemental Document—Maps of 

Impervious cover in relation to spring 

sites in the Washington metropolitan 

areas and Impervious cover in relation 

to spring sites in Virginia). 

Urban impervious surfaces can result 

in increased surface water flow after 

storm events due to decreased 

opportunity for immediate or proximal 

infiltration. The surface flow waters 

have higher temperatures, higher 

sediment loads, and higher levels of 

heavy metals (zinc, cadmium), nitrogen, 

phosphorus, and fecal coliform bacteria 

(Walsh et al. 2005, pp. 706–723). In 

addition to affecting water quality, 

urban impervious surfaces can affect 

water quantity; decreased infiltration 

can result in depletion of ground water 

reserves and ultimately cause springs to 

dry up over time (Frazer 2005, p. 3). 

When the average impervious cover is 

between 10 and 15 percent within a 

watershed, sharp declines in aquatic 

habitat quality and aquatic insect 


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diversity are likely to occur, while the 

number of pollution-tolerant species 

increase (Schueler 1994, pp. 100–102; 

Boward et al. 1999, p. 45; Center for 

Watershed Protection 2003, pp. 101–102 

(synthesis of 30 studies)). More recently, 

declines of 110 of 238 macroinvertebrate 

taxa were found in streams receiving 

runoff water from areas that contained 

between 0.5 to 2 percent of impervious 

cover (King et al. 2011, pp. 1659–1675). 

These results were consistent among the 

three physiographic regions evaluated 

(Mountain, Piedmont, and Coastal 

Plain); the Piedmont region includes the 

Washington metropolitan area 

amphipod sites. Further, higher 

gradient, smaller catchments such as 

those supporting sites occupied by the 

Kenk’s amphipod required less 

impervious cover than lower gradient, 

larger catchments to elicit a 

macroinvertebrate community response 

(i.e., the macroinvertebrate taxa from 

steeper sloped, smaller catchment areas 

showed a decline in response to 

relatively small amounts of impervious 

cover) (King et al. 2011, pp. 1659–1676). 

This finding is relevant, given that the 

results of our impervious cover analysis 

indicate that Kenk’s amphipod sites are 

located within areas containing 7 to 83 

percent impervious cover (see table 2). 

The hypotelminorheic zone, the main 

habitat required by the Kenk’s 

amphipod, may be more vulnerable to 

the effects of urban runoff than streams 

with respect to pollutants, erosion, and 

sedimentation because of the small size 

and shallow nature of the habitat. In 

addition, the aforementioned narrow 

buffer zones around the 

hypotelminorheic sites increase the 

habitat’s and species’ exposure to urban 

runoff. 

Poor water quality parameters have 

been documented by the USGS through 

chemical analyses of ground water, 

surface water, and sediments in the 

Rock Creek watershed (Anderson et al., 

2002, pp. 1–99; Miller et al. 2006, pp. 

1–48; Koterba et al. 2010, pp. 1–102; 

Phelan and Miller 2010, pp. 1–80). For 

example, five pesticides (carbaryl, 

chlorpyrifos, diazinon, dieldrin, and 

malathion) were detected in Rock Creek 

Park water samples at concentrations 

that exceed aquatic life water quality 

criteria (Anderson et al. 2002, p. 44). 

Furthermore, Rock Creek sediments 

contained polycyclic aromatic 

hydrocarbons (PAHs), polychlorinated 

biphenyls (PCBs), organochlorine 

pesticides, and toxic metals at 

concentrations that approached and 

exceeded guidelines for the protection 

of aquatic life (Miller et al. 2006, p. 21). 

In a 2008 study at five stream locations 

in Rock Creek Park, pharmaceuticals, 

pesticides, fragrances, flame retardants, 

detergents, and sterols were detected 

and attributed to low-level sources of 

wastewater entering the streams (Phelan 

and Miller 2010, pp. 37, 40–41). 

In the Washington metropolitan area, 

water quality degradation from urban 

runoff is the greatest concern for the 

Kenk’s amphipod at the Sherrill Drive 

Spring location (Culver and Sereg 2004, 

p. 69). Sherrill Drive Spring is close 

(approximately 115 ft (35 m)) to the 

edge of Rock Creek Park where there is 

an abrupt change from forested habitat 

to an urban landscape along 16th Street 

Northwest, which parallels the park 

boundary. A significant amount of 

impervious cover routes runoff into the 

catchment area surrounding the Sherrill 

Drive Spring. 

While there have been no laboratory 

studies conducted to evaluate the effects 

and tolerance of the Kenk’s amphipod 

or Stygobromus tenuis to chemical, 

nutrient, pesticide, or metal pollution, 

we know from published studies that 

amphipods may be one of the most 

vulnerable groups of organisms to 

chemical pollution due to their high 

sensitivity to toxicants and contaminant 

accumulation (Borgmann et al. 1989, p. 

756; Brumec-Turc 1989, p. 40). 

Sediment samples surrounding the 

springs were collected in September 

2001 at East Spring and Sherrill Drive 

Spring to analyze metal and organic 

contaminants. 

Toxic metals were found in the 

sediment samples. Values were similar 

for the two sites, although East Spring 

had the highest values for all toxic 

metals, with the exception of zinc 

(Culver and Sereg 2004, p. 65). 

However, because it was the springs’ 

sediments instead of water samples that 

were analyzed, it is difficult to know 

whether the value of the metals 

measured in the sediments exceed 

aquatic life standards in water or any 

published values for freshwater 

amphipod species. Furthermore, water 

samples taken from the springs in Rock 

Creek Park and at Burnt Mill Spring #6 

in June 2016 did not detect toxic metals 

(Pinkney 2017b, pers. comm.). Sources 

of trace metals in an urban environment 

may include vehicles, streets, parking 

lots, snowpacks, and rooftops (Center 

for Watershed Protection 2003, p. 73). 

However, although the Washington 

metropolitan area spring sites are 

exposed to these sources, there is no 

quantitative evidence that toxic metals 

are affecting the springs or the Kenk’s 

amphipod. 

Water samples collected from 2000 to 

2003 found nitrate levels as high as 30.8 

milligrams per liter (mg/L) at Sherrill 

Drive Spring (Culver and Sereg 2004, p. 

109). In 2016, nitrate concentrations at 

Sherrill Drive Spring were 3.9 mg/L and 

4.2 mg/L at Burnt Mill Spring #6 

(Pinkney 2017, pers. comm.). Statistical 

analysis of Maryland Biological Stream 

Survey (MBSS) data indicated that 

detrimental effects were present in fish 

and benthic communities at critical 

nitrate-N threshold values of 0.83 mg/L 

and 0.86 mg/L, respectively (Morgan et 

al. 2007, pp. 160–161). These threshold 

values are significantly lower than the 

values reported at Sherrill Drive Spring 

and Burnt Mills Spring #6. 

We do not know how typical the 

Sherrill Drive Spring or Burnt Mill 

Spring #6 nitrate concentrations are and 

if chronic exposure is occurring, but we 

know that Stygobromus specimens have 

not been detected at Sherrill Drive 

Spring since 2001 or at Burnt Mill 

Spring #6 since 2005 (see table 1). We 

also do not know the potential source of 

the nitrate since it could come from 

runoff containing fertilizers or animal 

waste or from sanitary sewer leaks. 

However, a sanitary sewer line runs 

adjacent to the Sherrill Drive Spring, 

and this sewer line has leaked in the 

past (Feller 1997, p. 37; Yeaman, 2014, 

pers. comm.). 

Other high levels of nutrients were 

also evident in the June 2016 sampling 

conducted by the Service’s Chesapeake 

Bay Field Office (Pinkney 2017b, pers. 

comm.). The EPA (2000) ecoregional 

proposed criterion for stream total 

nitrogen of 0.69 mg/L was exceeded at 

the following seepage spring locations: 

Kennedy Street Spring (1.9 mg/L), 

Sherrill Drive Spring (6.5 mg/L), East 

Spring (9.7 mg/L), Holsinger Spring 

(20.9 mg/L), and Burnt Mill Spring #6 

(24.2 mg/L). The EPA stream total 

phosphorus criterion of 0.036 mg/L was 

exceeded at all five seepage springs with 

a maximum concentration of 1.3 mg/L at 

Kennedy Street Spring. The MBSS 

thresholds were 1.3 mg/L total nitrogen 

and 0.043 mg/L total phosphorus for 

benthic communities (no thresholds 

were determined for fish communities) 

(Morgan et al. 2007, pp. 160–161). 

Chloride levels as high as 227 mg/L 

were detected at Sherrill Drive Spring. 

The EPA chronic ambient water quality 

criterion for chloride is 230 mg/L (EPA 

2016, entire). Although we do not know 

the exact source of the elevated chloride 

levels at Sherrill Drive Spring, one 

potential source could be road salt. The 

Washington metropolitan area receives, 

on average based on 69 years of data 

taken at Washington National Airport, 

approximately 19.5 inches of snow 

annually (Southeast Regional Climate 

Center 2017, entire; Current Results 

2017, entire). The District of Columbia 

Department of Public Works uses road 


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salt and other salt products to pre- and 

post-treat road surfaces before and after 

ice and snowfall events (District of 

Columbia Department of Public Works 

2017, entire). However, the NPS has 

discontinued the use of road salts at 

some locations within Rock Creek Park 

(Bartolomeo 2017, pers. comm.). The 

widespread use of salt to deice 

roadways has led to regionally elevated 

chloride concentrations equivalent to 25 

percent of the chloride concentration in 

seawater during winter. The 

concentrations can remain high 

throughout the summer even in less 

urbanized watersheds due to long-term 

(e.g., decades) accumulation of chloride 

in ground water (Kaushal et al. 2005, 

pp. 13518–13519). This phenomenon 

was documented by the Service’s June 

2016 detection of a chloride 

concentration of 227 mg/L at Sherrill 

Drive Spring (Pinkney 2017a, pers. 

comm.). Analyses of MBSS data on fish 

and benthic communities yielded 

critical chloride values of 17 mg/L for 

fish and 50 mg/L, respectively, as 

thresholds above which there would be 

detrimental effects on biotic 

communities (Morgan et al. 2007; pp. 

160–161). Thus, the concentrations 

measured in June 2016 (Pinkney 2017a, 

pers. comm.) at Kennedy Street Spring 

(56.3 mg/L), Holsinger Spring (70.7 mg/ 

L), Burnt Mill Spring #6 (115 mg/L), and 

Sherrill Drive Spring (237 mg/L) all 

exceed thresholds for benthic 

communities. Furthermore, chloride 

concentrations in ground water may 

move slower (e.g., dilute slower) than in 

surface waters and thus the effects from 

winter road salt application may be 

more persistent in the surrounding 

environment (Findlay and Kelly 2011, 

p. 66). 

At Coquelin Run Spring, ground 

water pollution from yard chemicals 

and road runoff (e.g., road salts, oil) 

could be a concern for the Kenk’s 

amphipod’s long-term viability. The 

USGS research on water quality 

degradation in other urban areas 

indicates that chemicals enter 

waterways and ground water primarily 

through runoff from rain events, and 

these chemicals have commonly been 

detected in streams and shallow ground 

water (USGS 1998, entire; USGS 1999a, 

pp. 1–3; USGS 1999b, p. 1; USGS 2001, 

p. 2). Although no water samples have 

been taken at the Coquelin Run Spring 

site, it is separated from backyards in 

this neighborhood by a narrow, wooded 

riparian strip (less than 100 ft) (30 m) 

that slopes steeply down to the site. 

Therefore, the Coquelin Run Spring may 

be at increased risk of exposure to 

chemical pollutants from the 

surrounding urban development. 

The other four Washington 

metropolitan area sites (Burnt Mill 

Spring #6, Holsinger Spring, East 

Spring, and Kennedy Spring) have 

wider buffers than Sherrill Drive Spring 

and Coquelin Run Spring, with buffer 

distances ranging from approximately 

272 ft (83 m) to 1,000 ft (305 m). East 

Spring and Kennedy Spring had much 

lower conductivity and nitrate levels 

than Sherrill Drive Spring in the 2000, 

2001, and 2003 sampling (Culver and 

Sereg 2004, pp. 55–58), but were still 

above criteria suggested by Morgan et al. 

(2007, p. 161). Surveys conducted in 

2015 and 2016 did not re-confirm the 

Kenk’s amphipod at any of these sites 

but consistently found Stygobromus 

tenuis at all the sites in higher numbers 

(e.g., greater than 40 observed at Burnt 

Mill Spring #6 during 1 sampling 

event). Urban runoff can decrease biotic 

richness and favor more pollutiontolerant species in urban streams 

(Center for Watershed Protection 2003, 

pp. 101–102). If S. tenuis has a higher 

tolerance than the Kenk’s amphipod to 

poor water quality parameters, the 

change in species’ composition 

discussed in the proposed rule’s (81 FR 

67270; September 30, 2016) Relative 

Abundance section and Factor E— 

Changes in Species Composition could 

indicate that urban runoff is negatively 

affecting the Kenk’s amphipod 

populations at these spring sites. 

The NPS manages the surrounding 

habitat at the four seepage spring sites 

supporting the Kenk’s amphipod in 

Rock Creek Park. While the NPS uses its 

regulatory authority to manage water 

quality concerns for the species within 

Rock Creek Park, the agency has little 

influence over the protection of or 

effects to any seep recharge areas 

occurring outside park boundaries, and 

over maintenance or repair of cityowned infrastructure such as storm 

water and sewer systems located near 

the spring sites. See the proposed rule 

(81 FR 67270; September 30, 2016) for 

a list of laws and policies influencing 

NPS management. 

In Virginia, poor water quality is not 

likely affecting the species at the Fort 

A.P. Hill and Voorhees Nature Park 

because the sites are located in 

watersheds that are primarily forested 

with little impervious surface (see table 

2). 

Summary of Water Quality—In total, 

poor water quality is believed to be a 

contributing stressor at all six of the 

Washington metropolitan area sites (i.e., 

46 percent of the total known sites). 

Water quality in this area is expected to 

worsen due to significant runoff events 

from anticipated increases in both 

winter and spring precipitation and the 

frequency of high-intensity storms. (See 

Factor A—Excessive Storm Water Flows 

and Factor E—Effects of Climate Change 

sections for more details.) However, we 

find that poor water quality is not 

impacting the Virginia spring sites 

because the sites are located in forested 

areas with low levels of impervious 

cover, and we do not anticipate those 

conditions to change into the future. In 

addition, the measures in Fort A.P Hill’s 

INRMP and the location of one site on 

conservation land provides protections 

to the species. 

Excessive Storm Water Flows 

Runoff from impervious surfaces after 

heavy rain events can result in flooding 

(Frazer 2005, p. 4; NBC News 2016, 

entire). Flash flooding can also result in 

erosion and sedimentation (Center for 

Watershed Protection 2003, pp. 30–33), 

which, if it occurs in the catchment 

area, can subsequently degrade a spring 

site’s value as habitat for the Kenk’s 

amphipod. 

In the Washington metropolitan area, 

excessive storm water flows are causing 

significant habitat degradation at two 

sites—Sherrill Drive Spring and 

Coquelin Run Spring. A washout at 

Sherrill Drive Spring from 16th Street 

was observed in 2016 making it difficult 

to find a seep to survey (Feller 2016f, 

pers. comm.). Coquelin Run Spring is 

severely degraded by runoff from the 

surrounding Chevy Chase Lake 

Subdivision, where severe erosion was 

first observed at this site in 2006 (Feller 

2016h, pers. comm.). Subsequent 

surveys of the site found evidence of 

plastic underground pipe and sheeting, 

which may have been an attempt to 

address water flow and erosion at the 

site, in close proximity to the original 

seep and further erosion of the site 

(Feller 2016a, pers. comm.; Feller 2016e, 

pers. comm.). A small flow was 

observed in May 2016 but was located 

several feet above the original seep 

documented in 2006. It is unknown 

what affect the pipe or plastic may have 

on the long-term hydrology of the site. 

Erosion from storm water flows has 

also been observed at the other three 

springs in Rock Creek Park, but not to 

the extent that it has been observed at 

Sherrill Drive and Coquelin Run 

Springs. It is unknown how much 

chronic or acute erosion and 

sedimentation causes a site to become 

unsuitable for the Kenk’s amphipod; 

however, Culver and Sereg (2004, p. 69) 

found that sediment transported by 

storm runoff results in the degradation 

of ground water animals’ habitat by 

clogging the interstices of gravels in the 


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spring seep, thereby preventing the 

species from using those interstitial 

spaces for shelter. It is uncertain to what 

extent the Kenk’s amphipod uses those 

interstitial spaces, but if they do, then 

it is plausible that this type of 

sedimentation would cause the habitat 

to become unsuitable for the species. 

At the Virginia sites, Mill Creek #2 

experiences sheet flow into the seep 

area off of a lateral slope during rainfall 

events due to the degree of slopes and 

close proximity to a stormwater culvert 

outlet (Applegate 2016, pers. comm.). 

However, erosion and sediment control 

repairs to the culvert and the surface of 

the associated unimproved trail 

conducted prior to the proposed rule 

has dramatically improved current 

conditions. Consequently, sheetflow is 

not considered a threat to the 

conservation of the Kenk’s amphipod at 

this location (Applegate 2017, pers. 

comm.). Sheet flow is not considered to 

be a problem at Voorhees Nature 

Preserve (Hobson 2017a, pers. comm.). 

Summary of Excessive Storm Water 

Flows—Excessive storm water flows are 

a contributing stressor at 38 percent (5 

of 13) of the species’ sites (Sherrill Drive 

Spring, Coquelin Run Spring, East 

Spring, Kennedy Street Spring, and 

Holsinger Spring). 

Sewer Line Breaks and Spills 

The same riparian areas that contain 

the habitats of the Kenk’s amphipod are 

among the principal areas where sewer 

lines are located in the Washington 

metropolitan area (Feller 2005, p. 2). 

Most of these sewer lines are old (most 

installed between 1900 and 1930 in the 

District of Columbia and between 1941 

and 1971 in Montgomery County, MD) 

and subject to periodic breakage and 

leakage (Shaver 2011, entire; Kiely 2013, 

entire). While there have been no 

laboratory or field studies evaluating the 

effect of sewage leaks or spills on the 

Kenk’s amphipod or the Stygobromus 

tenuis, adverse effects of sewage 

contamination on amphipods and other 

invertebrates have been documented 

(Simon and Buikema 1997, entire; de 

laOssa-Carretero et al. 2012, p. 137). 

Releases of large volumes of sewage 

(up to 2 million gallons (gal)) from 

sanitary sewer leaks have occurred in 

the District of Columbia and 

Montgomery County, MD. Coquelin Run 

Spring, Burnt Mill Spring #6, and 

Sherrill Drive Spring are most 

vulnerable to sewage spills because they 

are located downhill from several sewer 

lines (see table 2 in the proposed rule 

(81 FR 67270; September 30, 2016) for 

details). The Washington Suburban 

Sanitary Commission (WSSC) has 

documented numerous large (more than 

1,000 gallons) and small (more than 100 

gallons) leaks in both the Rock Creek 

and Northwest Brach drainages (WSSC 

2015). The District of Columbia does not 

have such detailed records, but half the 

District of Columbia’s 1,800 mi (2,896 

km) of sewer lines are at least 84 years 

old and faulty pipes result in two dozen 

sewer spills every year (Olivio 2015). 

The frequency of spills is likely to 

increase in the future as the sewer lines 

continue to age. 

At the Virginia sites, we have no 

information indicating sewer pipelines 

may affect the species. 

Summary of Sewer Line Spills—In 

total, sewer line breaks and spills are a 

potential concern at 23 percent (3 of 13) 

of the species’ sites. 

Water Pipe Breaks 

Bursting of large-diameter water pipes 

can cause significant erosion of 

surrounding areas as a result of the large 

volume of fast-moving water that exits 

the pipe at the break point. Bursting 

water pipes and the resulting erosion 

has been documented within the 

Washington metropolitan area, 

including areas near but not directly at 

a specific Kenk’s amphipod seep site 

(Dudley et al. 2013, entire). The 

exposure risk of bursting water pipes at 

locations that could affect Kenk’s 

amphipod sites is increasing given the 

age of the water pipe infrastructure (see 

table 2 in the proposed rule (81 FR 

67270; September 30, 2016) for more 

details). 

At the Virginia sites, we have no 

information indicating water pipeline 

breaks may affect the species. 

Summary of Water Pipe Breaks—In 

total, large water pipeline breaks have a 

potential to occur at 8 percent (1 of 13) 

of the species’ sites (Sherrill Drive 

Spring), while smaller water pipeline 

breaks could occur at 23 percent (3 of 

13) of the sites (Sherrill Drive Spring, 

Coquelin Run Spring, and Burnt Mills 

#6 Spring). 

Other Habitat Considerations 

The Kenk’s amphipod is likely 

susceptible to changes to the forest 

canopy and understory; this theory is 

supported by the fact that they can be 

found in leaf litter. The more common 

species Stygobromus tenuis has been 

found to actively exit the 

hypotelminorheic under appropriate 

conditions, presumably to forage 

(Kavanaugh 2009, p. 3), and they are 

found only in forested areas (Culver 

2016, pers. comm.). 

In the Washington metropolitan area, 

there have been no land-disturbance 

activities such as forest management or 

vegetation/habitat management 

activities conducted at Rock Creek Park 

or at the Montgomery County park in 

the vicinity of the seeps. At Rock Creek 

Park, the NPS has taken steps to prevent 

designated trails from being built in 

areas that could affect the Kenk’s 

amphipod, and there are no trails in 

close vicinity to the seep found at the 

county park. At the privately owned 

site, an underground pipe previously 

installed on the hillside where the seep 

is located was observed in 2016, and, 

despite the steep topography, there is 

the potential for foot traffic in the 

seepage area by the landowners. The 

Service is unaware of any tree removal 

ever occurring at this site. 

In general, stressors to the Kenk’s 

amphipod habitat at the Virginia sites 

are less significant than those in the 

Washington metropolitan area because 

land use is primarily agriculture and 

forest with little impervious surface. See 

the description of Fort A.P. Hill under 

the Ongoing and Future Conservation 

Measures section above. With the 

possible exception of the effects of 

climate change and the potential effects 

of small population dynamics (see 

Factor E below), we are unaware of any 

stressors at Voorhees Nature Preserve 

(Hobson 2017a, pers. comm.). The 

preserve is located 8.5 mi (13.7 km) east 

across the Rappahannock River from 

Fort A.P. Hill in Westmoreland County, 

Virginia. The 729-acre (295-hectare) 

parcel has been owned by The Nature 

Conservancy (TNC) since 1994. The goal 

of the preserve is to protect the mature 

coastal plain forest and freshwater tidal 

marsh (Truslow 2017a, pers. comm.). 

As of July 2017, human activity at the 

preserve is limited to maintenance of 

approximately 3 mi (4.8 km) of hiking 

trails, white-tailed deer management 

through a hunt lease with a local hunt 

club, and annual monitoring to ensure 

the protection goals of the property are 

being met. There is light recreational 

use from the 3 mi (4.8 km) of hiking 

trails located on the property. The trails 

are open only for foot travel 

(approximately several hundred visitors 

a year based on trail logs); no ATVs or 

bikes are allowed on the trails (Truslow 

2017b, pers. comm.). Dogs are also not 

allowed at the preserve (TNC 2017, 

entire). 

The seep where the Kenk’s amphipod 

was found is not impacted by the trail 

because it is located approximately 30 

to 40 ft (9.1 to 12.2 m) down slope of 

the trail, at the head of a ravine, and it 

is surrounded by dense vegetation, 

which makes access to the site difficult 

(Hobson 2017a, pers. comm.). There is 

also no visible erosion from the trail (C. 

Hobson 2017a, pers. comm.). 


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The TNC developed a sitemanagement plan upon assuming 

ownership. Timber harvesting will not 

occur where there is mature forest, and 

uplands will be kept in a forested 

condition to protect the property’s 

marsh from sedimentation runoff. In 

addition, TNC will not use pesticides 

(e.g., dimilin) to control future gypsy 

moth infestations (TNC 1994). 

In terms of the property’s protection 

status, TNC preserves are considered to 

be permanently protected. The deed 

does not contain restrictions on TNC 

selling or transferring the property; 

however, TNC policy would require that 

the property be transferred to an entity 

that would manage for similar 

conservation goals (e.g., a State natural 

resource agency or Federal agency), or 

that it be restricted by a conservation 

easement that would ensure permanent 

protection of the property (Truslow 

2017a, pers. comm.). 

The preserve is surrounded primarily 

by forest, and there is Service-owned 

National Wildlife Refuge land and Stateowned land west of the site. A soil 

enhancement facility was proposed in 

2014 at a parcel approximately 1 mile 

(1.6 km) northeast of the seep. The 

purpose of the facility would be to 

compost biosolids from sewage and sell 

the compost as fertilizer. If the site was 

approved and constructed, it would not 

impact the Kenk’s amphipod because 

the seep is at a higher elevation and in 

a different surface catchment area than 

the proposed soil enhancement facility. 

Summary of Factor A—Habitat 

modification, in the form of degraded 

water quality and quantity, is one of the 

primary drivers affecting Kenk’s 

amphipod viability at the Washington 

metropolitan area sites, despite ongoing 

conservation measures. Reductions in 

water quality continue to occur at those 

sites primarily as a result of 

urbanization, which increases the 

amount of impervious cover in the 

watersheds surrounding six of the 

Kenk’s amphipod sites. Impervious 

cover increases storm water flow 

velocities, decreases ground water 

filtration, and increases erosion and 

sedimentation. Impervious cover can 

also increase the transport of 

contaminants and nutrients common in 

urban environments, such as metals 

(zinc, cadmium), nitrogen, phosphorus, 

and fecal coliform bacteria. The 

Washington metropolitan area sites have 

narrow riparian buffers separating them 

from the surrounding development, 

increasing the sites’ exposure to poor 

water quality from runoff. While poor 

water quality has been documented at 

Sherrill Drive Spring and is likely 

affecting all six sites in the Washington 

metropolitan area, the seven Virginia 

sites are not thought to be affected by 

poor water quality because of the large 

forested buffers on Fort A.P. Hill and 

Voorhees Nature Preserve. 

Excessive storm water runoff from 

heavy rain events can result in flooding, 

which can cause erosion and 

sedimentation. Habitat degradation due 

to excessive storm water flows is having 

effects at two sites—Sherrill Drive 

Spring and Coquelin Run Spring—but 

has also been observed at the other four 

springs in Rock Creek Park, and may 

increase in the future. At the Virginia 

sites, we have no information indicating 

excessive storm water flows affect the 

species. 

Sewer and water line breaks and leaks 

are a concern at the Washington 

metropolitan area sites because most of 

them are located in the same riparian 

areas that contain the habitats of the 

Kenk’s amphipod. While leaks and 

breaks of these pipelines have not yet 

been known to directly affect the 

species or its habitat, the pipeline 

systems are subjected to chronic leaks 

and breaks, the frequency of which is 

likely to increase given the age of the 

infrastructure, and thus the exposure 

risk of the species to this stressor will 

continue to increase. Coquelin Run 

Spring, Burnt Mill Spring #6, and 

Sherrill Drive Spring are most 

vulnerable to sewage spills and water 

pipe breaks due to the pipe’s proximity 

to each site and the age of the pipes. At 

the Virginia sites, we have no 

information indicating sewer or water 

pipeline breaks will affect the species. 

Stressors to Kenk’s amphipod habitat 

are significantly less in scope and 

severity at Fort A.P. Hill and Voorhees 

Nature Preserve than at the Washington 

metropolitan area habitats, due to the 

location of the sites, the current and 

foreseeable mission of the managing 

entities, and the conservation measures 

described in the INRMP and TNC 

Management Plan. The risk is low that 

any disturbance to the surface habitat on 

those properties would result in adverse 

effects to the species. We acknowledge 

that the Washington metropolitan sites 

face a number of stressors that will 

continue into the future. Of the six 

Washington sites, only one site has a 

recent record of Kenk’s amphipod. We 

cannot confirm without additional 

consecutive negative survey results, but 

it is possible that this species is 

functionally extinct in the Washington 

metropolitan area given the stressors it 

faces and the lack of specimens found 

in recent survey results. Conversely, the 

seven Virginia sites do not face the same 

stressors as the Washington 

metropolitan area sites. Habitat quality 

at the Virginia sites is good and the sites 

all have some form of protection, either 

from the measures in the Fort A.P. Hill 

INRMP or the TNC nature preserve’s 

site-management plan. 

TABLE 3—RELATIVE VULNERABILITY OF KENK’S AMPHIPOD SEEP HABITAT SITES

Site name Location Current seep status Current biological status of the Kenk’s 

amphipod 

Sherrill Drive Spring .... Rock Creek Park, 

Washington, DC.

Approximately 50’ to road, documented decrease in water quality (chemical and sedimentation), within 10’ of 1924 sewer pipe 

and 130’ of 1955 30’’ water pipe.

Extirpated? Not found in recent surveys. No 

other Stygobromus present. Last detected 

2001 (8 surveys since and none found). 

Niemiller et al. (2017) eDNA study also 

supports extirpation of all Stygobromus 

here. 

East Spring .................. Rock Creek Park, 

Washington, DC.

Approximately 300–500’ buffer of protected 

forest, within 560’ of 6–8’’ 1921 water pipe.

Unknown. Not found in recent surveys but 

other Stygobromus present. Last detected 

2001 (7 surveys in 2015–2016 and none 

found). 

Kennedy Street Spring Rock Creek Park, 

Washington, DC.

Approximately 500’ buffer of protected forest, 

within 860’ of 6–8’’ 1911 water pipe.

Unknown. Not found in recent surveys but 

other Stygobromus present. Last detected 

2001 (5 surveys since and none found). 


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TABLE 3—RELATIVE VULNERABILITY OF KENK’S AMPHIPOD SEEP HABITAT SITES—Continued 

Site name Location Current seep status Current biological status of the Kenk’s 

amphipod 

Holsinger Spring .......... Rock Creek Park, 

Washington, DC.

Approximately 700–1,000’ buffer of protected 

forest.

Historical? Not documented since 1967. One 

survey in 2003 and 3 surveys in 2015 and 

none found; other Stygobromus species 

present. 

Burnt Mill Spring #6 ..... Northwest Branch 

Park, Montgomery 

County, MD.

In county park protected from further development, within 186’ of unknown age sewer 

pipe and 394’ of 6–8’’ 1959 water pipe.

Unknown. Not found in recent surveys but 

other Stygobromus species present. Last 

detected in 2005 (10 surveys since and 

none found). 

Coquelin Run Spring ... Private land, Montgomery County, MD.Erosion problems are already apparent, site 

has been modified with a plastic pipe and 

plastic material, and riparian forest is very 

narrow. Within 220’ of 1952 sewer pipe 

and 250’ of 6–8’’ 1954 water pipe.

Present in upslope portion of seep (1 individual found in 2016); lower section has 

some erosion and species absent in that 

section (3 surveys conducted in 2016 and 

none found). No other Stygobromus species were found in upper or lower portion 

of seep in 2016. 

Fort A.P. Hill (6 seeps) Department of Defense, Caroline 

County, VA.

Good habitat quality, sites unaffected by urbanization. Military exercises, forest management, and construction activities are at 

low risk to affect surface habitat due to the 

revised INRMP.

Present and recently discovered. One individual each found at Upper Mill 2, Mill 4, 

and Mount 2 in 2014 but not identified as 

the Kenk’s amphipod until 2016; 4 individuals found at Mill 5 in 2014. In 2017, there 

were 6 individuals found at Upper Mill 2, 1 

individual at Upper Mill 4, and 4 individuals 

at Mount 2. Two new sites were found in 

2017: Mill Creek 56 (16 individuals) and 

Mill Creek 59 (8 individuals found). 

Voorhees Nature Preserve (1 seep).Westmoreland County, 

VA.

Good habitat quality, owned by TNC. Permanently protected as a nature preserve.Recently discovered. One individual found in 

2017. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

In the September 30, 2016, proposed 

rule (81 FR 67270), we found no 

information indicating that 

overutilization was a factor affecting the 

Kenk’s amphipod. No new information 

from peer review or public comments 

indicates that overutilization is a 

concern for the species. 

Factor C. Disease or Predation 

In the September 30, 2016, proposed 

rule (81 FR 67270), we found no 

information indicating that disease or 

predation was affecting the Kenk’s 

amphipod. No new information from 

peer review or public comments 

indicates that disease or predation is a 

concern for the species. 

Factor D. The Inadequacy of Existing 

Regulatory Mechanisms 

The following existing regulatory 

mechanisms were specifically 

considered and discussed as they relate 

to the stressors, under the applicable 

Factors, affecting the Kenk’s amphipod: 

the Clean Water Act’s (CWA) National 

Pollutant Discharge Elimination System, 

Rock Creek Park Authorization Act of 

1890, and National Park Service Organic 

Act of 1916 (Factor A; summarized 

above in this final determination, but 

discussed in full in the proposed rule 

(81 FR 67270; September 30, 2016) and 

Nongame and Endangered Species 

Conservation Act (Factor B). 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

Small Population Dynamics 

The observed small size of each of the 

13 Kenk’s amphipod populations may 

make each one vulnerable to natural 

environmental stochasticity and humancaused habitat disturbance, including 

relatively minor impacts in their spring 

recharge areas. However, there is 

significant uncertainty regarding the 

extent to which the number of Kenk’s 

amphipods observed at the seep surface 

accurately reflects the actual population 

at each site given the species’ known 

ability to move between the surface and 

subsurface habitat. We are unaware of 

any reliable method to accurately 

estimate the actual population size of 

the Kenk’s amphipod at each of its 

historical and current sites. In addition, 

the multiple sites (six in the Washington 

metropolitan area and seven in Virginia) 

provide some protection against 

stochastic and catastrophic events 

affecting all sites simultaneously (see 

the Cumulative Effects section below). 

An eDNA (Niemiller et al. 2016, pp. 

1–7) and a hydrogeology study (Staley 

2016, pp. 1–46) were conducted in 

2016. However, neither study resulted 

in any information that helped us better 

understand the Kenk’s amphipod’s 

genetics, distribution, or potential for 

dispersal (e.g., metapopulation 

structure). Therefore, unless the 

populations are larger than we know or 

are hydrologically connected such that 

individuals can move between sites, we 

maintain that these small populations 

are vulnerable to the effects of small 

population dynamics. 

Species that are restricted in range 

and population size are more likely to 

suffer loss of genetic diversity due to 

genetic drift, potentially increasing their 

susceptibility to inbreeding depression, 

and reducing the fitness of individuals 

(Soule 1980, pp. 157–158; Hunter 2002, 

pp. 162–163; Allendorf and Luikart 

2007, pp. 117–146). Small population 

sizes and inhibited gene flow between 

populations may increase the likelihood 

of local extirpation (Gilpin and Soule ́

1986, pp. 32–34). With the exceptions 

for the Fort A.P. Hill populations of Mill 

Creek #2 and Mill Creek #4, which are 

separated by only approximately 360 ft 

(110 m), and Mill Creek #56 and #59, 

which are approximately 2,640 ft (805 

m) from the other two Mill Creek sites 

and 1,056 ft (322 m) apart from each 

other, all the other populations of the 

Kenk’s amphipod are isolated from 

other existing populations and known 

habitats by long distances, inhospitable 

upland habitat, and terrain that create 

barriers to amphipod movement. The 

level of isolation and the restricted 

range seen in this species, based on our 


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current knowledge of known habitat, 

make natural repopulation of known 

habitats (e.g., the District of Columbia 

sites and Burnt Mill Spring #6 where 

the species’ presence has not been 

recently confirmed) virtually impossible 

without human intervention. 

Effects of Climate Change 

Climate change may result in changes 

in the amount and timing of 

precipitation, the frequency and 

intensity of storms, and air 

temperatures. All of these changes could 

affect the Kenk’s amphipod and its 

habitat. The amount and timing of 

precipitation influence spring flow, 

which is an important feature of the 

habitat of this ground water species. 

Also, the frequency and intensity of 

storms affects the frequency, duration, 

and intensity of runoff events, and 

runoff transport of sediment and 

contaminants into catchment areas of 

Kenk’s amphipod sites, especially in the 

Washington metropolitan area, where 

there is a substantial amount of 

impervious cover in close proximity to 

the habitat (see Factor A summarized 

above and in detail in the proposed rule 

(81 FR 67270; September 30, 2016)). 

Below we discuss the best available 

climate predictions for the areas 

supporting the Kenk’s amphipod. 

The 2014 National Climate 

Assessment (Melillo et al. 2014, entire) 

predicts increasing ambient 

temperatures, increasing winter and 

spring precipitation, increasing 

frequency of heavy downpours, and 

increasing summer and fall drought risk 

as higher temperatures lead to greater 

evaporation and earlier winter and 

spring snowmelt (Horton et al. 2014, p. 

374 In Melillo et al. 2014). Without 

more specific information about how 

seeps are connected underground, as 

well as the ability of the amphipods to 

migrate within the soil column in 

response to drying from drought 

conditions, it is unclear to what degree 

the temporary drying of these habitats 

will affect the Kenk’s amphipod (Carter 

2016, pers. comm.). Alternatively, an 

increase in heavy downpours will likely 

result in increased runoff and resulting 

erosion of surface features at spring 

sites, based on previously documented 

events. The 2014 National Climate 

Assessment further indicates that 

overall warming in the Northeast, 

including Maryland and the District of 

Columbia, will be from 3 to 10 degrees 

Fahrenheit (°F) (1.7 to 5.6 degrees 

Celsius (°C)) by the 2080s (Horton et al. 

2014, p. 374 In Melillo et al. 2014). The 

Southeast region, which includes 

Virginia, is projected to see a regional 

average temperature increase of 4 to 8 °F 

(2.2 to 4.4 °C) (Carter et al. 2014, p. 399 

In Melillo et al. 2014). 

Data specific to the District of 

Columbia from NOAA’s National 

Climate Data Center (NOAA 2017, 

entire) shows that the average annual air 

temperature in the District of Columbia 

has already increased by approximately 

2 °F (1.1°C) from 1960, the decade 

corresponding to the first Kenk’s 

amphipod surveys, to 2016. This higher 

rate of change in the District of 

Columbia may be due to the urban heat 

island effect (Oke 1995, p. 187), which 

is an increase in ambient temperature 

due to heating of impervious surfaces. 

This activity also results in an increase 

in temperature of rainwater that falls on 

heat-absorbing roads and parking lots. A 

sudden thunderstorm striking a parking 

lot that has been sitting in hot sunshine 

can easily result in a 10 °F (5.6 °C) 

increase in the rainfall temperature. 

Menke et al. (2010, pp. 147–148) 

showed that these temporary increases 

in temperature of storm water can still 

result in a shift in the biotic community 

composition and even accelerate 

changes in species distributions. Based 

on the work of Menberg et al. (2014, 

entire), we expect these changes in air 

temperature to be reflected in the 

temperature of the shallow ground 

water at all sites within a few years, but 

at a lower magnitude. 

Increased temperature is stressful to 

aquatic life through several 

mechanisms. First, at higher 

temperatures, the metabolic rate of 

invertebrates and fish is higher and 

more rapid ventilation is needed by the 

animal to obtain oxygen, which is less 

soluble (i.e., less available) in warmer 

versus cooler water (Schiedek et al. 

2007, p. 1846). Second, the rates that 

cold-blooded animals metabolize certain 

chemicals into more toxic forms 

increase at higher temperatures. This 

characteristic can either cause sublethal 

effects that inhibit the animal’s ability to 

feed, breed, or escape from predators, or 

can be lethal due to increased toxicity 

at higher temperatures. For example, 

organophosphate insecticides are 

metabolically transformed into the more 

toxic oxon form. This oxon form is 

lethal to animals because it inhibits the 

enzyme acetylcholinesterase (Hooper et 

al. 2013, p. 36). Illustrating this toxicity, 

laboratory experiments exposed the 

Gammarus pseudolimnaeus amphipod 

to the organophosphates terbufos and 

trichlorofon (Howe et al. 1994, p. 58). In 

one set of experiments, terbufos was 

demonstrated to be seven times more 

toxic at 62 °F (17 °C) than at 45 °F 

(7 °C). And third, ammonia, derived 

from wastewater, fertilizers, and runoff 

from animal wastes, is more toxic to all 

aquatic life at higher temperatures 

because a greater fraction exists in the 

more toxic un-ionized form (EPA 2013, 

p. 7). Thus, the EPA aquatic life criteria 

are temperature (and pH) dependent 

with lower limits at higher temperatures 

for a given pH. It is important to note 

we do not have specific temperature 

tolerance information for the Kenk’s 

amphipod; however, there are studies of 

other amphipod species that indicate 

these animals have a sensitivity to 

elevated temperatures, as exhibited by 

reduced or eliminated egg survival at 

water temperatures above 75 °F (24 °C) 

to 79 °F (26 °C) (Pockl and Humpesch 

1990, pp. 445–449). 

In summary, if current climate change 

predictions become reality, by the 2080s 

some increase in ground water 

temperatures will occur at sites 

occupied by the Kenk’s amphipod, yet 

the magnitude and significance of these 

changes is difficult to predict. 

Change in Species Composition 

At most of the Washington 

metropolitan area sites supporting the 

Kenk’s amphipod, numbers of the 

Potomac ground water amphipod, 

which is the most widely distributed 

and abundant Stygobromus species in 

the lower Potomac drainage (Kavanaugh 

2009, p. 6), have increased as numbers 

of observed Kenk’s amphipods have 

declined (Feller 2016b, pers. comm.; 

Feller 2016c, pers. comm.). The exact 

cause of this change is not known, but 

it may be an indication that some 

stressor has led to a competitive 

advantage for the Potomac ground water 

amphipod (Culver et al. 2012, p. 29). 

Other than at Coquelin Run Spring, 

there are no obvious physical changes at 

these sites indicating a cause for the 

decline. However, as described in Factor 

A, impaired water quality could favor a 

more common species over a rare 

species. Culver and Sereg (2004, pp. 72– 

73) indicated that there is a possibility 

that the Kenk’s amphipod is a poor 

competitor with other Stygobromus 

species, which may be a factor 

promoting the Kenk’s amphipod’s 

natural rarity, and that in cave locations 

Stygobromus species strongly compete 

with each other. Only one site in the 

Washington metropolitan area was 

surveyed in 2017, Burnt Mills Spring 

#6. That site continues to have a large 

number of S. tenuis and no Kenk’s 

amphipod (Feller 2016g, pers. comm.). 

The more common species S. tenuis and 

S. foliatus are found at the Virginia 

sites, but they are less abundant than 

what has been observed in the 

Washington metropolitan area sites 

(Hobson 2017b, pers. comm.). While the 

Kenk’s amphipod may have always been 


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naturally rare, we conclude that the 

species may be getting rarer at the 

Washington metropolitan area sites due 

to the stressors discussed above. 

Summary of Factor E—The believed 

small population size at all of the sites 

makes each one of them vulnerable to 

natural environmental stochasticity and 

human-caused habitat disturbance, 

including relatively minor impacts in 

their spring recharge areas. The believed 

small size and isolation of sites also 

make each population vulnerable to 

demographic stochasticity, including 

loss of genetic variability and adaptive 

capacity. 

The best available climate data 

indicate that the areas supporting the 

Kenk’s amphipod will see increasing 

ambient temperatures, increasing winter 

and spring precipitation, increasing 

frequency of heavy downpours, and 

increasing summer and fall drought risk 

as higher temperatures lead to greater 

evaporation and earlier winter and 

spring snowmelt. Droughts could result 

in drying up of spring sites, while the 

increase in heavy downpours could 

result in erosion and sedimentation of 

sites. Ambient air temperature has 

increased by 3 °F (1.7 °C) since 1960, 

and is expected to increase by 8 to 10 °F 

(4.4 to 5.6 °C) by the 2080s. If current 

climate change predictions become a 

reality, by the 2080s some increase in 

ground water temperatures will occur at 

sites occupied by the Kenk’s amphipod, 

but the magnitude and significance of 

these changes is difficult to predict. 

Cumulative Effects 

Many of the factors previously 

discussed are cumulatively and 

synergistically affecting the Kenk’s 

amphipod primarily in the Washington 

metropolitan area. For example, Kenk’s 

amphipod habitat can be degraded by 

storm water runoff when there is not 

adequate forest buffer, which is likely to 

increase with more frequent and intense 

storms and precipitation levels in the 

future. Species with larger populations 

are naturally more resilient to the 

stressors affecting individuals or local 

occurrences, while smaller populations 

or individuals are more susceptible to 

demographic or stochastic events. 

Below we discuss the Kenk’s 

amphipod’s viability as expressed 

through the conservation biology 

principles of representation, 

redundancy, and resiliency, which 

illustrate how the cumulative and 

synergistic effects are affecting the 

species as a whole. 

Redundancy—The species has some 

redundancy given its known historical 

distribution of 13 sites across 4 

municipal jurisdictions and multiple 

streams. Currently, the species is known 

to be extant at one of the Washington 

metropolitan area sites and seven of the 

Virginia sites. We assume that the 

Sherrill Drive Spring site is extirpated. 

Although we cannot confirm without 

additional consecutive negative survey 

results, given the lack of recent positive 

surveys and the existing stressors at the 

five other Washington metropolitan area 

sites, it is possible that these sites are 

functionally extinct, which means that 

the population at each site is so reduced 

that the site population is no longer 

viable. 

The isolation of the two Montgomery 

County, MD, populations from other 

Washington metropolitan area 

populations and their occurrence along 

different tributary streams make it 

unlikely that a single catastrophic 

adverse event (e.g., a spill) will 

eliminate more than one occurrence at 

a time. In addition, the Virginia sites on 

Fort A.P. Hill occur in two stream areas, 

Mill Creek and Mount Creek, making it 

unlikely that a single military training 

event or other catastrophic event will 

eliminate more than one occurrence at 

a time. In addition, subsequent to the 

species’ proposal for endangered status, 

it was found in the spring of 2017 

approximately 8.5 mi (13.7 km) away 

and across the Rappahannock River 

from the known Fort A.P. Hill sites. 

This finding, together with the 

discovery of two new sites on Fort A.P. 

Hill, contributes to additional 

redundancy for the species. 

Representation—Based on the 

information about historical changes to 

the landscape across the Washington 

metropolitan area, we conclude it is 

likely that the species’ historical 

distribution was larger than the current 

distribution; therefore, the species may 

have previously experienced a loss in 

representation. Also, because we do not 

yet have sufficient information on the 

genetics of these populations, we cannot 

determine whether the species 

possesses a single genetic identity or has 

genetic variability across populations. 

However, the species is now known to 

occur within habitat supported by two 

different geological formations, the 

Wissahickon and Nanjemoy. While we 

conclude that the species’ 

representation has likely been reduced 

from historical levels, it may not be as 

limited as we thought at the time of the 

proposed rule given our expanded 

understanding of suitable habitat and 

the three new locations found during 

the spring 2017 surveys on public land. 

Resiliency—Based on the relatively 

small number of individuals found at 

the 13 known seeps, and the variability 

of stressors across the species’ range, the 

resiliency of each of the Kenk’s 

amphipod’s populations may be low to 

moderate. The small size of each of the 

13 habitat areas makes each population 

vulnerable to natural environmental 

stochasticity and human-caused habitat 

disturbance, including relatively minor 

effects in the spring recharge area. As a 

result of habitat fragmentation/isolation 

there is a lack of connectivity and 

genetic exchange between populations 

and, we assume, a lack of ability to 

recolonize extirpated sites. However, 

the larger number of Kenk’s amphipods 

found at two of the newly discovered 

sites, together with the expectation that 

seven of the sites will be adequately 

protected from habitat quality stressors, 

leads us to believe that the resiliency of 

the Kenk’s amphipod at a majority of its 

sites is higher than we thought at the 

time of the proposed listing rule. 

Determination 

Section 4 of the Act (16 U.S.C. 1533), 

and its implementing regulations at 50 

CFR part 424, set forth the procedures 

for determining whether a species is an 

endangered species or threatened 

species and should be included on the 

Federal Lists of Endangered and 

Threatened Wildlife and Plants (listed). 

The Act defines an endangered species 

as any species that is ‘‘in danger of 

extinction throughout all or a significant 

portion of its range’’ and a threatened 

species as any species ‘‘that is likely to 

become endangered throughout all or a 

significant portion of its range within 

the foreseeable future.’’ The phrase 

‘‘significant portion of its range’’ (SPR) 

is not defined by the Act, and, since the 

Service’s policy interpreting the phrase 

was vacated by the court in Center for 

Biological Diversity v. Jewell, No. 14– 

cv–02506–RM (D. Ariz. Mar. 29, 2017), 

we currently do not have a binding 

interpretation that addresses: (1) The 

outcome of a determination that a 

species is either in danger of extinction 

or likely to become so in the foreseeable 

future throughout a significant portion 

of its range; or (2) what qualifies a 

portion of a range as ‘‘significant.’’ We 

have examined the plain language of the 

Act and court decisions addressing the 

Service’s application of the SPR phrase 

in various listing decisions, and for 

purposes of this rulemaking we are 

applying the following interpretation for 

the phrase ‘‘significant portion of its 

range’’ and its context in determining 

whether or not a species is an 

endangered species or a threatened 

species. 

Two district court decisions have 

evaluated whether the outcomes of the 

Service’s determinations that a species 

is in danger of extinction or likely to 


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become so in the foreseeable future in 

a significant portion of its range were 

reasonable. Defenders of Wildlife v. 

Salazar, 729 F. Supp. 2d 1207 (D. Mont. 

2010) (appeal dismissed as moot 

because of public law vacating the 

listing, 2012 U.S. App. LEXIS 26769 

(9th Cir. Nov. 7, 2012)); WildEarth 

Guardians v. Salazar, No. 09–00574– 

PHX–FJM, 2010 U.S. Dist. LEXIS 

105253 (D. Ariz. Sept. 30, 2010). Both 

courts found that, once the Service 

determines that a ‘‘species’’—which can 

include a species, subspecies, or 

Distinct Population Segment of a 

vertebrate species (DPS) under section 

3(16) of the Act—meets the definition of 

‘‘endangered species’’ or ‘‘threatened 

species,’’ the species must be listed in 

its entirety and the Act’s protections 

applied consistently to all members of 

that species (subject to modification of 

protections through special rules under 

sections 4(d) and 10(j) of the Act). See 

Defenders, 729 F. Supp. 2d at 1222 

(delisting the Northern Rocky Mountain 

DPS of gray wolf except in the Wyoming 

portion of its range (74 FR 15123 (Apr. 

2, 2009)) was unreasonable because the 

Act unambiguously prohibits listing or 

protecting part of a DPS); WildEarth 

Guardians, 2010 U.S. Dist. LEXIS 

105253, at 15–16 (the Service’s finding 

that listing the Gunnison’s prairie dog in 

the ‘‘montane portion’’ of its range was 

warranted (73 FR 6660 (Feb. 5, 2008)) 

was unreasonable because the Service 

‘‘cannot determine that anything other 

than a species, as defined by the Act, is 

an endangered or threatened species’’). 

The issue has not been addressed by a 

Federal Court of Appeals. 

For the purposes of this rule, we 

interpret the SPR phrase in the Act’s 

definitions of ‘‘endangered species’’ and 

‘‘threatened species’’ to provide an 

independent basis for listing a species 

in its entirety; thus there are two 

situations (or factual bases) under which 

a species would qualify for listing: A 

species may be in danger of extinction 

or likely to become so in the foreseeable 

future throughout all of its range; or a 

species may be in danger of extinction 

or likely to become so throughout a 

significant portion of its range. If a 

species is in danger of extinction 

throughout an SPR, it, the species, is an 

‘‘endangered species.’’ The same 

analysis applies to ‘‘threatened species.’’ 

Therefore, the consequence of finding 

that a species is in danger of extinction 

or likely to become so throughout a 

significant portion of its range is that the 

entire species will be listed as an 

endangered species or threatened 

species, respectively, and the Act’s 

protections will be applied to all 

individuals of the species wherever 

found. 

Although there are potentially many 

ways to determine whether a portion of 

a species’ range is ‘‘significant,’’ we 

conclude, for the purposes of this rule, 

that the significance of the portion of 

the range should be determined based 

on its biological contribution to the 

conservation of the species. For this 

reason, we describe the threshold for 

‘‘significant’’ in terms of an increase in 

the risk of extinction for the species. We 

conclude that such a biologically based 

definition of ‘‘significant’’ best conforms 

to the purposes of the Act, is consistent 

with judicial interpretations, and best 

ensures species’ conservation. 

For the purposes of this rule, we 

determine if a portion’s biological 

contribution is so important that the 

portion qualifies as ‘‘significant’’ by 

asking whether, without that portion, 

the species in the remainder of its range 

warrants listing (i.e., is in danger of 

extinction or likely to become so in the 

foreseeable future). Conversely, we 

would not consider the portion of the 

range at issue to be ‘‘significant’’ if the 

species would not warrant listing in the 

remainder of its range even if the 

population in that portion of the range 

in question became extirpated (extinct 

locally). 

We interpret the term ‘‘range’’ to be 

the general geographical area within 

which the species is currently found, 

including those areas used throughout 

all or part of the species’ life cycle, even 

if not used on a regular basis. We 

consider the ‘‘current’’ range of the 

species to be the range occupied by the 

species at the time the Service makes a 

determination under section 4 of the 

Act. The phrase ‘‘is in danger’’ in the 

definition of ‘‘endangered species’’ 

denotes a present-tense condition of 

being at risk of a current or future 

undesired event. Hence, to say a species 

‘‘is in danger’’ in an area where it no 

longer exists—i.e., in its historical range 

where it has been extirpated—is 

inconsistent with common usage. Thus, 

‘‘range’’ must mean ‘‘current range,’’ not 

‘‘historical range.’’ A corollary of this 

logic is that lost historical range cannot 

constitute a significant portion of a 

species’ range where a species is in 

danger of extinction or likely to become 

so within the foreseeable future (i.e., it 

cannot be currently in danger of 

extinction in a portion of its range 

where it is already extirpated). While 

we conclude that a species cannot be in 

danger of extinction in its lost historical 

range, taking into account the effects of 

loss of historical range on a species is 

an important component of determining 

a species’ current and future status. 

In implementing these independent 

bases for listing a species, as discussed 

above, we list any species in its entirety 

either because it is in danger of 

extinction now or likely to become so in 

the foreseeable future throughout all of 

its range or because it is in danger of 

extinction or likely to become so in the 

foreseeable future throughout a 

significant portion of its range. With 

regard to the text of the Act, we note 

that Congress placed the ‘‘all’’ language 

before the SPR phrase in the definitions 

of ‘‘endangered species’’ and 

‘‘threatened species.’’ This placement 

suggests that Congress intended that an 

analysis based on consideration of the 

entire range should receive primary 

focus. Thus, the first step in our 

assessment of the status of a species is 

to determine its status throughout all of 

its range. Depending on the status 

throughout all of its range, we will 

subsequently examine whether it is 

necessary to determine its status 

throughout a significant portion of its 

range. 

Under section 4(a)(1) of the Act, we 

determine whether a species is an 

endangered species or threatened 

species because of any of the following: 

(A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; (B) 

Overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) Disease or predation; (D) 

The inadequacy of existing regulatory 

mechanisms; or (E) Other natural or 

manmade factors affecting its continued 

existence. These five factors apply 

whether we are analyzing the species’ 

status throughout all of its range or 

throughout a significant portion of its 

range. 

Kenk’s Amphipod Determination of 

Status Throughout All of Its Range 

Our review of the best available 

information indicates that the Kenk’s 

amphipod is known to be extant at one 

of the Washington metropolitan area 

sites and seven of the Virginia sites. We 

assume that the Sherrill Drive Spring 

site is extirpated. Although we cannot 

confirm without additional consecutive 

negative survey results, given the lack of 

recent positive surveys and the existing 

stressors at the other Washington 

metropolitan area sites, it is possible 

that these sites are functionally extinct. 

Three of the Virginia sites were recently 

discovered during the 2017 surveys of 

suitable habitat on publicly owned 

lands. While there appears to be 

evidence of extirpation at one site 

(Sherrill Drive Spring) and decline of 

the species at four Washington 

metropolitan area sites (East Spring, 


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Kennedy Spring, Holsinger Spring, and 

Burnt Mill Spring #6), and one 

individual was collected at Coquelin 

Run Spring, the number of Kenk’s 

amphipods found during the 2017 

surveys was slightly higher at two of the 

previously known Fort A.P. Hill sites 

(Mount Creek #2 and Upper Mill Creek 

#2), the same at one previously known 

Fort A.P. Hill site (Mill Creek #4), and 

higher at two new sites on Fort A.P. Hill 

(Mill Creek #56 and Mill Creek #59); 

one of the previously known Fort A.P. 

Hill sites was not surveyed (Mill Creek 

#5) due to lack of spring flow. In 

addition, the species was newly 

discovered at the Voorhees Nature 

Preserve. It is possible that the species 

could be found at additional locations 

in Virginia based on the amount of yetto-be-surveyed suitable habitat. 

The habitat loss and degradation 

(Factor A) from poor water quality 

parameters associated with urban runoff 

affecting the Kenk’s amphipod at the six 

Washington metropolitan area sites, 

despite existing regulatory mechanisms 

(Factor D), are likely to be exacerbated 

in the future by the increasing risk of 

exposure to breaks and leaks from the 

aging sewer and water pipe 

infrastructure (Factor A), as well as the 

predicted more frequent and intense 

rainfall events, resulting in sheet flow 

events, due to the effects of climate 

change (Factor E). However, poor water 

quality associated with urban runoff is 

not affecting the species at the seven 

sites in Virginia. Interspecific 

competition (Factor E) from larger 

amphipod species may also be affecting 

the Kenk’s amphipod at some of the 

Washington metropolitan area sites, but 

the available information is 

inconclusive, and those larger 

amphipod species, while found at some 

of the Virginia sites, have not been 

found in large numbers (Hobson 2017b, 

pers. comm.). Overutilization (Factor B), 

disease (Factor C), and predation (Factor 

C) are not known to be factors affecting 

the Kenk’s amphipod at any site. It is 

possible that the effects of small 

population dynamics (Factor E) may be 

having an effect at some, if not all, of the 

species’ locations, but there is some 

uncertainty associated with that 

hypothesis given the species’ known 

ability to move back and forth between 

the ground water and surface areas of 

the seeps and given the survey data 

indicating the species can reappear, 

sometimes in higher numbers of 

individuals, after several years of 

absence. It is also possible that 

increasing air temperatures as a result of 

climate change (Factor E) will cause 

ground water temperatures to eventually 

increase, that the ground water will 

become too warm by the end of the 

century for the Kenk’s amphipod to 

successfully reproduce, and that higher 

ground water temperatures will increase 

the species’ exposure, and sublethal and 

lethal response, to contaminants. 

However, there is some uncertainty 

associated with that hypothesis given 

the long timeframes (e.g., more than 50 

years) associated with the climate 

modelling and the unknown water 

temperature tolerance of the Kenk’s 

amphipod. 

Although there are some stressors that 

are expected to continue to result in the 

degradation and loss of some habitat 

sites for the Kenk’s amphipod, the risk 

of the species significantly declining 

across its range in the near term is very 

low given that it has persisted, albeit at 

decreased levels, despite historical 

levels of habitat loss in the Washington 

metropolitan area. Factors in favor 

include the species’ presence in 

relatively higher numbers at the Virginia 

sites. Furthermore, the existing stressors 

are not likely to cause species-level 

effects in the near term. The 

documented persistence of the species 

at one location in the Washington 

metropolitan area and seven locations in 

Virginia provides redundancy, 

resiliency, and representation to sustain 

the species beyond the near term. 

Therefore, we conclude that the risk of 

extinction of the Kenk’s amphipod in 

the near term is sufficiently low that it 

does not meet the definition of an 

endangered species under the Act. 

The Act defines a threatened species 

as ‘‘any species which is likely to 

become an endangered species within 

the foreseeable future throughout all or 

a significant portion of its range.’’ A key 

statutory difference between an 

endangered species and a threatened 

species is the timing of when the 

relevant threats would begin acting 

upon a species such that it is in danger 

of extinction now (endangered species) 

or likely to become so in the foreseeable 

future (threatened species). 

The foreseeable future refers to the 

extent to which we can reasonably rely 

on predictions about the future in 

making determinations about the future 

conservation status of the species (U.S. 

Department of the Interior, Solicitor’s 

Memorandum, M–37021, January 16, 

2009). We must look not only at the 

foreseeability of threats, but also at the 

foreseeability of the impact of the 

threats on the species (U.S. Department 

of the Interior’s Solicitor’s 

Memorandum, M–37021, January 16, 

2009). 

In considering the foreseeable future 

as it relates to the status of the Kenk’s 

amphipod, we considered the extent to 

which we could reliably predict the 

species’ risk of extinction over time. Our 

ability to make reliable predictions into 

the future for the Kenk’s amphipod is 

informed by the species’ survey data; 

the potential effects to the species from 

ongoing and predicted stressors, as well 

as the uncertainty surrounding the 

species’ response to those stressors; and 

ongoing and future conservation 

measures to address the known 

stressors. The future timeframe for this 

analysis is 30 years, which is a 

reasonably long time to consider as the 

foreseeable future given the Kenk’s 

amphipod’s life history and the 

temporal scale associated with the 

patterns of survey data and the past and 

current stressors outlined in the best 

available data. The timeframe for 

foreseeable future is based, in part, on 

projecting forward. A similar timeframe 

encompassed by the historical survey 

results shows decades in which the 

species was present, absent, and then 

present again at some seep sites. This 

timeframe also captures our best 

professional judgment of the projected 

potential range of future conditions 

related to the effects of climate change 

(i.e., the period in which the species’ 

response to the potential effects of 

climate change are reliably predictable) 

and cumulative effects. 

Since the analysis of potential effects 

from climate change was an important 

consideration in our analysis, it was 

necessary to consider a long enough 

timeframe to adequately evaluate those 

potential effects. However, we did not 

extend our risk assessment forecasting 

used in the listing determination 

process out as far as the existing climate 

change models (e.g., models that 

forecast effects over 80 years) discussed 

in the proposed listing rule (81 FR 

67270) due to (1) the increased 

uncertainty in the model results (i.e., the 

confidence intervals associated with 

temperature and precipitation 

projections); (2) the higher level of 

uncertainty of how the species may 

respond to any potential changes in its 

habitat that may result from changes in 

temperature and precipitation patterns; 

and (3) uncertainty associated with how 

society will respond to the predicted 

change in climate (e.g., take actions that 

will mediate or accelerate global 

emissions) that far into the future. As an 

example of biological uncertainty, there 

are significant questions regarding the 

extent to which the number of Kenk’s 

amphipods observed at the seep surface 

accurately reflects the actual population 

at each site given the species’ known 


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ability to move between the surface and 

subsurface habitat. 

These uncertainties are additive and 

undermine the Service’s confidence in 

making a risk assessment projection 

beyond 30 years. Therefore, as further 

described below, a projection of the 

threats and the effects to the species of 

30 years represents the timeframe over 

which the Service considers a reliable 

prediction to be possible. 

As we concluded above, the stressors 

likely to have the greatest influence on 

the Kenk’s amphipod’s viability over 

time include: Changes in habitat quality 

and quantity resulting from 

urbanization in the Washington 

metropolitan areas and the potential for 

the effects of small population dynamics 

and increased ground water 

temperatures due to climate change at 

all sites. Given the risk factors affecting 

the species currently and/or potentially 

in the future, we determined the 

following: 

• The best available information 

indicates that the risk is low that 

changes in habitat quality resulting from 

changes in temperature will result in 

aggregate or species-level effects in the 

foreseeable future. 

• There is significant uncertainty 

regarding the timeframe in which the 

predicted climate-induced changes to 

air temperature will manifest in ground 

water (i.e., whether those changes will 

occur within the foreseeable future). 

• There is significant uncertainty 

regarding the extent to which the 

number of Kenk’s amphipods observed 

at the seep surface accurately reflects 

the actual population at each site given 

the species’ known ability to move 

between the surface and subsurface 

habitat. The best available data indicate 

that the risk of the dynamics of small 

population size affecting the species is 

low because even if the species may 

exist in low numbers at most or all of 

the 13 known sites, it is very unlikely 

that all of the sites would be exposed to 

catastrophic or stochastic events at the 

same time. Therefore, the species is not 

likely to be extirpated at most or all of 

the sites within the foreseeable future. 

Taking into account the effects of the 

most likely stressors and the potential 

for cumulative effects to the species, our 

projections for foreseeable future 

conditions are that the risk is low that 

the Kenk’s amphipod will not continue 

to be distributed across multiple seep 

sites within the species’ current range. 

These multiple areas will help the 

Kenk’s amphipod withstand 

catastrophic events; meaning the risk is 

low that a significant weather or other 

event will cause extirpation of the 

species at most or all sites. Also, we 

project that the risk is low that the 

species will not continue to be present 

in multiple areas, especially in Virginia, 

in adequate abundance to withstand 

stochastic events. For example, the risk 

is low that a training or hunting event 

at Fort A.P. Hill causing damage to a 

seep site will cause extirpation of the 

species at that site. 

Based on our analysis of the species’ 

redundancy, resiliency, and 

representation, and our consideration of 

the species’ future stressors and 

conservation measures to address those 

stressors, we conclude that the Kenk’s 

amphipod is likely to remain at a 

sufficiently low risk of extinction such 

that it is not likely to become in danger 

of extinction in the foreseeable future 

and thus does not meet the definition of 

a threatened species under the Act. 

Determination of Status Throughout a 

Significant Portion of Its Range 

Consistent with our interpretation 

that there are two independent bases for 

listing species as described above, after 

examining the species’ status 

throughout all of its range, we now 

examine whether it is necessary to 

determine its status throughout a 

significant portion of its range. We must 

give operational effect to both the 

‘‘throughout all’’ of its range language 

and the SPR phrase in the definitions of 

‘‘endangered species’’ and ‘‘threatened 

species.’’ The Act, however, does not 

specify the relationship between the two 

bases for listing. As discussed above, to 

give operational effect to the 

‘‘throughout all’’ language that is 

referenced first in the definition, 

consideration of the species’ status 

throughout the entire range should 

receive primary focus and we should 

undertake that analysis first. In order to 

give operational effect to the SPR 

language, the Service should undertake 

an SPR analysis if the species is neither 

in danger of extinction nor likely to 

become so in the foreseeable future 

throughout all of its range, to determine 

if the species should nonetheless be 

listed because of its status in an SPR. 

Thus, we conclude that to give 

operational effect to both the 

‘‘throughout all’’ language and the SPR 

phrase, the Service should conduct an 

SPR analysis if (and only if) a species 

does not warrant listing according to the 

‘‘throughout all’’ language. 

Because we determined that the 

Kenk’s amphipod is not in danger of 

extinction or likely to become so in the 

foreseeable future throughout all of its 

range, we will consider whether there 

are any significant portions of its range 

in which the Kenk’s amphipod is in 

danger of extinction or likely to become 

so. 

Although there are potentially many 

ways to determine whether a portion of 

a species’ range is ‘‘significant,’’ we 

conclude, as noted above, for the 

purposes of this rule, that the 

significance of the portion of the range 

should be determined based on its 

biological contribution to the 

conservation of the species. For this 

reason, we describe the threshold for 

‘‘significant’’ in terms of an increase in 

the risk of extinction for the species. We 

conclude that such a biologically based 

definition of ‘‘significant’’ best conforms 

to the purposes of the Act, is consistent 

with judicial interpretations, and best 

ensures species’ conservation. 

We evaluate biological significance 

based on the principles of conservation 

biology using the concepts of 

redundancy, resiliency, and 

representation because decreases in the 

redundancy, resiliency, and 

representation of a species lead to 

increases in the risk of extinction for the 

species. Redundancy (having multiple 

resilient populations considering 

genetic and environmental diversity) 

may be needed to provide a margin of 

safety for the species to withstand 

catastrophic events. Resiliency describes 

the characteristics of a species that 

allow it to recover from stochastic 

events or periodic disturbance. 

Representation (the range of variation 

found in a species) ensures that the 

species’ ability to adapt to changing 

environments is conserved. 

Redundancy, resiliency, and 

representation are not independent of 

each other, and some characteristics of 

a species or area may contribute to all 

three. For example, distribution across a 

wide variety of habitats is an indicator 

of representation, but it may also 

indicate a broad geographic distribution 

contributing to redundancy (decreasing 

the chance that any one event affects the 

entire species), and the likelihood that 

some habitat types are less susceptible 

to certain threats, contributing to 

resiliency (the ability of the species to 

recover from disturbance). None of these 

concepts is intended to be mutually 

exclusive, and a portion of a species’ 

range may be determined to be 

‘‘significant’’ due to its contributions 

under any one of these concepts. 

For the purposes of this rule, we 

determine if a portion’s biological 

contribution is so important that the 

portion qualifies as ‘‘significant’’ by 

asking whether, without that portion, 

the representation, redundancy, or 

resiliency of the species would be so 

impaired that the species would be in 

danger of extinction or likely to become 


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so in the foreseeable future (i.e., would 

be an ‘‘endangered species’’ or a 

‘‘threatened species’’). Conversely, we 

would not consider the portion of the 

range at issue to be ‘‘significant’’ if there 

is sufficient resiliency, redundancy, and 

representation elsewhere in the species’ 

range that the species would not be in 

danger of extinction or likely to become 

so throughout its range even if the 

population in that portion of the range 

in question became extirpated (extinct 

locally). 

We recognize that this definition of 

‘‘significant’’ establishes a threshold 

that is relatively high. Given that the 

outcome of finding a species to be in 

danger of extinction or likely to become 

so in an SPR would be to list the species 

and apply protections of the Act to all 

individuals of the species wherever 

found, it is important to use a threshold 

for ‘‘significant’’ that is robust. It would 

not be meaningful or appropriate to 

establish a very low threshold whereby 

a portion of the range can be considered 

‘‘significant’’ even if only a negligible 

increase in extinction risk would result 

from its loss. Because nearly any portion 

of a species’ range can be said to 

contribute some increment to a species’ 

viability, use of such a low threshold 

would require us to impose restrictions 

and expend conservation resources 

disproportionately to conservation 

benefit: Listing would be rangewide, 

even if only a portion of the range with 

minor conservation importance to the 

species is imperiled. On the other hand, 

it would be inappropriate to establish a 

threshold for ‘‘significant’’ that is too 

high. This would be the case if the 

standard were, for example, that a 

portion of the range can be considered 

‘‘significant’’ only if threats in that 

portion result in the entire species’ 

being currently in danger of extinction 

or likely to become so. Such a high bar 

would not give the SPR phrase 

independent meaning, as the Ninth 

Circuit held in Defenders of Wildlife v. 

Norton, 258 F.3d 1136 (9th Cir. 2001). 

The definition of ‘‘significant’’ used in 

this rule carefully balances these 

concerns. By setting a relatively high 

threshold, we minimize the degree to 

which restrictions would be imposed or 

resources expended that do not 

contribute substantially to species 

conservation. But we have not set the 

threshold so high that the phrase 

‘‘throughout a significant portion of its 

range’’ loses independent meaning. 

Specifically, we have not set the 

threshold as high as it was under the 

interpretation presented by the Service 

in the Defenders litigation. Under that 

interpretation, the portion of the range 

would have to be so important that the 

species’ current level of imperilment in 

the portion results in the species 

currently being in danger of extinction 

or likely to become so throughout all of 

its range. 

Under the definition of ‘‘significant’’ 

used in this rule, the portion of the 

range need not rise to such an 

exceptionally high level of biological 

significance. (We recognize that, if the 

portion rises to the higher level of 

biological significance and the species is 

in danger of extinction or likely to 

become so in the foreseeable future in 

that portion, then the species would 

already be in danger of extinction or 

likely to become so in the foreseeable 

future throughout all of its range. We 

would accordingly list the species as 

threatened or endangered throughout all 

of its range by virtue of the species’ 

rangewide status so we would not need 

to rely on the SPR language for such a 

listing.) Rather, under this interpretation 

we ask whether the species would be in 

danger of extinction or likely to become 

so everywhere without that portion, i.e., 

if the species were hypothetically 

completely extirpated from that portion. 

In other words, the portion of the range 

need not be so important that its current 

status in that portion of its range—being 

merely in danger of extinction, or likely 

to become so in the foreseeable future— 

is sufficient to cause the species to be 

in danger of extinction or likely to 

become so in the foreseeable future 

throughout all of its range. Instead, we 

evaluate whether the complete 

extirpation (in a hypothetical future) of 

the species in that portion would at that 

point cause the species throughout its 

remaining range to be in danger of 

extinction or likely to become so in the 

foreseeable future. 

We are aware that the court in Center 

for Biological Diversity v. Jewell found 

that this definition of ‘‘significant’’ does 

not give sufficient independent meaning 

to the SPR phrase. However, that 

decision was based on two 

misunderstandings about the 

interpretation of ‘‘significant.’’ First, the 

court’s decision was based on its finding 

that, as with the interpretation that the 

court rejected in Defenders, the 

definition of ‘‘significant’’ does not 

allow for an independent basis for 

listing. However, this definition of 

‘‘significant’’ is not the same as the 

definition applied in Defenders, which 

looked at the current status within the 

portion and asked what the current 

effect on the entire range of the species 

is. By contrast, this definition of 

‘‘significant’’ looks at a future 

hypothetical loss of all members within 

the portion and asks what the effect on 

the remainder of the species would be; 

the current status of the species in that 

portion is relevant only for determining 

the listing status if the portion has been 

determined to be significant. This 

definition of ‘‘significant’’ establishes a 

lower threshold than requiring that the 

species’ current status in that portion of 

its range is already causing the species 

to be in danger of extinction throughout 

all of its range or likely to become so in 

the foreseeable future. In other words, 

this definition of ‘‘significant’’ captures 

circumstances that would not be 

captured by the definition used in 

Defenders, or by analyzing whether a 

species is in danger of extinction or 

likely to become so throughout all of its 

range: A species that is not currently 

likely to become an endangered species 

in the foreseeable future, but would be 

if a particular important portion of its 

range is completely lost, can 

nonetheless be listed now if the species 

in that portion is threatened or 

endangered (as opposed to only after the 

portion is in fact lost, as would be the 

case if the SPR language did not exist). 

The second misunderstanding was the 

court’s characterization of the listing 

determination for the African 

coelacanth as an indication that the 

Service and National Marine Fisheries 

Service (NMFS) have had difficulty 

accurately applying this definition of 

‘‘significant.’’ However, in that listing 

determination, the conclusion was that 

the species was not in danger of 

extinction throughout all of its range or 

likely to become so in the foreseeable 

future but it did warrant listing because 

of its status in a significant portion of its 

range. The only reason for not listing the 

entire species was that the population in 

that portion of the range met the 

definition of a DPS, and therefore the 

agency listed the DPS instead of the 

entire species. The population in an 

SPR is not automatically a DPS so, 

contrary to the court’s reasoning, the 

definition of ‘‘significant’’ can be 

applied and result in listing a species 

that would not otherwise be listed. (We 

also note another instance, in addition 

to the one cited in this case, in which 

this definition has been effectively 

applied. In the proposed rule to list the 

giant manta ray as a threatened species 

(82 FR 3694; January 12, 2017), NMFS 

found that the giant manta ray was not 

currently in danger of extinction or 

likely to become so in the foreseeable 

future throughout all of its range 

because the Atlantic populations were 

not experiencing the same risks as the 

Pacific populations. However, they did 

find that the Pacific populations 

constituted an SPR, because, without 

that portion, the smaller and more 


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sparsely distributed populations in the 

Atlantic would become vulnerable to 

demographic risks and would be likely 

to become in danger of extinction in the 

foreseeable future. Accordingly, the 

giant manta ray is proposed to be listed 

as a threatened species.) In light of these 

flaws, we are currently seeking 

reconsideration of the district court’s 

decision. 

To undertake this analysis, we first 

identify any portions of the species’ 

range that warrant further consideration. 

The range of a species can theoretically 

be divided into portions in an infinite 

number of ways. To identify only those 

portions that warrant further 

consideration, we determine whether 

there is substantial information 

indicating that there are any portions of 

the species’ range: (1) That may be 

‘‘significant,’’ and (2) where the species 

may be in danger of extinction or likely 

to become so in the foreseeable future. 

We emphasize that answering these 

questions in the affirmative is not a 

determination that the species is in 

danger of extinction or likely to become 

so in the foreseeable future throughout 

a significant portion of its range—rather, 

it is a step in determining whether a 

more-detailed analysis of the issue is 

required. 

In practice, one key part of identifying 

portions for further analysis may be 

whether the threats or effects of threats 

are geographically concentrated in some 

way. If a species is not in danger of 

extinction or likely to become so in the 

foreseeable future throughout all of its 

range and the threats to the species are 

essentially uniform throughout its 

range, then the species is not likely to 

be in danger of extinction or likely to 

become so in the foreseeable future in 

any portion of its range. Moreover, if 

any concentration of threats applies 

only to portions of the species’ range 

that are not ‘‘significant,’’ such portions 

will not warrant further consideration. 

If we identify any portions (1) that 

may be significant and (2) where the 

species may be in danger of extinction 

or likely to become so in the foreseeable 

future, we engage in a more-detailed 

analysis to determine whether these 

standards are indeed met. The 

identification of an SPR does not create 

a presumption, prejudgment, or other 

determination as to whether the species 

is in danger of extinction or likely to 

become so in the foreseeable future in 

that identified SPR. We must go through 

a separate analysis to determine 

whether the species is in danger of 

extinction or likely to become so in the 

SPR. To make that determination, we 

will use the same standards and 

methodology that we use to determine 

if a species is in danger of extinction or 

likely to become so in the foreseeable 

future throughout all of its range. 

Once we have identified portions of 

the species’ range for further analysis, 

we conduct a detailed analysis of the 

significance of the portion and the 

status of the species in that portion. 

Depending on the biology of the species, 

its range, and the threats it faces, it 

might be more efficient for us to address 

the significance question first or the 

status question first. If we address 

significance first and determine that a 

portion of the range is not ‘‘significant,’’ 

we do not need to determine whether 

the species is in danger of extinction or 

likely to become so in the foreseeable 

future there; if we address the status of 

the species in portions of its range first 

and determine that the species is not in 

danger of extinction or likely to become 

so in a portion of its range, we do not 

need to determine if that portion is 

‘‘significant.’’ 

Kenk’s Amphipod Determination of 

Significant Portion of Its Range 

Applying the process described 

above, to identify whether any portions 

warrant further consideration, we 

determine whether there is substantial 

information indicating that (1) 

particular portions may be significant 

and (2) the species may be in danger of 

extinction in those portions or likely to 

become so within the foreseeable future. 

To identify portions where the species 

may be in danger of extinction or likely 

to become so in the foreseeable future, 

we consider whether there is substantial 

information to indicate that any threats 

or effects of threats are geographically 

concentrated in any portion of the 

species’ range. 

We evaluated the current range of the 

Kenk’s amphipod to determine if there 

are any apparent geographic 

concentrations of potential threats to the 

species. The risk factors that occur 

throughout the Kenk’s amphipod’s 

range include the potential for the 

effects of small population dynamics 

and the potential for increased ground 

water temperature resulting from the 

effects of climate change. Habitat loss 

and degradation from poor water quality 

parameters associated with urban 

runoff, however, is occurring both 

currently and in the foreseeable future 

solely at the six Washington 

metropolitan area sites. Thus, this one 

area of the species’ range is subject to 

a type of habitat loss and degradation 

that is not affecting the species 

uniformly throughout its range. We 

identify the Washington metropolitan 

area sites as a portion where the species 

may be in danger of extinction or likely 

to become so in the foreseeable future. 

We next consider whether this portion 

may be significant. We can accomplish 

this by considering the biological or 

conservation importance of the portion. 

While the six Washington 

metropolitan area sites represent 46 

percent of the Kenk’s amphipod’s 

known populations and represent a 

diversity of sites because they occur on 

one of the two known geological 

formations, the risk is low that, should 

the species become extirpated in all of 

those locations, that loss would be 

sufficient to cause the remainder of the 

species to be in danger of extinction or 

likely to become so within the 

foreseeable future, given the Kenk’s 

amphipod would still be present in 54 

percent of its range (e.g., the seven 

Virginia sites). The Virginia sites are 

protected against the effects of poor 

water quality parameters. 

We have identified the Washington 

metropolitan area sites as a portion 

where the species may be in danger of 

extinction or likely to become so in the 

foreseeable future. However, there is not 

substantial information to indicate that 

this portion is significant. Therefore, 

this portion does not warrant further 

consideration to determine whether the 

species may be in danger of extinction 

or likely to become so in the foreseeable 

future in a significant portion of its 

range. 

To identify portions that may be 

significant, we consider whether there is 

substantial information to indicate that 

there are any natural divisions within 

the range or other areas that might be of 

biological or conservation importance. 

We identified the Virginia sites (spring 

seeps on Fort A.P. Hill and the Voorhees 

Nature Preserve) as a portion that may 

be significant. These sites are separated 

from the Washington metropolitan area 

sites by 60 mi (97 km). The spring sites 

in these areas occur in the Calvert 

geologic formation, whereas the 

Washington metropolitan area sites 

occur in the Wissahickon geologic 

formation. Given the separation between 

the Washington metropolitan sites and 

the Virginia sites and the inability of the 

Kenk’s amphipod to travel long 

distances, we conclude that there is no 

genetic exchange between these two 

areas. Therefore, we find that there is 

substantial information that there are 

natural divisions between the Virginia 

and Washington metropolitan sites and 

that the Virginia site may be significant. 

We did not find substantial evidence 

that the Washington metropolitan sites 

are a significant portion because, 

without that portion, there is no 

reasonable likelihood that the remainder 

of the species (i.e., those at the Virginia 


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45574 Federal Register / Vol. 82, No. 188 / Friday, September 29, 2017 / Proposed Rules 

sites) would be in danger of extinction 

or likely to become so in the foreseeable 

future, due to the paucity of threats 

affecting the Virginia sites. 

We have identified the Virginia sites 

as a portion that may be significant. We 

next consider whether the species may 

be in danger of extinction or likely to 

become so in the foreseeable future in 

this portion. We can accomplish this 

task by considering whether there is 

substantial information indicating that 

there are any threats to or effects of 

threats on the species that are 

concentrated in that portion. The 

Virginia sites are not affected by the 

same threats we identified for the 

Washington metropolitan area sites (e.g., 

water quality impacts and habitat 

degradation), because the Virginia sites 

occur in areas where land use is 

primarily agriculture and forest with 

little impervious surface and spring 

sites are surrounded by large forest 

buffers that would filter out any 

potential effects of runoff from the 

agricultural areas. We do not find there 

is substantial information indicating 

there is a concentration of threats in the 

Virginia portion. 

We have identified that the Virginia 

portion may be significant. However, 

there is not substantial information to 

indicate that the species may be in 

danger of extinction or likely to become 

so in the foreseeable future in this 

portion. Therefore, this portion does not 

warrant further consideration to 

determine whether the species may be 

in danger of extinction or likely to 

become so in the foreseeable future in 

a significant portion of its range. 

Our review of the best available 

scientific and commercial information 

indicates that the Kenk’s amphipod is 

not in danger of extinction (endangered) 

or likely to become endangered within 

the foreseeable future (threatened) 

throughout all or a significant portion of 

its range. Therefore, we find that listing 

the Kenk’s amphipod as an endangered 

or threatened species under the Act is 

not warranted at this time. 

We request that you submit any new 

information concerning the status of, or 

threats to, the Kenk’s amphipod to our 

Chesapeake Bay Field Office (see 

ADDRESSES) whenever it becomes 

available. New information will help us 

monitor the Kenk’s amphipod and 

encourage its conservation. If an 

emergency situation develops for the 

Kenk’s amphipod, we will act to 

provide immediate protection. 

References Cited 

A complete list of references cited in 

this rulemaking is available on the 

Internet at http://www.regulations.gov 

and upon request from the Chesapeake 

Bay Field Office (see FOR FURTHER

INFORMATION CONTACT). 

Authors 

The primary authors of this proposed 

rule are the staff members of the 

Chesapeake Bay Field Office and the 

Northeast Regional Office. 

Dated: September 7, 2017. 

James W. Kurth, 

Acting Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. 2017–21052 Filed 9–28–17; 8:45 am] 

BILLING CODE 4333–15–P 


asabaliauskas on DSKBBXCHB2PROD with PROPOSALS