i

SUMMARY

Carlsbad Caverns National Park proposes modification of the developed area above Carlsbad 

Cavern. As directed by the park’s general management plan (NPS, 1996), an infiltration study was 

performed to determine the impacts of the developed area on Carlsbad Cavern and groundwater. 

This study found contamination of cave pools from parking lot runoff and leaking or overflowing 

sewage lines and identified potential catastrophic contamination that could be caused by vehicle 

accidents or fires, structural fires, or fuel leaks. The general management plan also states, that based 

on the study the park will “complete a development concept plan to decide the future of surface 

facilities over Carlsbad Cavern.” This plan and EA fulfills this directive.

The goal of this plan is to protect the cave from existing sources of contamination, to prevent future 

damage to the cave and the groundwater system, and to provide a safe, quality visitor experience. 

To accomplish these goals, the park considered three alternatives that would 1) eliminate pollution 

sources above the cave (fuel storage tanks, paved areas, maintenance operations, and park

residences), 2) restore natural infiltration above the cave, 3) reduce catastrophic threats (spills, 

vehicle accidents, fires), and 4) implement mitigation measures to protect natural resources and the 

public where threats remain. 

ALTERNATIVES

No Action Alternative would provide a basis for comparing the management direction and

environmental consequences of the proposed action. The current buildings, facilities, and land-use 

policies would remain intact.

Alternative A would not significantly alter the development “footprint” above the cave. The actions 

in this alternative primarily involve installation of engineered devices that protect areas from

accidental spills, and collect, filter, and/or redirect storm water run-off. The sewer collection system 

would be replaced and the outfall system relocated. Although many sources of contamination would 

not be removed, a higher level of resource protection would be provided.

Alternative B (Park Preferred Action and Environmentally Preferred Alternative) would 

remove the most threatening sources of contamination from above Carlsbad Cavern and follow the 

same proposals as Alternative A to alleviate contamination from remaining facilities. This alternative 

also involves modification of land-use policies, including pavement removal and reconfiguration of the 

Bat Cave Draw parking lot, relocation of some maintenance functions, and removal of the Mission 

66 housing area and the tennis court. The actions in this alternative also restore natural drainage and 

infiltration to areas where pavement is removed. The sewer collection system would be replaced and 

the outfall system relocated.
ii

Alternative B would offer the best resource protection for the cost and with the fewest resource 

impacts. Contamination from parking lot runoff would be reduced by 268,200 gallons per year or 

19% of the total contaminated runoff (versus 7% under Alternative A). This alternative would restore 

infiltration and drainage to 149,500 square feet of formerly- paved areas (versus 31,200 square feet 

under Alternative A). Cultural resources would be impacted more under Alternative B, but would be 

mitigated through careful photo documentation and consultation with the New Mexico State Historic 

Preservation Office (SHPO) and park cultural resource staff.

Alternative Considered but Rejected: Facility Reduction and Land Use Modification

This alternative would have removed most of the non-historic structures from above the cave as well 

as the east parking lot near the visitor center. The west parking lot would be used as a turnaround 

and staging facility for shuttle buses carrying visitors from an off-escarpment parking facility. This 

alternative was rejected because of the adverse impacts of new construction and because an

engineering analysis indicated that a transit system was not practical for the park at this time.

PLANNING PROCESS

This environmental assessment (EA) has been prepared as part of the process described under the 

National Environmental Policy Act (NEPA) and the National Historic Preservation Act (NHPA), 

Section 106. All major actions by the National Park Service (NPS) that are not categorically

excluded from NEPA have to be evaluated by an EA or an environmental impact statement (EIS). 

The process involves developing alternatives to accomplish well-defined goals and then evaluating 

the potential impacts of those alternatives.

Internal scoping by NPS staff was done in the park in March 1999 to develop goals and objectives 

for the resource protection plan. The goals developed during this meeting were 1) protect natural and 

cultural resources, 2) provide visitor enjoyment, 3) improve effectiveness of park operations, and 4) 

provide cost-effective and environmentally responsible facilities for the park. Preliminary alternatives 

were developed using these objectives, and in June 1999, public scoping was conducted in the city 

of Carlsbad, New Mexico, to present the alternatives and gather public comments.

A meeting was held in September 1999 to perform a Choosing By Advantages (CBA) analysis of 

the alternatives and select a park-preferred alternative. In the CBA analysis, factors such as resource 

protection, visitor experience, and visitor and staff safety were used to evaluate and rate each of the 

alternatives. These ratings were then factored against the costs of each alternative to select a 

preferred alternative.

The public is invited to review the draft plan (this document) and make comments on the alternatives 

and the EA of those alternatives. Once the comment period is completed, the park will screen the 

comments to determine whether any important new issues or reasonable alternatives have been

suggested. If major substantive issues not covered adequately by the EA are raised or if the park 

wishes to consider new suggested alternatives, the EA would be rewritten to incorporate them and 

reissued for a second 30-day review. If commentors correct or add factual information that has no 

bearing on the determination of significant impact, the information would be added to the EA when 
iii

possible. If any of the issues point to the potential for significant impacts, the park will publish a 

notice of intent to prepare an EIS. Otherwise, a Finding of No Significant Impact (FONSI) will be 

issued and the revised plan will be published and implemented.

Public Comment

If you wish to comment on the EA, you may mail comments to the name and address below. This 

EA will be available for public review for 30 days. Please note that names and addresses of people 

who comment become part of the public record. If you wish us to withhold your name and/or 

address, you must state this prominently at the beginning of your comment. We will make all 

submissions from organizations, businesses, and from individuals identifying themselves as

representatives or officials of organizations or businesses available for public inspection in their 

entirety.

Cave Resources Protection Plan, Carlsbad Caverns National Park, 3225 National Parks 

Highway, Carlsbad, NM 88220 [or email: cave_planning@nps.gov]

Further Compliance

The specific actions under any selected alternative would require additional description and

discussion to satisfy the compliance requirements of NEPA and NHPA, Section 106. Detailed 

descriptions and work scopes would be developed for each phase of the project. Consultation with 

the SHPO, Affiliated Native American Tribes, and the U.S. Fish and Wildlife Service would be done 

prior to each project phase. Site-specific detailed surveys for state or federally-listed plant and 

animal species would be conducted prior to any activity under the selected alternative.
iv

CONTENTS

Purpose and Need for Action ......................................................................... 1

Background .............................................................................................. 2

Site Description and Existing Conditions .......................................................... 4

Facilities ............................................................................................. 4

Sewage System ..................................................................................... 4

Natural Resources................................................................................... 8

Cultural Resources ................................................................................ 15

Alternatives ............................................................................................. 18

Sewage System Rehabilitation Common to All Alternatives ................................... 18

No Action Alternative ............................................................................... 19

Visitor Center Area ............................................................................... 19

Bat Cave Draw .................................................................................... 19

Maintenance Facility .............................................................................. 20

Historic Office and Residence Area ............................................................ 20

Mission 66 Housing Area ........................................................................ 20

Tennis Court And Helipad Area ................................................................ 20

Sewage System .................................................................................... 20

Alternative A: Implement Technological Measures ............................................ 21

Visitor Center Area ............................................................................... 21

Bat Cave Draw .................................................................................... 21

Maintenance Facility .............................................................................. 21

Historic Office and Residence Area ........................................................... 22

Mission 66 Housing Area ........................................................................ 22

Tennis Court and Helipad Area ................................................................. 22

Sewage System .................................................................................... 22

Alternative B: Partial Relocation of Facilities (Park and Environmentally Preferred) .... 24

Visitor Center Area ............................................................................... 24

Bat Cave Draw .................................................................................... 25

Maintenance Facility .............................................................................. 25

Historic Office and Residence Area ......................................................... 26

Mission 66 Housing Area ........................................................................ 26

Tennis Court and Helipad Area ................................................................. 26

Sewage System .................................................................................... 30

Alternatives Considered but Rejected ................................................................ 33

Facility Reduction and Land Use Modification ............................................... 33

Sewage System Improvement Options ......................................................... 33

Rehabilitation of Collection System ............................................................ 34

Sewage Outfall Options Considered but Rejected ............................................ 34
v

Environmental Consequences ....................................................................... 39

Air Quality ......................................................................................... 39

Soils and Vegetation .............................................................................. 40

Cave and Groundwater Resources ............................................................... 41

Rare, Threatened or Endangered Specie s ...................................................... 43

Cultural Resources ................................................................................ 45

Visitor Use and Experience ..................................................................... 47

Socioeconomics .................................................................................. 48

Further Compliance Requirements and Additional Work .................................... 49

Natural Resources ................................................................................ 49

Cultural Resources ............................................................................... 49

Space Allocation Plan ........................................................................... 51

References................................................................................................ 52

Consultation/Coordination ........................................................................... 54
vi

MAPS

Vicinity ..................................................................................................... 3

Existing Development .................................................................................... 5

Sewage System Existing Conditions (Collection) .................................................... 6

Sewage System Existing Conditions (Outfall) ....................................................... 7

Potential Contamination Sources ..................................................................... 12

Outfall Alignment Common to All Alternatives .................................................... 18

Alternative A ............................................................................................. 23

Alternative B (Park and Environmentally Preferred Alternative) ................................. 27

Bat Cave Draw Concept Plan .......................................................................... 28

Off-Escarpment Maintenance Facility Location .................................................... 29

Sewage Outfall Options ................................................................................ 35

Sewage System Spill Locations, Dates, and Quantities ............................................ 57

TABLES

1. Summary of Contamination Risks ............................................................... 13

2. Program Requirements for Off-escarpment Maintenance Facility .......................... 26

3. Comparative Summary of Alternatives ..........................................................31

4. Summary Comparison of Impacts ............................................................... 32

5. Summary for Outfall System .................................................................... 38 

APPENDICES

Appendix 1. Estimated Costs of Preferred Alternative .............................................. 55

Appendix 2. Sewage Overflow Mitigation Program ................................................. 56
1

PURPOSE AND NEED FOR ACTION

Carlsbad Caverns National Park proposes modification of the developed area above Carlsbad Cavern. 

The purpose of this plan is to: 1) protect the groundwater and cave resources from continuing chronic 

exposure to contamination; 2) protect the cave resources from potential catastrophic contamination; 

and 3) protect visitors to Carlsbad Cavern from potential hazardous conditions due to contamination. 

The goals of this plan may be reached through prevention measures as outlined in “The Alternatives” 

section.

The National Park Service (NPS) is mandated by the Federal Cave Resources Protection Act of 1988 

to protect Carlsbad Cavern. Section 2c states, “It is the policy of the United States that Federal lands 

be managed in a manner which protects and maintains, to the extent practical, significant caves.” The 

Cave and Karst Management Plan for the park (NPS, 1995) outlines several objectives, including to 

“protect and perpetuate natural cave systems from internal and external threats” and to “establish 

regulations, guidelines, and permit stipulations that ensure maximum safety for the cave visitor, park 

employees, and preservation of park resources.”

A study was conducted in the developed area of the park to evaluate the effects of development on 

cave resources and natural groundwater infiltration in accordance with the 1996 General 

Management Plan (NPS, 1996) that states:

Facts on water infiltration patterns, and how development has affected water 

migration into Carlsbad Cavern, are needed to better understand and mitigate 

human-induced changes in the cave ecosystem. A study has been initiated to 

determine the rates, amounts and routes of water infiltration into the cavern. It 

will also identify and characterize potential contamination sources in the vicinity 

of the cavern and assess possible hazards and cave resource impacts from such 

contaminants.

The infiltration study was performed as part of a Colorado School of Mines master’s thesis (Brooke, 

1996) in conjunction with an investigation by the International Ground Water Modeling Center (van der 

Heijde et. al., 1997). This study identified areas in the cave threatened or already affected by

contamination due to surface facilities, as well as probable pollution sources. The most affected areas 

of Carlsbad Cavern are 1) Quintessential Right, 2) Left Hand Tunnel, 3) New Section, 4) Main

Corridor between Devil’s Spring and Iceberg Rock, and 5) locations in Chocolate High, the New 

Mexico Room, the Scenic Rooms, and the Big Room Area (see the Potential Contamination Sources 

map, page 12). The study reported:

Most of the unnaturally high concentrations of aluminum, zinc, total organic 

carbon, and nitrate... can be related to rather chronic, relatively low-level, 

releases at specific locations at the surface...A variety of accident, spill and 

leakage scenarios can threaten the water quality in the cavern, and even public 

health. Major potential sources identified in this study are: 1) leaks in the sewer 

lines; 2) spills and vehicle fires with subsequent contaminated runoff from the 

public parking lots and road segments in the western part of the [developed] 

area; and 3) spills, leaking tanks, fires and other accidental releases from the 

maintenance yard.
2

Spills of hazardous materials, including oil and gasoline, into the subsurface could pose a potential threat 

to visitors. Such a danger could cause the cave to be closed until the danger was eliminated. It could 

also severely damage or destroy cave biota and the cave ecosystem.

BACKGROUND

Carlsbad Caverns National Park encompasses approximately 47,000 acres of wilderness and 

nonwilderness lands in the Guadalupe Mountains of southern New Mexico (see the Vicinity map, 

page 3). The park preserves and provides opportunities for visitors to view a large portion of the 

Capitan Reef, the best exposed Permian-age fossil reef in the world. The park also contains one of 

few protected northern Chihuahuan Desert ecosystems and contains species of plants and animals 

that are at the northernmost limits of their geographic distribution. Cultural resources in the park 

represent a long and varied history of human uses from prehistoric times to the present.

The park is a designated World Heritage Site that contains many world-class caves including 

Carlsbad Cavern. The Big Room of Carlsbad Cavern is the largest, most easily accessible chamber 

in North America. Carlsbad Cavern is also home to a world-famous colony of migratory Mexican 

free-tailed bats and one of the largest colonies of migratory cave swallows in the United States.

About 250 acres of surface area around Carlsbad Cavern have been developed to provide access 

and support for the 500,000-600,000 annual visitors to Carlsbad Caverns National Park. Cave 

tours began in the early 1900s and continue to the present. To satisfy housing and park operational 

needs of a new and increasingly popular national park, offices, residences, and parking areas were 

constructed above Carlsbad Cavern near the natural entrance to the cave beginning in 1926. The 

first elevator shaft was built in 1931, and a second shaft was excavated in 1954. Beginning in 1961-

62, a period of major facility expansion in the NPS known as Mission 66, left its mark on Carlsbad 

Caverns. During the Mission 66 era, the visitor center and maintenance areas were expanded and 

additional buildings were constructed to provide housing for park personnel.
Vicinity Map

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service ›

130/20040 DSC March 2000

north

Whites City

Carlsbad

CARLSBAD CAVERNS

NATIONAL PARK

Guadalupe Mountains

National Park

NEWMEXICO

TEXAS

to Interstate 40

to El Paso

„

Â

62

180

285

Driving Distances from Carlsbad, NM

to Carlsbad Caverns NP- 27 miles

to Guadalupe Mtns NP- 55 miles

to El Paso, TX- 165 miles

to Albuquerque, NM- 300 miles

NEWMEXICO

Albuquerque

Carlsbad

Farmington

Tucson

TEXAS

COLORADO

El Paso

ARIZONA

Deming

CARLSBAD CAVERNS

NATIONAL PARK

62

180

3
4

SITE DESCRIPTION AND EXISTING CONDITIONS

FACILITIES

Currently, nearly all development related to park operations, employee housing and visitor services is 

located on the surface directly above Carlsbad Cavern. The development consists of nineteen

primary buildings, a road system and parking for over 900 vehicles (see the Existing Development 

map, page 5).

The development is separated by an arroyo known as Bat Cave Draw. Current developed areas on 

the south side of Bat Cave Draw include a visitor center with large parking lots on the east and west 

sides of the building. The visitor center houses museum exhibits on the resources of Carlsbad Cavern 

and includes elevators for easy access into the cave and areas for ticket sales and interpretive 

programs. The visitor center also contains a restaurant, cooperating association bookstore, souvenir 

shop, park offices, kennels, a theater, exhibit areas and storage space.

The development within Bat Cave Draw is primarily used for overflow parking and to support the 

summer bat flight interpretive program at the natural entrance of the cave. The development includes 

an access road, paved parking lot, a comfort station, and an amphitheater overlooking the natural 

entrance to Carlsbad Cavern. Portions of the development within the draw and most of the

structures north of Bat Cave Draw comprise the Caverns Historic District which is listed on the 

National Register of Historic Places.

The buildings to the north of Bat Cave Draw are used for logistical support of park functions, 

research, administrative offices, maintenance, and staff and researcher quarters. In addition to the 

buildings, there is a concrete tennis court for park personnel use, a maintenance storage area, several 

employee parking areas, and a helipad.

SEWAGE SYSTEM

The sewage collection system includes the smaller diameter (4- to 6-inch) collection pipes that 

collect wastewater from individual office, residential, and maintenance buildings. The collection

system includes every sewer pipe on the north side of Bat Cave Draw and west of the “Begin Outfall 

Pipe” manhole (see Sewage System map, page 6).

The outfall system includes the larger diameter (6- to 8-inch) transmission pipes that convey the 

wastewater to the treatment location without additional collection from individual buildings or 

subsystems. The main outfall pipeline runs parallel to the ridgeline of the escarpment and cavern 

system below for 1,939 feet before heading south off the ridge to a series of evaporation ponds 

where sewage is disposed and treated. These evaporation ponds, commonly referred to as sewage 

lagoons, are located at the base of the escarpment on NPS property.
K

EY: 1 Mis

sion66EraResidence

2Mission66EraResidence

3EmployeeQuarters

4EmployeeQuarters

5MaintenanceStructure

6MaintenanceStructure

7MaintenanceStructure

8MaintenanceStructure

9MaintenanceStructure

10EmployeeQuarters

11EmployeeQuarters

13EmployeeQuarters

15EmployeeQuarters

16LawEnforcementOffice

17Superintendent’sOfficeComplex

18BatFlightRestroom/LiftStation

19Natural CaveEntranceandAmphitheater

HistoricStructure

Non-historicStructure

ExistingDevelopment

CarlsbadCavern

ResourceProtectionPlan

CarlsbadCavernsNational Park

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130/20041DSCMarch2000

›north

0

100

300FEET

5

CAVERNSYSTEM(subsurface)
KEY:

Existing Building

Existing Sewer

Collection

Pipe with Size

Sewage System

Existing Conditions

(collection)

Carlsbad Cavern

Resource Protection

Plan

Carlsbad Caverns

National Park

US Department of the Interior

National Park Service

130/20048 DSC March 2000

›north

0 50 150 FEET

6” S

6” S

6” S

6” S

6” S

6” S

4” S

6” S

6” S

6” S

6” S

BEGIN OUTFALL PIPE

Restroom /Sewage Lift Station

FLOW

4” S

4” S

4”

4”

4”

4”

4”

4”

4”

4” S

4”

4”

4”

4”

4”

4”

4”

6” S

Park Housing

Maintenance

Facility

Visitor Center

Bat Cave Draw

4”

6

6” S

6” S
Existing Sewage

Outfall Pipe

Visitor

Center

›north

0 .25 .5 miles

Existing Sewage

Disposal Lagoons

Existing 250,000

Gallon Water Tank

Existing Water Treatment

and Pump House Building

Sewage System

Existing Conditions

(outfall)

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

130/20049 DSC March 2000

7
8

NATURAL RESOURCES

Carlsbad Caverns National Park contains one of the best preserved northern Chihuahuan Desert 

ecosystems. The escarpment is a mountainous ridge of limestone that has been lifted above the plains 

to the south and east. Below the escarpment, visitors can observe the transition from high desert 

scrubland into the sparse grassland characteristic of the low Chihuahuan Desert. The developed area 

contains a mixture of cacti, agave, and other plants characteristic of a high desert scrubland. In Bat 

Cave Draw, there is a mixture of trees and scrub including juniper, hackberry, soapberry, and Mexican 

buckeye.

Surface Rare, Threatened or Endangered Species

A rare plant survey was conducted by the New Mexico Natural Heritage Program in December 1999 

(Chauvin, 1999). There were no rare plants found in either the developed area or in the proposed offescarpment maintenance area. No survey was conducted along the route of the proposed sewage line 

realignment. Once final design decisions are made, all affected areas will need to be re-surveyed in the 

proper season for all current state and federally-listed species. 

The project area also contains several state-listed noxious weeds. The park would develop plans to 

prevent the spread of these noxious plants prior to any activities associated with the proposed

alternatives.

There are several species of mammals, birds, and reptiles whose habitat may be affected by activities 

under the proposed alternatives. Once final design decisions are made and prior to any construction 

activity, site-specific surveys for these species and their habitats would be conducted.

Subsurface Rare, Threatened or Endangered Species

No threatened or endangered species listed by the federal or state government have been identified in 

the park’s subsurface environment. The cave does have colonies of several bat species and the 

entrance area is occupied by a colony of Cave swallows. 

Some invertebrates such as flatworms have been found in the pools of Carlsbad Cavern (Ek, 1991). 

Changes in pool chemistry and water level could adversely impact these organisms. Researchers have 

also identified several species of bacteria unique to cave environments in Lechuguilla Cave and Spider 

Cave in the park (Northup et al., 1999; Northup et al., 1997, Northup et al., 1994; and Cunningham et 

al., 1995). No studies have been done to identify these microbes in Carlsbad Cavern, but similar 

environmental conditions exist, and could be favorable for bacteria growth. These bacteria are sensitive 

to changes in moisture conditions and changes in water chemistry.
9

Cave and Groundwater Resources

Infiltration. The natural drainage and infiltration patterns above Carlsbad Cavern have been disrupted 

by park development. Under undisturbed conditions, most rainfall would be absorbed into the soil and 

taken up by plants or evaporated. Water would flow into Bat Cave Draw only during intense

thunderstorms. Now, the buildings and paved areas, which are impervious to water, focus drainage into 

culverts, drains, and eventually Bat Cave Draw. Any water that does not evaporate or is not used by 

plants becomes part of the groundwater system.

Water moves downward primarily through fractures in the limestone that underlie the developed area 

and Bat Cave Draw. Eventually, the groundwater moving through the fractures appears in the cave as 

seeps or drips. These drips have created the numerous speleothems (cave formations) and pools found 

in Carlsbad Cavern. Over time, this water continues downward from the cave passages through

fractures to the water table, approximately 200 feet below the deepest known point in the cave.

Contamination Sources. Any contaminants generated at the surface and carried by groundwater will 

reach the cave and eventually the water table. These contaminants pose a threat to human health and 

the cave ecosystem. The sewage system and the parking lots are the most significant chronic

problems, and the fuel storage tanks pose the highest potential risk.

The sewer lines in the park vary in size, construction material, and condition. Some pipes are more than 

50 years old and backup frequently due to blockages (NPS, 2001). Some blockages are caused by 

accumulation of grease and other materials in system low points and some are caused by the intrusion 

of roots into the clay-tile pipes. The oil and grit separator in the maintenance area wash bay functions 

poorly and permits a discharge of toxic pollutants pressure washed from vehicles and their components 

into the normally domestic waste stream. The collection and conveyance system starts in the residential 

and maintenance areas and runs by gravity to a small lift station located in the Bat Cave Draw 

restrooms near the natural entrance to Carlsbad Cavern (see the Existing Development map, page 5). 

The lift station forces the sewage up to the ridge of the escarpment. There is also a sewage lift station 

near the underground lunchroom that forces sewage up 750 feet to the surface. Sewage flows by 

gravity from the visitor center along the escarpment ridge and drops off the ridge to sewage lagoons at 

the base of the escarpment. Total wastewater generated by visitors and staff in the park is

approximately 10 million gallons per year. When the system backs up or has root intrusions, sewage 

flows out of manholes and onto the ground. These releases expose the groundwater system to raw 

sewage and pose a threat to human health and surface water quality.

The two main parking lots have the capacity for over 900 cars, 63 recreational vehicles, and

approximately 500 feet of unmarked space that can be used for either recreational vehicles or cars. 

There is also an average of 25 cars parked in the residential area on the north side of Bat Cave Draw. 

These cars are generally parked all day, not for just four hours a day as the average visitor is parked. 

However, these 25 cars produce an effective visitation of 72 cars per day or 26,026 cars per year 

(Bremer, 1998). This means that resident parking accounts for almost 14% of the park’s yearly vehicle 

use.
10

The parking lots not only alter natural infiltration patterns, they act to collect and store hazardous 

materials generated by automobiles, maintenance operations, and residential activities. Kitchen floor 

mats and other items from the concessionaire restaurant kitchen are washed daily behind the visitor 

center. This contaminated water attracts animals but drains into the sewage system. The maintenance 

facility makes wide use of solvents and other materials required for vehicle maintenance. Although 

staff tries to avoid spills, some may still occur.

Between rainstorms, oil, fuel, antifreeze, and other contaminants accumulate on the pavement. When it 

rains, contaminants are carried off the pavement and into the fractured limestone above the cave. Most 

of the contaminants are carried by the first half-inch of rainfall. The parking lots collect rainwater from 

a total of 458,000 square feet (10.5 acres). This results in 143,000 gallons of potentially contaminated 

water entering the groundwater system in every half-inch storm. Between 1978 and 1998 there was an 

average of 10 storms per year that produce more than a half inch of rain (Bremer, 1998), totalling 1.4 

million gallons of potentially contaminated water entering the groundwater system every year. Some of 

the contaminants are absorbed by the thin soil and the rock, but unmitigated exposure to these materials 

would lead to contamination of the groundwater and the cave (Bremer, 1998). Organisms in the soil 

and rock could also be damaged by this contamination.

The park is conducting a dye-trace study in Bat Cave Draw. This study involves injecting

approximately 25,000 gallons of water containing a non-toxic, biodegradable dye into Bat Cave Draw. 

Water samples and charcoal dye traps were collected prior to the dye injection. Analysis of these 

samples showed detectable amounts of the dye already in the groundwater system. This dye is also 

used to give antifreeze its distinctive green color and is the likely source of dye found in cave pools and 

drips. This means that there is contamination from parking lot runoff still moving through the

groundwater system into the cave even though the park has restricted parking in the Bat Cave Draw 

parking lot for four years. While the amounts of dye, and probably antifreeze, are below levels that 

would pose a threat to human health, these data do indicate that chronic contamination of groundwater 

has happened in the past and will continue unless preventative measures are taken. 

Chronic contamination from automobiles is not as hazardous as a fuel spill or fire in the developed area. 

There is a 3,000-gallon propane tank located in the Mission 66 housing area and two 1,000-gallon 

propane tanks in the maintenance area. Propane is a heavy gas and any leaks from these tanks or 

associated lines would flow downward into Bat Cave Draw and potentially into the cave entrance. 

There are also three large liquid fuel tanks in the park: a diesel tank for the generator behind the visitor 

center, and one gasoline and one diesel tank at the maintenance yard. Fuel leaked during refueling, or if 

a truck overturned and ruptured, would rapidly enter the groundwater system. The thin soil cover and 

thick, fractured unsaturated zone (the portion of the groundwater system above the water table) would 

limit the effectiveness of standard remediation methods. In the case of a structural or vehicle fire, 

water or chemicals used to put out the fire would also rapidly enter the groundwater system, carrying 

contaminants into the subsurface.
11

The storage tanks pose a threat to the cave and groundwater, not only from spills during refueling, but 

from leaks in the tanks and associated lines. Though the tanks meet Environmental Protection Agency 

guidelines and are double-walled and monitored, there is still some potential for leakage. The source, 

contamination type, affected areas, and level of risk are summarized in Table 2 (page 13). Mitigation 

and prevention measures suggested by the infiltration study (Brooke, 1996) are described in the 

proposed alternatives. The locations of potential contamination sources are shown on the Potential 

Contamination Sources map (page 12).

Wetlands and Floodplains. There are no wetlands or 100-year floodplains within the project area.
X

3

BigRoom

NewMexico

Room

ScenicRooms

LeftHandTunneland

toQuintessentialRight

BatCave

GuadalupeRoom

NewSection

KEY:

1ParkingWestofVisitorCenter

2ParkingEastofVisitorCenter

3VisitorCenter

4ParkOffices

5EmployeeHousing

6MaintenanceYard

7BatCaveDrawParkingLot

8BatFlightComfortStationandLiftStation

9MainRoadbetweenpointsAandB

10MainRoadbetweenpointsBandC

11AccessRoadbetweenpointsBandD

12ServiceRoadbetweenpointsDandE

13ServiceRoadbetweenpointsAandE

14SewerLine(X)

15SewerLine(Y)

16SewerLine(Z)

A

B

C

D

E

1

24

5

3

6

7

8

9

10

11

13

X

14

Y

Y

Z

15

16

CAVERNSYSTEM(subsurface)

SEWERSYSTEM(subsurface)

PotentialContamination

Sources

CarlsbadCavern

ResourceProtectionPlan

CarlsbadCavernsNational Park

USDepartmentofthe Interior

National ParkService

130/20042DSCMarch2000

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0

100

300FEET

12

MainCorridor

12

Chocolate

High
Table 1. Summary of Contamination Risks; See location map on page 12 (modified from van der Heijde, et. al., 1997)

Item 

#

Source Potential Problems Risk and Affected Cavern Area

1 RV/Bus parking lot west of 

visitor center

1. chronic release of metals, oil and other

contaminants from cars, carried by runoff

2. car fire/crash with spill and subsequent

infiltration

Moderate risk to Quintessential Right.

High risk to Quintessential Right, moderate risk to Big 

Room

2 Car parking lot east of 

visitor center

1. chronic release of metals, oil and other

contaminants from cars, transported by

runoff

2. car fire/crash with spill and subsequent

infiltration

Moderate risk to Quintessential Right 

High risk to Quintessential Right

3 Visitor center 1. utility line breaks

2. storage tank leak (chronic) or spill 

3. sewage

Some risk to Quintessential Right

Moderate risk to Quintessential Right

Moderate risk to Quintessential Right

4 Park offices 1. sewage High risk to the Main Corridor

5 Employee housing 1. sewage

2. propane tank leaks (chronic) or spill (while 

filling)

Both problems pose a Moderate risk to Main Corridor, 

Left-Hand Tunnel and New Section/Guadalupe Room

6 Maintenance yard 1. chronic releases of metals, oil and other

contaminants from vehicle washing and 

maintenance

2. car fire/crash with spill

3. sewage

4. buried tank leaks (chronic) or spill (while 

filling)

5. leaks from stored materials

All problems pose a high risk to the New Section, LeftHand Tunnel, Quintessential Right, and the Natural 

Entrance area

7 Bat Cave Draw 1. chronic release of metals, oils and other

contaminants from cars

2. car fire/crash with spill

High risk to Main Corridor and moderate risk to LeftHand Tunnel and Quintessential Right

Extreme risk to Main Corridor, high risk to Left-Hand 

Tunnel and Quintessential Right
Table 1. Summary of Contamination Risks (continued)

8 Pumphouse 1. sewage overflow, line leaks High risk to Main Corridor, moderate risk to Left-Hand 

Tunnel and Quintessential Right

9 Main road between service

road to maintenance yard 

and road to Bat Cave Draw

1. chronic release of metals, oils and other

contaminants from cars

2. car fire/crash with spill

Both problems pose a moderate risk to the Chocolate 

High and Scenic Rooms areas

10 Main road between road to 

Bat Cave Draw and visitor 

center parking lots

1. chronic release of metals, oils and other

contaminants from cars

2. car fire/crash with spill

Both problems pose a moderate risk to the Scenic 

Rooms, Boneyard, and part of the Big Room

11 Paved road down Bat Cave 

Draw to Amphitheater

1. chronic release of metals, oils and other 

contaminants from cars 

2. car fire/crash with spill

Both problems pose a high risk to New Mexico Room 

and Scenic Rooms

12 Service road through office 

area

1. chronic release of metals, oils and other

contaminants from cars

2. car fire/crash with spill

Both problems pose a high risk to Main Corridor

13 Road north of maintenance 

yard and service road to 

maintenance yard

1. chronic release of metals, oils and other

contaminants from cars

2. car fire/crash with spill

Both problems pose some risk to seeps along seep line in 

Walnut Canyon

14 Sewer line from north side 

of Bat Cave Draw to 

pumphouse in Bat Cave 

Draw

1. sewage overflow and line leaks High risk to Main Corridor

15 Sewer line from visitor 

center along Bat Cave 

Draw

1. sewage overflow and line leaks Extreme risk to Left-Hand Tunnel and Quintessential 

Right

16 Sewer line from Bat Cave 1. sewage overflow and line leaks Moderate risk to Quintessential Right and Lake of the 

Clouds
15

CULTURAL RESOURCES

Caverns Historic District

The Caverns Historic District, listed on the National Register of Historic Places, consists of an

assemblage of NPS buildings and landscaped features surrounding the natural entrance of Carlsbad 

Cavern, dating from the mid-1920s through the early 1940s. These buildings and landscaped features 

are on the slopes and ridges above Bat Cave Draw and at the bottom of the draw where the terrain 

was leveled and terraced for visitor access to the cave. The earliest buildings and the terracing are 

constructed of limestone from the surrounding hillside. The architectural style of the buildings is of both 

the Pueblo Revival style and the New Mexican Territorial style.

The Caverns Historic District contains 13 administrative, residential, and maintenance buildings and 

their surrounding landscaping (Colby, 1988). Originally, 19 rock buildings were constructed on the 

north slope of the draw between 1926 and 1932. Six of these original structures have since been 

removed. Construction on the earliest park facilities, including the three-tiered parking area in Bat 

Cave Draw, began in 1926. In 1927-1928, construction was begun on several of the rough-cut stone 

buildings that remain today. These facilities were designed by the first park superintendent and built by 

park rangers. A second construction phase was undertaken during 1931-1932, which added several 

more stone buildings, including the elevator tower. Between 1938 and 1942, additional residential and 

maintenance buildings were designed and built above the cave entrance. The construction was done 

by Civilian Conservation Corps (CCC) crews stationed at the nearby Rattlesnake Springs camp.

The visitor center was completed in 1957, encasing the original 1932 elevator tower. In 1961-1962, 

two additional multiple dwelling units, a maintenance building, and the tennis court area were 

constructed on the top of the hill on the north side of the draw. These projects were part of the NPS’s 

Mission 66 design and construction program intended to revitalize the national parks through a 

massive 10-year program of capital investment to improve the deteriorating conditions of NPS 

facilities following World War II (Carr and Allabeck, 1998).

The Mission 66 residences are not considered eligible for the National Register of Historic Places. 

They do not meet the individual significance criteria under the National Historic Preservation Act for 

the following reasons:

A. Association with events that have made significant contributions to the broad patterns of 

our history: While the Mission 66 program marked a change in construction and design 

philosophies of the NPS, the hallmark of the program was the development of the central visitor 

centers, not necessarily individual housing units within parks. While the park Mission 66 housing 

was part of that broader national program, the housing complex at Carlsbad Caverns is typical of 

Mission 66 housing in many other national parks, including other parks in New Mexico.
16

B. Associated with the lives of significant persons: The park’s Mission 66 housing was designed 

by staff of the NPS Western Office, Division of Design and Construction. The plans for the park’s 

housing were one of many similar designs incorporated around many NPS units.

C. Works of architecture that embody distinctive characteristics of a type, period or method 

of construction or that represent the work of a master, or that possess high artistic value: 

The blocky, modernistic design of the park’s Mission 66 housing does not represent any distinctive 

style or significant method of construction. In fact, the design of the Mission 66 residences departs 

from the previous NPS architectural style of rustic architecture designed to blend in with the local 

landscape. Again, several other highly similar examples of Mission 66 housing exist in other NPS 

sites within the state. 

D. Likely to yield information important in history: The park holds complete design drawings of 

all of the Mission 66 residences, as well as project completion reports and photographs of the 

construction. The likelihood of any additional significant information coming from the buildings 

themselves is minimal.

This historic setting is managed as a “cultural landscape,” which, in NPS terms, is defined as a 

reflection of human adaptation and use of natural resources and is often expressed in the way land is 

organized and divided, patterns of settlement, land use, systems of circulation, and the types of

structures that are built (NPS, DO-28). The character of a natural landscape is defined both by 

physical materials such as roads, buildings, walls, and vegetation, and by use reflecting cultural values 

and traditions. The buildings and designed landscape features represent the rustic theme for facility 

development used during the early years of NPS construction in parks. This philosophy emphasized 

the use of local materials and building techniques used in harmony with the natural setting of the 

landscape. The current Cultural Landscape Inventory for the Caverns Historic District defines the 

landscape as encompassing all of the designed buildings and landscaping from the tops of the ridges 

adjacent to Bat Cave Draw.

The period of significance for which both the Caverns Historic District and the cultural landscape of 

the Cavern entrance area are managed is 1926-1942. Several more buildings were added to the 

developed area after 1942. The Bat Flight Amphitheater was completed in 1963. The Mission 66 

residences lie outside the boundaries of the Caverns Historic District but are within the managed 

boundaries of the cultural landscape. However, since their construction does not fall within the historic 

district’s and cultural landscape’s period of significance, they detract from the cultural landscape the 

park is attempting to preserve.

Caves in general, and Carlsbad Cavern in particular, play a significant role in the oral history and 

cultural traditions of many Native American tribes. The park is actively involved in consultations with 

13 Native American tribes concerning their historic and cultural ties to park lands. The Caverns area 

should be considered as an ethnographic landscape because of archaeological and ethnographic 

resources within the project area.
17

Archeological Resources

In October 1999, a Class III archeological survey of approximately 115 acres within the developed 

area surrounding the natural entrance of Carlsbad Cavern was conducted by Pecos Archeological 

Consultants of Carlsbad, New Mexico (Hunt, 1999). Twenty-four isolated manifestations and 19 

archeological sites were encountered during the survey. The survey examined all areas within the 115-

acre tract that were not paved or contained in currently standing buildings. Park staff identified one 

additional site for a total of 20 sites in the project area.

Archeological sites within the developed area fall into two distinct types: prehistoric and historic Native 

American occupations and historic Anglo-American habitation of the area. The former consists of 

food processing sites, such as ring middens or hearth features, and lithic scatters. Ring middens, 

constructed and used to bake vegetal materials for human consumption, are large features and are the 

result of multiple usage, sometimes over centuries. Hearth features consist of circular or amorphous 

scatters of burned rock and represent heating fires kindled by individuals or small groups, perhaps 

only for a single event. The lithic scatters are sparsely deposited, small-scale sites with few artifacts. 

They most likely represent a single event where toolmaking or tool maintenance work occurred.

The historic occupation of the area resulted in many sites, including campsites, temporary housing 

sites, quarries, guano mining-related sites, and trash dumps. Material in the survey area

reflects the area’s continued use from the late 19th century into present times. The Caverns Historic 

District is virtually a continuous scatter of cultural material reflecting activities related to ranching, 

guano mining, CCC construction, tourism, and NPS family life.
18

ALTERNATIVES

The goal of each of the alternatives is to protect the cave environment, cultural resources, surface 

resources, groundwater resources, and human health while providing a quality visitor experience. Some 

facilities and services are necessary to provide for visitor enjoyment and to preserve the character of the 

Caverns Historic District, but resource impacts of these facilities could be reduced. These alternatives 

offer a range of solutions to reduce the impacts of contamination on the cave environment.

The park evaluated eight options for rehabilitating the portion of the sewage system that conveys waste 

from the developed area off the escarpment. The options ranged from replacing or relining the existing 

outfall system along its current alignment to replacing the outfall system with a biological wastewater 

treatment facility near the visitor center. All of the options included replacing the collection system with 

new plastic pipe. Each option was evaluated based on six primary factors: cave protection, impact to 

surface resources, water re-use and conservation, education and new technology, sustainability, and park 

operations (ease of use). The rejected outfall options and reasons for rejection are summarized in the 

“Alternatives Considered but Rejected” section (page 33). 

SEWER SYSTEM REHABILITATION COMMON TO ALL ALTERNATIVES

Under Alternatives A and B, the park proposes to reroute the sewage outfall line so that it runs south 

from the visitor center, and then along a maintenance access road to the existing evaporative sewage 

lagoons (see outfall alignment figure below). The sewage lagoons would be rehabilitated and relined to 

prevent any leaks into the groundwater system. This route minimizes the risk of contamination from 

sewage to Carlsbad Cavern by shortening the amount of outfall line that lies directly above the cave. 

This alternative also minimizes new impacts to undisturbed surface resources by utilizing existing utility 

corridors and the existing lagoons. A plan to mitigate sewage overflows has also been developed

(Appendix 2, page 56).

Outfall Alignment Common to All Alternatives
19

Once final location and design are completed on the sewage line realignment are completed, surveys of 

all state and federally-listed plant and animal species will be conducted. A revegetation plan that 

addresses mitigation of noxious weeds would also be developed and approved by park resource

management staff. 

NO ACTION ALTERNATIVE 

Under the No Action Alternative, the current buildings and facilities would remain. All of the current 

land-use policies would remain intact. The character of the Caverns Historic District and surrounding 

cultural landscape would remain unaltered. The No Action Alternative provides a basis for comparing 

the management direction and environmental consequences of the proposed action. Should the No

Action Alternative be selected, the NPS would respond to future needs and conditions associated with 

the Carlsbad Caverns Resource Protection Plan without major actions or changes in course.

Visitor Center Area

The visitor center building would be left intact. The parking lots on the east and west of the visitor center 

would remain unaltered. Paved areas and structures would continue to act as impervious barriers to 

infiltration. Parking areas would act to collect and focus contaminants into Bat Cave Draw.

Chronic contamination from parking lot runoff would continue. Potential groundwater contamination from 

leaks or spills from the visitor center storage tanks and chronic contamination from parking lots would 

continue to be a threat. Threats from damaged, leaking, or overflowing sewage lines to groundwater and 

the cave ecosystem would continue.

Bat Cave Draw

The entrance road and parking lot would be left in Bat Cave Draw. The historic stone walls would be 

retained. Current runoff and infiltration patterns would remain as they are. Chronic groundwater

contamination from parking lot runoff would continue and potential contamination from automobile 

accidents or fires would continue to be a threat. Threats from damaged or leaking sewage lines to 

groundwater and the cave ecosystem would continue.

Maintenance Facility

All maintenance facility underground storage tanks would be left intact. Runoff patterns would continue 

as they are. Chronic releases of hazardous materials from parking lot runoff would continue. Threats to 

groundwater from underground storage tanks and other hazardous stored materials would continue. 

Threats from damaged or leaking sewage lines to groundwater and the cave ecosystem would continue.
20

Historic Office and Residence Area

All buildings would be left intact and used for their current purposes. All land-use and parking policies 

would remain intact. Current runoff and infiltration patterns would remain as they are. Potential threats 

to groundwater from resident automobile repair and other hazardous material would be unmitigated. 

Threats from damaged or leaking sewage lines to groundwater and the cave ecosystem would continue.

Mission 66 Housing Area

All buildings would be left intact and used for their current purposes. All propane storage tanks would be 

left in place, and all land-use and parking policies would remain intact. Current runoff and infiltration 

patterns would remain as they are. Potential threats to groundwater from resident automobile

maintenance and other hazardous material would continue. Threats from damaged or leaking sewage 

lines to groundwater and the cave ecosystem would continue.

Tennis Court And Helipad Area

The tennis court and helipad area would be left intact. Current runoff and infiltration patterns would 

remain as they are. 

Sewage System

All existing pipes in the sewage collection system would remain and continue to deteriorate and leak 

contaminants into the groundwater. The outfall system would remain over Bat Cave, Left-Hand Tunnel, 

and Quintessential Right (see the Existing Sewage Outfall System map, page 7) and would continue to 

leak sewage into the cave. Collection and outfall pipes would be repaired as leaks and overflows were 

found, but could still release large amounts of sewage before detection.
21

ALTERNATIVE A: IMPLEMENT TECHNOLOGICAL MEASURES

Alternative A (see Alternative A map, page 23) does not significantly alter the developed area above the 

cave. Pavement would be removed from about 0.25 acres and revegetated with native plants. Under this 

alternative, contaminated runoff would be reduced by approximately 97,200 gallons per year (7% of the 

total). Oil/grit separators and containment areas would be installed to treat and contain spills, and to 

collect and filter or redirect storm water runoff. This alternative would remove some sources of 

contamination, and would provide a higher level of resource protection than is currently present. For all 

activities under this alternative, construction would take place in the winter to reduce the effects of these 

activities on visitors and wildlife, particularly bats.

Visitor Center Area

Alternative A would eliminate parking of vehicles adjacent to the north side of the visitor center and 

institutes a policy to restrict parking of the concessionaire trash truck at the visitor center except to pick 

up trash. Stormwater would be redirected to the south away from Bat Cave Draw by regrading the 

parking lots. Oil and grit filters would be installed to collect parking lot runoff and the filtered water 

directed into the drainages south of the visitor center. The parking lots would be sealed to prevent 

infiltration of volatiles into the groundwater.

Spill containment measures would be constructed at the filling area for the 6,000-gallon underground 

diesel fuel storage tank. An enclosed wash area with grease traps would be constructed for the 

concessionaire restaurant kitchen.

Bat Cave Draw

The historic stone walls would be retained. Parking would be provided for disabled visitors only. A 

passenger drop-off zone for disabled visitors in passenger cars and tour buses would be defined. 

Pavement would be removed from the center tier of the parking area and would be revegetated with 

native plants. The revegetated area would be used for bioretention and runoff treatment. Bioretention is 

stormwater management where plants and soil are used to efficiently and naturally filter runoff from 

developed areas before the water enters the groundwater system. Catch basins and filters would be 

installed to treat runoff from the remaining paved areas.

Maintenance Facility

Underground storage tanks would be removed and an alternative heating system used in the buildings to 

allow removal of the propane tanks. The oil and grit separator in the auto shop would be rehabilitated and 

a containment system constructed for hazardous material use areas. Staff would be trained in spill 

accident prevention and response. Stormwater runoff would be contained and filtered, and park garbage 

trucks would be required to park off the escarpment.
22

Historic Office and Residence Area

Automobile repair and maintenance by residents would be restricted in the residential area. The effects 

of runoff from paved areas would be mitigated by containing and treating the water. Propane tanks 

would be removed and an alternative heating system used.

Mission 66 Housing Area

Automobile repair and maintenance would be restricted in the residential area. The effects of runoff 

from paved areas would be mitigated by containing and treating the water. Propane tanks would be 

removed and an alternative heating system used. The number of vehicles per residence would be 

restricted.

Tennis Court and Helipad Area

The tennis court would remain at the current site. 

Sewage System

The collection system would be rehabilitated and the outfall system would be rerouted so that it runs 

south from the visitor center, and then along a maintenance access road to the existing evaporative 

sewage lagoons. The sewage lagoons would be rehabilitated and relined to prevent any leaks into the 

groundwater system. 
Alternative A

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

130/20043 DSC March 2000

›north

0 100 300 FEET

GENERAL NOTES:

All structures north of Bat Cave Draw would

be converted to alternative HVAC system once

propane tanks have been removed.

Building to Remain

UST- Underground Storage Tank (fuel)

Mission 66 Housing

Remove propane tanks

Contain and treat runoff

Restrict auto repair

Visitor Center Area

Construct enclosed wash area with grease trap

for restaurant use

Prohibit parking behind building

Park garbage truck off escarpment

Construct spill containment measures at filling

area for 6,000-gallon fuel tank

General notes for VC Parking Lots

Install catch basins to collect and filter

runoff

Release storm water to the south where

feasible

Historic Office and Housing Area

Remove propane tanks

Contain and treat runoff

Restrict auto repair

Maintenance Facility

Install catch basins to collect and filter

storm water

Remove both USTs

Remove propane tank

Rehabilitate oil/water separator in auto shop

Park garbage truck off escarpment

Tennis Court and Helipad Area

Remove lighting

Bat Cave Draw

Remove pavement from center tier of

parking lot, revegetate and use as

a bioretention area

Install catch basins to collect and filter

storm water

2

3
24

ALTERNATIVE B: PARTIAL RELOCATION OF FACILITIES (Park Preferred Action 

and Environmentally Preferred Alternative)

The Park Service has been mandated to identify an environmentally preferred alternative that protects 

the environment for succeeding generations, assures safe and pleasing surroundings for all generations, 

attains beneficial use of the environments without degradation, preserves important historic, cultural and 

natural aspects of our heritage, achieves a balance between population and resource use, and enhances 

the quality of renewable resources and maximizes recycling of depletable resources. In the context of 

this project, the environmentally preferred alternative would be the one that would reduce the impacts of 

existing surface development on natural resources while preserving cultural resources and would have 

minimal adverse effect on other natural resources and visitor experience. 

Alternative B (see Alternative B map, page 27) removes the most threatening sources of contamination 

from above Carlsbad Cavern. This alternative would remove 4.2 acres of pavement and reconfigure the 

roadway in the Bat Cave Draw parking lot. Contaminated runoff would be reduced by approximately 

268,200 gallons per year (19% of the total). This alternative would also remove the Mission 66 housing 

area and the tennis court, and would relocate the hazardous functions from the maintenance area. 

Where facilities and pavement remain, specialized stormwater systems would be installed to contain 

spills, and to redirect, collect, and filter stormwater runoff. For all activities under this alternative, 

construction would take place during the winter to reduce the effects of these activities on visitors and 

wildlife, particularly bats. The estimated costs of this alternative are summarized in Appendix 1 (page 

55).

Visitor Center Area

Use of park-provided shuttle transportation by park employees would be encouraged. Laws would be 

enforced to prevent the use of park roads by unauthorized commercial vehicles to reduce the magnitude 

of potential spills from vehicle accidents. Both policies encourage reduced vehicle use in the existing 

parking areas adjacent to the visitor center.

The east and west parking lots would be redesigned to direct stormwater to the south into a collection 

and filtration system. Parking lots would be sealed to prevent infiltration of volatiles into the groundwater. 

The redesign would also better utilize space and improve vehicle circulation and pedestrian access to the 

views off the escarpment.

Spill containment areas would be constructed at the filling point for the 6,000-gallon underground diesel 

fuel storage tank. The filling point for the storage tank would be relocated further west to reduce the 

potential for the refueling truck to back off the pavement into Bat Cave Draw and spill fuel. An enclosed 

wash area with grease traps would be constructed for the concessionaire restaurant kitchen.

Bat Cave Draw

Pavement would be removed from the current parking area, retaining the majority of the historic stone 

walls (see the Bat Cave Draw Concept Plan map, page 28). A turnaround and drop-off area would be 

relocated to the far west end of the existing parking lot. Ten accessible parking spaces would be 

provided. A new stone retaining wall would be required to connect the lower road to the upper road at 
25

the turnaround. Portions of the middle wall would be removed or buried to accommodate the new 

roadwork. Salvaged stone from removed portions of the original stone wall would be incorporated into 

the new retaining walls for the turnaround. The new walls would match the character and construction 

techniques of the original structures.

An eight-foot-wide concrete walk would be constructed along the upper tier from the new turnaround 

location to the Natural Entrance to accommodate disabled access, maintenance work, and rescue 

operations. 

A natural bioretention area would be established to treat runoff from the remaining paved road and 

turnaround. Native vegetation and natural drainage patterns would be restored in areas where pavement 

has been removed. Vegetation would be selected that would not damage the historic walls over time. A 

detailed design plan of changes to the historic walls would be provided to the New Mexico SHPO for 

their concurrence.

The park would locate off-site parking to accommodate the overflow parking removed from Bat Cave 

Draw under this alternative. The NPS anticipates needing overflow parking only for Memorial Day, 

Independence Day, and Labor Day weekends (approximately nine days per year). A private commercial 

service would be contracted at the expense of the government to provide shuttle service to the visitor 

center.

Maintenance Facility

Non-historic maintenance facility buildings and underground storage tanks would be removed.

Chemical/hazardous material storage, excess material storage, auto shop, paint storage building, heavy 

equipment storage, trash collection and recycling facilities would be relocated onto park land off the 

escarpment (see Off Escarpment Maintenance Facility map, page 29). The final off-escarpment 

maintenance facility design would be developed, including the exact location of buildings, access roads, 

and utility lines. Further NEPA compliance would have to be completed prior to any construction to 

evaluate all the impacts of the facility relocation. This compliance would include cultural resource 

surveys and SHPO concurrence and surveys for rare, threatened, and endangered plant and animal 

species.

The square footage requirements of an off-escarpment facility are summarized below. Carpentry,

plumbing and electrical shops would move into remaining historic buildings. Remaining space in historic 

buildings would be adapted for limited small equipment and non-hazardous material storage. A restroom 

and breakroom would be provided for maintenance employees. Propane tanks would be removed and an 

alternative heating system for remaining buildings would be installed.

Emergency vehicles would continue to be housed in existing parking bays. The paved area would be 

reduced to allow for only limited employee parking. Chronic contamination from remaining paved areas 

would be mitigated by redirecting runoff to collection filtration systems. Natural drainage conditions 

would be restored where possible and revegetated with native plants.
26

Table 2. Program Requirements for Off Site Maintenance Facility

Function Square Footage

General Office Space 2,000

Shop Space/Storage 5,000

Covered Vehicle Storage 2,200

Paint Storage 1,000

2000-gallon above ground fuel storage and pump area 2,000

Parking/maintenance yard

Total

20,000

 32,200 SF (0.74 acres)

Historic Office and Residence Area

A park policy for required residency and housing priorities would be established, and the sewage lines 

would be upgraded. An alternative heating system would be installed for each of the residential and 

office buildings. Historic buildings that are not used for housing or office space would be converted to be 

used by researchers or other park partners, for curatorial storage, and storage space for nonhazardous 

materials. 

Defined parking areas would be provided and a park policy established that would restrict automobile 

maintenance by residents. The use of park-provided shuttle service by employees would be encouraged. 

The effects of runoff from paved areas would be mitigated by containing and treating the water or by 

redirecting the flow to existing treatment facilities. Bare areas would be repaired and revegetated with 

native plants.

Mission 66 Housing Area

All Mission 66 residences and the 3,000-gallon propane tank would be removed. Natural drainage 

conditions would be restored where possible and revegetated with native plants. Offices currently

located in this area would be relocated off the escarpment.

Tennis Court and Helipad Area

The tennis court would be removed, natural drainage conditions would be restored, and the area would 

be revegetated with native plants. New Mexico SHPO and park cultural resources staff would develop a 

detailed plan for removing the tennis court without adversely impacting cultural resources.
Alternative B

(Preferred)

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

130/20044 DSC March 2000

›north

GENERAL NOTES:

For Bat Cave Draw improvements see

Alternative B: Bat Cave Draw Concept

(page 26)

For relocated facilities see Alternative B:

Off-Escarpment Maintenance Facility and

Alternative B: Off-Escarpment Parking

(pages 27 and 28)

All structures north of Bat Cave Draw would

be converted to alternative HVAC system once

propane tanks have been removed.

Building to Remain

Building to be Removed

UST- Underground Storage Tank (fuel)

KEY:

Proposed accessible

parking ~10 spaces

Visitor Center

Construct enclosed wash area for restaurant use

Prohibit parking behind building

Park garbage truck off escarpment

Reconfigure west parking lot to improve circulation

General notes for VC Parking Lots

Install catch basins to collect and filter

runoff

Release storm water to the south where

feasible

Relocate filling point and

construct spill containment area

for 6,000-gallon UST

Reconfigure east parking lot to provide

space in front of VC for off-escarpment

views

Mission 66 Housing

Remove structures and revegetate

site

Remove propane tank and revegetate

Tennis Court and Helipad Area

Remove tennis courts and revegetate

site

Bat Cave Draw

Remove pavement and revegetate

site, minimizing disturbance of

historic stone walls

Construct paved walkway to cave

entrance

Install catch basins to collect and

filter runoff from remaining

pavement

0 100 300 FEET

Maintenance Facility

Relocate chemical storage, storage yard, auto shop,

paint shop, heavy equipment, trash collection, and

recycling area

Remove UST and propane tank

Install catch basins to collect and filter storm water

Remove non-historic structures and revegetate sites

Remove employee parking and revegetate

2

7
GENERAL NOTES:

The proposed bioretention area will serve

as a natural filter for storm water run-off

from the hill north of the draw

A system of catch basins to collect and

filter storm water is proposed

for the new accessible parking area

›n

0 100 FEET

orth

Alternative B:

Bat Cave Draw Concept

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

Existing

entrance road

10 accessible

parking spaces

Proposed stone

retaining wall

(see section above)

Remove pavement

and revegetate

Existing stone

wall (historic)

Superintendent’s

office building

Restrooms/

sewage lift

station

Proposed Accessible

sidewalk

2

8

Bioretention area

The turn-around would be designed to fit within

the current boundaries of the parking lot and would

not expand beyond the current historic walls to the

south or into the hillside to the north.

TW

4366

TW

4360

Elevation

4380

37’ 8’ 37’ 31’ 39’ 15’

Edge of existing

parking lot

Side

w

alk

Bioretention area

Bioretention area

N

atural arro

y

o

E

xisting

W

all

E

xisting

W

all

E

xisting

W

all

TW

4357

Remove existing

paved surface

SECTION THROUGH PROPOSED

BIORETENTION AREA AT

BAT CAVE DRAW

BAT CAVE DRAW PROPOSAL

Notes:

TW = Top of Wall

Elevations in feet are approximate

Section is not to scale
0

4000

Feet

AlternativeB:

Off-Escarpment

MaintenanceFacility

CarlsbadCavernsNational Park

USDepartmentofthe Interior

National ParkService

130/20055 IntermountainGISProgram-

DenverFebruary2000

NKe

y

ProposedFeatures

MaintenanceArea

AccessRoad

LandOwnership

CarlsbadCavernsN.P.

StateLand

BLMLand

PrivateLand

29
30

Sewage System

The collection system would be rehabilitated and the outfall system would be rerouted so that it runs 

south from the visitor center, down the escarpment, and then along a maintenance access road to the 

existing evaporative sewage lagoons. The sewage lagoons would be rehabilitated and relined to 

prevent any leaks into the groundwater system. 
No Action Alternative A-Technological Measures B- Partial Relocation of Facilities (Park and 

Environmentally Preferred Alternative)

There would be no changes to current 

land-use practices or to non-historic 

buildings. The underground storage

tanks would remain.

Meets project objectives.

No, contamination sources would

remain above the cave and continue

to degrade cave and groundwater

resources.

The paved area would be reduced in Bat 

Cave Draw and runoff from remaining

paved areas and buildings would be

contained, filtered, or redirected.

The underground storage tanks would be

removed from the maintenance and

housing areas. The parking lots would be

sealed and policies on parking lot use

would be changed.

The sewage outfall line would be rerouted 

to minimize exposure to cave and

groundwater resources.

Meets project objectives.

Partially, but significant runoff from Bat

Cave Draw would still threaten cave and

groundwater resources. Activities and

facilities that are hazardous to these

resources would remain above the cave.

The paved area would be reduced in Bat Cave

Draw and runoff from remaining paved areas and 

buildings would be contained, filtered, or

redirected.

The underground storage tanks would be

removed from the maintenance and housing

areas. The parking lots would be sealed and

policies on parking lot use would be changed.

Some of the hazardous maintenance and other

activities would be relocated from above the

cave. Policies would be established to restrict

auto repair and fertilizer use.

The sewage outfall line would be rerouted to

minimize exposure to cave and groundwater

resources.

Meets project objectives.

Yes, the primary sources of contamination to

cave and groundwater resources would be

eliminated or mitigated. More natural infiltration

conditions would be restored around Bat Cave

Draw.
Table 4. Summary Comparison of Impacts

Impact Topic No Action Alternative A- Technological Measures

B- Partial Relocation of Facilities

(Preferred Alternative)

Air Quality

Continuing chronic air quality 

degradation around open 

sewage lagoons

Short-term and non-cumulative impacts during 

construction and demolition

Continuing chronic air quality degradation around 

open sewage lagoons

Short-term and non-cumulative impacts during construction and 

demolition

Continuing chronic air quality degradation around open sewage 

lagoons

Soils & Vegetation None

Minor and local changes from erosion and runoff

0.25 acres of vegetation restored in Bat Cave 

Draw

Minor and local changes from erosion and runoff

4.2 acres of vegetation restored in Bat Cave Draw

1.3 acres of vegetation lost in new maintenance area and access 

road

Cave Resources

Continued degradation of 

groundwater and cave 

formations

Potential contamination from 

spills/ accidents unmitigated

Potential effects from sewage leaks reduced

Contaminated parking lot runoff reduced by 

97,200 gallons per year (7%)

Infiltration and drainage restored to 0.65 acres.

Potential effects from sewage leaks reduced

Contaminated parking lot runoff reduced by 268,200 gallons per 

year (19%)

Infiltration and drainage restored to 4.2 acres.

Threatened or

Endangered Species

Potential poaching of plant 

and animal species along park 

roads and parking lots

Potential poaching of plant and animal species 

along park roads and parking lots

Possible adverse impacts to plant and animal 

habitat

Potential poaching of plant and animal species along park roads 

and parking lots

Possible adverse impacts to plant and animal habitat

Cultural

Resources

No short-term impacts

Some adverse effect on historic integrity of the 

Bat Cave Draw parking area – mitigated by photodocumentation of the parking area prior to 

construction

Character and integrity of the overall Caverns 

Historic District and cultural landscape would be 

retained.

Permanent impacts on Caverns Historic District

Impacts on cultural landscape are permanent but beneficial

Archaeological and historic sites would be protected and avoided

Removal of Mission 66 residences, the non-historic maintenance 

structures, and the tennis courts would enhance the character of 

the Caverns Historic District

Visitor Use and Experience

No short-term impacts

Threats from spills and 

accidents which could pose a 

health hazard to visitors 

remains unmitigated

Minor reduction of some potential health threats to 

visitors

Temporary visual and audible impacts

Minor reduction of some potential health threats to visitors

Temporary visual and audible impacts
33

ALTERNATIVES CONSIDERED BUT REJECTED

FACILITY REDUCTION AND LAND-USE MODIFICATION

This alternative would have removed most non-historic structures from above the cave and eliminated 

most of the threats to the groundwater system from the developed area. The east parking lot would have 

been removed from the visitor center. The west parking lot would have been redesigned as a turnaround 

and staging facility for shuttle buses. A visitor parking facility would have been constructed off the 

escarpment and shuttle service would have been provided to the visitor center. 

The pavement in the parking lot in Bat Cave Draw would have been removed and a turnaround

constructed similar to Alternative B. The non-historic buildings in the maintenance area would have been 

removed and a new maintenance facility would have been constructed off the escarpment. All of the 

Mission 66 buildings would have been removed, and the number of residents reduced in the historic 

residence area. The non-occupied historic buildings in the housing and maintenance area would have 

been converted to curatorial and storage space. 

Reasons for Rejection

This alternative was rejected because a transportation engineering analysis indicated that a transit 

system was not practical for the park at this time. A shuttle system could also negatively impact visitor 

experience, by forcing visitors to stage their cars and visit the park on the shuttle’s schedule. The costs 

of developing a transit system and constructing new facilities off the escarpment would be substantial 

and would offer only slightly more resource protection than the preferred alternative, B.

SEWAGE SYSTEM IMPROVEMENT OPTIONS

The sewage collection system includes the smaller diameter (4- to 6-inch) collection pipes that collect 

wastewater from individual office, residential, and maintenance buildings. The collection system includes 

every sewer pipe on the north side of Bat Cave Draw and the sewer forcemain between the comfort 

station and the gravity outfall manhole on the visitor center side of the arroyo.

The outfall system includes the larger diameter (6- to 8-inch) transmission pipes that convey the 

wastewater to the treatment location without additional collection from individual buildings or

subsystems. The main outfall pipeline runs parallel to the ridgeline of the escarpment and cavern system 

below for 1,939 feet before heading south off the ridge to the sewage lagoons. Sewage is disposed and 

treated in a series of evaporation ponds commonly referred to as sewage lagoons. The lagoons are 

located at the base of the escarpment on NPS property.

The collection system pipes the sewage from the residence and office area on the north side of Bat 

Cave Draw to the comfort station. The outfall system pipes the sewage from the visitor center and then 

off the escarpment.
34

REHABILITATION OF COLLECTION SYSTEM

One proposed option for the sewer system was to rehabilitate the system that collects sewage from the 

maintenance and historic office and residence area and carry it to the station in Bat Cave Draw. 

Rehabilitation would be accomplished by first conducting a television inspection on the entire sewer 

system to locate wall failures, tree root intrusions, and other blockages. A survey would have to be 

conducted to locate low points in any of the pipe runs that could cause sewage buildup. Low points and 

blocked sections of pipe would have to be excavated and replaced. The entire system would then be sliplined.

Reasons for Rejection: The repair history of the collection system indicates that a large number of the 

sewage lines have significant intrusions. Minor collapse areas in the system would also make it

impractical to use proposed slip-line technology. An analysis of the costs indicates that it would be more 

expensive to survey and inspect the lines and then replace the damaged pipe than to replace the whole 

system with better pipes.

SEWAGE OUTFALL OPTIONS CONSIDERED BUT REJECTED

One objective of the outfall redesign was to minimize the total amount of cave exposed to sewage by 

making the outfall route as short as possible. The current route maximizes exposure of the sewage line 

by running over a significant amount of cave. All of the options would require some ground disturbance, 

but each option was evaluated on the basis of how much new area would be disturbed. In order to 

ensure that the system is dependable and serves the needs of the public, each option was evaluated on 

the basis of ease of operation and maintenance.

The park considered a wide range of options to protect the cave and groundwater resources from 

exposure to sewage. Each alternative was evaluated based on six primary factors: cave protection, 

impact to surface resources, water re-use and conservation, education and new technology, 

sustainability, and park operations (ease of use). These options ranged from rehabilitating the current line 

to using a Living Machine® to treat the waste and reusing the treated water at the visitor center. A 

Living Machine® is a biological waste treatment system that removes contaminants using plants,

bacteria, and other non-chemical treatments in a series of tanks enclosed in a building similar to a 

greenhouse. The water from this system could be used for toilet flushing and other non-potable uses. 

The Living Machine® would provide an educational opportunity to teach the public about sustainable 

technology and water re-use.
35

Outfall line route 1

Visitor

Center

›north

.5 .25 0 .5 miles

Sewage Treatment

Site A

Sewage Outfall Options

Carlsbad Cavern

Cave Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

Sewage Treatment

Site B

Outfall line route 2
36

Rehabilitate Existing Outfall

Slip line the existing outfall sewage line (Route 1) and rehabilitate the existing lagoons (Site A).

Reason for Rejection: The sewage outflow would still flow over significant portions of the cave and 

future releases could threaten cave resources. Vehicle access to portions of the sewage line would 

cause a great deal of surface disturbance. With time, the system would deteriorate and we would 

return to the conditions we have now.

REPLACE EXISTING OUTFALL

Replace the outfall sewage line (Route 1) with double-walled HDPE pipe and rehabilitate the existing 

lagoons.

Reason for Rejection: The sewage outflow would still flow over significant portions of the cave and 

future releases could threaten cave resources. Vehicle access to portions of the sewage line would 

cause a great deal of surface disturbance. With time, the system would deteriorate and we would 

return to the conditions we have now.

REROUTE OUTFALL AND CONSTRUCT NEW LAGOONS

This option is similar to the proposed alternative, except that new sewage lagoons would be

constructed near the existing water evaporation pond at the base of the escarpment (Site B) and there 

would be no sewage line along the access road. The sewage from the comfort station in Bat Cave 

Draw would be pumped up to the visitor center and then piped down the escarpment to the south. 

The sewage line from the edge of the escarpment to the base of the escarpment would be kept 

aboveground (Route 2) to monitor and prevent releases. The existing sewage disposal ponds would 

be removed and revegetated.

Reasons for Rejection: This option would increase the amount of surface impact outside the 

developed area at a higher cost. The new sewage lagoons would require major excavation of new 

areas along the base of the escarpment.

LIVING MACHINEâ WITH WATER REUSE SYSTEM

This option eliminates the need for an outfall sewage line by placing the primary treatment system 

(Living Machine) adjacent to the visitor center. This option would require construction of a smalldiameter effluent sewer to be constructed down the escarpment (Route 2) to a newly-constructed 

leach field (Site B). The existing sewage lagoons would be demolished and the area revegetated. This 

option would require plumbing the existing buildings with a gray-water system for toilet flushing.

Reason for Rejection: Because of additional plumbing costs and higher maintenance needs, this 

option would cost significantly more than the traditional sewage treatment options with only a slight 

increase in resource protection. This option treats the sewage above the cave and would still expose 

portions of the cave to future sewage releases. The construction of a leach field would disturb new 

surface areas below the escarpment.
37

LIVING MACHINEâ BELOW ESCARPMENT, REPLACE OUTFALL SEWER

The outfall sewage line would be relocated (Route 2) and a Living Machine and leach field would be 

constructed near the existing sewage lagoons (Site A). The existing sewage lagoons would be

demolished and the area revegetated.

Reason for Rejection: Because of higher maintenance needs, this option would cost significantly 

more than the traditional sewage treatment options with only a slight increase in resource protection. 

This option would require a significant amount of improvement along the access road to provide an 

educational benefit. 

LIVING MACHINEâ BELOW ESCARPMENT, SLIPLINE EXISTING OUTFALL

The outfall sewage line would be slip-lined (Route 1) and a Living Machine and leach field would be 

constructed near the existing sewage lagoons (Site A). The existing sewage lagoons would be

demolished and the area revegetated.

Reason for Rejection: This option would require higher maintenance costs than the selected

alternative. The sewage outflow would still flow over significant portions of the cave and future 

releases could threaten cave resources. This option would require a significant amount of improvement 

along the access road to provide an educational benefit. 

COMPOSTING TOILETS

The use of composting toilets for each building in the historic residence and office area would change 

the wastewater conveyed over the cave from raw sewage to water that has had solid waste and some 

contaminants removed from it. 

Reasons for Rejection: The use of composting toilets would add to the life cycle cost of each of the 

alternatives and was considered an objectionable substitute for traditional indoor plumbing.
Table 5. Summary of Sewage Outfall Options (see map on page 33)

Option Outfall Route Treatment Location Cost Primary Reason for Rejection

Selected Alternative- Reroute Outfall to existing lagoons 2 A 2,507,000 Selected alternative presented for 

comparison

1-Rehabilitate Existing Outfall 1 A 1,038,000

The sewage outflow would still flow 

over significant portions of the cave 

and future leaks could threaten cave 

resources.

2-Replace Existing Outfall 1 A 2,188,000

The sewage outflow would still flow 

over significant portions of the cave 

and future leaks could threaten cave 

resources.

3-Reroute Outfall and Construct New Lagoons 2 B 2,821,000

This option costs more and would 

cause more damage to surface 

resources than the selected option.

5-Living Machine® with Water Reuse System 2 Visitor Center 2,905,000

This option would still expose large 

portions of the cave to potential 

sewage leaks.

6-Living Machine® below Escarpment, Replace Outfall Sewer 2 B 3,600,000

This option costs significantly more 

than the selected option with only 

slightly more protection to resources.

7-Living Machine® below Escarpment, Slip-line Existing 

Outfall 2 A 2,567,000

This option would require a significant 

amount of improvement along the 

access road to provide a benefit 

beyond the selected alternative.
39

ENVIRONMENTAL CONSEQUENCES

Impacts, both adverse and beneficial, were evaluated in terms of context (are the effects site-specific, 

local, or even regional?), duration (are the effects short-term, lasting less than one year, or long-term, 

lasting more than one year?), and intensity (are the effects negligible, minor, moderate, or major?).

In addition to determining the environmental consequences of the preferred and other alternatives, the 

NPS’s Management Policies 2001 (2000) requires analysis of potential effects to determine whether 

or not actions would impair park resources. The fundamental purpose of the national park system is to 

conserve park resources and values. National Park Service managers must always seek ways to 

avoid, or minimize adverse impacts on park resources and values. However, the NPS has the 

discretion to allow impacts to park resources and values when necessary and appropriate to fulfill the 

purposes of a park, as long as the impact does not constitute impairment of the affected resources and 

values. An impact to any park resource or value may constitute an impairment. An impact would be 

more likely to constitute an impairment to the extent that it has a major or severe adverse effect upon a 

resource or value whose conservation is 1) necessary to fulfill specific purposes identified in the 

establishing legislation or proclamation of the park; 2) key to the natural or cultural integrity of the 

park; or 3) identified as a goal in the park’s general management plan or other relevant NPS planning 

documents.

To analyze potential impacts in this EA, the thresholds of change for the intensity of an impact are 

defined as follows:

Negligible-the impact is at the lowest levels of detection

Minor-the impact is slight, but detectable

Moderate-the impact is readily apparent 

Major-the impact is a severe or adverse impact or of exceptional benefit

Impairment- a major, adverse impact to a key resource or value

The park was required to assess cumulative impacts in the decision-making process. Cumulative 

impacts are the environmental impacts that result from the alternative when added to other past, 

present, and reasonable foreseeable future actions regardless of what agency or person undertakes 

such other actions.

AIR QUALITY

No Action Alternative. There are no activities that would affect air quality under the No Action 

Alternative.

Alternatives A and B. Under Alternatives A and B, some minor disturbance to air quality would 

result from dust particles being blown into the air during destruction of buildings and removal of 

underground storage tanks and paved surfaces. There would be slight increases in air pollutant 
40

emissions from heavy machinery during these activities as well. These effects on air quality would be 

localized and temporary. No state or federal air quality standards would be exceeded. 

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

adversely impact air quality. Since there are no activities under the No Action Alternative, this 

alternative would not be a component of the cumulative impacts. Minor disturbances to air quality 

under Alternatives A and B would contribute to cumulative impacts on air quality.

Conclusion: There would be site-specific, short-term, minor adverse impacts to air quality during 

activities under Alternatives A and B. Because there would be no major, adverse impacts to a 

resource or value whose conservation is 1) necessary to fulfill specific purposes identified in the 

establishing legislation or proclamation of the park; 2) key to the natural or cultural integrity of the 

park; or 3) identified as a goal in the park’s general management plan or other relevant NPS planning 

documents, there would be no impairment to park resources or values.

SOILS AND VEGETATION

No Action Alternative. There are no activities that would affect soils or vegetation under the No 

Action Alternative.

Alternative A. Areas where sewage lines would be replaced, buildings demolished, and tanks and 

pavement removed would undergo accelerated erosion until native vegetation was reestablished. 

Interim water runoff in disturbed areas might change soil nutrient transport. 

Vegetation would be restored to 0.65 acres in Bat Cave Draw, resulting in a long-term positive impact 

on natural resources in this area. Water infiltration and groundwater flow patterns would be restored 

above this area after 75 years of imperviousness.

Alternative B. Areas where the sewage lines would be replaced, buildings demolished, and tanks 

and pavement removed would undergo accelerated erosion until native vegetation was reestablished. 

Interim water runoff in disturbed areas might change soil nutrient transport. 

Vegetation would be restored to 1.2 acres in Bat Cave Draw, two acres in the Mission 66 residence 

area, and one acre in the maintenance and tennis court areas. Revegetation would result in a long-term 

positive impact on natural resources in these areas. Water infiltration and groundwater flow patterns 

would be restored above this area after 75 years of imperviousness. The off-escarpment maintenance 

facility would result in a loss of 0.75 acres of vegetation and the access road would result in a loss of 

0.6 acres of vegetation. 

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

adversely impact soils and vegetation. Since there are no activities under the No Action Alternative, 

this alternative would not be a component of the cumulative impacts. 
41

Activities under Alternative A would result in site-specific, short-term, minor adverse impacts to soils 

and would contribute to the overall cumulative impacts on soils. Restoration of vegetation to 0.25 

acres would result in site-specific, long-term, moderate beneficial impacts to vegetation and would 

contribute to the cumulative impacts on vegetation.

Activities under Alternative B would result in site-specific, short-term, minor adverse impacts to soils 

and would contribute to the overall cumulative impacts on soils. Restoration of vegetation to a net 2.9

acres would result in site-specific, long-term, moderate beneficial impacts to vegetation and would 

contribute to the cumulative impacts on vegetation.

Conclusion: There would be site-specific, short-term, minor adverse impacts to soils and site-specific, 

short- to long-term beneficial impacts to vegetation during activities under Alternatives A and B. 

Because there would be no major, adverse impacts to a resource or value whose conservation is 1) 

necessary to fulfill specific purposes identified in the establishing legislation or proclamation of the 

park; 2) key to the natural or cultural integrity of the park; or 3) identified as a goal in the park’s 

general management plan or other relevant NPS planning documents, there would be no impairment to 

park resources or values.

CAVE AND GROUNDWATER RESOURCES

No Action Alternative. Sewage spills from pipes and manholes would continue to threaten cave 

resources. Contamination of cave formations would continue, leading to their long-term degradation. 

An average of 1.4 million gallons of contaminated water per year (100% of the total) would still run off 

the parking lots and into the groundwater system every year. Potential contamination from automobile 

accidents as well as fuel tank leaks and spills would pose a continuing threat to cave resources as well 

as human health. Natural drainage and infiltration patterns above the cave would remain altered.

No wetlands or 100-year floodplains exist within the project area or would be affected by actions 

under this alternative.

Alternative A. The adverse effects on cavern water quality from sewage releases would be reduced 

by replacing the sewage collection system and rerouting the sewage outfall system to remove sewage 

from the escarpment as quickly as possible.

Pavement would be removed from 0.65 acres in Bat Cave Draw. This could eliminate a minimum of 

97,200 gallons of contaminated water per year (7% of the total). The removal of pavement in Bat 

Cave Draw would help restore natural drainage and infiltration to this area.

No wetlands or 100-year floodplains exist within the project area or would be affected by actions 

under this alternative.

Alternative B. The adverse effects on cavern water quality from sewage releases would be reduced 

by replacing the sewage collection system and rerouting the sewage outfall system to remove sewage 

from the escarpment as quickly as possible.
42

Vegetation would be restored to 1.2 acres in Bat Cave Draw, two acres in the Mission 66 residence 

area, and one acre in the maintenance and tennis court area. This could eliminate a minimum of 

268,000 gallons of contaminated water per year (19% of the total). The removal of pavement and 

buildings would help restore natural drainage and infiltration to these areas.

No wetlands or 100-year floodplains exist within the project area or would be affected by actions 

under this alternative.

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

beneficially impact cave and groundwater resources. The No Action Alternative leaves all the sewage 

lines and paved areas as they are and would contribute to the continuing degradation of cave and 

groundwater resources. 

Under Alternative A, removal of paved surfaces, treatment of runoff, replacement and reconfiguration 

of sewage lines, and changes in some land-use polices would slow, but not stop most degradation of 

cave and groundwater resources. The long-term effects would still be steady, gradual reduction of 

groundwater quality and degradation of cave formations. Local, long-term, moderate impacts to cave 

and groundwater resources from Alternative A would contribute to cumulative adverse impacts on 

cave and groundwater resources.

Under Alternative B, removal of paved surfaces, treatment of runoff, and changes in some land-use 

policies would stop most of the degradation. The local, long-term, major beneficial impacts to cave 

and groundwater resources from Alternative B would contribute to cumulative beneficial impacts on 

cave and groundwater resources.

Conclusion: There would be site-specific, long-term, major adverse impacts to cave and groundwater 

resources under the No Action Alternative. There would be local, long-term, moderate negative 

impacts to cave and groundwater resources under Alternative A. There would be local, long-term, 

major beneficial impacts to cave and groundwater resources under Alternative B. 

Because under the No Action Alternative there would be major, adverse impacts to a resource or 

value whose conservation is 1) necessary to fulfill specific purposes identified in the establishing

legislation or proclamation of the park; 2) key to the natural or cultural integrity of the park; or 3) 

identified as a goal in the park’s general management plan or other relevant NPS planning documents, 

the No Action Alternative would result in impairment to park resources or values.
43

RARE, THREATENED OR ENDANGERED SPECIES

Surface Species

There would be no adverse impacts on known rare, threatened or endangered plant species from any of 

the alternatives. A plant survey conducted by the New Mexico Natural Heritage Program (Chauvin, 

1999) did not identify rare, threatened or endangered plants in either the developed area or in the 

proposed off-escarpment maintenance area. 

No Action Alternative. There would be no adverse impacts on threatened or endangered plant or 

animal species.

Alternative A. The developed area is within the habitat of some state and federally-listed plant and 

animal species. Sewage line replacement and realignment under this alternative may adversely affect 

these habitats.

Alternative B. The developed area and the off-escarpment maintenance facility are within the habitat 

of some state and federally-listed plant and animal species. Sewage line replacement and realignment 

under this alternative may negatively affect these habitats. Construction of an off-escarpment 

maintenance facility and access road may adversely impact habitats. Detailed surveys for these species 

and habitats would be conducted prior to any activity and plans would be developed to mitigate potential 

negative impacts.

Subsurface Species

No threatened or endangered species listed by the federal or state government have been identified in 

the park’s subsurface environment. The cave does have several colonies of bats and a colony of Cave 

swallows. While little microbial research has been done in Carlsbad Cavern, the conditions are favorable 

for microbial growth and it is likely unique microbes exist. These microbes are sensitive to changes in 

moisture conditions and changes in water chemistry.

No Action Alternative. There would be no adverse impacts on threatened or endangered subsurface 

species. This alternative would allow chronic contamination of the groundwater to continue that could 

adversely impact the cave’s natural ecosystem.

Alternative A. There would be no adverse impacts on threatened or endangered subsurface species. 

The bats and Cave swallows occupy the cave from March through October, so any construction

activities would take place preferably between November and February.

This alternative would reduce the amount of contaminants entering the groundwater and would reduce 

the adverse impacts of surface activities on the cave’s natural ecosystem.
44

Alternative B. There would be no adverse impacts on threatened or endangered subsurface species. 

The bats and Cave swallows occupy the cave from March through October, so any construction

activities would have to take place preferably between November and February.

This alternative would reduce the amount of contaminants more than Alternative A. It would restore 

more natural infiltration and moisture to the cave that is beneficial to the cave’s natural ecosystem.

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

adversely impact rare, threatened, or endangered plant and animal species. Since there are no activities 

under the No Action Alternative, this alternative would not be a component of the cumulative impacts. If 

further studies find rare, threatened, or endangered species in the project area, site-specific, long-term, 

minor adverse impacts to species under Alternatives A and B would contribute to the cumulative impacts 

on these species.

Conclusion: Current surveys indicate that there are no known rare, threatened, or endangered plant or 

animal species within the project area, although the area contains suitable habitat for some threatened or 

endangered species. If these species do occur within the area, there would be site-specific, long-term, 

minor adverse impacts to these species under Alternatives A and B. Because there would be no major, 

adverse impacts to a resource or value whose conservation is 1) necessary to fulfill specific purposes 

identified in the establishing legislation or proclamation of the park; 2) key to the natural or cultural 

integrity of the park; or 3) identified as a goal in the park’s general management plan or other relevant 

NPS planning documents, there would be no impairment to park resources or values.
45

CULTURAL RESOURCES

The period of significance for the Caverns Historic District is 1926 to 1942. A building, structure, or 

element of a structure is significant if it retains enough of its original craftsmanship, style, or construction 

to reflect its original appearance or function during its period of significance. If a structure or element 

was constructed during the period of significance and supports the overall historic context of that period, 

then it would be contributing to the Caverns Historic District.

More recent construction that matches the character and appearance of those originating during the 

development of the Caverns Historic District are considered supporting. These are generally buildings 

less than 50-years old, so they are not eligible for the National Register, but do reflect the character of 

the Caverns Historic District. 

Buildings like the paint storage building would be supporting to the overall district because its construction 

style and materials reflect the period of significance (it matches the appearance of the other structures), 

but non-contributing to the Historic District because it was added after the period of significance and is 

not individually eligible for the National Register of Historic Places.

No Action Alternative. This alternative would have no new effect on cultural resources within the 

Cavern Historic District and cultural landscape. The non-contributing and non-supporting elements within 

the Cavern Historic District would remain.

Alternative A. Most of the proposed actions would have no adverse effect on historic or archeologic al 

resources. Construction of a water collection and filtration system, repair or replacement of the sewer 

lines, or construction of new sewer lines, if necessary, would be planned to avoid known archeological 

and historical sites. Changes in the heating and cooling systems of the historic structures would be 

designed to have no adverse effect on those structures. Revegetation projects would be designed to 

avoid all archeological and historic sites. The proposed change to the Bat Cave Draw parking area 

would have no adverse effect on the structure since the original walls, terraces, and appearance would 

remain. Construction activities would temporarily introduce non-historic visual, audible, and atmospheric 

elements into the district’s setting.

Prior to any action, the parking area would be fully documented to standards agreed to with the New 

Mexico SHPO. The character and integrity of the overall Caverns Historic District and cultural

landscape would be retained. All of the projects described in this alternative would require additional 

consultation and compliance documentation with the New Mexico SHPO before they could be

implemented. Pavement removal and revegetation would be designed to prevent erosion or burial of 

archeological and historic resources. 
46

Alternative B. This alternative would permanently, adversely impact the Bat Cave Draw parking lot, an 

element of the Caverns Historic District and the cultural landscape. As in Alternative A, water collection 

and filtration systems, revegetation projects, and sewerline repair or replacement projects, would avoid 

all archeological and historic sites. Redesign of parking areas and restoration of natural drainage patterns 

would be designed to avoid secondary erosional effects on archeological and historic resources. 

Installation of alternative heating systems to historic structures would be designed so that there is no 

adverse effect on the structures.

The proposed changes to the Bat Cave parking area would have a permanent, adverse effect on this 

structure, but not on the overall character of the cultural landscape. The proposed actions would include 

removing or altering 300 feet (15%) of the original retaining walls of the parking area. The park would 

photo-document the existing condition of the retaining walls before undertaking the project.

Reconstruction of the walls for the bus turn-around would be done in a manner that matches the 

character of the original wall and would reuse removed materials. Terraces would be revegetated with 

native plants with root systems that would not cause future damage to the remaining walls. The turnaround would be designed to fit within the current boundaries of the parking lot and would not expand 

beyond the current historic walls to the south or into the hillside to the north.

Construction of a new maintenance facility off of the escarpment would require a full archeological 

survey. Once detailed site plans were developed, an archeological survey of the area would be

completed. Design plans and work contracts would stipulate that construction activities would have no 

effect on any archeological or historic properties. Environmental and cultural resource compliance would 

have to be done once the proposed designs were finalized.

Removal of non-historic structures in the developed area would have no adverse effect on the Caverns 

Historic District and cultural landscape. The automotive and carpentry shop (1962), are within the 

historic district and listed as supporting the historic architectural and landscape setting though not eligible 

for listing on the National Register. Since the period of significance for the district is considered to be 

1926-1942, removal of these structures would not detract from the overall character of this Caverns 

Historic District.

The two Mission 66 residential units lie outside the boundaries of the Caverns Historic District. They are 

not eligible for the National Register. Since the period of significance for the district is defined as 1926-

1942, removal of these structures would have no adverse affect on the character or integrity of the 

Caverns Historic District or cultural landscape. Removal of the Mission 66 residences and non-historic 

maintenance buildings would be done in a manner that would cause no effect on surrounding historic 

structures and archeological or historic sites.

Removal of the tennis court would have no adverse effect on the Caverns Historic District and cultural 

landscape. This structure is non-historic and lies outside the boundary of the Caverns Historic District. 

The removal would have no adverse effect on the integrity of the historic district. The modern structures, 

however, were built on top of an extensive prehistoric and historic scatter. Remains of several midden 

rings and other American Indian artifacts are intermingled with historic materials associated with the 

early living quarters of the guano mining era and the park staff. Tarpaper shacks were occupied in this 

area prior to the construction of the stone residences of the Caverns Historic District immediately to the

west. Removal of the tennis court and other more recent structures would be designed and carried out in 
47

consultation with the New Mexico SHPO to minimize the effects on the underlying historic remains of 

the site. 

Under this alternative, the proposed actions would result in a permanent, major adverse effect on

individual elements within the Caverns Historic District, but permanent, moderate effects on the overall 

cultural landscape. The proposed actions would result in no adverse effects on the overall character and 

integrity of the historic district. Archeological and historic sites would be protected and avoided during all 

construction and deconstruction phases of this plan. Since the Mission 66 residences, the non-historic 

maintenance structures, and the tennis court fall outside the designated period of significance, their 

removal could enhance the character of the Caverns Historic District by returning the appearance of the 

area to one similar to the early 1940s. All of the projects described in this alternative would require 

additional consultation and compliance documentation with the New Mexico SHPO before they could be 

implemented.

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

adversely impact cultural resources. Since there are no activities under the No Action Alternative, this 

alternative would not be a component of the cumulative impacts. Permanent, minor to moderate adverse 

impacts to cultural resources under Alternatives A and B would contribute to the cumulative impacts on 

these resources.

Conclusion: There would be permanent, minor adverse impacts to cultural resources under Alternative 

A. There would be permanent, moderate adverse impacts to cultural resources under Alternative B. 

Because there would be no major, adverse impacts to a resource or value whose conservation is 1) 

necessary to fulfill specific purposes identified in the establishing legislation or proclamation of the park; 

2) key to the natural or cultural integrity of the park; or 3) identified as a goal in the park’s general 

management plan or other relevant NPS planning documents, there would be no impairment to park

resources or values.

VISITOR USE AND EXPERIENCE

No Action Alternative. There would be no immediate effect on visitor experience under this

alternative. However, long-term effects from chronic contamination, as well as from spills and accidents 

in the developed area, would have a major adverse impact on visitor experience at the park.

Contaminants from the developed area would continue to build up in the cave and groundwater system. 

Spills and accidents would require surface cleanup, possibly with heavy machinery, or could require a 

shutdown of in-cave operations until the effects of the spill were evaluated and mitigated.

Alternatives A and B. Reducing bus access and parking in Bat Cave Draw could inconvenience 

visitors during peak visitation times. Since 1997, the park has been restricting access and parking to this 

area to handicapped visitors and buses with very few complaints. The use of off-escarpment parking and 

visitor shuttles would reduce the traffic on the main park road. This reduces the potential for catastrophic 

spills of gasoline and other materials during vehicle-vehicle accidents and helps to protect park wildlife by 

reducing the number of vehicle-animal accidents.
48

Construction activities would temporarily introduce adverse visual and audible elements to the visitor 

experience. Construction would take place during the off season to reduce the effects of these 

activities on visitors, so the impacts would be temporary and minor.

These alternatives would reduce only some of the potential cave contamination from spills of hazardous 

materials in Bat Cave Draw, including oil and gasoline. Reducing the potential for hazardous material 

contamination in the cave would ensure the safety of visitors and would prevent possible cave closures.

Alternative B. Restoration of a scene similar to that of the early 1940s would enhance the visitor 

experience at the park and could provide additional opportunities to interpret the park’s early history for 

visitors. The Caverns Historic District period of signific ance was from the 1920s through the CCC era, 

closing in 1942. Preservation of the historic and landscape resources contained within the period of 

significance would allow the park to interpret the founding of the park and the major construction and 

development that took place during that period. The removal of non-historic buildings and paved areas 

would restore some of the natural setting of the area above the cavern.

Eliminating private vehicle parking, moving the bus turn-around and drop-off location away from the 

cave entrance would enhance and protect the natural qualities of the Bat Flight experience and improve 

the safety hazards that currently exist with vehicles driving close to pedestrian traffic near the natural 

entrance. This alternative would also reduce the amount of exhaust fumes and number of disturbances 

by vehicle headlights on the Bat Flight Program.

Cumulative Impacts: Reasonable foreseeable future actions such as rehabilitation of the visitor center, 

rehabilitation of the sewage collection system, and resurfacing of parking lots have the potential to 

adversely impact visitor use and experience. Since there are no activities under the No Action

Alternative, this alternative would not be a component of the cumulative impacts. Short-term, minor to 

moderate adverse impacts to visitor use and experience under Alternatives A and B would contribute to 

the cumulative impacts on visitors.

Conclusion: There would be short-term, minor to moderate, adverse impacts to visitor use and

experience under Alternatives A and B. Because there would be no major, adverse impacts to a 

resource or value whose conservation is 1) necessary to fulfill specific purposes identified in the 

establishing legislation or proclamation of the park; 2) key to the natural or cultural integrity of the park; 

or 3) identified as a goal in the park’s general management plan or other relevant NPS planning

documents, there would be no impairment to park resources or values.

SOCIOECONOMICS

There are no actions under any alternatives that would limit visitation or access by the public to Carlsbad 

Cavern. The socioeconomic impact of the proposed and considered alternatives are therefore removed 

from further impact analyses.
49

FURTHER COMPLIANCE REQUIREMENTS AND ADDITIONAL WORK

If the preferred alternative (Alternative B) is selected, all of the following actions would be carried 

out. If Alternative A is selected, the actions listed under Bat Cave Draw, the existing maintenance 

area, and the historic office and residence area would be carried out. If the No Action Alternative 

is selected, none of the following actions would be necessary. 

NATURAL RESOURCES

Once final design decisions are made, all affected areas will need to be re-surveyed in the proper 

season for all current state and federally-listed plant species. No exotic plants would be used to 

revegetate areas where pavement or buildings have been removed. Native species adapted to the 

area would be selected that would not damage cultural resources. Detailed descriptions and work 

scopes would be developed for each phase of the project and approved by park resource

management staff prior to revegetation. The project area also contains several state-listed noxious 

weeds. The park would develop plans to prevent the spread of these noxious plants prior to any 

activities associated with the proposed alternatives.

There are several species of mammals, birds, and reptiles whose habitat may be affected by 

activities under the proposed alternatives. Once final design decisions are made and prior to any 

construction activity, site-specific surveys for these species and their habitats would be conducted.

CULTURAL RESOURCES

Memorandums of Agreement will be developed in consultation with the New Mexico SHPO, 

affiliated American Indian tribes, and the park to resolve adverse effects to individual historic 

structures, archeological of ethnographic resources, the Caverns Historic District, and the cultural 

landscape.

Visitor Center Area

The New Mexico SHPO would be provided with full details of parking lot redesign and evaluation 

of effects of redesign and modified drainage patterns on known archeological resources.

Archeological monitoring of actions within 100 feet of any known archeological site would be 

required.

Bat Cave Draw Area

The New Mexico SHPO would be provided with full details of proposed modifications to the Bat 

Cave parking lot, including the bus turn-around site and modifications to the historic retaining 

walls; details on deconstruction and new construction methods; plans to retain the original

character of the parking area within the modified structures; and complete documentation of 

existing conditions and setting of existing historic walls. Archeological monitoring of actions within 

100 feet of any known archeological site would be required.
50

Existing Maintenance Area

The New Mexico SHPO would be provided with full details of demolition methods and efforts to 

mitigate incidental damage to historic structures; detail on new heating/cooling systems to be 

installed on historic structures and their effect on the integrity of the buildings; details on restoring 

natural drainage patterns and the effects on known historic and archeological features.

Archeological monitoring of actions within 100 feet of any known archeological site would be 

provided. 

New Maintenance Area

Once a final site and design specifications are developed, further NEPA compliance would be 

condcucted to evaluate the impacts of the site relocation. An archeological survey would be 

conducted in the area surrounding the construction site, including any adjacent roads, parking 

areas, and utility corridors. The New Mexico SHPO would be provided with survey results for 

concurrence on eligibility of sites, construction details, and any primary or secondary effects on 

known archeological or historic sites. The park would monitor actions within 100 feet of any 

known site, but would select a location away from archeological sites. 

Historic Office and Residence Area 

The New Mexico SHPO would be provided with full details on alternative heating/cooling systems 

to be added to historic structures and their effect on the integrity of the structures. Details would 

also be provided on installation of water containment and filtration systems, plans to repair and 

revegetate portions of the area, and the effects of those actions on archeological and historic sites.

Removal of Mission 66 Residences

Photo-documentation of the existing condition of the Mission 66 houses and research of associated 

documentation of their construction and development since 1962 would be completed prior to any 

demolition. The New Mexico SHPO would be provided with full details on demolition plans. 

Details would also be provided on efforts to avoid or mitigate effects on surrounding archeological 

sites or historic structures. 

Tennis Court Area

A plan would be developed to remove the concrete surface without adverse impact to the 

underlying historic and archeological resources. This could involve limited testing for subsurface 

materials. 

Consultation with Native American Tribes

The park has ongoing consultation relationships with 13 Native American tribes. Each of these 

tribes has expressed interest and concerns about the management of Carlsbad Cavern and

surrounding resources. The park would consult with these tribes on each phase of this plan.
51

SPACE ALLOCATION PLAN

One of the primary goals of this plan is to protect cave resources while maintaining services and 

facilities for the public. Some resource protection can be accomplished through management 

decisions and changes in park policy. One such decision reduces the number of residents and 

employees in the developed area above Carlsbad Cavern. Reducing the number of residents 

reduces the amount of sewage generated and the number of vehicle s parked above the cave.

As of June 2000, there were approximately 50 residents occupying the housing area on the north 

side of Bat Cave Draw. The park has instituted a policy of not providing housing for new,

permanent employees. By October 31, 2001, all of the permanent employees, except for three 

required-occupant law enforcement officers, were moved out of the park. There are currently at 

most 22 (summer maximum) residents in the housing area, reducing the total by 28 people (56%) 

from previous levels.

Medium-term Plans

The goal over the next one to five years is to reduce the number of residents by more than 50%. 

The east group of Mission 66 buildings will be used for five to ten years as office and curatorial 

space for the Resources Stewardship and Science Division. This space is needed during the visitor 

center rehabilitation that is proposed to begin within the next five years. During this time, the 

possibility of constructing or leasing office space off of the escarpment will be investigated. 

All of the required occupants and most of the seasonal and volunteers will be moved into the 

historic buildings. The women’s seasonal dorms will be located in one of the western Mission 66 

buildings. 

An engineering evaluation will be performed on the existing sewage collection system to

determine which lines need to be replaced to stop sewage releases. Priorities will be established 

for replacement and rehabilitation of sewage lines based on resource protection and availability of 

funds. During this time, additional funding sources will be located for long-term facility removal 

and/or relocation.

Long-term Plans

The park will maintain housing for 17 to 20 seasonal and volunteer employees, and temporary 

research housing in the historic buildings. At the same time, the park will pursue options to provide 

seasonal dorm space off the escarpment and may provide a transportation service to the park to 

reduce the impacts of vehicles on park resources. This would reduce the impacts from resident 

vehicles by almost 90% and would reduce the sewage output from residents by almost 95%. The 

park will also examine options for removing non-essential office, storage, and curatorial functions 

out of the developed area.
52

REFERENCES

Bremer, Mark. 1998. Preliminary assessment of environmentally-sound methods for treating and/or 

diverting rainwater run-off from parking lots and roads in the vicinity of Carlsbad Cavern. 

National Park Service draft report.

Brooke, Mark. 1996. Infiltration pathways at Carlsbad Caverns National Park determined by 

hydrogeologic and hydrochemical characterization and analysis. Master’s Thesis, Colorado 

School of Mines, Golden, Colorado.

Carr, Ethan and Sarah Allabeck. 1998. Mission 66: Contextual history of National Park Service 

planning, design, and construction, 1945-1972, Draft Proposal.

Chauvin, Yvonne. 1999. Plant species survey for Carlsbad Cavern developed area. New Mexico 

Natural Heritage Program, University of New Mexico Biology Department. Report to Carlsbad 

Caverns National Park.

Colby, Catherine. 1988. National Register of Historic Places, inventory — nomination form, The 

Caverns Historic District, National Park Service.

Cunningham, K.I., D.E. Northup, R.M. Pollastro, W.G. Wright, E.J. LaRock. 1995. Bacteria, fungi 

and biokarst in Lechuguilla Cave, Carlsbad Caverns National Park, New Mexico. In: Deepseated geochemical environments in karst. A.N. Palmer (editor) Environmental Geology. 25; 1, 

Pages 2-8. Springer International. New York-Berlin, International.

Carlsbad Caverns National Park. 1996. Final General Management Plan and Environmental Impact 

Statement, Carlsbad Caverns National Park, Carlsbad, New Mexico.

Cave and Karst Management Plan, Carlsbad Caverns National Park, 1995. On file at Carlsbad 

Caverns National Park, New Mexico.

Ek, David. 1991. Master list of cave invertebrates found within Carlsbad Caverns National Park. 

On file in cave resources office, Carlsbad Caverns National Park, New Mexico.

Federal Cave Resources Protection Act of 1988. 102 Stat. 4546. Public Law 100-691-Nov.18, 

1988. H.R. 1975.

Hunt, James B. 1999. Class III archeological survey report for the United States Department of the 

Interior’s National Park Service, Carlsbad Caverns National Park, PAC Report No. 99041, 

NMCRIS No. 66195.

National Park Service, Carlsbad Caverns National Park, 2001. Briefing statement for the

Appropriations Subcommittee Hearing on the wastewater system rehabilitation project. On file 

at Carlsbad Caverns National Park, NM.
53

National Park Service, 2001. DO#12, Conservation Planning, Environmental Impact Analysis and 

Decision Making.

National Park Service, 1997. DO#28, Cultural Resource Management Guideline.

National Park Service, 2001. Management Policies.

Northup, D.B., M.N. Spilde, and P.J. Boston, 1999. Microbial interactions with the limestone walls 

of Lechuguilla Cave, Carlsbad Caverns National Park, New Mexico, USA. Journal

of Conference Abstracts, v.4(2):95, 11th Bathurst Meeting July 13th-l8th, 1999 Cambridge, 

United Kingdom.

Northup, D.B., K. Lavoie, and L. Mallory. 1997. Microbes in Caves. NSS News, v.55(4): 111.

Northup, D.B., D.L. Carr, M.T. Crocker, K.I. Cunningham, L.K. Hawkins, P. Leonard, W. C. 

Welbourn. 1994. Biological Investigations in Lechuguilla Cave. December, 1994 NSS Bulletin 

56(2): 54-63.

van der Heijde, Paul K.M., Kenneth B. Kolm, Helen Dawson, Mark Brooke. 1997. Determining 

water infiltration routes from buildings located above Carlsbad Cavern, Carlsbad Caverns 

National Park, Carlsbad, New Mexico. International Groundwater Modeling Center report 

IGWMC-GWMJ 97-01, Golden, Colorado.
54

CONSULTATION/COORDINATION

Prepared By

Paul Burger, Hydrologist, Carlsbad Caverns National Park

Mark Bremer, Civil Engineer, Carlsbad Caverns National Park

Mark Pritchett, Landscape Architect/Job Captain, Denver Service Center

Carlsbad Caverns National Park

Paula Bauer, Interpretive Ranger

Dan Cockrum, Former Chief of Facility Management

Earl Coppersmith, Buildings and Utilities Foreman

Jeff Denny, Former Cultural Resource Specialist

Frank Deckert, Former Superintendent

Ed Greene, Chief of Interpretation

Aleta Knight, Project Coordinator and Compliance Officer

Dale Pate, Cave Resources Branch Chief

Jason Richards, Environmental Protection Specialist

David Roemer, Biologist, GIS Specialist

Jimmy Sillas, Roads and Trails Foreman

Gary Vequist, Former Chief, Resource Management and Visitor Protection

Renee West, Biological Resources Branch Chief

Denver Service Center

Ken Franc, Project Manager

Bob Merrick, Civil Engineer

Mark Tabor, Landscape Architect

Sandy Schuster, Editor

Intermountain System Support Office

Brian Carlstrom, GIS Specialist
55

Appendix 1. Estimated Costs of Preferred Alternative 

(based on NPS, Denver Service Center Class C estimate in 2002 dollars)

Description Cost

Employee Residence Area

Remove existing Mission 66 residences $ 166,038 

Remove 6000 gallon propane tank $ 6,000 

Change HVAC system $ 265,661 

Subtotal $ 437,699 

Existing Maintenance Area

Remove non-historic maintenance buildings $ 33,123 

Revegetate site $ 2,188 

Remove 1000 gallon propane tanks $ 4,862 

Remove 2000 gallon UST $ 36,465 

Adapt remaining buildings for office and storage space $ 270,450 

Change HVAC system $ 86,544 

Subtotal $ 433,632 

Off Escarpment Maintenance Area

Construct new general maintenance buildings $2,215,260 

Construct paint storage building $ 158,016 

Construct parking/maintenace yard $ 243,101 

Construct access road $3,008,378 

Install water lines $ 65,637 

Install sewage lines $ 82,654 

Install electrical and telephone lines $ 87,516 

Revegetation $ 109,396 

Subtotal $5,969,958 

Bat Cave Draw

Remove Pavement $ 84,852 

Install storm water treatment (catch basins) $ 18,233 

Provide HC parking $ 40,112 

Construct Shuttle turn-around $ 218,791 

Revegetation $ 43,758 

Subtotal $ 405,746 

Existing Visitor Center Area

Install storm water treatment (catch basins) $ 36,465 

Reconfigure parking $ 121,551 

Seal and chip parking lots $ 493,981 

Construct enclosed wash area for restaurant $ 30,388 

Construct spill containment area and new diesel tank filling area $ 60,775 

Subtotal $ 743,160 

Sewage System Improvements- Collection

Includes construction and revegetation Subtotal $ 127,500 

Sewage System Improvements- Outfall

Includes construction and revegetation Subtotal $1,240,000 

GROSS TOTAL $9,357,695 
56

Appendix 2. Overflow Mitigation Program

ß Manually pump cave-holding tank three days a week (Tuesday, Thursday, and Saturday). 

Manual pumping increases water flow through holding tank and system, and decreases collection 

and buildup of solid materials. 

ß In 2001, installed high-density polyethylene interior linings on manhole covers. This action 

decreased the amount of exfoliating material from steel lids from collecting in manholes and 

contributing to line blockages.

ß Contract for annual professional cleaning of sewer outfall system. Service will commence in FY 

2003.

ß Annual inspection of all sewer outflow manholes for buildup of solid debris will commence in FY 

2003.

ß A Line Item PMIS package to replace the complete outfall sewer line is scheduled for 

commencement in 2003.

ß Barring extreme circumstances, unplugging of outfall sewer lines will occur only during daylight. 

The increased safety risks for park personnel caused by night operations is clear and warrants 

delaying work until daylight. The required equipment for unplugging the outfall line is heavy, 

bulky, and requires at least two people to move, setup, and operate. The terrain is uneven, 

treacherous, and rattlesnakes are present. Precautions, including notifying residents in park will 

result in minimizing or completely avoiding any discharge at night. 
Sewage System

Spill Locations, Dates,

and Quantities

Carlsbad Cavern

Resource Protection Plan

Carlsbad Caverns National Park

US Department of the Interior

National Park Service

›north

0 200 600 FEET

MANHOLE F

February 13, 2002 - 100 gallons

BUILDING #7 Cleanout

January 3, 2002 - 20 gallons

BUILDING #14A Cleanout

January 3, 2002 - 100 gallons

MANHOLE 4a

July 12, 1998 - unknown spill quantity

April 16, 2001 - 15,000 gallons

January 3, 2002 - 7,000 gallons

SURFACE PIPE BREAK

May-June, 1998 - unknown spill quantity

SEWAGE DISPOSAL POND #4

Summer, 1979 - 1,000,000 gallons

MANHOLE 8b

October 20, 2001 - 7,000 gallons

February 18, 2002 - 11,000 gallons

September 12, 2002 - unknown quantity

5

7