United States
Environmental Protection
Agency
Environmental Monitoring Syste
Laboratory
Las Vegas NV 89114
Research and Development
EPA-600/S4-81-060 Aug. 1981
Project Summary
Geothermal Environmental
Assessment Baseline Study:
Vegetation and Soils of the
Roosevelt Hot Springs
Geothermal Resource Area
K. W. Brown and G. B. Wiersma
Identification and elemental con-
centrations of indigenous soil and
plant systems found on the Roosevelt
Hot Springs Known Geothermal
Resource Area (KGRA) are described.
Twenty-three different soils and five
separate plant communities are geo-
graphically mapped and identified. Of
147 plant species identified, 58 are
forbs; 53, shrubs; and 36, grasses.
Three sites, each measuring 25
hectares, were selected for long-term
vegetative assessment. A permanent
enclosure measuring 24.4 by 24.4
meters was constructed at each of
these sites to assess undisturbed
vegetation versus long-term effects of
livestock grazing and geothermal
development. Biomass, plant species,
percentage composition, ground
cover, and livestock-carrying capaci-
ties were determined at each site.
Surface soils and Artemis/a triden-
tata leaf tissue were collected for
elemental analysis. Elemental concen-
trations were found to be similar in
distribution and magnitude to those
found in soils and plants of similar
areas.
Lithium, due to its low environ-
mental levels, 1.1 ±0.3 ppm and 2.0 ±
1.8 ppm in soil and plant tissues,
respectively, when compared to the
relatively high concentration in the
geothermal fluid, 25.3 ppm, was iden-
tified as the key element for the detec-
tion of geothermal contamination.
This Project Summary was develop-
ed by EPA's Environmental Monitor-
ing Systems Laboratory, Las Vegas,
NV, to announce key findings of the
research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Exploration and development of geo-
thermal resources has expanded rapidly
m recent years. A number of locations
under consideration or in various stages
of development include the Imperial
Valley, Klamath Falls, Rio Grand Rift
Zone, and a relatively new site, Roose-
velt Hot Springs. These areas are also
important as farming and recreational
sites, wildlife habitats, and livestock
rangeland Since geothermal energy
may supply a significant portion of our
nation's future energy needs, it is
important that an evaluation of the
environmental impact of geothermal
development on these lands be made.
In December 1975, Roosevelt Hot
Springs was recognized as a potential
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KGRA when the Phillips Petroleum
Company filed a plan of operation for
geothermal exploration with the U.S.
Geological Survey (USGS). As a result,
in 1976 the USGS prepared and distri-
buted an Environmental Analysis (EA)
statement concerning the proposed
Roosevelt Hot Springs geothermal
operations, as is required by the U.S.
Geothermal Steam Act of 1 970 and by
Section 102 (2) (C) of the National
Environmental Policy Act of 1969
In addition to the parameters listed in
the EA, the Geothermal Steam Act of
1970 (Title 30 CFR 270.34K) requires
that existing environmental baseline
data be collected on air and water
quality, noise, and land subsidence
activities and that both biological and
ecological parameters be identified on
the leased lands.
Collection of baseline data was
initiated by the Phillips Petroleum
Company and the U.S. Environmental
Protection Agency. In addition, the
EPA's Environmental Monitoring Sys-
tems Laboratory in Las Vegas (EMSL—
LV) developed a monitoring strategy and
also conducted laboratory studies to
identify the behavior and movement of
selected geothermal brine contami-
nants in plants and soils: Identification
of potential biological indicators of geo-
thermal contamination and the estab-
lishment of permanent ecological
assessment study areas at three undis-
turbed sites on the Roosevelt Hot
Springs KGRA were accomplished.
Results from the field and laboratory
studies will be used to provide a data
base for a kinetic model and a pollutant
exposure commitment analysis for the
development of an integrated monitor-
ing system at the Roosevelt Hot Springs
KGRA.
Descriptions and elemental concen-
trations of the soils and vegetation and
the assessment of these lands for
grazing and wildlife habitats are pre-
sented in this report.
Conclusions and
Recommendations
The results of this investigation have
identified and geographically defined a
wide diversity of soil types and plant
communities found on the Roosevelt
Hot Springs KGRA. Its proximity to the
northern transition zone of the major
southwest deserts may account for this
KGRA exhibiting characteristics of both
the hot desert formations to the south
and the cold desert formations to the
north
The dominant plant species,
occurring in nearly every plant
community on the KGRA, was big sage-
brush, Artemisia tridentata. This
species, common throughout the north-
western United States, accounted for
more than 44 percent of the total vege-
tative composition. Other important
species included rabbitbrush (Chrys-
othamnus stenophyllus), pinyon pine
(Pmus edulis), juniper (Juniperus
osteosperma), and the grasses, cheat-
grass (Bromus tectorum) and squirrel-
tail (Sitanion hystrix).
The concentrations of 26 elements
found in 289 soil and plant samples wtll
serve as baseline levels for assessing
changes associated with the develop-
ment of geothermal resources at the
Roosevelt Hot Springs KGRA. In addi-
tion, trend studies on vegetative compo-
sition and condition can be conducted
within the three permanent enclosures
free from disturbance and grazing by
livestock. At present, the vegetative
composition in these enclosures con-
sists primarily of sagebrush, A. triden-
tata (68 percent), seven species of
grasses (24 percent), and forbs (nearly 2
percent).
The above-ground vegetation or
biomass, as determined at each study
site, varied from 3032 to 5222 kg/ha in
1977 and from 5224 to 5883 kg/ha in
1978. These measurements prpvide the
bases for assessing vegetative change
associated with geothermal resource
development.
The authors propose that periodic
sampling of soils and vegetation be
conducted in this area to verify pollutant
containment as geothermal exploration
and development continue, with lithium
being the key element for detecting
geothermal leakage.
The EPA authors K. W. Brown and G. B. Wiersma are with the Environmental
Monitoring Systems Laboratory, Las Vegas, NV 89114.
The complete report, entitled"Geothermal Environmental Assessment Baseline
Study: Vegetation and Soils of the Roosevelt Hot Springs Geothermal Re-
source A rea." (Order No. PB 81 -223 299; Cost: $11.00. subject to change) will
be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA authors can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
P.O. Box 15027
Las Vegas, NV89114
A US GOVERNMENT PRINTING OFFICE 1981 -757-012/7261
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