United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NV 89114
Research and Development
EPA-600/S7-84-088 Jan. 1985
&ERA Project Summary
Monitoring Approaches for
Assessing Quality of High
Altitude Lakes: Colorado Flat
Tops Wilderness Area
Barry P. Baldigo and John R. Baker
Three high altitude lakes were selected
and sampled to develop monitoring
approaches for assessing lake sensitivity
to acid deposition. Sampling of Ned
Wilson, Oyster and Upper Island lakes in
the Flat Top Wilderness Area of Colorado
was conducted in 1982 and 1983. These
lakes are representative of the range of
lakes sensitive to acid deposition in the
area.
Data collected show the three study
lakes are biologically and chemically
similar. Available literature suggests
biological communities of the study
lakes are sensitive to acidification, with
major impacts expected as pH drops
below 5.5. Lack of specific acidity
sensitivity data for most species of
organisms inhabiting the study lakes
precludes precise predictions of
biological response to acidification.
However, annual sampling for
community changes and indicator
species of phytoplankton, zooplankton,
and macroinvertebrate populations is
recommended. Data on fish population
structure and maintenance mecha-
nisms are needed before fish
community information can be used for
monitoring, but metal concentration
data for fish tissue and sediments
should be collected for residue levels.
Nineteen physical and chemical water
quality parameters, including eight
metals, are recommended for annual
scans.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory. Las Vegas, NV. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
This report summarizes results of a
joint U.S. Environmental Protection
Agency and U.S. Geological Survey
sampling effort conducted during 1982
and 1983 on three lakes in the Flat Tops
Wilderness Area of northwestern
Colorado. Sampling was conducted to
provide an assessment of the current
biological and chemical conditions of
these index lakes which is essential for
assessing monitoring requirements and
long term designs for these and similar
lakes. Distributions, abundances and
types of biota resident in these lakes
determine the type of biological
monitoring program most suitable for
sampling frequencies, site selection and
distribution, and identifying sensitive
communities or community components.
A basic understanding of the physical and
chemical characteristics is necessary for
parameter selection and determining
sampling sites, distributions, and
frequencies. Factors such as parameter
responsiveness to acidification, ease of
measurement, temporal, spatial, and
vertical variability are important consid-
erations in monitoring designs.
Located within the boundaries of the
White River National Forest, the Flat Tops
Wilderness Area of northwestern
Colorado includes numerous lakes, many
higher than 3300 m in elevation.
-------
Background
Approximately 370 lakes within the
Flat Tops Wilderness Area have been
estimated to be very sensitive to
acidification. All have alkalinities, either
predicted or measured, less than or equal
to 200 //eq/L CaCO3; some have been
recorded at 70 peq/L CaC03. The high
sensitivity of most lakes results
principally from the small amounts of
calcarious sediments in their
watersheds. Basalt caprock underlies
most lake beds and watersheds of the
higher altitude lakes. Additionally, small
watershed-to-lake surface area ratios
reduce the water/soil contact time of
runoff. Hence, the small amounts of
CaC03 in sediments have little chance to
dissolve in these runoff waters.
The severity of acid precipitation
effects in the Flat Tops could increase due
to expansion of the oil shale industry.
Expansion of synfuels(including oil shale)
production and coal-fired power plants on
the Rocky Mountain western slope
"Energy Belt" may increase hydrogen ion
concentrations in wet and dry deposition
and will undoubtedly, contribute increas-
ing amounts of SO2 and NO, to the
atmosphere.
Monitoring Requirements
Unique sampling problems are
encountered in wilderness areas.
Because the Flat Tops are accessible only
by foot or horseback, severe restrictions
are placed on the use of the cumbersome
and/or fragile equipment used in more
conventional studies. Additionally,
sampling is normally restricted to summer
(ice free) months due to a heavy
snowpack most of the year. Because
monitoring approaches and techniques
tested in the lakes of the Flat Tops have
helped identify techniques best suited for
these conditions, refined monitoring
strategies suitable for application in
these types of areas can now be
suggested.
Methods and Materials
Samples collected each year and
methods used in their collection are
summarized in Table 1.
Results and Discussion
Components of the Flat Tops lakes zoo-
plankton, phytoplankton and fish
communities are subject to alterations as
the pH of water approaches 5.5, and
certain macroinvertebrate species are
known to be sensitive to waters with pH
values of 6.0 to 6.5. Once these levels are
reached disruptions will be expected in
the biotic communities of the study lakes.
Currently, summer daytime pH levels in
all three study lakes are typically above 6.0.
Phytoplankton
Within-lake differences in phytoplank-
ton assemblages were apparent in all
lakes. However, between-station and
depth related variability were largely
attributable to rare species with dominant
and co-dominant species relatively uni-
formly distributed throughout each lake.
Discrete samples from the deep site on
Upper Island Lake yielded slightly more
diverse assemblages at 1 m than at 5 and
10m. The majority of taxa collected at the
various strata were present in the 1 m
sample, suggesting that a near surface
sample taken from a stratified lake will
collect most of the more common phyto-
plankton species.
Annual and seasonal variability of the
phytoplankton community were high in
all lakes. Also, bet ween-lake differences
in the composition and abundance of
phytoplankton communities were
apparent in samples collected on
approximately the same dates. Because
of differences in the succession patterns
of the phytoplankton assemblages in the
various lakes, and because different
assemblages were noted in individual
lakes during mid August of two
successive years, it seems unlikely that
once-a-year sampling will provide ade-
quate data to depict long term changes in
phytoplankton assemblages in the
various lakes. Differences in succession
patterns need to be further investigated
during the open water period. It is
suggested that near-surface (e.g., 1-1.5
m) quantitative samples be collected and
composited from 3 to 4 sites per lake at
two week intervals, to examine
succession patterns. In addition, replicate
discrete quantitative samples should be
taken at three depths (e.g., 1.5, 5 and 10
m) during a period of strong stratification
and again during isothermal conditions to
examine distribution throughout the
water column.
Zooplankton
Zooplankton species richness in the
three Flat Tops study lakes is low and
changes in diversity will probably not be
useful in future monitoring. However,
permanent changes in community
composition (acid sensitive and acid
tolerant species) can be indicative of acid-
ification. Sensitivity to acidification of the
copepod species (Diaptomus spp.), having
distributions restricted to high altitude
lakes, are not known and their sensitivity
should be determined for possible use in
future monitoring.
Annual zooplankton differences within
individual lakes, based upon August
sampling during successive years, were
minor. Differences that were noted were
attributable principally to occurrences of
rare species. Because with-in lake
variability between sites was also low, it
appears that replicate, depth-integrated
samples collected at a single deep site
during the period of strong stratification
would be adequate to characterize the
zooplankton communities of the study
lakes for purposes of showing differences
between lakes and over time.
Seasonal variability and succession
patterns of zooplankton communities
were not addressed in this study,
consequently no conclusions or
recommendations can be made regarding
optimal sampling frequencies or seasons.
Sampling at a single deep site at two-
week intervals during the open water
period would provide considerable infor-
mation on succession patterns of
zooplankton assemblages. Knowledge of
these patterns would aid in the design of
long-term monitoring programs with
respect to required sampling frequencies
and optimal sampling periods (e.g.,
stratified vs. non-stratified lake condi-
tions).
Macroinvertebrates
Different macroinvertebrate commu-
nities occupied the littoral (shoreline) and
profundal (deep) zones of the three Flat
Tops lakes. Qualitative sampling in the
littoral zone yielded more diverse assem-
blages than were found in quantitative
grab samples from the profundal zone. To
adequately characterize macroinverte-
brate communities of individual lakes it is
essential that both zones be sampled.
Because the acidification sensitivity of
individual taxa is not well known, it is
important to examine entire assemblages
occupying various habitats using changes
in indices of community structure, (e.g.,
diversity, richness, density) when pos-
sible.
Annual differences in various study
lake's macroinvertebrate communities
indices were significant, hence frequent
(yearly) sampling may be necessary to
access annual variability. Because recruit-
ment and emergence affect "seasonal"
species population size, temporal vari-
ation during ice free periods should be
determined at least once. Except for one
shallow Ned Wilson Lake site, bet wee n-
site macroinvertebrate community indices
-------
Table 1. Summary of Sample Sites. Dates, Numbers and Types Collected During 1982 and 1983 Flat Tops Lakes Surveys. Field Measureable
Parameters, e.g.. Temperature, pH, D.O.. Conductivity, etc.. are not Included in this Summary
Lake
Ned Wilson
Oyster
Upper Island
Ned Wilson
Oyster
Upper Island
Ned Wilson
Sites
1.2.3.4
"
"
shoreline
"
2
2
2
2
shoreline
spring
1.2
"
"
shoreline
2
1.2.3.4
"
4
shoreline
1.2.3.4
2
2
2
2
2
2
2
2
2
1.2,3,4
M
shoreline
"
"
"
"
1.2
"
"
shoreline
1.2.3.4
4
4
4
4
4
1.2.3,4
4
4
shoreline
shoreline
1.2.3.4
Sample
Phytoplankton
Zooplankton
Macroin vertebrates
Fish-metal content
Fish-stomach contents
Phytoplankton
"
"
"
Macroinvertebrates
"
Phytoplankton
Zooplankton
Macroinvertebrates
11
Sediments-metal content
Phytoplankton
Zooplankton
Macroinvertebrates
Macroinvertebrates
Phytoplankton
"
"
"
"
a
"
"
'•
"
Zooplankton
Macroinvertebrates
"
"
••
"
Fish-metal content
Phytoplankton
Zooplankton
Macroinvertebrates
"
Phytoplankton
"
"
"
"
"
Zooplankton
Macroinvertebrates
"
a
Fish-metal content
Alkalinity, Color
Type
D.I.G.1
V.T.4
Ekman
Grab"
"
••
"
Qual*
"
D.I.G.
V.T.
Ekman
Qual
D.I.G.
V.T.
Ekman
Qual
D.I.G.
Grab
"
"
a
"
"
"
a
••
V.T.
Ekman
Qual
H.D.7
B.K.*
10-R.'
D.I.G.
V.T.
Ekman
Qual
D.I.G.
Grab
tt
Grab, 1Om"
Grab. 5m
Grab. 1m
V.T.
Ekman
Qual
10-R
D.I.G.
Reps.
23
1
3
6
1
1
1
1
1
5
1
2
1
3
3
1
2
1
3
3
1
1
1
2
2
2
2
2
2
2
3
3
4
4
4
3010
5
2
3
3
3
2
2
2
2
2
2
3
3
3
3010
2
1 pe,
Total No.
8
4
12
6
1
1
1
1
1
5
1
4
2
6
3
1
8
4
3
3
4
1
1
2
2
2
2
2
2
2
12
12
4
4
4
30
5
4
6
6
3
8
2
2
2
2
2
12
3
3
30
2
'site
Date1
08/17/82
"
~
09/01/82
08/17/82
07/21/82
08/04/82
09/10/82
10/03/82
08/17/82
08/18/82
08/18/82
ft
*
//
M
n
08/20/82
••
it
••
07/25/83
04/14/83
06/28/83
07/20/83
07/29/83
08/12/83
08/17/83
08/30/83
09/10/83
09/28/83
08/25/83
n
n
ft
n
••
ft
08/24/83
tt
tt
n
O8/27/83
08/10/83
08/24/83
08/27/83
tt
"
tt
tt
tt
ft
tt
08/25/83
-------
Table 1. (Continued)
Lake
Sites
Sample
Type
Reps.
Total No.
Date'
Oyster
Upper Island
1.2 Total P. Nitrate
1,2,3.4 Nitrite. Ammonia.
TOO, DOC, Surfate,
Chloride. Fluoride,
and Total Metals
D.I.G.
3 per site
08/24-27/83
* Actual day may vary by ± one day.
"Depth Integrated Grab (Van Dorn) sample.
3Only one replicate phytoplankton sample per site processed in 1982.
^Vertical Tow-Standard Wisconsin Plankton Net; bottom to surface.
sGrab sample at surface.
'Qualitative Triangular Dip Net (570(im mesh).
7Hester-Dendy Plate sampler.
^Rectangular Basket with rocks.
910-rock method.
'"Three replicates analyzed,
1 'Discrete Depth sample.
were not significantly different in any
lake during either year, hence replicate
samples from one deep site should
adequately assess the status of prof undal
invertebrate assemblages in these index
lakes during future monitoring.
Salamanders
Salamanders in Oyster Lake may serve
as useful monitors because they breed in
pools subject to influx of snowmelt
pollutants. Sensitivity of various
Ambystoma tigrinum life stages to acidi-
fication are not known, and should be
determined for use in future monitoring.
Increased acidification of Oyster Lake
could result in decreased population or
loss of salamanders. A. tigrinum sen-
sitivity to acidic conditions should be
determined for possible use in future
monitoring.
Limited sampling and visual observa-
tions revealed the presence of salmonids
in two of the three study lakes. It is not
known whether trout in these lakes are
reproducing naturally or whether they
are the result of repeated stocking.
Because early life stages are more
sensitive to acidification and associated
effects (e.g., metal releases) than are
adults, artificially maintained populations
would not be good monitors of acidifica-
tion induced changes. On the other hand,
naturally reproducing populations would
likely be affected by any reduction in
ambient pH levels, or by additional
releases or mobilization of metals
because of the high vulnerability of egg
and larvae stages. Determination of fish
population structure and maintenance
mechanisms is an initial essential step
toward incorporation of fish surveys into
a monitoring program.
Metal concentrations in whole
homogenized brook trout were low in Ned
Wilson Lake during both 1982 and 1983.
Two specimens of cutthroat trout
collected from Upper Island Lake during
1983 yielded levels of copper, nickel and
zinc an order of magnitude higher than
were found in Ned Wilson Lake brook
trout. Concentrations in gills of fish from
both lakes were much lower than in
whole fish. Because these metals are
biocumulative, it is recommended that
analyses of whole fish (e.g. three
specimens/lake) be conducted once
annually to monitor tissue residue levels.
Metals in Sediments
Concentrations of metals within
sediments of the study lakes are within
expected ranges for unimpacted Western
U.S. water bodies. Because changes in
sediment metal chemistry may occur as a
result of increased metal inputs or
changes in water chemistry, annual
collection and analysis of sediment
samples for metal content should be an
integral component of a long-term
monitoring program.
Water Quality
Physical and chemical water quality
data for the study lakes were similar to
those reported for other lakes in this
region of Colorado. Mean alkalinity
values were less than 100//eq/l in two of
the lakes, but exceeded 200 /ueq/l in one
lake. The pH levels in the low alkalinity
lakes were 6.3 to 6.8, whereas pH in the
third lake exceeded 8.0. Conductivity
levels were typically low (64-112)
/umhos/cm) reflecting the low
concentration of dissolved substances in
the water. Concentrations of total metals
were also low, with aluminum, iron,
calcium and magnesium being the most
abundant elements. Toxic metals were
not measured in concentrations that pose
any hazard to aquatic life.
Key water quality parameters
recommended for monitoring include the
nitrogen species (NO2, NO3, and NH3),
sulfates, pH, alkalinity, conductivity, total
phosphorus, temperature, dissolved
oxygen, total and dissolved organic
carbon and dissolved inorganic carbon.
Annual scans of total recoverable and
dissolved aluminum, copper, lead, nickel,
iron, silver, calcium and magnesium
should also be included.
Conclusions
Lack of acid sensitivity data for most
species of organisms inhabiting the study
lakes preclude concise predictions of bio-
logical response to acidification. Testing
for acid sensitivity of certain potentially
indicator species, assemblages and whole
lake ecosystems may help formulate
accurate predictions of acid deposition
effects on biota of high altitude lakes.
-------
Barry P. Baldigo and John R. Baker are with Lockheed Engineering & Management
Services Co.. Inc., Las Vegas. NV 89109.
Wesley L. Kinney is the EPA Project Officer (see below).
The complete report, entitled "Monitoring Approaches for Assessing Quality of
High Altitude Lakes: Colorado Flat Tops Wilderness Area." (Order No. PB 85-
117 232; Cost: $ 19.00, 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 Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
P.O. Box 15027
Las Vegas. NV 89114
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
------- |