United States
Environmental Protection
Agency
Office of Acid Deposition, Environment
Monitoring and Quality Assurance
Washington DC 20460
Research and Development
EPA/600/S4-86/007 Feb. 1987
Project Summary
Characteristics of Lakes in the
Eastern United States
The United States Environmental
Protection Agency (EPA) initiated the
National Surface Water Survey (NSWS)
to assess the present chemistry of
surface waters, to quantify the temporal
variability and key biological resources
associated with these surface waters
and to initiate long-term monitoring in
characteristic systems.
. The NSWS is a three-phase study
focusing on regions of the U.S. that are
potentially susceptible to change as a
result of acidic deposition, and is one of
several major projects in the Acid Dep-
osition Aquatic Effects Research Pro-
gram in the EPA Office of Research and
Development.
This Project Summary was developed
by EPA's Office of Research and Devel-
opment, Washington, DC, to announce
key findings of the research project that
is fully documented in three separate
volumes (see Project Report ordering
information at back).
Introduction
The Aquatic Effects Research Program
addresses four primary policy-related
issues:
the extent of damage to aquatic* re-
sources as a result of current levels of
acidic deposition;
the anticipated extent and rate of
change to these resources in the
future;
levels of damage to sensitive surface
waters associated with various rates
of acidic deposition; and
the rate of change or recovery of
affected systems, given decreases in
acidic deposition rates.
Four major research projects within the
Aquatic Effects Research Program specif-
ically address these issues within a
regionalized framework. These projects
and their goals are:
National Surface Water Survey
(NSWS): to determine the present
chemistry, characterize the temporal
variability in chemistry, and determine
the key biological resources of lakes
and streams in potentially sensitive
regions of the U.S.;
Direct/Delayed Response Project: to
predict future changes in these re-
sources at present levels of acidic
deposition, giving consideration to
both the terrestrial and aquatic vari-
ables that influence these changes;
Watershed Manipulation Project: to
verify that predictions of future change
are reasonably sound by manipulating
watershed catchments or system
components; and
Long-Term Monitoring Project: to test
the validity of predicted future changes
through long-term monitoring of re-
gionally characteristic lake and stream
systems.
The NSWS, including surveys of both
lakes and streams, addresses the first
goal of the Aquatic Effects Research
Program. The Eastern Lake Survey-Phase
I (ELS-I) was designed to statistically
describe present surface water chemistry
on a regional scale. To further the current
understanding of the effects of acidic
deposition on aquatic resources requires
that the present chemical status of sur-
face waters be understood on large
geographical scales.
Summary
The ELS-I was conducted in the fall of
1984 and had three primary objectives:
determine the percentage (by number
and area) and location of lakes that are
acidic in potentially sensitive regions
of the eastern U.S.
determine the percentage (by number
and area) and location of lakes that
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have low acid neutralizing capacity
(ANC) in potentially sensitive regions
of the eastern U.S.; and
determinethechemical characteristics
of lake populations in potentially sen-
sitive regions of the eastern U.S. and
provide the data base for selecting
lakes for further study.
To accomplish these objectives, a water
sample was collected from each of 1612
lakes. This subset of lakes was selected
from within three regions of the eastern
U.S. (the Northeast, Upper Midwest and
Southeast) expected to contain lakes
having a low capacity to neutralize acidic
inputs. Each region was divided into
subregions, shown below:
Each subregion was further stratified
by alkalinity map class, which differenti-
ated among areas within each subregion
based on the surface water alkalinity
range expected to dominate in different
areas within these subregions.
A suite of chemical variables and
physical attributes thought to influence,
or be influenced by, surface water acidi-
fication was measured for each lake. The
results of these measurements form the
ELS-I data base.
The ELS-I design, in which lakes were
selected by a systematic random process
from the population of lakes in the regions
investigated, permits the use of the ELS-I
data base to estimate the chemical status
of lakes within a specific region or sub-
region. Additionally, the data base can be
used to investigate correlative relation-
ships among chemical variables on a
regional basis.
The full report. Characteristics of Lakes
in the Eastern United States, consists of
three volumes. Volume I, Population
Descriptions andPhysico-ChemicalRela-
tionships, provides details aboutthe ELS-I
design and its implementation, presents
data collected in the ELS-I, discusses
results obtained and draws conclusions
about these results. Volumes II and III
contain descriptive statistics for each lake
sampled and a data compendium of site
characteristics and chemical variables.
The purpose of the full report is to
describe the results and to make the ELS-I
data available to researchers and policy
makers as more in-depth analyses and
interpretive efforts are undertaken. Addi-
tional analyses of these data will be
performed in subsequent activities of the
EPA Aquatic Effects Research Program
and by independent researchers.
The use and interpretation of any data
set are restricted by the design, the quality
of the data obtained and the sampling
protocols. These aspects of the Survey
should be well understood before drawing
conclusions both within and beyond the
scope of the original objectives. For
Upper Midwest
Southern New England (1D)
NOTthcentral Wisconsin (2Q
Upper Great Lakes Area (2D)
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example, these data alone may not be
sufficient to determine causality. How-
ever, Survey data, coupled with data from
ongoing and future projects, are expected
to significantly advance our understand-
ing of the relationship between acidic
deposition and lake water chemistry.
Selected Results
The first two observations presented
below address the first two ELS-I objec-
tives. The remaining observations address
the third objective of the Survey. These
observations lead to hypotheses that can
be tested in subsequent phases of the
NSWS and/or the Aquatic Effects Re-
search Program.
It should be noted that the numbers and
percentages of lakes cited are population
estimates.
Extent and Location of
Acidic and Low pH Lakes
The subregions in the eastern U.S. that
contain the largest proportion of acidic
(ANC <0 /ueq L"1) and low pH (<5.0) lakes
are the Adirondacks (1A), the Upper
Peninsula of Michigan (2B), and Florida
(3B).
Acidic Lakes
Within the Northeast (Region 1), the
Adirondacks (1 A) had the largest esti-
mated number (138) and percentage
(11%) of lakes with ANC <0 /ueq L'1,
followed by Southern New England
(1D; 5%),, and the Poconos/Catskills
(1B; 5%).* Maine (1E) had the lowest
percentage of acidic lakes (<1 %). Most
acidic lakes in the Adirondacks occur-
red in the western portion of the
subregion.
In the Upper Midwest (Region 2), 10
percent of the lakes in the Upper
Peninsula of Michigan (28) had ANC
<0 /ueq L~1, and three percent in
Northcentral Wisconsin (2C) were
acidic. In Northeastern Minnesota (2A)
and the Upper Great Lakes Area (2D)
no acidic lakes were sampled.
In the Southeast (Region 3), no acidic
lakes were sampled in the Southern
Blue Ridge (3A). In contrast, an esti-
mated 22 percent of the lakes in Florida
(3B)hadANC<0/ueqL/1.
Acidic lakes in the Northeast had
higher concentrations of sulfate, cal-
cium, and extractable aluminum than
did acidic lakes in the Upper Midwest
and Southeast.
Low pH Lakes
The estimated number of lakes and lake
area with low pH (pH <5.0) also varied
substantially among and within regions.
Within the Northeast, the Adirondacks
(1 A) had the largest estimated number
(128) and percentage (10%) of lakes
with pH <5.0. Subregion 1D(Southern
New England) contained the second
highest estimated number (66) and
percentage (5%) and the largest area
(2295 ha, 6%) of low pH lakes. Maine
(1E) had the fewest lakes (8, <1 %) and
least area (95 ha) with pH <5.0.
In the Upper Midwest, no lakes with
pH <5.0 were observed in Northeast-
ern Minnesota (2A) or the Upper Great
Lakes Area (2D). The Upper Peninsula
of Michigan (2B) was estimated to
contain 99 lakes with pH <5.0, repre-
senting nearly the same proportion as
in the Adirondacks (9% and 10%,
respectively).
In the Southeast, no lakes with pH
<5.0 were sampled in the Southern
Blue Ridge (3A). Florida (3B) had the
highest estimated number and per-
centage of lakes (259, 12%) and the
largest estimated lake area with pH
<5.0.
Extent and Location of Low ANC
Lakes
The estimated number of lakes with
low ANC varied among and within
regions:
Within the Northeast, the Adirondacks
(1A) contain the highest percentages
of lakes with ANC <50 /ueq L"1 and
<200 A/eq L"1 (35% and 70%, respec
lively). Central New England (1 C) and
Maine (1E) contain the next highest
percentages of lakes among all ELS-I
subregions with ANC <200 Aieq L"1
(68% and 67%, respectively).
Northcentral Wisconsin (2C) contained
the highest percentage (41%) of lakes
with ANC <50 /ueq L"1 among all
subregions. Northeastern Minnesota
(2A) and Northcentral Wisconsin con-
tained the highest percentage of lakes
in the Upper Midwest with ANC <200
fjeq L"1 (57%). Although the Upper
Great Lakes Area (2D) contained the
lowest percentages of lakes with ANC
<200 /aeq L"1 in the Upper Midwest, it
contained the largest number of lakes
among all ELS-I subregions in this
category (1411).
The Southern Blue Ridge (3A) con-
ta i ned the lowest percentage ( 1 %) a nd
number (4) of lakes in the ELS-I with
ANC <50 £teq L"1 and the lowest
number of lakes with ANC <200
L"1 among all subregions. Florida (3B)
contained the highest number of lakes
among all ELS-I subregions with ANC
<50 yueq L"1, and the second highest
number of lakes with ANC <200 A150 /ueq L"1). This subregion
also had the lowest median sulfate
concentration, 31.8 /ueq L"1. Florida
(3B) contained the largest number of
lakes with high sulfate concentrations
(846 or 40% with S0«~2 >1 50 /ueq L'1).
Subregion 3B also had the most vari-
able sulfate concentrations of any
subregion.
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Calcium
Calcium concentrations were lowest in
the Upper Midwest and Florida lakes.
Within the Northeast Region, Southern
New England (1D) had the highest
percentage and number of lakes with
calcium concentrations <50 yueq L"1
(10%; 133). The Adirondacks (1A)
contained the second highest per-
centage and number (8%; 108) of low
calcium lakes (<50 /ueq L"1).
Northcentral Wisconsin (1C) contained
the highest percentage (22%) and
second highest number (34) of low
calcium lakes among all ELS-I sub-
regions. The Upper Peninsula of
Michigan (2B) contained the second
highest percentage (16%) of low cal-
cium lakes and the Upper Great Lakes
Subregion (2D) contained the second
highest number (256) of low calcium
lakes in the Upper Midwest.
In the Southeast, 12 percent of the
lakes in the Southern Blue Ridge (3A)
had low concentrations of calcium,
whereas in Florida (3B), 19 percent of
the lakes were in this group. Florida
contained the highest number (402) of
low calcium lakes among all subre-
gions.
Extractable Aluminum
Extractable aluminum concentrations
were higher in lakes with lower pH values,
and higher in the Northeast than in other
regions.
The largest estimated number of
clearwater lakes (true color <30 PCU)
having extractable aluminum concen-
trations >150 fjg L"1 occurred in the
Adirondacks (1A; 82 lakes or 10%).
Few lakes in the Poconos/Catskills
(1B; 3 lakes or <1%) and Southern
New England (10; 7 lakes or 1%) had
extractable aluminum >150/ug L"1. No
clearwater lakes sampled in Maine
(1E) had extractable aluminum con-
centrations >50 /ug L"1.
Extractable aluminum concentrations
in clearwater lakes were lower in the
Upper Midwest (80th percentile = 8.5
/ug L"1) than in the Northeast (80th
percentile = 11.6 /jg L"1). Extractable
aluminum was lowest in clearwater
lakes in Northeastern Minnesota (2A;
80th percentile = 3.0 /ug L'1), and
highest in clearwater lakes in the
Upper Peninsula of Michigan (2B; 80th
percentile = 11.9 /ug L"1).
Extractable aluminum concentrations
in clearwater lakes were low in the
Southern Blue Ridge (3A; 80th per-
centile = 2.5 fjg L ). In Florida (3B),
clearwater acidic lakes had lower
extractable aluminum concentrations
(80th percentile = 18.6 /ug L"1) than did
clearwater lakes in the Adirondack
Subregion (1 A; 80th percentile = 29.4
n L-1).
In each region extractable aluminum
concentrations were higher at lower
pH values. The Northeast had the
greatest increase in extractable alum-
inum with decreasing pH and Florida
the least increase at low pH values.
Dissolved Organic Carbon
Dissolved organic carbon (DOC) con-
centrations did not correlate with the
distribution of acidic or low ANC lakes.
In the Northeast, as in other regions,
80 percent of acidic lakes contained
concentrations of DOC <5 mg L"1. A
positive relationship existed between
pH and DOC. Those lakes with highest
DOC concentrations were drainage
lakes with short hydraulic residence
times and high ANC.
In the Upper Midwest, most acidic
lakes, especially those in the Upper
Peninsula of Michigan (2B) and North-
central Wisconsin (2C), were clear-
water, low DOC, seepage lakes. Lakes
in Northeastern Minnesota (2A) had
the highest concentrations of DOC in
the Upper Midwest and no acidic lakes
were sampled in this subregion.
In the Southeast, only the lakes within
the Okefenokee Swamp exhibited a
strong association between low pH
and high DOC. No apparent relation-
ship between pH and DOC was evident
in Florida (3B) lakes.
Major Cations and Anions.
The anions were most useful in char-
acterizing differences in the relative
importance of major ions among regions
and subregions.
In the Northeast, sulfate was the
predominant anion at the 20th per-
centile in three of the subregions
(Adirondacks, 1A; Poconos/Catskills,
1B; and Central New England, 1C).
Sulfate was also the dominant anion
at the median value in the Adirondacks.
In Maine(1 E), bicarbonate ion concen-
trations exceeded sulfate at both the
20th percentile and the median.
Chloride was the dominant anion in
Southern New England (1D) at both
the 20th percentile and median values
estimated for the population.
Bicarbonate was the dominant anion
at the 20th percentile and median
values in the Upper Midwest, with the
exception of the Upper Peninsula of
Michigan (28) and Northcentral Wis-
consin (2C), where sulfate was domi-
nant at the 20th percentile.
The ionic composition of lakes in
Florida (3B) was similar to that of lakes
in Southern New England (1D) in that
sodium was the dominant cation and
chloride the dominant anion at the
20th percentile. Total ionic concentra-
tion of many Florida lakes was high.
Organic anions, as indicated by anion
deficit, were not the dominant anions
in any subregion at either the 20th or
50th percentile. Concentrations of
organic anions were lowest in the
Northeast.
Conclusions and Future Studies
The results of the ELS-I presented in
the full report are largely descriptive but
lead one to formulate hypotheses that
can be tested with this data base, singu-
larly or combined with other data. The
statistical design of the Survey makes it
possible to test hypotheses related to
acidification using regional data and
relate the results to defined, regional lake
populations.
Five major observations from the ELS-I
are given below. Each is followed by a
related question that should be addressed
in the future:
Sulfate concentrations in lakes across
the Northeast and the Upper Midwest
show an apparently strong relationship
with the general patterns of sulfate
deposition as measured by the National
Trends Network.
What is the nature of the relationship
between lake chemistry and atmos-
pheric deposition of sulfate?
The majority of acidic lakes in all three
regions contained relatively low con-
centrations of organic acids.
Ho w important are the contributions ol
organic acids in explaining the occur-
rence of acidic lakes?
Some portions of the coastal areas ol
the Northeast contained moderate
numbers of acidic lakes.
To what degree can the acidity ofthest
coastal lakes be attributed to a neutra
salt effect from sea spray deposition?
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The estimated hydraulic residence
times for clearwater lakes were ap-
proximately 3 times greater than for
darkwater lakes. Residence time was
inversely related to DOC.
Does an apparent difference in hydrol-
ogy between clearwater, acidic lakes
and darkwater, higher ANC lakes
indicate that acidic lakes generally are
not derived from darkwater lakes?
Florida (3B) contained the largest
proportion of acidic lakes and the
chemistry of many Florida lakes dif-
fered considerably in many respects
from lakes in the Northeast, Upper
Midwest and Southern Blue Ridge
(3A).
To what degree are the acidic lakes in
Florida affected by acidic deposition,
and are other factors important in
explaining the occurrence of acidic
lakes in Florida?
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The complete report was prepared by numerous contributors with various
affiliations.
Dixon H. Landers is the EPA Project Officer (see below).
The complete report consists of three volumes, entitled "Characteristics of Lakes
in the Eastern United States:" (Set Order No. PB 87-110 375/A S; Cost: $ 79. OO)
"Volume I. Population Descriptions and Physico-Chemical Relationships,"
(Order No. PB 87-110 383/AS; Cost: $18.95)
"Volume II. Lakes Sampled and Descriptive Statistics for Physical and Chemical
Variables,"(Order No. PB 87-110 391/AS; Cost $36.95)
"Volume III. Data Compendium of Site Characteristics and Chemical
Variables,"(Order No. PB 87-110 409/AS; Cost $36.95)
The above reports will be available only from: (costs subject to change}
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Office of Acid Deposition, Environmental Monitoring and
Quality Assurance
U.S. Environmental Protection Agency
Washington, DC 20460
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-86/007
0000329
PS
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