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

-------
   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)

-------
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.

-------
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?

-------
• 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?

-------
     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

-------