United States
Environmental Protection
Agency
Office of Water
Nonpoint Source Control Branch
Washington, DC 20460
EPA 440/5-89-003
1989
oEPA Report to Congress:
Water Quality of the Nation's Lakes
Printed on Recycled Paper
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Report to Congress:
Water Quality of the Nation's Lakes
Nonpoint Source Control Branch
Office of Water Regulations and Standards
Office of Water
U.S. Environmental Protection Agency
1989
BBfiaES.
60604-3590
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AT
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Contents
Foreword
Executive Summary
Problem Definition
1
3
5
Pollution Control and Lake Restoration 15
iii
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Foreword
ection 314 of the Clean Water Act, as amended by
the Water Quality Act of 1987, requires the States to
submit to the Environmental Protection Agency, as
part of their 305(b) biennial reports, information on
the water quality of their lakes, including:
(a) an identification and classification accord-
ing to eutrophic condition of all publicly-
owned lakes in such State;
(b) a description of procedures, processes,
and methods (including land use require-
ments), to control sources of pollution to
such lakes;
(c) a description of methods and procedures,
in conjunction with appropriate Federal
agencies, to restore the quality of such
lakes;
(d) a description of methods and procedures
to mitigate the harmful effects of high
acidity, including innovative methods of
neutralizing and restoring buffering capa-
cities of lakes and methods of removing
from lakes toxic metals and othertoxic sub-
stances mobilized by high acidity;
(e) a list and description of those publicly-
owned lakes in such state for which uses
are known to be impaired, including those
lakes which are known not to meet ap-
plicable water quality standards or which
require implementation of control pro-
grams to maintain compliance with ap-
plicable standards and those lakes in which
water quality has deteriorated as a result of
high acidity that may reasonably be due to
acid deposition; and
(f) an assessment of the status and trends of
water quality in lakes in such State, includ-
ing but not limited to, the nature and extent
of pollution loading from point and non-
point sources and the extent to which the
use of the lake is impaired as a result of
such pollution, particularly with respect to
toxic pollution.
The Act, as amended, further requires the Ad-
ministrator of the Environmental Protection Agency
to transmit to the Senate Committee on Environment
and Public Works and House Committee on Public
Works and Transportation a report on the status of
water quality in our Nation's lakes.
The following report summarizes the information
submitted by the States in response to the April 1,
1988 legislative requirements described; where
necessary, information developed by EPA supple-
ments the State-reported data. This Report to Con-
gress, therefore, represents the Agency's summary
of the water quality of lakes throughout this Nation as
currently perceived and documented by the States in
response to Section 314.
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Executive Summary
Status
The status of water quality in our Nation's lakes has
been assessed according to use impairment,
threatened uses, and trophic condition (a measure
that determines the "aging process" of a lake). Of
12,413,837 lake acres assessed by 34 States, 25 per-
cent were found to be impaired or partially impaired,
and 20 percent threatened by pollution. "Threatened"
waters refers to those lakes that fully support their
designated uses but that may not fully support uses in
the future because of anticipated sources or adverse
trends of pollution. Approximately 50 percent of
22,000 lakes classified by trophic status were either
eutrophic or hypereutrophic (nutrient-rich or "old").
From a national perspective, a statistically-
designed sampling framework was not used to es-
timate the water quality of lakes across the country.
Therefore, this report cannot state actual status and
trends or classify the trophic condition of the Nation's
lakes with statistical confidence. The numbers
reported in the 1988 assessments are in many cases
incomplete.
Causes of Impairment and
Sources of Pollution
States identified 12 specific causes of use impairment
in lakes, with nutrients and siltation/turbidity the most
significant pollutants. Nutrients are elements, primari-
ly phosphorus and nitrogen, that promote plant and
algae growth. Excessive nutrients may increase the
productivity of the lake to the point where algal
blooms and aquatic vegetation impede recreational
activity and diminish the lake's aesthetic value. At the
end of their growing season the algae and aquatic
vegetation die, and their decomposition consumes
dissolved oxygen. Such oxygen depletion results in
conditions unsuitable for fish; severe depletion may
cause fish kills.
Siltation is the process by which soil or rock is car-
ried by water to a lake and deposited as sediment. As
the silt settles, the lake becomes more shallow, often
producing conditions that stimulate macrophyte
(aquatic plant) growth. Dense vegetation, shallow-
ness, and changes in lake bed/sediment composi-
tion adversely affect recreation and fish habitats. The
habitat suitable for coolwater sport fisheries may
decline or even disappear.
Turbidity is an indirect measure of the transparen-
cy (light penetration) of the lake. High turbidity result-
ing from matter suspended in the water reduces
transparency, producing what is often perceived as a
"cloudy" condition. High turbidity also inhibits algal
productivity and may affect feed ing habits of fish and
food chain organisms.
States classified the sources of pollution causing
use impairment as either point source, nonpoint
source, or natural. According to the States, 76 per-
cent of the pollution affecting lakes originates from
nonpoint sources, 11 percent from point sources,
and 12 percent from natural sources. Agricultural
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nonpoint source runoff was the most frequently
reported source; however, urban runoff and resource
extraction (mining) are major sources in specific
areas.
Pollution Control and Lake
Restoration
The sources of pollution to a lake, be they point or
nonpoint, will determine the approach used to control
pollution. Point sources are usually controlled
through wastewater treatment and permit programs.
Nonpoint sources, because they are diffuse by na-
ture, are best controlled by watershed management.
Once the sources of pollution have been success-
fully addressed, in-lake restoration may begin. The
specific causes of use impairment in the lake will
determine the restoration techniques to be used. For
example, nutrient inactivation may reduce or
eliminate algal blooms, while dredging will deepen a
shallow lake, and harvesting can remove rooted
vegetation. In this report, lake restoration techniques
are organized and explained by six basic objectives:
(1) control of algae; (2) deepening; (3) removal of
rooted vegetation; (4) improvement of fisheries; (5)
acid mitigation; and (6) toxic removal.
Trends
Information that can be used to define water quality
trends in lakes is extremely limited. Many lakes have
been sampled only once or twice during the past 15
years and the range of seasonal and annual fluctua-
tions in key parameters is not well documented. To ac-
curately reflect trends in lake water quality, data must
be collected consistently over several years. Of the 38
States reporting the water quality of their lakes in
1988, most did not have the baseline data necessary
for trend analysis.
In comparison with the 1986 305(b) report, how-
ever, the number of lakes considered eutrophic in-
creased more than 10 percent, while the number of
mesotrophic and oligotrophic lakes decreased 8 and
7 percent, respectively. This finding is based on more
extensive data, with 63 percent more lake acres as-
sessed in the 1988 Lake Water Quality Assessment
than by the 1986305(b) report.
The baseline data therefore are building, and will
be further augmented in future 305(b) reports by ac-
tivities authorized by the Water Quality Act of 1987.
Grants made under Section 314 as well as the con-
tinuing emphasis on lake water quality assessment
will strengthen both the quantity and quality of data
on the water quality of this Nation's lakes.
Lakes are being considered as ecological units
subject to many factors, and monitored fora number
of significant parameters in addition to traditional
trophic state parameters. As technical and scientific
knowledge of lake systems continues to grow, along
with our database of lake water quality information,
understanding the changes that are occurring in lake
water quality also increases.
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Problem Definition
Introduction
In the 1988 Lake Water Quality Assessments, most
States identified a lake as "impaired" or "threatened" in
terms of designated uses being met, a relatively new
concept now generally accepted as the most realistic
appraisal process for lake waters. Lake acres that
were reported "not meeting" or only "partially meet-
ing" designated uses were considered impaired, al-
though the criteria used to determine impairment vary
from State to State according to differing regional ex-
pectations of lake water quality.
States also identified their lakes according to
trophic condition. Traditionally, the trophic state
designation has been used to classify a lake accord-
ing to its nutrient status. Eutrophication, a general
measure of nutrient status, can be viewed as an in-
dication of the lake's natural aging process, the chan-
ges that normally occur over hundreds even
thousands of years, evolving the lake into a wetland,
and finally, dry land (Fig. 1). Although a natural evolu-
tion, the eutrophication process can be accelerated
by human activities. "Cultural eutrophication" is the
term applied to the effects of human activities on
water quality (e.g., careless use of detergents, fer-
tilizers, and pesticides, unwise waste disposal, poor
mining and construction practices) and result in per-
turbations that can usually be reversed.
The eutrophication progression can be described
by a series of trophic states:
Oligotrophic - clear waters with little
organic matter or sediment, and minimum
biological activity;
Mesotrophic - waters containing more
nutrients and therefore exhibiting more
biological productivity;
Eutrophic waters extremely rich in
nutrients, with high biological productivity;
Hypereutrophic - murky, highly productive
waters, closest to the wetland status.
General Characteristics of Traditional Lake
CHARACTERISTICS OLIGOTROPHIC
Nutrient Level Low
Organic Matter Content Low
Biological Productivity Low
Lake Age Young
Water Transparency High
Oxygen Depletion Hypolimnion No
Average Depth Oeep
Trophic Status Classifications
MESOTROPHIC
Medium
Medium
Medium
Medium
Medium
Yes
Moderate
EUTROPHIC
High
High
High
Old
Low
Yes
Shallow
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NATURAL
OLIGOTROPHY
MESOTROPHY
EUTROPHY
HYPEREUTROPHY
TIME
MAN INDUCED
1000'S OF YEARS
100'S OF YEARS
YEARS
EUTROPHY/HYPEREUTROPHY
10'S OF YEARS
E/H
Figure 1.Above: The progression of natural lake aging or eutrophication through nutrient-poor (oligotrophy) to nutrient-rich
(eutrophy) states. Hypereutrophy represents extreme productivity characterized by algal blooms or dense macrophyte popula-
tions (or both) plus a high level of sedimentation. The diagram depicts the natural process of gradual nutrient enrichment and
basin filling over along period of time (e.g., thousands of years).
Below: Man-inducted or cultural eutrophication in which lake aging is greatly accelerated (e.g., tens of years) by increased in-
puts of nutrients and sediments to a lake, as a result of watershed disturbance by man.
Dystrophic is also a lake classification but not
necessarily a part of the eutrophication progression.
Dystrophic systems are often low in nutrients yet
highly colored with dissolved humic organic matter
(sphagnum bog).
The trophic state of a lake is most commonly
determined by using Carlson's Trophic State Index
(TSI). This index was developed from the inter-
relationships of summer transparency (clarity of the
water as measured by the Secchi disk), epilimnetic
concentrations of chlorophyll a, and total phos-
phorus. The TSI values range between 0 and 100 with
increasing values indicating more eutrophic condi-
tions.
When considering the results of the TSI calcula-
tions, one should keep in mind the assumptions on
which the Carlson formulae are based: (1) Secchi
transparency is a function of phytoplankton
biomass; (2) phosphorus is a factor limiting algal
growth; (3) total phosphorus concentration is direct-
ly correlated with algal biomass. Therefore, Carlson's
TSI may not be applicable to lakes where suspended
solids are a major source of turbidity, when nitrogen
is the factor limiting algal growth (as is the case in
Delaware and many southern U.S. lakes), or when
total phosphorus does not correlate with algal
biomass.
To compensate for these inadequacies, several
States have developed other ways to determine the
trophic status of lakes. For example, Indiana
measures seven parameters in addition to the three
used for Carlson's TSI: dissolved phosphorus, or-
ganic nitrogen, nitrate, ammonia, dissolved oxygen,
plankton, and light transparency.
Trophic State and Lake Uses
Although changes in lake water quality may be track-
ed by monitoring for trophic state, experience has
shown that the trophic state of a lake does not always
define its use. Some States believe that advanced
eutrophication does not necessarily eliminate a lake's
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designated recreational uses, nor is an oligotrophic
lake always best for recreational activities. These
States have recognized this apparent disparity be-
tween positive recreational uses and the negative
connotations associated with eutrophic conditions,
adjusting the ways they determine trophic status to
reflect desired use (such as warmwater fishing) and
public perceptions in addition to measurable physi-
cal, chemical, and biological parameters.
A eutrophic condition, therefore, is not necessarily
"bad" in terms of using the lake, nor are eutrophic or
mesotrophic conditions necessarily abnormal or
outside of ecological expectation based on lake and
watershed characteristics. For example, most lakes
assessed in Iowa and Nebraska either fully or partial-
ly support designated uses, even though all 114 Iowa
lakes are classified as eutrophic, and 22 of 23
Nebraska lakes evaluated are either eutrophic or hy-
pereutrophic. However, as the aging process ac-
celerates (usually because of cultural eutro-
phication), the lake and its watershed require greater
management to maintain the lake's designated uses.
Table 1 summarizes the trophic status of lakes as
reported by the States. The total number of lakes
listed is the number assessed, not the total number of
lakes in the State. The assessments were done by in-
lake monitoring and evaluation (based on profes-
sional judgement, lake uses, known pollution
sources, and other subjective information). One
problem with accumulating and interpreting the data
presented from the States is that the data are col-
lected in a variety of ways: most states have not per-
formed a complete census on their lakes and there is
no indication as to why the lakes they assessed were
selected. If the lakes were assessed in response to a
problem or public complaint, or based on easy ac-
cessibility, rather than on random selection, there is
probable bias in the reported information. It is likely
that the more remote and/or pristine lakes are under-
represented in some State assessments.
Given the limitation on the data compilation, the
States reported that 50 percent of all lakes assessed
for trophic status were either eutrophic or hyper-
eutrophic (Fig. 2); 24 percent, mesotrophic; 11 per-
cent, oligotrophic; and less than 1 percent,
dystrophic. Trophic status for the remaining 15 per-
cent assessed was unknown.
Of the total acres assessed in 34 States, 25 per-
cent were reported as impaired and 20 percent were
considered threatened (Table 2). The States used dif-
ferent criteria in developing the categories of "im-
paired" and "threatened"; therefore, the results
should not be compared among States. Of the States
that reported, New Jersey did not indicate impair-
Unknown
Hypereutrophic
excessive nutrients)
and
Eutrophic
(nutrient rich)
Oligotrophic
(minimal nutrients
Mesotrophic
(some nutrients)
* assessed for something other than trophic state
Figure 2.Lakes in each trophic status classification as
reported by States for all U.S. lakes assessed (%).
ment (because of insufficient monitoring data), but
did list its total 51,000 lake acreage as "threatened."
States are becoming increasingly aware that
eutrophic condition is to be considered in the context
of lake and watershed history, characteristics, and
uses; not negatively, but comprehensively to show
the overall condition of the lake. Determining
whether a lake is supporting designated uses helps
the lake manager or concerned individual assess the
lake's "health." That assessment also may point to
potential problems that can be averted to protect the
future health of the lake.
Causes of Use Impairment
States identified 12 specific causes of pollution in
lakes with impaired uses (Table 3). Nutrients and silta-
tion/turbidity were two significant pollutant groups.
These factors play principal roles in determining a
lake's trophic state. For example, Minnesota reported
that 75 percent of its citizen complaints concerned
eutrophication, usually identified as algal blooms and
directly related to excessive nutrients. Algal blooms
were also reported as a problem in North Carolina. Sil-
tation is a concern in South Dakota, where several
lake restoration projects have been designed to
remove sediment.
Nutrients are elements, primarily phosphorus and
nitrogen, that promote growth, especially that of
plants and algae. Excess nutrients may increase the
productivity of the lake to the point where algal
blooms and aquatic vegetation impede recreational
activity and diminish the aesthetic value of the lake.
Siltation is the process by which particles of soil or
rock are carried by water to a lake and deposited as
sediment. Turbidity is an indirect measure of the
transparency (light penetration) in the lake; high
turbidity results from matter suspended in the water
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Table 1. - Trophic status report.
STATE
AL
AR
CT
DE
DC
FL
ID
IL
IN
IA
KS
KY
MD
MA
Ml
MN
MS
NB
NV
NH
NY
NC
ND
OK
OR
PA
PR
Rl
SC
TN
UT
VT
VA
WA
Wl
TOTALS
LAKES ASSESSED
35
71
160
31
3
91
554
412
404
114
193
92
59
478
682
12,034
127
23
9
415
3,340
144
216
74
204
37
18
54
41
119
127
-
248
140
2,153
22,902
OLIGO-
4
0
34
0
0
57
0
2
75
0
0
14
2
133
98
1,203
0
0
1
161
85
11
0
5
46
1
0
4
0
21
33
19
20
58
605
2,692
MESO-
16
59
78
0
1
19
55
25
144
0
68
27
13
289
367
3,009
0
1
4
172
132
21
0
49
78
29
3
41
0
33
44
72
49
24
746
5,668
EU-
11
4
17
31
0
13
499
239
67
114
125
51
44
56
217
7,822
33
12
4
82
84
25
216
8
69
7
14
9
40
55
50
28
120
45
802
11,013
HYPER-
0
0
0
0
0
0
0
146
0
0
0
0
0
0
0
0
0
10
0
0
0
9
0
12
11
0
0
0
1
10
0
0
0
0
0
199
DYS-
0
0
0
0
0
0
0
0
118
0
0
0
0
0
0
0
0
0
0
0
0
8
0
0
0
0
0
0
0
0
0
11
1
0
0
138
UNK*-
4
8
31
0
2
2
0
0
0
0
38
0
0
2,381
0
0
94
0
0
0
3,039
70
0
0
0
0
1
0
0
0
0
589
58
13
0
6,330
"Unknown means these lakes were either not assessed or not assessed for trophic status.
states not listed in the table either did not report the information or reported in a way that was inconsistent with the format of
the table.
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Table 2. Impaired and threatened lakes.
ACRES
STATE
AL
CT
DC
FL
GA
IL
IN
IA
KS
KY
LA
ME
MD
Ml
MN
MS
MO
NE
NC
NH
NY
ND
OH
PR
Rl
SC
SD
TN
VT
VA
WA
WV
Wl
WY
REPORTED
504,336
82,900
377
2,085,120
417,730
305,847
104,540
81,400
175,189
228,385
713,719
994,560
32,583
840,960
3,411,200
500,000
288,012
145,300
305,367
151,000
750,000
625,503
117,323
11,146
16,520
963,000
1,598,285
538,657
229,146
161,562
613,582
23,460
971,000
411,244
ASSESSED
491,566
37,562
136
947,200
417,730
183,572
104,540
80,249
173,911
214,483
517,476
994,560
17,448
424,021
1,435,554
500,000
288,012
85,518
305,367
149,854
750,000
619,333
90,771
11,146
16,089
410,407
662,532
538,657
227,121
161,089
156,518
19,171
971,000
411,244
IMPAIRED
86,080
12,389
136
637,440
5,373
160,641
179
53,448
57,256
35,148
141,141
38,211
2,610
119,836
236,845
18,260
2,311 j
3,214
11,897
19,146
295,332
48,125
59,835
7,345
1,401
1,165
94,720
86,648
49,206
13,737
33,684
19,171
722,000
23,239
THREATENED
-
8,176
0
-
140
22,455
104,361
18,902
116,655
152,544
87,034
-
4,606
161,894
-
-
-
-
50,330
4,603
29,942
570,170
25,733
1,745
11,425
-
548,000
75,828
153,319
-
116,210
0
179,300
146,491
TOTALS 18,398,953 12,413,837
3,095,438
2,485,502
- State did not report this data.
Percent impaired = 25 percent; Percent threatened = 20 percent.
states not listed in the table either did not report the information or reported in a
way that was inconsistent with the format of the table.
that creates what may be perceived as a
"cloudy" condition. As the material set-
tles, the lake becomes more shallow,
often producing conditions that en-
courage macrophyte growth. If this
vegetation becomes too dense, it may af-
fect both recreation and fish habitats. A
lake that becomes too shallow may im-
pede recreational activities such as swim-
ming, boating, and fishing.
Metals and inorganics also were iden-
tified as significant causes of use impair-
ment in lakes. Metals include cadmium,
lead, zinc, copper, silver, iron, and man-
ganese. The largest cause of impaired
lake use in North Carolina has been dis-
charges from coal-fired power plants to
two lakes (Belews and Hyco), producing
excessive selenium levels in these lakes.
This selenium contamination has caused
a drastic decline in fish population and
reproduction in both lakes. Metals (iron
and manganese), generated by active
and abandoned coal mining, are sig-
nificant factors affecting lake use in West
Virginia.
Mercury is the principal inorganic
responsible for impairment in lakes. Mer-
cury contamination has been a problem
in northeastern Minnesota lakes, where a
study is being conducted to determine
the source of the mercury. Most fish can
be consumed from 92 percent of the large
lakes (greater than 5,000 acres) sampled,
but fish cannot be eaten from 1 percent.
Of the small lakes (less than 5,000 acres)
sampled, some fish can be consumed
from 80 percent.
Organic enrichment and low dissolved
oxygen (DO) also account for some of the
use impairment in lakes. The biological
decomposition of organic matter - from
agricultural runoff, algae, aquatic vegeta-
tion, and/or municipal/industrial dis-
charge - consumes oxygen. If the
oxygen is consumed more rapidly than it
can be replaced, the oxygen supply may
be depleted to the extent that fish are
stressed or unable to survive. Of the fish
kills reported in Nebraska and Minnesota,
71 percent and 69 percent, respectively,
resulted from such conditions.
The presence of pathogen indicator
organisms may also restrict the use of
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Table 3. - Major causes of pollution in lakes with impaired uses (% acres).4
STATE
CT
FL
IL
IN
KS
KY
LA*
MD
MN
MS*
MO
NH
NM
NY
NC
OH
OK
PR
Rl
SC
SD
VA*
VT
WA
WV
AVERAGE
NUTRIENTS
36
7
15
32
<1
19
33
99
62
34
24
31
36
11
21
23
30
19
45
20
69
12
27
a
1
8
1
76
6
3
10
<1
29
5
SILTATION/BURBIDITY
15
15
48
<1
13
6
1
33
16
4
23
38
20
5
80
10
8
20
15
ORGANIC ENTIRCHMENT/DO
4
15
19
22
11
53
<1
10
5
19
5
29
5
8
THERMAL MODIFICATION
<1
2
11
1
FLOW ALTERATION
<1
75
12
<1
13
6
4
OTHER HABITAT MODIFICATION
<1
6
74
3
PATHOGENS
6
<1
1
12
27
1
2
<1
7
76
14
<1
5
6
6
AQUATIC PLANTS & ALGAE
22
8
9
22
29
49
1
6
PESTICIDES
4
3
<1
31
24
9
2
9
<1
3
PRIORITY ORGANICS
1
7
2
36
4
6
2
METALS/INORGANICS
1
27
2
4
100
67
13
36
2
<1
53
14
12
8
4
4
6
28
15
OTHER*
16
27
1
12
1
9
<1
9
10
6
21
2
6
5
** These numbers represent the relative impact of each pollutant on the use impairment in lakes.
#This category includes primarily unknown toxicity, non-priority organics, and taste/odor problems associated with water supplies.
Identified no major causes; however, these moderate/minor impacts cause the use impairment in lakes.
states not listed in the table either did not report the information or reported in a way that was inconsistent with the format of the table.
10
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lakes. Tests for fecal coliform bacteria are commonly
used as an indicator of human or animal wastes con-
taminating water bodies. Such contamination often
may result from runoff from animal feed-lots, rural or
urban areas heavily populated with domestic and/or
wild animals, or improperly treated municipal was-
tewater, including combined sewer overflows. The
feces from warm-blooded animals contains many
pathogens, some causing disease in humans. There-
fore, the presence of fecal indicator organisms in a
lake may lead to restrictions being placed by public
health officials on contact recreation (e.g., swim-
ming) and fish consumption. The feces from
warmblooded animals may also contain pathogens
that cause disease and perhaps fish kills. For ex-
ample, in Kansas most of the reported fish kills can be
traced to pathogens from animal feedlots and
agricultural runoff.
Impairments caused by thermal modification
usually result from warmwater discharges (primarily
from some type of cooling process) into a lake or its
tributaries. This temperature increase adversely af-
fects the sport fishery that prefers cool water. Reser-
voir releases or withdrawal of cool bottom water may
also limit or destroy the habitat for coolwater
fisheries. Flow alteration can impair lakes in various
ways. Most typical is either decreasing inflow or in-
creasing outflow, both of which lower the water level.
This may limit fish habitat and recreational activities.
Acidic conditions can also adversely affect the fish
population of a lake. pH is a measure of the hydrogen
ion concentration in the water and is used to indicate
acidity or alkalinity. A pH of 7.0 is considered neutral,
pH less than 7.0 is technically acidic, and pH greater
than 7.0 is alkaline. According to the National Acid
Precipitation Assessment Program (NAPAP), most
fish populations tolerate pH levels between 6.0 and
9.0 without apparent difficulty; significant impact on
some species begins at pH = 5.5; serious damage
for almost all species occurs below 5.0; and relatively
few species can sustain populations in waters below
pH = 4.5. The pH at which a State considers a lake
impaired may vary depending on various charac-
teristics of the lake and fish species present. The
lake's ability to offset changes in pH (buffering
capacity) must also be considered since small chan-
ges in pH can harm aquatic life.
Although only a few States have assessed the ex-
tent of adverse impacts resulting from excessive
acidity, it appears that relatively few lakes have low
pH values. For example, only 9 lakes with pH values
less than 4.5 were reported in Massachusetts and 4
lakes in New Hampshire. New Hampshire also
reported 27 lakes with pH between 4.5 and 5.0. Of the
1,000 lakes sampled in Maine, the State reported 50
with a pH less than 5.0, and Wisconsin estimated be-
tween 100 and 200 lakes are acidic. However, States
indicated that many more lakes are considered sen-
sitive to acidic inputs because of their low buffering
capacity. Acidic inputs to a lake may result from
precipitation, mine drainage, or naturally decompos-
ing humic material.
Toxic is defined by EPA as any pollutant or com-
bination of pollutants that harms aquatic or terrestrial
life or adversely affects human health. Although low
dissolved oxygen, pathogens, and acidity may have
toxic effects on aquatic life, most States reported
their toxic problems in terms of more priority
toxicants such as pesticides, organics, metals, and
inorganics. Most of these toxicants can accumulate
in the food chain and thereby pose a public health
problem if contaminated fish are consumed. These
toxicants are considered "priority" in that they are
listed as such by the Environmental Protection Agen-
cy pursuant to Section 307(a) of the Clean Water Act.
Twenty-one States reported the detection of
priority toxicants, most often PCBs, pesticides
(chlordane, atrazine, alachlor), metals, and mercury.
These pollutants were found in lake water, sediment,
and fish tissue. Priority pollutants usually are not
found statewide, but in specific local areas, where
they result from extensive urban or agricultural
runoff, mining activities, or industrial point source
discharges.
In many instances, levels of priority pollutants war-
rant fishing bans or consumption advisories such as
have been in place for sport fish consumption in Il-
linois d uring the past few years. New York also has is-
sued consumption advisories for almost 40 water
bodies and banned fishing in the Upper Hudson be-
cause of high levels of PCBs in fish. To control fish
consumption, fishing at Syracuse's Onondaga Lake
was once banned. Even though it is now allowed as
recreation, people are warned not to eat their catch.
Pesticides are chemical compounds used to
destroy pests in both agricultural and urban areas.
They include chemicals such as chlordane, atrazine,
alachlor, dieldrin, DDT, and toxaphene. In Kansas
lakes, detectable concentrations of agricultural pes-
ticides (e.g., atrazine and alachlor) were found in 34
percent of the 128 lakes sampled for pesticides. As-
sessment of fish tissue, a more sensitive indicator
than lake water of some toxicants, demonstrates a
more widespread effect. Fifty-seven percent of the
lake acres assessed in Kansas exceeded the Nation-
al Academy of Science guidelines for protection of
predators, with chlordane, PCBs, dieldrin, and hep-
tachlorthe principal causes.
11
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Urban activities have also affected
Kansas lakes, with two 1986 intensive
lake surveys finding elevated levels of
chlordane residue in the edible portion
of fish. A correlation was established
between high chlordane levels and
urban areas.
Priority organics include such
chemicals as PCBs, phenols, and
dioxin. PCBs are most often reported
as a problem in lakes. PCBs are a
group of toxic, persistent chemicals
used to insulate transformers and
capacitators and to lubricate gas
pipeline systems. Of the lake acres
monitored for toxicants in New York,
approximately 20 percent were af-
fected to some degree by PCBs or
pesticides, with fish consumption ad-
visories in effect for several lakes be-
cause of PCB-contaminated sedi-
ments. Ground-based sources such
as landfills appear to be the source of
these pollutants.
Sources of Pollution
States classified the sources of pollu-
tion causing use impairment as either
point source, nonpoint source, or
natural. Table 4 summarizes these
sources by State, with 76 percent
originating from nonpoint sources, 14
percent from point sources, and 10
percent from natural sources.
Point sources are defined as dis-
crete conveyance discharges (e.g.,
through a pipe) and include municipal
and industrial discharges and com-
bined sewer overflow. Most nonpoint
source pollutants are transported by
surface runoff, groundwater, and at-
mospheric deposition. These pol-
lutants originate from streets, lawns,
construction sites, forests, mines, and
agricultural lands. Point sources are
usually chronic and site-specific in im-
pact, whereas nonpoint sources are
episodic and/or diffuse.
An objective definition of "natural"
sources of pollution has not been
developed; therefore this report relies
on the States categorization and is
somewhat variable. For example, one
Table 4. - Major known sources of pollution in lakes with
impaired uses (%).
STATE
CT
FL
IL
IN
KS
KY
LA
ME
MD
MN
MS
MO
NH
NM
NY
NC
ND
OH
OK
PR
Rl
SD
VA
WA
WV
POINT
SOURCE
49
12
4
58
0
8
12
2
3
27
0
0
0
0
6
35
0
17
0
1
0
2
1
2
46
NONPOINT
SOURCE
20
88
96
42
2
26
87
98
97
73
100
100
70
100
94
63
100
83
100
55
100
96
63
98
54
NATURAL
31
0
0
0
98*
66
1
0
0
0
0
0
30
0
0
2
0
0
0
44
0
2
36
0
0
PREDOMINANT
CATEGORY
Municipal
Agriculture
Agriculture
Municipal
Mineral-Intrusion
Lake Sediments
Agric./Urban Runoff
-
Agriculture
-
Agriculture
Flow Modification
Acid Precipitation
Agric./Recreation
-
In-place contaminants
Agriculture
Agriculture
Agriculture
Urban Runoff
-
Agriculture
Agric./Urban Runoff
Agriculture
Resource Extraction/
Industrial
AVERAGE 11
76
12
* Use impairment in Kansas is identified by the violation of water quality criteria. The
criteria established in the state of Kansas do not adequately reflect the agricultural
NPS impacts on the lakes. Additional information shows well over 50 percent of the
total lake impacts result from agricultural NPS pollution.
states not listed in the table either did not report the information or reported in a way
that was inconsistent with the format of the table.
12
-------
State considered in-place contaminated lake sedi-
ments as a nonpoint source whereas another State
considered contaminated sediments a natural
source of pollution. Generally, mineral intrusion and
salinity are considered natural sources of pollution
and reflect the geology of the area, except in heavily
irrigated sites.
Figure 3 shows how nonpoint sources such as
precipitation, surface runoff, and groundwater, plus
the natural geology and topography of the land can
influence the water quality of lakes. This hydrologic
cycle illustrated the balance between water inputs
and outputs that influences lake water quality. Inputs
include direct precipitation, groundwater, and sur-
face runoff; whereas outputs are surface discharge
(outflow), evaporation, losses to groundwater, and
water withdrawn for domestic, agricultural, and in-
dustrial purposes.
Most States find nonpoint sources of pollution
responsible for most of the use impairment in lakes,
several attributing 100 percent of the impairment to
nonpoint sources. Agricultural nonpoint source
runoff was the most frequently reported source.
Nebraska observed that "even where domestic point
sources are indicated as being partially responsible
for this problem, it is suspected that the effect of non-
point sources would still preclude support of the use
if the point sources were eliminated." Vermont
reported nonpoint sources "now the most
widespread remaining water pollution problem af-
fecting the quality of the State's water."
One notable exception to these observations is
shown in Table 4. Kansas attributed nearly all its
major lake problems to natural conditions such as
low inflow and mineral intrusion that result in viola-
tions of the State dissolved oxygen and metal criteria.
Kansas measures use impairment based on its water
quality criteria, which do not reflect the agricultural
nonpoint source impacts on lakes. Additional infor-
mation showed that well over 50 percent of the total
number of lakes affected in Kansas could be traced
to agricultural runoff.
Kentucky also considers natural conditions
responsible for most of the use impairment in that
State's lakes. This assessment reflects the release of
iron and manganese from the lake sediments under
anoxic conditions. Selenium-contaminated lake
sediments are also responsible for use impairment in
North Carolina lakes; however, North Carolina con-
siders contaminated sediment a nonpoint source.
Although States use varying criteria to determine
whether a lake is maintaining its uses, most causes of
pollution in lakes are rooted in nonpoint sources.
Even some pollutants identified as occurring natural-
ly or originating from specific causes, often can be
controlled as nonpoint sources.
PRECIPITATION /
-EVAPORATION
INFILTRATION
GROUND WATER FLOW
WATER TABLE
SEEPAGE
Figure 3.Hydrologic cycle.
BEDROCK
13
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Pollution Control and Lake Restoration
Introduction
The source of pollution to a lake will determine the ap-
proach used to protect or restore lake uses. Point
sources are usually controlled through permit restric-
tions on wastewater discharges. Nonpoint sources,
because of their diffuse nature, are best controlled by
effective watershed management. As point sources
are brought under control in most areas, the impact of
nonpoint sources becomes more visible and relevant.
The 1986 305(b) Water Quality Inventory found
that 76 percent of use impairment in lakes resulted
from nonpoint source pollution; this 1988 report con-
firms that assessment, also finding 76 percent of the
impairment caused by nonpoint sources. The 1988
State data on which this report is based reflect, how-
ever, assessments of 63 percent more lakes than
were surveyed for the 1986 Inventory.
Once the sources of pollution have been success-
fully addressed, in-lake restoration activities may be
appropriate. Lake restoration works only when all
parties concerned cooperate in its design and im-
plementation. In developing restoration plans for
specific lakes, EPA Regions work with a number of
State and Federal agencies, among them the local
Soil and Water Conservation District, the Agricultural
Stabilization and Conservation Service County Com-
mittee, the Soil Conservation Service, the U.S. Fish
and Wildlife Service, the U.S. Geological Survey, the
U.S. Army Corps of Engineers, and any other or-
ganization involved with lakes.
Pollution Control
Point Sources. Over the past 20 years, the States
have made great strides in controlling point sources
of pollution through National Pollutant Discharge
Elimination System (NPDES) permits, State permits,
construction of wastewater treatment facilities, and
industrial pretreatment programs.
Wastewaters from cities, industries, businesses,
and homes comprise a source of pollutants affecting
lake water quality. Wastewaters receive different
treatment based on the water quality needs of the
receiving stream. Treatment levels are generally
referred to as primary, secondary, and advanced.
Primary treatment plants used by municipalities
and industry generally remove about 35 percent of
pollutants on the average; secondary treatment
around 85 percent. Neither primary nor secondary
treatment removes phosphorus and nitrogen (which
significantly affect lakes) except as these nutrients
are attached to solids. Large cities and manufac-
turers use advanced wastewater treatment plants to
remove these nutrients.
Small-scale systems, including septic systems
(which can also act as nonpoint sources) may be
used by communities and individual property
owners. The effects of these small waste disposal
systems on water quality depend on their location:
the soil characteristics, groundwater tables, usage
conditions, and slope of the terrain.
15
-------
Effective operation and maintenance are key fac-
tors in assuring that waste disposal systems avoid
degrading water quality. No matter how large or
small the system whether it serves a city of millions
or a household of two it must be properly installed
and operated, and maintained on a regular schedule.
Nonpoint Sources. Daily, natural, and routine
human activities - be they on the lakeshore or many
miles upstream in the watershed (the land that drains
into the lake) - contribute nutrients, sediment, and
other pollutants to a lake, principally as runoff from
streets, construction sites, forests, mines, and
agricultural land. Effective control of nonpoint sour-
ces could prevent lake water quality problems,
eliminating the need for costly restoration projects.
The approaches that can be taken to reduce or
eliminate nonpoint source pollution are discussed in
the following paragraphs.
Best management practices, commonly referred
to as BMPs, are designed to prevent or reduce the
quantity of pollution entering a lake. BMPs have been
successfully applied to control the potential nonpoint
source pollution associated with many land uses, in-
cluding agriculture, silviculture, construction, mini-
ng, and urban activities. Among these BMPs are
conservation tillage, integrated pest management,
animal waste management, porous pavements, road
and skid trail management, land surface roughening,
stormwater management, bank stabilization and
riprapping, lakeshore management, sedimentation
traps, runoff diversions, redesigned streets and park-
ing lots, and detention/sedimentation basins.
Knowledge developed by activities authorized under
Section 319 of the Water Quality Act will significantly
increase citizens' ability to control nonpoint sources
of pollution. In addition, various Department of
Agriculture programs, such as the Conservation
Reserve Program, play an important role in address-
ing agricultural sources of lake pollution.
A growing number of communities protect lakes
with regulations and ordinances that require BMPs to
prevent problems caused by erosion and pollution.
In the State of Washington, for example, the com-
munity of Mountlake Terrace regulates construction
to minimize its contribution to nonpoint source pollu-
tion. Where possible, planned development within a
lake's watershed can limit the entry of pollutants into
a lake.
Pollution control also is often brought about by
local opposition to activities that may degrade a lake,
prompting direct State or local agency intervention.
Throughout the Nation, citizens are forming lake as-
sociations to protect, manage, and restore their
lakes. These associations often promote local or-
dinances that restrict land use activities to control
pollution. For example, Kentucky's mining regula-
tions contain a petition process that allows land in a
lake's watershed to be declared unsuitable for mini-
ng. Such a petition process has been used to protect
the water quality of Cannon Creek Lake in Kentucky.
State Programs
Several States have enacted legislation and set up
lake management and nonpoint source pollution con-
trol programs. Although a few programs have a
regulatory component, they are predominantly volun-
tary and are based on cost sharing, incentives
promoting good land management, technical assis-
tance, and information/education.
South Dakota controls nonpoint source pollution
through a combination of regulatory and voluntary
measures that focus on their major nonpoint source
problem: agricultural runoff. The South Dakota
Erosion and Damage Control Act regulates and per-
mits "any land-disturbing activities within the State
which result in soil erosion and sediment damage."
Also, the State's Surface Water Quality Standards
specify eight parameters that can be considered in-
dices for nonpoint source pollution. Examples are (1)
suspended solids likely to be associated with most
agricultural land-disturbing activities, (2) total dis-
solved solids and conductivity associated principally
with irrigation return flows, and (3) coliform bacteria
associated with livestock operations. The State notes
that its water quality standards are inadequate for
documenting the impact of agricultural runoff.
Slightly more than half of the States use a
regulatory approach to control pollution through
site-specific criteria and lake water quality standards.
These standards are derived largely from profes-
sional judgement and literature values, with monitor-
ing data also used. Washington, which has long had
standards, modified them in 1988 to establish both a
site-specific nutrient (total phosphorus) criterion for
Long Lake Reservoir and criteria for toxic substan-
ces. Also, in 1988, Washington began taxing tobacco
products to fund water pollution control programs.
Up to 20 percent of the $45 million generated each
year is earmarked for nonpoint source control;
another 10 percent, for protection of lakes and rivers.
In reality, lakes benefit from both funds because of
the close connection between lake water quality and
nonpoint source pollution.
16
-------
Some States have established State lake manage-
ment programs designed specifically to protect, en-
hance, and restore their lakes. Among them are
Maine, Indiana, Illinois, Massachusetts, New York,
New Jersey, South Dakota, Connecticut, Florida,
Minnesota, Idaho, North Dakota, New Hampshire,
Ohio, Wisconsin, North Carolina, and Michigan.
The Illinois lake program is a good example of a
comprehensive State lake management program.
The major program components include monitoring,
lake classification to guide decisionmaking, develop-
ment and implementation of lake/watershed
management plansfor public lakes underthe Federal
Clean Lakes Program, and education, technology
transfer, technical assistance, and coordination.
Since the program began in 1977, the Illinois En-
vironmental Protection Agency (IEPA) has compiled
assessment information and baseline water quality
and sediment data under Illinois' Ambient Lake
Monitoring Program (ALMP). The ALMP defines
trends in significant lakes and diagnoses lake
problems, evaluates progress in pollution con-
trol/restoration programs, and updates the State lake
classification system.
More than 700 volunteers have participated in
monitoring 250 lakes under Illinois' Volunteer Lake
Monitoring Program (VLMP), which, in addition to in-
creasing citizen knowledge and encouraging local
involvement, gathers fundamental information on the
State's lakes. A historic data baseline is being
developed, as are lake protection and management
plans.
The IEPA has also developed a lake classifica-
tion/needs assessment that can be used to establish
protection, monitoring, and technical assistance
priorities, rank watershed land treatment projects,
plan for recreational use, and screen candidates for
Clean Lakes Program assistance.
Educational and technical assistance to citizens,
lake managers, and local government officials
promotes a better understanding of Illinois' lake
ecosystems and encourages comprehensive
management of these resources.
Several States have acted to reduce the precur-
sors of acid precipitation through emission control
programs. For example, New York was the first State
to mandate reductions in emissions that contribute
to acid precipitation (State Acid Precipitation Control
Act, 1984). The State is now proposing to formally
adopt the Federal New Source Performance Stand-
ards for emissions of oxides of nitrogen.
Michigan has also acted to reduce emissions.
From 1974-86, sulfur dioxide emissions from station-
ary sources in the State were cut by 82 percent with
all sulfate emissions standards met by 1987.
Both New Hampshire and Vermont believe that
reducing out-of-State emissions must be the first
step in addressing the effects of acid precipitation in
their States. Pointing out that 99.9 percent of the pol-
lutants responsible for the damage in the State
originate outside its borders, Vermont said that the
problem will not be solved by treating the symptoms
without treating the causes.
Lake Restoration
Lake restoration corrects lake problems, using
ecologically sound principles to improve the lake on a
long-term basis. To successfully restore lake water
quality, the source of the problem must be identified
and appropriate control measures then implemented.
A lake problem is usually best controlled when ad-
dressed in its watershed by the procedures
described previously in this Report. After the sources
of pollution have been eliminated or reduced to the
appropriate level, some in-lake measure such as
sediment removal can also restore water quality for
long periods of time. Others - alum treatment, for
example, restore water quality on a short-term
basis to reduce loss of user days while watershed
controls are being put in place. Unless the source of
pollution is addressed, in-lake restoration efforts be-
come repetitive and costly.
Before restoration can begin, a thorough diagnos-
tic study of the lake must be completed to determine
the cause of the problem, as well as the feasibility
both of restoration itself and of the proposed restora-
tion techniques. A technique that works well for one
lake may not be appropriate for another. The existing
lake and watershed conditions and characteristics
are key factors in a successful restoration project,
and influence the potential for improvement in
various lakes. In areas with high precipitation and
easily erodible soils that contain excessive nutrients
or organic materials, a lake can be improved only
minimally, and will probably never be transparent and
pristine. Therefore, the best attainable water quality
should be determined before deciding on the
feasibility of restoration and the appropriate restora-
tion techniques.
Restoration techniques for lakes continue to be
developed. The lake restoration demonstration
projects in the mid-1970s pioneered many techni-
ques that have since been refined. The principal res-
toration techniques briefly described here are
explained more fully in the Lake and Reservoir Res-
toration Guidance Manual (LRRGM) published by
17
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EPA in response to legislative mandate to compile in-
formation about restoration techniques for public
use. Further information on lake restoration will be
available to the public in technical updates to the
LRRGM.
The States that have reported lake restoration ac-
tivities are summarized in Table 5. These lake
rehabilitation techniques are designed to improve
the lake; not all of them necessarily target the source
of the problem.
As mentioned previously in this Report, excessive
nutrients and siltation caused significant impairment
of use in lakes. Nutrient input to lakes encourage
macrophyte growth and algal blooms. Also, as ex-
plained previously, the decomposition process of
algae and plants consumes oxygen, possibly lower-
ing the dissolved oxygen to a level that stresses or
even kills fish. Sedimentation may also stimulate
algal and macrophyte growth by providing a suitable
substrate for macrophytes and transporting the
necessary nutrients. Sediment input to a lake can
also reduce its depth - impeding boating and other
water recreation.
Because nutrients and sedimentation have been
recognized as major causes of lake use impairment,
the restoration techniques described in this Report
focus on abating their adverse effects, and are
presented according to the problems they cause.
Also, as required by the legislation, techniques to
mitigate the effects of acidity and toxics on lake water
quality are discussed in this Report.
Restoration techniques, therefore, are presented
in the following categories (Table 6):
1. Control of nuisance algae,
2. Deepening to eliminate shaliowness,
3. Removal of nuisance rooted vegetation,
4. Improvement of fisheries,
5. Acid mitigation,
6. Toxics removal.
Control of Nuisance Algae
Phosphorus precipitation and inactivation:
Precipitation removes phosphorus from the water
column; inactivation controls phosphorus release
from the sediments. Alum (aluminum sulfate) is most
frequently used because phosphorus binds tightly to
its salts under most conditions, creating a floe that
settles out, leaving the water clear. If enough alum is
added, a layer of aluminum hydroxide will settle to the
bottom, preventing phosphorus release. However,
the lake should be deep enough to prevent resuspen-
sion of sediments that precipitated via alum addition.
This technique is most effective on lakes where
nutrient inflow has been diverted, and has been
proposed for both Delevan Lake, Wisconsin, and Hills
Pond, Massachusetts.
Sediment removal: Controls nutrient release from
sediments by removing the layer of the most highly
enriched materials. In this procedure, a dredge
(several types exist) loosens the sediment, which is
then transported as a slurry through a pipeline to a
remote disposal area. Although the residue may (if it
does not contain toxic material) be used as fill or fer-
tilizer, the costs of dredge spoil disposal can be high.
In small lakes, however, draining the lake and remov-
ing sediments may be economically feasible. Sedi-
ment removal can be effective, as demonstrated on
Lilly Lake in Wisconsin and Lake Lansing, Michigan.
Care must be taken in depositing the sediments, so as
not to adversely affect adjacent wetlands.
Dilution and flushing: The nutrient concentration
is lowered by introducing nutrient-poor water from
another source, thus starving the algae. Large
amounts of additional water also can flush the algae
from the lake faster than they can grow. This techni-
que is limited by the availability of water from an out-
side source and the rapid rate of algal growth.
Therefore, few examples exist, with Moses Lake,
Washington being a notable exception. At this lake,
water from the Columbia River was diverted through
the lake, producing dramatic improvement.
Biological controls: Plant-eating fish and plant
pathogenic organisms can be introduced into a lake
to control nuisance aquatic vegetation. Grass carp, a
non-native species originally imported from Malaysia
in 1962, can control, even eradicate plants within
several seasons. The Little Pond, Maine Clean Lakes
Project successfully used this technique to control
algal blooms. Six insect species imported by the U.S.
Department of Agriculture under quarantine are being
used in the South to control alligatorweed and water
hyacinth. The introduction of non-native species
should be used with caution and with a comprehen-
sive understanding of the native species/community
interactions. Significant negative environmental im-
pacts, for example, reduction/elimination of native
and/or desired species resulting from over-competi-
tion of non-native species, are a possibility.
Aquatic macrophyte harvesting: Vegetation is
mechanically cut and removed from the lake. This
18
-------
Table 5. - Lake rehabilitation technique
STATE
Cl
DE
FL
GA
IL
IN
IA
KS
ME
MD
MA
M
MN
M':
M;
H'J
NI
Nh
NJ
|S|V
ND
OH
OK
PA
Rl
SD
TX
VT
VA
W4
W,
NUTRIENT MANAGEMENT
X
X
X
X
X
X
X
X
X
X
X
X
PHOSPHORUS PRECIPITATION/INACTIVATION
X
X
X
X
X
X
X
X
X
SEDIMENT REMOVAL/DREDGING
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
DILUTION/FLUSHING
X
X
X
X
X
X
X
X
X
BIOLOGICAL CONTROLS
X
X
X
X
X
X
X
AQUATIC MACROPHYTE HARVESTING
X
X
X
X
X
X
X
X
X
X
X
ARTIFICIAL CIRCULATION
X
X
X
X
X
X
X
X
HYPOLIMNETIC AERATION
X
X
X
X
FOOD CHAIN MANIPULATION
X
X
X
X
X
CHEMICAL CONTROLS
X
X
X
X
X
X
X
X
X
X
X
DIVERSION
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
SEDIMENT BASIN/TRAP
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
DRAWDOWN
X
X
X
X
X
X
X
X
X
X
X
SHADING/SEDIMENT COVER
X
SEDIMENT OXIDATION
X
HYPOLIMNETIC WITHDRAWAL
X
X
X
X
X
X
INTRODUCTION OF NON-NATIVE SPECIES
X
states not listed in the table either did not report the information or reported in a way that was incons stent with the format of the table.
19
-------
Table 6. - Lake rehabilitation techniques by restoration objectives.
TECHNIQUE
Phosphorus Precipitation
Inactivation
Sediment Removal/Dredging
Dilution/Rushing
Biological Controls
Introduction of Non-Native Species
Aquatic Macrophyte Harvesting
Artificial Circulation
Hypolimnetic Aeration
Food Chain Manipulation
Chemical Controls
Diversion
Sediment Basin/Trap
Drawdown/Waterlevel
Management
Shading/Sediment Cover
Sediment Oxidation
Hypolimnetic Withdrawal
Nutrient Addition
CONTROL
NUISANCE
ALGAE
X
X
X
X
X
X
X
X
X
X
X
X
ELIMINATE
EXCESSIVE
SHALLOWNESS
X
X
X
REMOVE
ROOTED
PLANTS
X
X
X
X
X
X
IMPROVE
FISHERIES
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ACID
MITIGATION
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TOXICS
REMOVAL
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procedure reduces the oxygen stress and fish kills as-
sociated with decaying vegetation. Harvesting also
increases open water and improves aesthetics. How-
ever, harvesting must be repeated regularly, and does
not completely address eutrophication over the long
term, because it only reduces nutrient loading from
sediments and does not eliminate external nutrient
loading to the lake. In some cases, such as Lake
Hopatcong, New Jersey, and Blackhawk Lake, Iowa,
it does remove significant amounts of nutrients. Har-
vesting may not be appropriate in some situations be-
cause it can stimulate growth and reproduction in
some plant species.
Artificial circulation: Circulation mixes the lake
waters, eliminating thermal stratification. It may con-
trol algal blooms by introducing dissolved oxygen to
the bottom, thereby inhibiting phosphorus release
from the sediments. This technique has been used on
Hampton Manor Lake, New York.
Hypolimnetic aeration: Not intended to destratify
the lake (as with artificial circulation), this procedure
brings cold hypolimnetic water to the surface of deep
lakes where it is aerated by contact with the atmos-
phere and then returned to the hypolimnion. This
technique may be used to maintain a coldwater
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fishery in a lake where the hypolimnion is normally
anoxic (oxygen-depleted), or to eliminate taste and
odor problems in drinking water withdrawn from a
cold hypolimnion. The Lake Como, Minnesota, Clean
Lakes Project is using this technique.
Hypolimnetic withdrawal: Very little documenta-
tion exists on this procedure designed to withdraw
water from the deepest areas of a lake, which may be
extremely rich in nutrients. Spiritwood Lake, South
Dakota, reduced algal blooms by removing nutrient-
rich water from the hypolimnion (in addition to im-
plementing watershed erosion controls). Lake
Warramaug, Connecticut, also has had good results
using this technique.
Food chain manipulation: Zooplankton grazing
might be used to control algae in the open water of a
lake or reservoir. This requires analysis of the or-
ganisms that exist within the lake.
Chemical controls: Perhaps the oldest and most
widely used method to manage weeds, herbicides
can rapidly reduce vegetation for periods of weeks to
months. Chemical control is not a long-term restora-
tion technique because it does not address the
causes of the problem, nor are nutrients and organic
matter removed from the lake. In fact, nutrients se-
questered as plant biomass can be released back into
the water column as a result of decay of the plant
biomass. This can resuult in phytoplankton blooms.
Eola Lake in Florida is using this technique.
Diversion: This method diverts nutrient-laden
water entering the lake into an alternative site, either a
treatment plant for waste disposal, or some form of
detention basin. The latter may be a settling facility or
a natural area such as a wetland. Sewage, septic tank
seepage, and runoff containing high levels of
nutrients are usually the waters targeted for diversion.
Deepening a Lake
Sedimentation basin: Designed to hold runoff
long enough for sediment to settle to the bottom of the
containment structure, sedimentation basins are
positioned strategically in the watershed to trap the
runoff. This technique is both restorative and preven-
tive. Lake Tahoe in Nevada has used this technique.
Diversion: Described earlier as a technique for
removing nutrients, diversion also can be used to
prevent sediments from filling the lake. Diverted water
is held in a sedimentation basin for settling long
enough for sediments to settle out.
Sediment removal (dredging): Also described in
a previous section, dredging is an effective technique
for deepening a lake and enhancing recreational ac-
tivities such as swimming, boating, etc. However, it
should be noted that the presence of some shallow
shoreline areas with aquatic macrophytes is impor-
tant to the habitat and propagation of certain fish
species. In the restoration of a shallow lake a balance
between the maintenance and enhancement of
recreational activities and fish habitat must be recog-
nized to ensure the overall health of the lake ecosys-
tem.
Control/Elimination of Nuisance Rooted
Vegetation
Drawdown: Water is drawn from the lake to ex-
pose sediments to prolonged freezing and drying
conditions that will kill plants. This procedure also al-
lows repair of dams and docks, sediment removal,
and other management practices. However, some
plants are not affected by the exposure and in others
growth is stimulated. At most, this technique should
be employed no more that every two years, to avoid
development of resistant weed species and damage
to benthic invertebrates. If the lake water level is con-
trolled by a dam, this is an inexpensive technique, al-
though costs will be associated with the loss of the
use of the lake.
Shading and sediment covers: Dyes can be ap-
plied to the water to limit light available for plant
growth and sediments can be covered to stop such
growth. Sediment covers are most effective in small
areas where, if properly installed, they can completely
eliminate plants. Because they are difficult to place
over growing plants, covers are best applied during
winter drawdown or early spring.
Sediment removal (dredging), biological con-
trols, macrophyte harvesting, and chemical con-
trols also are used to control vegetation. These
techniques were described previously.
Improve Fisheries
Many of the techniques previously described can be
used to improve fisheries, with the selection of the
specific technique dependent on the geographic area
and characteristics of the lake. For example, in lake
systems altered by chemical or biological factors
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(e.g., acidity), more acid-tolerant species may be in-
troduced.
The most commonly used techniques to improve
fisheries (all described previously) include draw-
down, artificial circulation, food chain manipula-
tion, hypolimnetic aeration, and chemical
controls.
Acid Mitigation
Designed primarily to restore the aquatic ecosystem
to a pH level that ensures an adequate and healthy
fishery, restoration of an acidified lake involves two
basic strategies:
1. Modification of the physical and chemical
environment, and
2. Modification offish populations.
The techniques selected will depend upon the
geographic, political, institutional, and economic
constraints within which the lake manager operates.
Many of the techniques involve liming and the use of
alkaline materials.
Modification of the physical/chemical environ-
ment: "Liming" or the addition of other alkaline
materials is the most widely used technique for raising
the pH in lakes. Lime may be applied to the lake water
column, lake sediments, watershed, or feeder
streams. Other less commonly used techniques to
mitigate high acidity in lakes are changing the land
cover, managing reservoir surges, and adding
nutrients to alter the lake chemistry. Changing the
land cover involves eliminating vegetation that
produces acidic litter (e.g., conifers). Reservoir water
drawdown and discharge can be altered to prevent
the acidic surge that can occur with snow melt and
spring rains. Supplying nutrients to a lake increases
its biological productivity, thereby increasing the
lake's pH and acid neutralizing capability.
Modification of fish populations: Five restoration
techniques are used to modify fish populations in
lakes affected by acidity. These include placing lime-
stone gravel in spawning beds, stocking with adult
fish, stocking with acid-resistant fish, creating new
fisheries, and installing limestone filters in hatchery in-
takes.
Four eastern States (Maryland, Maine, New York,
and Pennsylvania) and Michigan described acid
mitigation efforts in the 1988 Lake Water Quality As-
sessments. Maryland has been working extensively
over the past two years in an effort to control acidity
by liming streams and lakes.
Approximately 200 surveyed Massachusetts lakes
either have been affected or are susceptible to acidic
inputs. Massachusetts has one State-funded pro-
gram that addresses the issue: in the past two years,
this program has limed nine ponds. In June 1988, the
State published Acid Rain in Massachusetts, a
volume documenting the current status of the prob-
lem and the State's mitigation efforts to date.
Pennsylvania, where State law prohibits discharge
of substances to State waters without approval, has
adopted a policy of approving the addition of
neutralizing agents only as part of a closely
monitored experimental project designed to study
the effectiveness and costs of liming. Under this
policy, one lake (White Deer) has been treated twice
with agricultural limestone (aglime).
Toxic Removal
Toxics may be present in a lake either in the water
column or in the sediment. The appropriate removal
technique depends on the location and nature of the
toxic pollutants present. In general, techniques to
remove toxics from the water column include:
Dilution/flushing. Dilution is the introduction of
toxic-free water that mixes with the contaminated
water and by thus reducing the relative concentration
of the toxics in the lake may minimize their adverse ef-
fects. Flushing the toxic-contaminated water from the
lake may improve the condition of the lake, but may
also create a problem downstream.
Chemical treatment and/or pH adjustment.
Under appropriate pH conditions and/or upon treat-
ment with particular chemicals, some toxics will
precipitate out of the water column and settle to the
bottom of the lake. Although this removes the toxic
pollutants from the water column, it may result in a
problem with contaminated sediments.
Removal of toxic pollutants from bottom sedi-
ments isthefocus of the five-year demonstration pro-
gram authorized under Section 1l8(c)(3). Know-
ledge gained from this program should produce new
technology to control in-place pollutants. Current
techniques to remove or minimize the effects of con-
taminated lake sediments include:
Dredging. The most commonly used method to
remove contaminated sediments from a lake is by
dredging, which loosens the sediment and transports
it as a slurry through a pipeline to a remote disposal
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areas. Since the dredge spoils are contaminated, the
disposal area must be completely contained so that
runoff will not recontaminate the lake, another area, or
leach into the groundwater. The physical action of
dredging may also resuspend toxics in the water
column.
Sediment covers. Contaminated sediments may
be covered with materials such as toxic-free sand,
gravel, or clay to protect the aquatic life from adverse
impacts of recycling toxics in the water column. How-
ever, unless the source of contamination is controlled
these covers will also become contaminated. Sheet-
ing material, such as a plastic-type liner that is resis-
tant to damage by the toxics present, may also be
used to line the bottom of the lake. However, these are
difficult to apply over large areas and may slip on
steep grades or float to the surface after trapping
gases beneath them.
Pollution control and lake restoration are in-
separable: it is impossible to truly restore a lake on a
long-term basis without controlling the sources of
pollution to that water body. Some restoration techni-
ques (such as dredging and chemicals) work for the
short term, however, temporarily alleviating the prob-
lem while the pollution is being controlled. As the
States and their citizens become more aware and in-
volved in protecting and restoring their'lakes, they
are realizing the need to thoroughly analyze the
lake's condition and the options for improving its
water quality before beginning restoration proce-
dures.
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U.S. Environmental Protection Agency
Region 5, library (pi.. 12.0
77 West Jackson Boulevard, 12th floor
Chicago, II 60604-3590
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