STATE-OF-THE-ART-SUMMARY
LAKE RESTORATION
PROCEDURES AND THEIR EFFECTIVENESS


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Stute-uf-The-Art Summary; Lake Eostoratioix,	Dec. 12,1974
Procedures and their Effectiveness
Research § Development Program, Chief
Southeast Region IV
Thomas E. Maloney, Chief, Eutrophication § Lake Restoration
Branch, N.E.R.C. Corvallis
Thru: Dr. A. F. Bartsch, Director, N.E.R.C. Corvallis
Summary
We are distributing 300 copies of the attached to the
various Water Research Resource Institutes and State
Pollution Control Agencies, plus other organizations
in the eight States of our Southeast Region.
Action
Many thanks for the excellent cooperation and consider-
ation in this matter.
Background
Memo of date September 6, 1974 requesting State-Of-The-
Art summaries.
E. P. Lomasney, Chief,
Research § Development Program
Southeast Region IV
cc. Charles Frank

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RESEARCH RESULTS -ANALYSES
R&D PROGRAM
Environmental Protection Agency
Region IV
1421 PEACHTREE STREET, N.E. ATLANTA, GEORGIA 30309
The attached presentation represents the first of
a series of State-Of-The-Art papers that will be
issued by the Research § Development Program Office
of the Southeast Region. The presentations will
be geared to the current research needs of our
region and will pertain to subject matter with the
latest information and data constituting the exper-
ience of our Agency's R 5 D effort. We have select-
ed these particular subjects because of inquiries
received from many of the people closely associated
with the pollution problems.
It is our intension to offer these presentation at
intervals. They will all be concerned with subject
matter .relative to our program and the latest inform-
ation on State-Of-The-Art for a number of areas that
constitute the major problems in the control and abate-
ment of pollution, for the protection of the environ-
ment. These presentations will be brief and simple
in context.
Edmond P. Lomasney, Chief
Research 5 Development Program
Southeast Region IV

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RESEARCH RESULTS ANALYSES

m)	R&D PROGRAM
Environmental Protection Agency
Region IV
1421 PEACHTREE STREET, N.E. ATLANTA, GEORGIA 30309
No. I	DECEMBER 13, 1974
STATE OF TIE ART SUWARY
LAKE RESTORATION
PROCEDURES AND TOR EFFECTIVENESS
Thomas E. Maloney, Chief
Eutrophication § Lake Restoration Branch
National Environmental Research Center
Corvallis, Oregon 97330

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Lake Restoration: Procedures and Their Effectiveness
Many lakes throughout the world are undergoing accelerated aging (eutror
phication). Lafces vary tremendously in their chemical, physical and
biological characteristics depending upon their mode of origin, their
location, the characteristics of their watershed and their uses.
Contaminants may impact lake environments in various ways, depending
upon the nature of the substance. Nutrient rich plant growth stimulators
such as domestic sewage and commercial fertilizers accelerate the aging
process of a lake. Sedimentation may add to the eutrophication problems.
Toxic substances may poison water supplies, interfere with normal biolog-
ical activity or render commercial and sports fish and crustaceous fish
unfit for consumption. Heated water released to the lakes may alter the
natural thermal structure and upset the composition of the lake communities.
There are two approaches to rehabilitating degraded lakes; (1) restric-
ting the input of undesirable materials and (2) providing in-lake treat-
ment for the removal or inactivation of undesirable materials. Reducing
or eliminating the sources of waste loading is the only restoration
measure needed to achieve the desired level of improvement in certain
lakes in which natural flushing results in substantial improvements in
quality. However, in many lakes, particularly those with slow flushing
rates, in-lake treatment schemes may also be required before significant
improvements will be realized. Remedial measures which restrict the
input of contaminants include advanced Waste treatment, nutrient diver-
sion and allocthonous sediment control.
Because of the key role of phosphorus in eutrophication, coupled with
the present unfavorable prospect of controlling any other nutrient,
elimination of phosphorus to lakes is the goal of most restoration

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procedures. Advanced waste treatment (AWT) probably represents the best
method currently available for curbing phosphorus input to waterways at
moderate costs. Phosphorus removal efficiency of 80-90 percent can be
achieved by chemical precipitation with alum, ferric salts or lime.
Although to date there has not been documentation evaluating AWT as a
means of restoring a lake, preliminary results both in this- country and
Europe have been encouraging.
In 1972, the Environmental Protection Agency initiated the National
Eutrophication Survey. The purpose of the survey is to learn what the
impact of municipal sewage treatment is on our nations lakes. During
the spring of 1973, its efforts were concentrated in the Southeastern
United States. Tributary and Municipal Sewage Treatment Plant (MSTP)
sampling had begun or was initiated in all of the states to be sampled
east of the Mississippi River. Table 1 lists the number of lakes,
stream sites and MSTP's sampled in Region IV during the 1973 sampling
year.
Table 1. Number of Lakes, Stream Sites, and Sewage
Treatment Plants Sampled During the .1973
Sampling Year in Region IV
State
Lakes
Stream Sites
Waste Effluents
Alabama
Georgia
Florida
Kentucky
11
17
42
5
5
14
18
18
118
100
104
48
35
96
102
220
35
46
46
14
12
59
38
44
Mississippi
South Carolina
North Carolina
Tennessee

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In order to establish the present trophic status of the lakes, each one
was sampled at least three times during the sampling year. During each
sampling visit, various water parameters were measured and when included
with historical data, if available, were used to assess the trophic
condition of the lake.
Sampling of municipal sewage treatment plants and selected tributaries
allowed for an assessment of the percentage contribution of nutrient
loading from each point source as well as non-point sources. MSTP's
were selected with the cooperation of the State Water Pollution Control
Agencies and sampled on a monthly basis by the plant superintendent.
Monthly samples at the designated stream sites were collected through
the volunteer efforts of the National Guard in each of the involved
states.
After data collection and analysis, an individual lake report will be
prepared that summarizes the data from all phases of the Survey as well
as any available historical data. These reports will contain several
sections:
A.	The present trophic condition of the lake presented as a
compilation and summarization of Survey data and augmented by
historical data when available.
B.	Limiting nutrient evaluation of the lake based on algal assay
results and supported by field data.
C.	Nutrient loading assessment based on an evaluation of the
loading estimates (in mass per unit time) of phosphorus and
nitrogen and the percentage contribution from point sources
and non-point sources.

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Based on an analysis of the data for the lakes* sampled in 1973 (of
which 88 were in Region IV), some general statements can be made: (1)
there are about 15 lakes that can be called oligotrophia that is they
have a very good trophic condition; (2) about 45 lakes can be called
mesotrophic; (3) about 51 lakes are considered eutrophlc and have occa-
sional nuisance algae problems; and (4) there are about 104 of the 215
lakes ranked that fall into a class than can be expected to have more
frequent nuisance conditions.
A final analysis of these data is incomplete, and a comprehensive evalu-
ation of each lake cannot be made until the Individual lake reports are
written. However, preliminary analysis of these data indicates possibly
40-50 percent of the lakes surveyed in Region IV have symptoms of accel-
erated eutrophication.
The individual lake reports will present an analysis and evaluation of
all phases of the Survey and should assist the states 1n setting their
priorities of implementing lake restoration and should indicate which
lakes or reservoirs are the most suitable candidates for restoration.
The preparation of the report for the Region IV sta.tes have been started
and is scheduled for completion during the first half of 1975.
Nutrient diversion offers a possible lake restoration technique in
situations where the incoming nutrient load is entering from point
sources. This technique has been used successfully in Lake Washington
in Washington. During 1963-1968, the sewage was diverted step-wise and,
after February 1968, received no more effluent. The condition of the
lake changed rapidly and sensitively with the changes in the nutrient
input.
Lake dredging not only removes sediment buildup, but also serves to
remove a potential nutrient source. Little information is available on
*The Florida lakes were not included because they are generally considered
to be unique due to the subtropical Florida climate.

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the chemical and biological effects of dredging, but projects are now
underway which.will evaluate the total environmental effects. When all
costs are Included, contract unit prices for lake dredging ranges from
$0.45 to $1.00 per cubic yard of material removed. The major factors
influencing costs are: (1) the project size; (2) to type of material to
be excavated; (3) distance to disposal sites; and (4) the availability
of properly equipped dredging contractors. The relatively high costs of
dredging make this technique prohibitively expensive on most large
lakes, but dredging is a restorative technique that has been used for
years on small lakes and ponds.
Nutrient inactivation is accomplished by adding some type of material to
the water that will bond with, absorb or otherwise make the nutrients
unavailable to aquatic plants. Alum, sodium aluminate, fly ash and
various other materials have been investigated as nutrient inactivation
agents. Although some pilot results with this technique have been
encouraging, its applicability on a large-scale has not been determined.
Under certain conditions the water quality of lakes can be improved by
diluting or replacing the existing lake water with water of a higher
quality. This technique has been successful in restoring some lakes,
but its application is limited to lakes with ready access to a large
supply of high quality water.
Covering the bottom sediments with sheeting materials or particulate
matter is being investigated as a means of preventing nutrient exchange
and retarding rooted plant growth. Limited experience with this techni-
que have encoutered problems with balooning of sheeting and rupturing
seals of particulate matter when gas is produced within the sediments.
Investigation of this technique in pilot lakes is continuing.

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It is sometimes possible to replenish the oxygen supply of anaerobic
waters of eutrophic lakes by disrupting the thermal stratification by
aeration or by aerating the hypolimnion directly without disturbing the
thermal regimen. Definite improvements in water quality and in the
quality of the biota have occurred as a result of artificial destrati-
fication and hypolimnetic aeration. Although the response of a given
lake to these treatment measures is unpredictable, destratification and
hypolimnetic aeration are potential mechanisms for improving the water
quality of certain lakes.
Lake drawdown has been investigated as a control measure for rooted
vegetation, as a means of retarding nutrient release from the sediments
and as a lake deepening mechanism through sediment consolidation. Much
investigation is still needed for a clear understanding of the efficacy
of using drawdown as a lake restoration procedure.
In many lakes in advanced stages of eutrophication attempts have been
made to control nuisance organisms through mechanical, biological and
chemical means. In general, it is felt that the mechanical harvesting
of water weeds has only a short-term beneficial effect. Typical operat-
ing costs for mechanical harvesting range from $50 to $140 per hour (2.5
acres), but in some cases may be much higher. The efficiency of mechan-
ical harvesting is inversely proportional to the weed density.
Biological control agents under investigation for use as control agents
for algae and higher aquatic weeds include microorganisms such as viruses,
bacteria and fungi. Many of the organisms being investigated show
considerable promise. Other biological control agents under investi-
gation, especially in the Southeast section of the country, include
insects, fish and aquatic mammals.

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/cr toys, f.hemicals have long been utilized to control or eliminate undesired
algae arid aquatic weeds. Chemical agents, however, offer only temporary
relief and usually the treatment has to be continuously repeated to
achieve the desired results. However, use of chemicals is often required;
especially in cases where the waters must be kept navigable. Several
algicides and herbicides have been registered by the U. S. Environmental
Protection Agency for in-lake treatment of algae and macrophytes.

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