A
SUMMARY OF KENNESAW STATE UNIVERSITY LAKE PROJECTS
(Lake
Allatoona and Lake Acworth)
Prepared by Joseph
M. Dirnberger, Ph.D. - Principal Investigator
TABLE
OF CONTENTS
HISTORY
OF LAKE PROJECTS AT KSU
SUMMARY
OF MAJOR LIMNOLOGICAL FINDINGS IN LAKE ALLATOONA
1.
Excessive nutrients from human activity have resulted in eutrophication
of Lake Allatoona.
2.
Trophic state is primarily a function of phosphorus from non-point
sources along the Etowah River.
3.
Tributaries other than the Etowah River elevate trophic state in many embayments.
4.
Temporal variability in loading, as well as overall load, is important.
5.
Loss of depth from sedimentation was observed embayments.
6.
From a human health perspective, there is need for concern, but not alarm.
IMPLICATION
OF LIMNOLOGICAL DATA FOR MANAGEMENT ALTERNATIVES
1.
Etowah Arm.
2.
Little River Arm.
3.
Allatoona Arm.
LIMITED
DATA FROM 1999 - NEED FOR CONCERN?
HISTORY
OF LAKE PROJECTS AT KSU
Early in 1990, the Tri-Regional
Association, a multi-county/regional development center, was formed to
explore regional solutions to the future challenges of water supply, transportation,
solid waste disposal and wastewater treatment. Lake Allatoona, a U.S. Army
Corps of Engineers reservoir, was identified as a Regionally Important
Resource. The Burruss Institute of Public Service at Kennesaw State College
was awarded a U.S. Environmental Protection Agency Clean Lakes Phase I
study. Matching funds were provided by Bartow County Water and Sewer Department,
Cherokee County Water Authority, and the Cobb County Water System.
The Lake
Allatoona Phase I Clean Lakes study describes the physical characteristics
of the lake (area, depth, mean flow); the general chemical and biological
characteristics of the lake (temperature, dissolved oxygen, nutrients,
algal population, fish population, trophic state, toxins, bacterial contamination);
watershed characteristics (drainage area, land use, topography, geology
and soils); and possible pollutant sources. Also included is the feasibility
analysis of management alternatives for water quality protection. Funding
was extended for continued monitoring at selected sites from May 1993 to
October 1996, and included additional sites of interest identified as "critical"
areas on Lake Allatoona and upstream influences on the watershed.. The
final report (1992-96) was delivered to the Georgia Environmental Protection
Division in September 1997. The data from the study are necessary
in the evaluation and assessment of management strategies.
The data are being used in setting water quality standards for Lake Allatoona
and in assessing the impact of proposed increases in permitted discharge
from wastewater treatment facilities. The study aided in the
formation of the Lake Allatoona Task Force, a representative body
of local agencies and groups considered to be shareholders in Lake Allatoona,
originally chair by U.S. Representative Buddy Darden and now by U.S. Representative
Bob Barr. In 1999, the Lake Allatoona Authority was formed.
Another study initiated by
the Burruss Institute (and funded by Cobb County) involved Lake
Acworth, a smaller impoundment whose swim beach at the City of Acworth
was closed because levels of bacteria exceeded state standards. The study
(1994-95) examined the same parameters as those in the Lake Allatoona study.
Goals of the study were to describe water quality, to assess problems associated
with eutrophication, sedimentation, and health hazards, and to develop
appropriate management strategies. In 1997, the City of Acworth funded
a three-month study of Lake Acworth to assess changes in bacteria concentrations
since the previous study and to further examine sources of contamination.
Total funding for lake projects
to KSU has exceeded one million dollars since 1992. More than 50,000 water
quality measurements have been made over 232 dates at a total of 65 sites.
The lake projects have greatly enhanced undergraduate
science education at KSU. To date, over 30 students have been directly
involved in lake-related research projects (nine individual research project
students, five research assistants, 12 team research students, and numerous
student volunteers). In addition, equipment purchased for the project has
been used extensively in courses such as limnology and ecology. Currently,
there are plans to connect automated environmental monitoring equipment
to a web site for use in science courses.
SUMMARY
OF MAJOR LIMNOLOGICAL FINDINGS IN LAKE ALLATOONA
(click
here to see map of Lake Allatoona)
1. Excessive
nutrients from human activity within the watershed have resulted in eutrophication
of Lake Allatoona. Based on all major indicators of trophic status,
Lake Allatoona is classified in a range from strongly mesotrophic to eutrophic
depending on location (in eutrophic lakes, the probability that use of
the lake will be impaired is significant).
- Comparisons of current
data with limited historical data suggest Lake Allatoona, located within
a rapidly developing watershed, is becoming increasingly eutrophic.
-Eutrophic conditions occur
where nutrients from entering tributaries are the greatest.
-A bloom of picoplankton
in 1993 resulted in difficulty in treating water for drinking.
 |
Photograph of picoplankton cells.
The most dramatic and unusual change in water quality over the five years
of monitoring occurred in the late summer of 1993. Water samples
at several sites became difficult to filter for both chlorophyll and fecal
coliform bacteria. The drinking water treatment facilities reported
a dramatic increase in the amount of flocculating chemicals used to treat
drinking water during the same period. Microscopic examination revealed
the presence and numerical dominance of a small rod shape cell (~0.5 X
2 µm). |
-Photic depth, secchi depth,
and near-bottom oxygen levels declined over 5 yrs. at some sites.
 |
An example of changes in dissolved oxygen
over time. For dissolved oxygen at 9 m at the dam (1E), summer time
values >2.0 mg/l tended to occur more often in later years of the study.
Click on graph to enlarge. |
2. Trophic
state over the main (Etowah) arm of Lake Allatoona is primarily a function
of nutrients (particularly phosphorus) entering the lake from the Etowah
River, originating largely from non-point sources such as agricultural
and forestry practices.
 |
Total phosphorus load into Lake Allatoona
from May 1992 to April 1993. Click on graph to enlarge. |
- Nitrogen to phosphorus ratios
were in the range expected from croplands and forested areas.
- Relatively high turbidity
(associated with phosphorus), high fecal coliform bacteria concentrations,
and low conductivity are consistent with significant soil loss from agricultural
land rather than urban runoff.
- Many parameters increase
in concentration with increasing stream discharge indicating non-point
sources.
- The water quality data
from sites upstream along the Etowah River indicate that sources of nutrient
loading are numerous, geographically widespread, and diverse in type.
3. Tributaries
other than the Etowah River elevate trophic state in many embayments relative
to the main axis of the lake.
-Embayments with narrow
openings tend to have higher chlorophyll levels than their nearest main
arm site.
- Nutrient profiles indicate
that water quality in these embayments is influenced to a large extent
by retention time of the embayment and nutrient concentrations of tributaries
entering the embayment.
-Influences of urban development
on lake water quality were clearly observed in the Little River embayment
where chlorophyll concentrations were generally twice as high as those
at the dam. High concentration of phosphorus in water entering into this
embayment from Noonday Creek (a small watershed which contains >1/3 of
all urban development within the entire watershed) originate from point
sources as well as from nonpoint sources associated with urban development.
4. Temporal
variability in loading, as well as overall load, is important. Pollutant
loads originating from non-point sources are particularly variable over
time due to changing weather conditions and such variability was observed
to have negative effects on the lake, particularly in the Allatoona Arm:
-The bloom of a single
species of picoplankton occurred during a dramatic shift in relative concentrations
of phosphorus and nitrogen during drier condition.
-Non-algal turbidity in the
lake increased dramatically after major rain events (particularly during
winter months), reducing light penetration and impairing aesthetics of
the lake.
 |
An example of visibility data.
Visibility as measured by secchi depth over 5 years in the Allatoona Arm
(Station 28A) fluctuates seasonally with lower visibility occurring in
winter when storm events are more common and the lake is drawn down.
Other events such as the picoplankton bloom in 1993 affect visibility.
Click on graph to enlarge. |
5. Loss
of depth from sedimentation due to suspended solid load has not greatly
impaired overall lake use. However, significant sedimentation of embayments
was observed, particularly those associated with more urban watersheds
and visibility was greatly reduced throughout the lake after storm events.
6. From
a human health perspective, there is need for concern, but not alarm.
-Fecal coliform bacteria
levels rarely exceeded state standards in the lake, though much higher
levels were measured in tributaries, and suggests the potential for sudden
input of coliform bacteria during storm events.
 |
An example of changes in fecal coliform
bacteria concentration over 4 years in three of Lake Allatoona tributaries.
Click on graph to enlarge. |
-Few potentially toxic substances
were found above detectable levels, and only mercury and copper at a single
site exceeded state criteria. A single point source is not indicated.
IMPLICATION
OF LIMNOLOGICAL DATA FOR MANAGEMENT ALTERNATIVES
1.
Etowah Arm
The Etowah Arm is the largest
part of the lake in both surface area and volume. Water quality in this
arm can be considered as "potentially threatened". Water quality generally
meets the needs of most users, but chlorophyll levels and oxygen depletion
indicate that this arm is sufficiently mesotrophic to warrant concern about
future degradation. Most of the phosphorus enters the lake from the Etowah
sub-watershed (77%) and this phosphorus accounts for the general trophic
level in this arm. Management efforts in this watershed
should focus on agricultural and forestry practices. Future urbanization
using responsible development practices can be accommodated in this watershed
by improvements in rural non-point source control. Of the three areas of
the lake, the Etowah Arm is the largest by surface area and volume providing
the greatest use for recreation and flood control. Given that the lake
is currently a tremendous economic resource for the region ($113 million
per year; A. L. Burruss Institute of Public Service, 1994), present water
quality should be maintained at levels considered mesotrophic.
2.
Little River Arm
Embayments that receive tributaries
from more urbanized watersheds are more eutrophic than the main lake and
tended to have much higher rates of sedimentation. This is most clearly
observed in the Little River Arm, where water quality can be considered
"impaired" in that use is diminished often. The arm is sufficiently eutrophic
(chlorophyll a concentration typically exceeds 15 µg/l from April
to October and visibility is typically less than 1.5 meters) to be considered
unsuitable for swimming and aesthetics. Of all urban development in the
Lake Allatoona watershed, 50% occurs within the Noonday and Little River
sub-watersheds that drain into this embayment. Both point and non-point
sources from urban land use contribute to the eutrophication of the Little
River Embayment. Management efforts in this watershed
should focus on urban stormwater control and development practices, and
the success of these efforts should be considered in setting point source
permits.
3.
Allatoona Arm
Water quality in the Allatoona
Arm can be considered "threatened" in that significant degradation has
impaired use at times. Use of the lake as a source for drinking water was
impaired during the summer of 1993. Shift in the N:P ratio in summer of
1993 is a reasonable explanation for the previously unobserved bloom of
nanoplankton in the Allatoona Arm of the lake. Because nutrient concentrations
actually decline during this time, the sudden dominance of a single species
is likely the result of the inability of other species to tolerate extreme
fluctuations in nutrient concentrations. Variability in load over time,
as well as total load, contributes to the negative impact of nonpoint sources
on the lake. Management efforts in this watershed should focus on practices
that detain stormwater. There are no major point sources along tributaries
that enter this arm and forestry and agricultural practices are minimal.
As a result, practices associated with development must be strictly managed
to reduce non-point runoff in order to prevent transition of this large
lake arm to a eutrophic state, and to protect a drinking water source valued
at $18 million per year (A. L. Burruss Institute of Public Service, 1994).
In particular, management efforts in this watershed
should focus on practices that detain stormwater in order to reduce variability
in nutrient levels (i.e. retention ponds and wetlands).
 |
Photograph of Allatoona Arm tributary
after a storm event. Note the bright reddish color as sediments are
carried downstream hours after rainfall. |
