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8/6/2019 Appendix D - Pre-Hydro Water Quality Study
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Lake Milton Hydroelectric Project Hydro Energy Technologies, LLC
Pre-Hydro Water Quality Study November 11, 2010
1
FERC Project No. 13402
Lake Milton Hydroelectric Project
Hydro Energy Technologies, LLC
PRE-HYDRO WATER QUALITY STUDY
By:
31300 Solon Rd Suite 12
Solon, Oh 44139
November 11, 2010
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TABLE OF CONTENTS
1 PROJECT BACKGROUND .............................................................................................................. 3 1.1 STUDY OBJECTIVES .......................................................................................................................... 3
2 PROJECT DESCRIPTION AND PROPOSED OPERATIONS .................................................... 4 2.1 DESCRIPTION OF EXISTING DAM, RIVER AND IMPOUNDMENT .......................................................... 4 2.2 DESCRIPTION OF PROPOSED PROJECT AND OPERATIONS..................................................................11
3 METHODOLOGY ............................................................................................................................18 3.1 LITERATURE REVIEW.......................................................................................................................18 3.2 INSTRUMENTATION..........................................................................................................................18 3.3 SAMPLING METHODS AND LOCATIONS ............................................................................................18 3.4 SAMPLING SCHEDULE ......................................................................................................................24
4 RESULTS AND DISCUSSION ........................................................................................................24 4.1 GENERAL REVIEW OF FACTORS IMPACTING DO AT HYDROPOWER FACILITIES...............................24
4.1.1 Reservoir Factors ..................................................................................................................24 4.1.2 Watershed Factors .................................................................................................................30 4.1.3 Tailwater Factors ..................................................................................................................30 4.1.4 Special Case – Below Ice Oxygen Depletion .........................................................................34
4.2 BIOLOGICAL EFFECTS OF LOW DISSOLVED OXYGEN .......................................................................35 4.2.1 Growth ...................................................................................................................................36 4.2.2 Reproduction .........................................................................................................................36 4.2.3 Behavior and Swimming Performance ..................................................................................36 4.2.4 Early Lifestages .....................................................................................................................37 4.2.5 Fisheries Diversity .................................................................................................................37 4.2.6 Susceptibility to Disease ........................................................................................................38 4.2.7 Trophic Interactions ..............................................................................................................38 4.2.8 Non-Fish Species Response to Low Dissolved Oxygen .........................................................38
4.3 SUMMARY OF RESERVOIR CHARACTERISTICS AT LAKE MILTON .....................................................39 4.4
G
ENERALE
XISTINGW
ATERQ
UALITYD
ATA AT THEP
ROJECTS
ITE................................................39
4.5 PRE-HYDRO DO LEVELS BELOW DAM.............................................................................................40 4.6 PRE-HYDRO TEMPERATURE DATA BELOW DAM .............................................................................42 4.7 PRE-HYDRO DO & TEMPERATURE LEVELS IN LAKE UPSTREAM OF DAM .......................................46 4.8 DISCUSSION OF POTENTIAL MITIGATION MEASURES TO IMPROVE DO LEVELS BELOW DAM .........48
4.8.1 Bypass Flows .........................................................................................................................48 4.8.2 Selective Withdrawal .............................................................................................................48
5 CONCLUSIONS & PROPOSED STANDARDS ............................................................................49 6 REFERENCES ...................................................................................................................................52 APPENDIX A – RAW STUDY DATA ......................................................................................................55
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PRE-HYDRO WATER QUALITY STUDY
LAKE MILTON HYDROELECTRIC PROJECT (FERC #13402)
1 PROJECT BACKGROUND
Pursuant to section 4.38(b) of the Code of Regulations Hydro Energy Technologies, LLC
(HET) has completed the first stage consultation requirements for the proposed
hydroelectric facility at the Lake Milton Dam (FERC # P-13402).
During consultation the USACE requested that data be collected to determine the existing
or “pre-hydro” water quality conditions (specifically dissolved oxygen and temperature).In the Provisional Nationwide Permit issued by the USACE on June 7, 2010 condition 3states the following:
Dissolved oxygen monitoring from August to October is to be conducted to
determine the existing condition of the Mahoning River directly downstream of
the dam. This data will be utilized in mitigating dissolved oxygen levels if
necessary.
1.1 Study Objectives
The primary goal of this study was to determine the existing or “pre-hydro” water qualityconditions (specifically dissolved oxygen and temperature) directly downstream of the
dam from August to October. This information will be used to mitigate dissolved oxygenlevels if necessary during hydro operation. Study objectives include:
a. Estimate the existing range of dissolved oxygen (DO) below the dam in
mg/L as well as in % saturation from August to October.b. Calculate the existing range of water temperature below the dam from
August to October.
c. Determine Pre-hydro DO and temperature levels and stratification patternsin Lake Milton upstream of the dam by depth from August to October.
d. Collect data to determine if hydro operation using gate 2 during the winter
will affect DO and temperature levels downstream or upstream of the dam.
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2 PROJECT DESCRIPTION AND PROPOSED
OPERATIONS
2.1 Description of Existing Dam, River and Impoundment
The original dam located along the Mahoning River was constructed in 1913 by theCity of Youngstown for the purposes of flood protection and water supply to the steel
mills located in the city of Youngstown, Ohio. In 1970 seepage and evidence of
instability on the downstream west abutment was noted. Youngstown relinquished
control of the dam to the Ohio Department of Natural Resources and ODNR began
rehabilitation of the dam which it completed in 1988. Although the dam no longersupplies water to the steel mills in Youngstown, it continues to provide flood protection
to the Mahoning Valley as well as low flow regulation and recreational opportunities tothe area. The dam is operated by the Lake Milton State Park under the supervision of the
Pittsburgh District of the US Army Corps of Engineers (USACE). The nominal surface
area of the existing impoundment created by the existing dam is 1,685 acres.
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LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
STREET LEVEL MAP
Proposed PlantLocation
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LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
PROJECT LOCATION MAP
Proposed Plant
Location
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The proposed hydro plant shown in Figure 2-1 is located on the Mahoning River
and is fed by a total drainage area of approximately 273 square miles. Flow levels at the
proposed site were determined using the data from the USGS gaging station 03091500 onthe Mahoning River located .3 miles downstream of the Milton Dam near Pricetown.
Figure 2-1 – Mahoning River Watershed
USGS
Gaging
Station
Proposed
Hydro Site
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Figure 2-2 and Table 2-1 represent the daily mean flows from August
1979 to August 2009 for the Mahoning River at the Pricetown gaging station:
Mahoning River FDC
0
500
1,000
1,500
2,000
2,500
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
% Time Flow Exceeded
F l o w ( c
f s )
Figure 2-2
% Time Flow Exceeded Q (cfs)
0 2,430
5 1,110
10 835
15 615
20 466
25 362
30 289
35 247
40 213
45 186
50 172
55 162
60 152
65 138
70 12975 115
80 97
85 85
90 70
95 47
100 13 Table 2-1
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Monthly mean data from the USGS Station from years 1979 to 2009 was used to
create the hydrograph and data table for the Mahoning River labeled Figure 2-3 and
Table 2-2 respectively.
Mahoning River Hydrograph
0
50
100
150
200
250
300
350
400
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
M e a n F l o w ( c
f s )
Figure 2-3
Month Mean Flow (cfs)
Jan 320
Feb 338
Mar 365
Apr 290
May 290
Jun 284
Jul 251
Aug 256
Sep 276
Oct 237
Nov 240
Dec 298Mean 287.1
Table 2-2
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downstream. The Corps' policy for our projects is for non-degradation of water quality. What we
would do, is gather and collect lake and downstream data to define the current state, then
calibrate a model. Then we would model various scenarios and see what happens. I would start by
modeling the parameters water temperature and dissolved oxygen, but there may be other
parameters. The CE-QUAL and CE-QUAL2 models have been used at other reservoir projects,
but there may be other models.
Werner
Mean Lake Elevation
934
936
938
940
942
944
946
948
950
E l . ( f t ) 1990-2007
Jan 2008- Aug 2009
1990-2007 942.59 942.35 943.65 946.73 948.03 948.19 948.19 948.21 948.03 947.27 945.03 942.95
Jan 2008- Aug 2009 940.02 941.13 942.93 947.35 948.32 948.46 948.38 948.09 948.04 947.31 944.93 942.53
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 2-4 – Mean Historical Lake Elevations obtained from the USACE Pittsburgh District
2.2 Description of Proposed Project and Operations
The current design (Figure 2-5) uses the existing intake and connects a 800 mm
diameter 650 KW S-Type Kaplan Turbine to the exisiting 60" outlet pipe on gate 2 belowthe dam. The proposed powerhouse would be constructed over the existing discharge
location where the turbine and generator will be housed. The proposed location of the
turbine and powerhouse are shown in Figure 2-6 & Figure 2-7.
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Figure 2-5
NEW TRASH RACK WITH 1” BAR SPACING INSTALLED OVER EX.
TRASHRACK
NEW 800 MM DIA.
TUBULARHORIZONTAL
KAPLAN
Spillway
Using Ex.
Gate 2
Conduit
LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
PROJECT PLAN - PROPOSED
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Figure 2-6 - Photo of existing dam and outlet works
Figure 2-7 – Conceptual Sketch of Dam and Proposed Powerhouse
Proposed
Powerhouse
Location
Existing
Spillway Existing OutletWorks
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LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
PROFILE – EXISTING CONDITIONS
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NEW
TRASHRACK
WITH 1” BAR SPACING
INSTALLED
OVER EXISTING
EX. APRONS
ELECTRIC ACTUATORSFOR SLUICE GATES
962.4
EXISTING
STRUCTURE
AIR VENT
SLOT FOREMERGENCY
BULKHEAD
EX. SLUICE GATES
EXISTING 60” DIA.CAST IRON CONDUIT
SLUICE GATE STEM
907.0
EX. END SILL
922.0
915
USE EXISITN
STILLING BASIN
USE EXISITNG 3’CONCRETE FLOOR SLAB AS
SYSTEM FOUNDATION
SUMMER POOL EL. 948.0
WINTER POOL EL. 940.8
EX. SPILWAY CREST EL. 951
INVERT EL. 913.0
901.0
TAILWATER LEVEL El 908.0
LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
PROJECT PROFILE - PROPOSED
PROPOSED 800 MM DIA.
HORIZONTAL TUBULAR
KAPLAN TURBINE
PROPOSED POWERHOUSE
CONSTRUCTED OVEREX. STRUCTURE
SILT BUILD UP
1” BAR SPACING
.25” BAR THICKNES
1” BAR WIDTH
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The proposed flow operations during hydro operation do not modify lake
elevations or discharge levels dictated by the USACE. The only modification is thetiming of which gates are used. Since the 250 cfs capacity turbine will be installed on
gate 2, all flows up to 250 cfs are proposed to be discharged through gate 2 so that hydro
power production can be continuous throughout the year except during winter whenwater is typically discharged through the lower gates.
All flows above 250 cfs would be discharged through an alternate gate. Table 2-3and Figure 2-8 show how the proposed gate use schedule would differ from existing
operations. The total flow use curve is shown in Table 2-4.
CURRENT DISCHARGE CAPACITY AT LAKE MILTON (CFS)
Lake E. (ft) GV 1 GV 2 GV 3 GV 4 Total
940 600 600 690 0 1890
942 620 620 700 0 1940
948 690 690 770 0 2150
952 740 740 810 0 2290
DISCHARGE CAPACITY WITH HYDRO (CFS)
Lake E. (ft) GV 1 GV 2 GV 3 GV 4* Total
940 600 250 690 690 2230
942 620 250 700 700 2270
948 690 250 770 770 2480
952 740 250 810 810 2610 Table 2-3 – Gate Discharge Capacity at Lake Milton (Current and with Hydro)
*Gate 4 is currently inoperable and will be repaired by HET if Hydro is approved.
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Flow Duration Curve November to April 1978-2008
0
500
1,000
1,500
2,000
2,500
0 10 20 30 40 50 60 70 80 90 100
% Time Flow Exceeded
F l o w ( c f s )
Total Flow
Hydro Flow
Figure 2-8
% Time Flow Ex. Total Flow (cfs) Hydro (cfs) Other 60" Discharge Pipes (cfs)
0 2,430 250 2218
5 1,110 250 898
10 835 250 623
15 615 250 403
20 466 250 25425 362 250 150
30 289 250 77
35 247 247 35
40 213 212 1
45 186 186 0
50 172 172 0
55 162 162 0
60 152 152 0
65 138 138 0
70 129 129 0
75 115 115 0
80 97 97 0
85 85 85 0
90 70 70 0
95 47 47 0
100 13 0 13 Table 2-4 – Total Flow Use Curve
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3 METHODOLOGY
3.1 Literature Review
A literature review was conducted to present a brief summary of general factors
impacting DO levels at hydro power facilities. Included is a discussion of the specific
site conditions at the Lake Milton Project and how these specific reservoir and rivercharacteristics might influence DO levels during hydro operation. Also included is a
summary of the biological effects of low DO.
3.2 Instrumentation
HET used the YSI ProODO Optical Dissolved Oxygen Meter for this study. This is anaccurate portable unit measuring dissolved oxygen (in either mg/L or % saturation) as
well as temperature and barometric pressure with short term data logging capability (80
hours or more of up to 2,000 data points). The data sheet for this unit is shown in Figure
9 and Figure 10.
Additionally DO and other water quality measurements taken by the OEPA in 2006 at the
project site as well as temperature data from USGS gage 03091500 located .3 milesdownstream of the Milton Dam near Pricetown as well as USGS gage 03090500 located
upstream of the proposed project below the Berlin Dam will be used to supplement data
obtained by HET. Water quality data at Berlin Lake provided to HET from the USACE
Pittsburgh District in 2009 was also used in this analysis.
3.3 Sampling Methods and Locations
Condition 3 of the provisional NWP 17 states that the testing must occur directly downstream of the dam. Therefore samples were taken within the stilling basin directly below
the dam as well as further down stream and in the lake at varying depths (Figure 14).
HET took spot samples as well as continuously logged data (Figure 11 and Figure 12).
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Figure 9
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Figure 10
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Figure 13 – General HET Sampling Locations
Stilling Basin
WWTP Outfall
CR @ Gas
Line
Pricetown @
Northbridge
Upstream of
Dam @ the
Intake at Varying
De ths
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Figure 14 – Sampling locations
LAKE MILTON HYDROELECTRIC PROJECT
FERC # P-13402
PLAN & PROFILE OF EXISTING DAM
GATE 4
GATE 3
GATES
1&2
Upstream
of Dam
Samples Taken
at 5 Ft.
Increments
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3.4 Sampling Schedule
A total of 219 Samples were taken from August 9th
, 2010 to October 6, 2010. All flows were
discharged through gate 2 during the study therefore most samples were taken directly
downstream of gate 2 where the most re-aeration was occurring and DO levels were the highest.More samples were taken in August and September as DO levels are typically lowest during
these two months. HET used spot sampling as well as continuous logging with 1 hour intervals.There were 42 samples in August that were not used (not included in the 219 total) due to excess
algae growth on the probe during logging compromising the results. The sample summary is
shown in Table 5 and the raw data is included in Appendix A.
Table 5: Summary of Samples Used in this Study
Month Gates 1&2 Gate 3 Gate 4 Lake Other Total
Aug 70 27 2 16 2 117
Sep 68 4 4 9 4 89
Oct 2 1 1 9 0 13
Total 140 32 7 34 6 219
4 RESULTS AND DISCUSSION
4.1 General Review of Factors Impacting DO at Hydropower Facilities
Sections 4.1 and 4.2 including all tables and figures are taken entirely from the 2002 EPRI reportentitled Maintaining and Monitoring Dissolved Oxygen at Hydroelectric Projects: Status Report
which provides an excellent summary of issues related to dissolved oxygen at hydro projects
located at reservoirs. The sections directly taken from the EPRI report are shown in italics.
4.1.1 Reservoir Factors
Reservoir processes that affect DO are significantly influenced by the physical characteristics of
reservoirs. Probably the most significant characteristics are the volume and through-flow of the
project, which can be represented by the calculated retention time (summer volume/average flow
rate) of water in the project. Run-of-river projects typically have retention times of less than
about 25 days; storage projects typically have retention times greater than about 200 days.“Transitional” projects have retention times that fall within the range of about 25 to 200 days.
At summer pool, Lake Milton has a storage capacity of 24,000 acre feet and a mean flow of
287.1 cfs which calculates to an average retention time of 42.1 days.
Thermal Stratification
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Retention time and depth of outlet are the main factors that affect thermal stratification within
reservoirs, which, in turn, affect the routing of “density currents” through reservoirs. An
understanding of these density currents is important to determining how DO is affected at
various locations within reservoirs.
Figure 15 illustrates typical temperature profiles depicting annual stratification patterns for various types of reservoir projects. Thermal stratification begins when the reservoir surface
water warms and floats on top of the colder water in the reservoir. Figure 16 illustrates the
relationship between density and temperature of water. As the warm season progresses, the
epilimnion enlarges due to solar incidence and mixing caused by wind energy. The metalimnion
also increases in volume due to the withdrawal of hypolimnetic water through the outlets, as well
as the spring and summer inflows that are cooler than the epilimnion but warmer than the
hypolimnion. These inflows seek an appropriate water depth in the metalimnion having a density
somewhere between the epilimnion and the hypolimnion. The metalimnia and hypolimnia in
hydropower reservoirs are very dynamic due to the relatively high flows through these projects
and the use of lower level outlets. It is in these two layers where density currents occur and DO
is dominated by consumption processes and not replenished by the atmosphere or algal productivity.
In deep storage reservoirs, stratification is strong (large difference in temperature between the
top and bottom) and generally persists through the summer and fall. Quite often the colder water
in the reservoir originally during the winter may remain in the hypolimnion until the next fall.
This is especially true if the outlet is at a mid-level point within the reservoir and the withdrawal
zone does not extend to the reservoir bottom.
In transitional reservoirs, thermal stratification is somewhat weaker than in storage
impoundments because the cold winter inflows are released more rapidly from the bottom. The
winter water is replaced by warmer inflow water as the warming pattern progresses into thesummer and fall. Usually these types of reservoirs will maintain some form of stratification even
though it will be weaker than that of storage impoundments. Transitional reservoirs that have
storage impoundments a short distance upstream will not demonstrate this typical thermal
pattern if the inflows remain cold through the summer and fall because cold inflows drop
beneath the warm surface and continue to maintain the strong thermal stratification.
For run-of-river reservoirs, the colder water is released even more rapidly and the resulting
stratification is weaker, particularly in June, July, and August. Often during these latter two
months stratification may not even occur, except under low flow conditions such as those that
occur during droughts.
At Lake Milton Thermal Stratification is minimal in August (see section 4.7) and resembles that
of a run of river reservoir. The reservoir is relatively shallow (40 ft at the intake during summer)and two of it’s 4 intakes are located at the bottom and the other two are approximately 7 ft higher
than the bottom but would generally still be considered low level intakes. A summary of the
reservoir characteristics at Lake Milton are shown in
Table 8 in section 4.3 of this report.
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Figure 15
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Figure 16
Environmental Processes in Reservoirs that Affect DO
The environmental processes that affect DO can be separated into three longitudinal zones and
four thermal layers. The longitudinal zones include the riverine, transitional, and lacustrine
zones. The thermal layers include the epilimnion, the warmer portion of the metalimnion (which
usually is composed of interflows that result from inflows to reservoirs during the months of May
through September), the cooler metalimnion (which usually represents inflows during the months
of March and April), and the hypolimnion. In the areas of the U.S. where inflows are comprised
of significant amounts of snowmelt, cooler inflows may persist until June. These zones and layers
are illustrated in Figure 17 showing that DO within a reservoir is usually low immediately above
the sediments and in the warmer metalimnion, which occupies a comparatively larger portion of
the reservoir.
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Figure 17
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Table 6
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As discussed in the previous section, the lower layers are density currents that essentially are
isolated layers that do not mix in the reservoir until the temperatures of the layers become about
the same as the epilimnion, usually in the fall of each year. Hence, to determine how the DO
balance is affected in a reservoir, it is important to analyze the changes that take place in each
layer of water. The longitudinal zones are useful for describing the changes in water quality as
the water passes through the reservoir. Table 6 presents a limnological description of the processes involved in these zones and the resulting DO dynamics.
4.1.2 Watershed Factors
Clearly, the amount of precipitation and inflow temperatures affect thermal stratification, but
other factors can also be important. For example, the size of the watershed draining into the
reservoir affects not only the amount of flow through the reservoir but the natural organic
loading and other non-point sources of nutrients to the reservoir as well. Precipitation intensity
and frequency also affect the transport and timing of watershed water quality constituents such
as organic matter. Since thunderstorms occur more frequently in the southeast (Kennedy and
Gaugush 1988), the reservoirs in this region may receive greater loads.
Regarding streamflow patterns, upstream reservoir projects significantly alter the natural
hydrologic runoff, e.g., high spring natural runoff quantities can be shifted to late summer and
fall high volume reservoir releases. Such a shift in flow quantity significantly affects downstream
reservoir processes affecting DO.
Another significant watershed factor that affects DO levels is the dominant source of inflow. The
typical storage impoundment will have one or two primary sources of inflow, accounting for 70
percent or more of the reservoir inflow volume. However, some impoundments can have
significantly dispersed inflow quantities coming from multiple tributaries. Such dispersed inflows
can complicate significantly the reservoir processes that may affect DO within a reservoir. Anupstream (reservoir) with low-level releases can significantly alter temperature in the inflow.
(EPRI 1990).
Reservoirs having watersheds with significant snowmelt during the spring can exhibit the
same DO dynamics seen for southeastern reservoirs. However, these dynamics will lag in time
corresponding with the temperature and peak inflow hydrology that is characteristic in the
northern regions. In the south, the peak inflow hydrology is dominated by more direct runoff
from spring rains that occur during March through May.
4.1.3 Tailwater Factors
The DO in the tailwater is affected primarily by characteristics of the hydropower releases,
various tailwater hydraulic conditions, the presence of aquatic weeds, and various DO
consumption processes. Mechanistic formulations for riverine DO predictions can be found in a
comprehensive review by Bowie et al. (1985). A qualitative description of the factors is provided
here.
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Characteristics of DO in Reservoir Releases
The large volume of reservoir releases usually dominates water quality in tailwaters. Hence,
changes in operational characteristics can significantly change DO in downstream reaches and
cause both short- and long-term cyclical variations.
The cyclical nature of DO in a tailwater is significantly affected by the mode of operation for
hydro generation and must be considered in determining the exposure characteristics of
sitespecific DO variation to aquatic life. For instance, brief exposures of fish to DO levels as low
as 3 mg/L may not be harmful (EPRI 1990).
Because of the dominant influence of flow and release DO level on downstream DO levels,
seasonal variations in these factors are important. High release flow and DO is common in the
winter. Low flow and high DO is common in the spring during filling of the reservoirs
concurrent with cold water temperatures. Flows increase with summer power generation and
low DO is common in summer and fall due to warmer water being released from within the
reservoir.
Re-Aeration
Atmospheric re-aeration occurs at the air-water interface and affects dissolved oxygen
concentrations throughout the water column by turbulent mixing of surface water to deeper
depths. The re-aeration rate is usually stated as a product of a re-aeration coefficient, K 2 (see
EPRI 1990 Appendix C) and the DO deficit below saturation. Expressions for the reaeration
coefficient have been developed by many investigators, where K 2 is directly related to mean
velocity and inversely related to mean depth, suggesting a dual effect of an increase in flow on
K 2. However, increased depth is more significant than increased velocity, so the reaeration rate
typically decreases with higher flow in most rivers (see Figure 18). Higher flows also reduce thetravel times between two river stations, decreasing the opportunity for re-aeration as well as the
re-aeration coefficient.
Figure 18
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Aquatic vegetation (algae, macrophytes) contributes oxygen to the water column during
photosynthesis and consumes oxygen for respiration. Photosynthesis is roughly confined to the
third of the day with the highest solar radiation, while respiration is more evenly distributed
throughout the day and night (depending primarily on temperature). Photosynthetic oxygen
production can be quite high, normally exceeding respiration demand during this third of theday (except perhaps on overcast days), while respiration demands prevail at night when there is
no photosynthesis. Thus, the aquatic plant community can be a net source of oxygen in daytime
hours and a net demand for oxygen at night. Depending on the aquatic plant density, respiration
during low flow can create localized reaches of low DO in pre-dawn hours that are lower than
the low DO caused by dam releases. Daily average production and demand may vary, but are
often in approximate balance with one another in the range of 5 to 10 g O2 /m2 /d each.
Sediment Oxygen Demand (SOD)
Bacterial decomposition of organic matter (leaf litter, dead bacterial growth, and dead aquatic
plants) in sediments also consumes oxygen from the water column. Another source of organicdeposits is particulate matter from wastewater treatment plant discharges. Respiration of the
benthic community during decomposition of organic sediments can create significant oxygen
demands, especially in pools where organic deposits may be significant and the residence time of
water over the sediments is prolonged. Sediment oxygen demand of most river mud falls in the
range of 0 to 2 g O2 /m2 /d, but can exceed 10 g O2 /m2 /d downstream from municipal and industrial
discharges.
Research conducted by Mackenthun and Stefan (1993) on the effects of near bottom flow
velocities on SOD indicates that oxygen demand increases linearly with water velocity over the
range of velocities tested (1.0 to 10.0 cm/s [0.03 to 0.33 ft/s]). In quiescent lake water in
Minnesota, average SOD values range from 0.5 to 2.0 g/m2
/d (Fang and Stefan 1993). Therefore,SOD can double if flow velocities are minimally increased (on the order of 1.0 cm/s (0.03 ft/s).
Poorly designed lake aerators systems can disturb sediments and lower or negate their ability to
aerate the hypolimnion (see further discussion in Section 4 – Hypolimnetic Aeration).
Other Factors
Temperature plays a role in tailwater atmospheric heat exchange due to solar and atmospheric
radiation. Heat transfer and release temperatures both effect the temperatures of tailwaters.
Heat transfer plays the dominant role during times of low flow, while release temperatures are
more influential during periods of high flow. Solar radiation also provides energy for plant
photosynthesis with associated oxygen production. As discussed earlier, temperature determines
both the saturation oxygen concentration and the rates of most physical and biochemical
processes affecting DO. The rates of many biochemical processes can double with a 10 _C (50ºF)
rise in temperature in the range of temperatures found in many tailwaters.
There are additional factors specific to certain tailwaters that may have important effects on the
local oxygen budget. These include: oxidation of reduced chemical elements (iron, sulfide, and
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manganese) in releases, quantity and quality of tributaries, presence of toxic compounds, and
respiratory demands of localized heavy concentrations of mussels or other fauna.
4.1.4 Special Case – Below Ice Oxygen Depletion
Low dissolved oxygen conditions can also arise in colder climates during the winter months that
may kill fish. This “winterkill” condition is common in eutrophic lakes and reservoirs that have
long periods of ice and snow cover. Severe oxygen depletion under ice leads to fish losses.
Winterkill usually occurs when a water body is entirely ice- and snow-covered. Open ice allows
for a greater level of light penetration and subsequent photosynthetic activity of plants and
algae. Photosynthetic activity, in turn, produces oxygen. Dissolved oxygen levels are, therefore,
lowest when light penetration is minimized by snow and ice cover. Often times, DO depletion is
coupled with the build-up of toxicants such as ammonia (NH 3) and hydrogen sulfide (H 2S) (Fast
1994).
Two processes lead to low DO concentrations under ice-cover: (1) respiratory oxygen demand and other oxidation processes exceed the level of oxygen output from photosynthesis and (2) the
total oxygen reserve at the time the water body freezes over is insufficient to compensate for
oxidation and respiration losses during time of ice-cover (Fast 1994).
Minimum fish requirements for DO are lower under ice-cover than during other times of the
year due to lower fish activity levels and subsequent low metabolic rates. Wetzel (1983) suggests
that fish can survive at DO levels as low as 2 mg/L when water temperatures range from 2º to
5ºC (36º to 41ºF). Other researchers have indicated that fish will survive at even lower DO
levels (Table 7) and that tolerance is species- and lifestage-specific.
Table 7
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Lakes and reservoirs most likely to be affected by winterkill are shallow, eutrophic, have little
water flow-through, have mucky, silty or black organic bottom sediment and whose shorelines
have a large amount of submergent or emergent plant vegetation (Piening 1977, Nickum, 1970).
Analysis of oxygen depletion rates under 70 Canadian lakes by Mathias and Barcia (1980),
indicates that the principal source of DO depletion occurs in the sediments rather than in thewater column. Sediments in eutrophic lakes consumed oxygen three times as fast as oligotrophic
lakes (0.23 vs. 0.08 g/m2 /d). According to a literature review conducted by Ellis and Stephan
(1989), the biochemical oxygen demand associated with the decomposition of organic materials
in the sediments of ice-covered lakes may be the largest demand on DO.
It is very difficult to assess the effects of winterkill management practices, because there is little
opportunity to establish a control time or period. Comparing across years within the same water
body is confounded by considerable year-to-year variation. Site-specific variation between water
bodies even geographically proximate does not lend itself to valid comparisons. Only prevention
of winterkill over many seasons, especially in water bodies that only occasionally experience
winterkill (i.e., once every three, five or ten years) can convincingly demonstrate winterkill prevention techniques. Few experiments have provided such a rigorous assessment, but most
provide value judgments regarding a winterkill prevention techniques’ efficacy.
Several of the technologies used to mitigate low DO levels in reservoir releases during warm
months can also be utilized for mitigating factors that cause winterkill conditions. Designing
wintertime aeration systems may be complicated by severe weather and icing conditions. In
addition, some technologies that cause mixing of stratified water layers may cause ice to weaken
or disappear. If the ice surface is used recreationally (e.g., skating, ice fishing), such options
may not be feasible. Wintertime aeration systems are not addressed specifically in this report.
4.2 Biological Effects of Low Dissolved Oxygen
Dissolved oxygen (DO) is one of the most influential water quality parameters on the health of
aquatic ecosystems and fisheries populations. When DO concentration fall below certain levels,
water becomes incapable of sustaining aquatic life. Above the lethal limit, DO acts as a limiting
factor to the growth of fish.
A full discussion on biological responses of fish, based on the investigation of numerous studies,
is included in EPRI 1990 (Section 5). A brief summary of those findings is included here, with
the addition of recent studies.
The focus of the discussion below is on salmonids (Family Salmonidae), as there are morestudies investigating the effect of low DO on these species than with other species, since they are
readily available, easy to maintain and of great economic importance. Although it could be
argued that low DO concentrations have adverse effects on all species of fish in all water body
types, in the following discussion secondary emphasis has been placed on those species likely to
be impacted by hydropower operation. Discussion is grouped by physiological responses or
population responses to varying dissolved oxygen concentrations.
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4.2.1 Growth
In general, for salmonid species, as dissolved oxygen levels decrease there is a corresponding
drop in median growth rates. The effects of low DO are amplified at higher water temperatures
as a result of increased metabolic activity (EPRI 1990).
4.2.2 Reproduction
Very little information is available on the effects of low dissolved oxygen on the fecundity,
fertility and reproductive success of fish. What information that does exist (EPRI 1990) suggests
that low dissolved oxygen has a negative effect.
4.2.3 Behavior and Swimming Performance
Fish can detect zones of low dissolved oxygen and will actively try to avoid them. Early
lifestages (e.g., larvae, juveniles) fish appear less able to detect areas of low DO and are,
therefore, less able to avoid them. The distribution of fish within a body of water can be affected by the avoidance behavior of some fish species to areas of low DO.
There is often a strong link between DO levels and water temperatures. In a thermally stratified
water body experiencing hypolimnetic DO depletion, DO and temperature are two of the most
influential factors affecting the distribution of fish species. As water below the thermocline
becomes depleted of DO, fish are faced with a trade-off between moving to shallow warmer
water with higher levels of DO and associated heat stress or remaining in cool, DO depleted
waters and the associated hypoxic stress. Below are some recent examples of studies conducted
on the effects of low DO on the behavior (especially habitat selection) of fish.
Aku et al. (1997) compared the vertical distribution of cisco (Coreonus artedi) in a basin of alake during and after oxygenation to an unoxygenated lake. The use of hypolimnetic oxygenation
increased dissolved oxygen concentrations and expanded cisco habitat up to 9 m (29.5 ft) in
depth. Expansion was limited by water temperature.
Bodensteiner and Lewis (1992) observed that freshwater drum (Aplodinotus grunniens)
aggregated in pockets of warm backwater eddies in winter. These warmer areas had higher
dissolved oxygen levels than other, cooler portions of the river. The authors speculate that
winterkills may be associated with periodic man-made or natural disruptions to thermal refuges
and subsequent drops in dissolved oxygen levels.
Jones and Reynolds (1999) compared the parental care and hatching success in subsequent brood cycles of the common goby (Pomatoschistus microps) reared in hypoxic and normal
oxygen conditions. In low dissolved oxygen, males increased the amount of time and the tempo
with which they fanned eggs in the nest. In addition, they spent less time engaged in nest-
building activities. Males under low oxygen conditions lost more weight than those in normal
oxygen conditions, and were more likely to abandon a second brood. Hatch weight and survival
of offspring did not differ between those reared in hypoxic and normal oxygen conditions,
although eggs hatched an average of one day earlier under normal oxygen conditions.
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Knights et al. (1995) used radiotelemetry to observe the winter habitat selection of bluegills
(Lepomis macrochirus) and black crappie (Pomoxis nigromaculatus) under varying levels of
dissolved oxygen, water temperature and current velocity. When DO concentrations were above
2 mg/L, both species selected areas with water temperatures greater than 1 C (34ºF) with no
detectable current. When DO dropped below 2 mg/L, fish moved to areas of higher DO despitelower temperatures and current velocities at or above 1 cm/s (0.03 ft/s). For these warmwater
species, DO appears to be the dominant factor in the trade-off between temperature and
dissolved oxygen.
Matthews and Berg (1997) observed the habitat selection of rainbow trout (Oncorhynchus
mykiss) in a California stream whose temperatures frequently rises to lethal levels. Distribution
in two stream pools (pools 1 and 2) was largely based on temperature and dissolved oxygen.
Pool 1 was observed to have a bottom temperature of 21.5 C (70.7ºF) and a top temperature of
28.9 C (84.0ºF), while pool 2 had a bottom temperature of 17.5 to 21 C (63.5º to 89.8ºF) and a
surface temperature of 27.9 C (82.2ºF). After August 5, when stream temperatures were
dangerously high, no trout were found in pool 1. Pool 2, however, contained trout throughout the study period. Most trout were found in the region of the pool with the lower temperature
where dissolved oxygen was lowest. For this coldwater species, temperature appears to be the
dominant factor in the trade-off between temperature and dissolved oxygen.
4.2.4 Early Lifestages
For salmonid species, whose earliest lifestages occur in gravel substrates, low dissolved oxygen
in the intergravel spaces can delay development and hatching, and increase the mortality of
embryos.
Although the early lifestages of salmonids do not have a greater need for dissolved oxygen thanother lifestages, intergravel dissolved oxygen levels are typically lower than overpassing waters.
Intergravel DO levels are dependent upon DO diffusion rates, rates of water convection, and
rates of respiration of intergravel organisms. Studies and field observations indicate that DO
levels in natural salmonid redds are approximately 3 mg/L lower than overpassing water (EPRI
1990).
For non-salmonids, early lifestages tend to be more sensitive to the adverse affects of low DO
than other lifestages. In the range of 3 to 6 mg/L, several investigations show a reduction in
survival and significant damage to early lifestages. Susceptibility to low levels of DO among
non-salmonids is species-specific. Largemouth bass, black crappie, white bass and white sucker
appear to be more tolerant of low DO levels than channel catfish, walleye, northern pike and smallmouth bass.
4.2.5 Fisheries Diversity
Previous studies have looked at the abundance of fish and their relative health in relation to
dissolved oxygen levels. There is some indication that lower levels of dissolved oxygen may
negatively influence the diversity of fish communities. These types of studies are limited,
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however, in their ability to quantify the long-term effects of exposure to low levels of DO on fish
communities (EPRI 1990).
4.2.6 Susceptibility to Disease
Fish show an increased susceptibility to disease when exposed to low levels of dissolved oxygen.Caldwell and Hinshaw (1995) observed significant variation in mortality rates of rainbow trout
associated with different levels of dissolved oxygen when fish were exposed to the bacteria
Yersinia ruckeri. Interestingly, increased mortality was observed in both hypoxic and hyperoxic
conditions relative to normal oxygen conditions.
4.2.7 Trophic Interactions
Provided that there is a species-specific response of organisms to low levels of DO, there could
be possible disruptions to organism interactions when exposed to non-lethal but reduced levels
of DO. Breitburg et al. (1997) showed that low dissolved oxygen affects predation rates in a
“zooplankton – fish larvae – larval predator food web”. For example, low non-lethal levels of dissolved oxygen greatly increased predation of larval fish by sea nettles. Changes in species
interactions varied according to each species physiological tolerance for low dissolved oxygen
levels and the subsequent effects of low DO on escape behavior, swimming response, and feeding
behavior. Low DO may greatly affect the relative importance of differing energy pathways.
Although this research was conducted to evaluate low DO in an estuarine environment, it is
possible that a similar disruption in trophic interactions may occur in riverine or lacustrine
environments.
4.2.8 Non-Fish Species Response to Low Dissolved Oxygen
As shown in the example above, DO levels affect all aquatic organisms, not just fish. Dinsmoreand Prepas (1997a and b) describe the changes in Chironomus spp. abundance and biomass and
the changes in macroinvertebrate abundance and diversity following hypolimnetic oxygenation
in a eutrophic lake. Hypolimnetic oxygenation occurred in the northern basin of Amisk Lake
from 1988 to 1981. During that time, mean summer DO levels in the deep hypolimnion (25 m [82
ft]) rose from a pre-treatment level of 0.0 mg/L to 2.7 mg/L. Profundal (15 to 25 m [49 to 82 ft])
Chironomus spp. abundance increased from <100 to >2000 per m3. Unlike previous studies,
measures of diversity (Shannon-Weaver indices) decreased with increased oxygenation. Similar,
but less pronounced, patterns of density and abundance occurred in the south basin undergoing
smaller increases in DO levels. A nearby reference lake showed no change in macroinvertibrate
communities during the same study period. Response to oxygenation among several
macroinvertebrates was species-specific with some species increasing in abundance and densitywhile other species declined.
Nie et al. (1999) observed tadpole habitat selection during the warmer months at two ponds. One
pond, exposed and shallow, was wind mixed and experienced complete water column turnover.
A second pond, protected and deeper, experienced incomplete water turnover. It was found that
DO in the second pond fell below critical levels at depths of less than 2 m (6.6 ft). When this
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occurred, the tadpoles favored depths near 2 m (6.6 ft), reversing their winter tendency to move
towards shore and shallower water.
4.3 Summary of Reservoir Characteristics at Lake Milton Table 8: Summary of Lake Milton Reservoir Characteristics
Lake Characteristics Lake Milton Classification
Retention Time (Days) 42.1 Transitional
Approximate Depth (ft) at Summer Pool
at Dam
40 Run of River
Aug/Jul Thermal Stratification Minimal Run of River
Dam Intake Location Bottom N/A
Modification of Flows Yes Transitional
Upstream Resevoir Yes N/A
Type of Reservoir Upst Transitional N/A
Mean Flow (cfs) 287.1 N/A
Drainage Area (sq mi) 273 N/ASource of Inflow Approx 91% from Berlin
and 9% other drainage and
tributaries
N/A
Type of Tailwater Shallow and Fast N/A
4.4 General Existing Water Quality Data at the Project Site
Existing Water Quality Data for this segment of the Mahoning River is shown in Table 9.
Table 9: Water Quality Data from EPA Sampling For Mahoning River Upstream and Downstream
of Proposed Project (OEPA, 2008)
Location
Drainage
Area (sq.
miles)
Current
Aquatic
Life Use
Attain-
ment
Status IBI MIWB QHEI ICI
Mahoning River UST of
Lake Milton (RM 70.7)248 WWH Partial 28-30 8.41-9 78.5 30
Mahoning River DST of
Lake Milton (RM 62.7) 274 WWH Partial 26-34 8.14-9.18 80.5 34
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DO (%) Levels Below Dam
0
20
40
60
80
100
120
7 8 9 10 11
Month
D O ( % )
All HET Samplesin varyingLocations belowthe Dam
HET MedianValues
EPA 2006Samples
Figure 21
Figure 22 – Water Quality measurements taken on September 6, 2010
Stilling Basin
8 mg/L94.4 % sat
23.7 C
WWTP Outfall
8 mg/L
93.9 % sat
23.6 C
CR @ Gas Line
7.54 mg/L
88.4% sat
23.3 C
Pricetown @
Northbridge
8.1 mg/L
94.1% sat
22.8 C
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4.6 Pre-Hydro Temperature Data Below Dam
Approximately 91% of the Inflow at Lake Milton is from the Berlin Lake Dam, a 70 foot
deep reservoir operated by the USACE located about 8 miles upstream of the proposed project(Figure 23). Berlin’s intake is at the bottom of the dam releasing the cooler water settling at the
bottom during the summer (Figure 24). This cool water flowing in from Berlin is warmed inLake Milton as evidenced by the warmer mean outflows below the Lake Milton Dam (Figure
25). In general 2010 temperature samples obtained by HET during the study as well as the data
obtained from the USGS gage were warmer than average temperatures below the dam duringAugust and closer to the mean in September and October (Figure 27 & Figure 28).
Project
Location
Figure 23
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Berlin Thermal Stratification
0
10
20
30
40
50
60
70
80
7.0 9.0 11.0 13.0 15.0 17.0 19.0 21.0 23.0 25.0 27.0
Temp (C)
D e p t h ( f t )
Apr
May
Jun
Jul
Aug
Figure 24 – Mean Thermal Stratification Patterns at Berlin Dam 1969 to 2009 (reservoir 8 mi upstream 70 ft
deep with low level intake). Data was obtained from the USACE in 2009.
Mean Temperature Data from USGS gages
0
5
10
15
20
25
jan feb mar apr may jun jul aug sep oct nov dec
T e m p ( C )
Milton Outflow Temp
Inflow from Berlin
Figure 25 – Mean Temperature Data from USGS gages upstream and downstream
of the proposed project (1992-2010 for Lake Milton outflow and 1969-2009 for
Berlin outflows).
Approx. Intake
El. At Berlin
Dam
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Temperature Data (C) below Lake Milton Dam
0
5
10
15
20
25
30
7 8 9 10 11
Month
T e m p e r a t u r e ( C O
All HET Samples atvarying locationsbelow dam
HET median Values
Figure 28 – Temperature Data obtained from the 2010 HET study directly below
the dam
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4.7 Pre-Hydro DO & Temperature Levels in Lake Upstream of Dam
The data shows that Lake Milton behaves like a run-of-river reservoir in terms of thermal
stratification patterns (Figure 29). During the study period (August to October) stratification wasgreatest in on August 30
th, 2010, and by October 6, 2010 the lake was completely unstratified
and mixing was complete. The lake will likely remain uniform top to bottom until the weatherbegins to warm in the spring.
Lake Temperature Upstream of Dam
0
5
10
15
20
25
30
35
40
45
0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0
Temp (C)
D e p t h
16-Aug
30-Aug
18-Sep
6-Oct
Figure 29 – Temperature Profile of Lake Milton at the Dam Intake (note complete mixing
and lack of thermal stratification by Oct 6th
)
In general dissolved oxygen levels at the dam intake mirrored temperature patterns
showing the greatest top to bottom disparity in August and mostly uniform levels top to bottomwere reached by October 6th (Figure 30 and Figure 31).
of Intakes 1 & 2
of Intakes 3 & 4
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Lake DO levels
0
5
10
15
20
25
30
35
40
45
0 2 4 6 8 10 12
DO (mg/L)
S a m p l e D e p t h ( f t )
Aug-16
30-Aug
18-Sep
6-Oct
Figure 30
DO (%) Upstreeam of Lake Milton Dam
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100 120 140
DO (%)
D e p t h ( f t ) 16-Aug
30-Aug
18-Sep
6-Oct
Figure 31
. of Intakes 1 & 2
of Intakes 3 & 4
of Intakes 1 & 2
of Intakes 3 & 4
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4.8 Discussion of Potential Mitigation Measures to Improve DO Levels Below Dam
4.8.1 Bypass Flows
Bypass flows involve discharging flows through one of the existing non-hydro gates. Changes in
the timing and duration of flow releases, as well as spilling or sluicing water, increasing mixing
flows can all be used to boost DO levels (Peterson et al. 2001).
Benefits
Bypass flows are the existing condition as well as the least invasive mitigation for low DO
levels. No additional structures, machinery or pipelines are required. Bypass flows can beincreased incrementally until either the minimum standards are reached or 100% of the flow is
being bypassed.
Cost
Any flow that is bypassed is flow that is not converted in to renewable energy. The over use of
bypass flows can threaten project feasibility and financial sustainability.
4.8.2 Selective Withdrawal
Selective withdrawal is a method of improving water quality both downstream and upstream of a
dam. DO concentrations downstream of a reservoir are improved by withdrawing water at an
elevation above the thermocline. DO concentrations in a stratified reservoir can be increased by
discharging water from the hypolimnion layer, however, this approach will decrease DOdownstream. The feasibility of incorporating a selective withdrawal system to enhance DO
levels depends on many factors, including the configuration of the discharge structure, reservoir
stratification cycle, energy budget, reservoir water quality distribution and characteristics,economics of modifications, and competing objectives (EPRI 1990).
The Lake Milton Dam already has the infrastructure in place to use selective withdrawaltechniques. Using the existing vertical wet well that extends throughout the depth of the
reservoir, water may be drawn from different elevations by actuating a series of gates or raising
or lowering a bulkhead (Figure 32). There is some trade off with selective withdrawal including:
Improving water quality downstream may decrease water quality in the reservoir and
vice-a-versa. Drawing water from above the thermocline will increase DO levels downstream but
would also increase temperature levels downstream where as drawing from the
hypolimnion will decrease DO downstream but would lower water temperatures
downstream.
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Figure 32
5 CONCLUSIONS & PROPOSED STANDARDS
The pre-hydro DO levels below the Lake Milton Dam are well above the state average. This ismost likely due to the re-aeration that currently occurs in the tailwaters beginning with the
discharge splashing and spraying out of the outlet pipes and continuing with the shallow fast
moving conditions of the river extending for several miles. Based on the results of this studyHET proposes the following standards and operating procedures August to October:
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1. Minimum Acceptable DO Levels & Temperature Range to be Maintained During
Hydro Operation
Table 10: Proposed Minimum DO Levels to be Maintained During Hydro Operation
State
Average
State
Min
Level
State M
Leve
mg/L % Sat Temp © mg/L % Sat Temp © mg/L mg/L % Sat
August 3.19 - 7.48 37.8 - 89.2 19.7-26 6 70 19.7-26 5 4 110
September 6.23 - 8.31 71.5 - 92.7 15.8-29.2 6 70 15.8-29.2 5 4 110
October 6.56 - 8.82 67.3 - 90.5 10.2-22.5 6 70 10.2-22.5 5 4 110
Proposed Min Acceptable
Levels During Hydro
Pre-Hydro Sample Range (Includes
HET, EPA & USGS Data)
2. Proposed Mitigation for Lowered DO levels or Out of Range Water TemperatureDuring Hydro Operation - If levels drop below the proposed standards, HET will use
bypass flows until DO levels reach 6 mg/L and 70% saturation and temperature is within the
pre-hydro range. HET proposes to use the selective withdrawal method as a secondarymitigation option if hydro operation is significantly reduced from August to October (more
than 40% of the total flow is being bypassed). If no combination of bypass flows and
selective withdrawal methods are able to maintain the pre-hydro standards, hydro operation
will be shut down and 100% of flows will be bypassed (existing condition), until theproposed standards can be met.
3. DO Monitoring During Hydro Operation – HET will provide continuous, monitoring of
DO levels below the dam during hydro operation from August to October for the first 3 yearsof operation. HET will use the YSI Pro ODO and post the real time data (mg/L and % sat)
on the internet. The website address will be provided to all interested parties. Temperature
and flow will continue to be monitored by the USGS gage .3 miles down stream and the datacan be access through the USGS website.
4. Proposed Winter Hydro Operations - According to the ERPI report (1990) reservoirs thatlack thermal stratification in the winter (such as Lake Milton) allow mixing of the water from
all elevations. Therefore elevation of the intake is not a critical factor in the winter in terms
of DO and temperature at Lake Milton. So the current practice of switching to the lowergates in the winter is not consequential in terms of temperature and dissolved oxygen above
or below the dam. According to the EPRI report (1990) this practice makes sense for somestorage reservoirs several hundred feet deep which typically use mid level intakes and where
extreme stratification occurs in the late summer and fall (temperature range of approximately20 degrees Celsius or more). Lake Milton does not meet any of these criteria. It is shallow
(approximately 40 ft in the summer and 32 feet in the winter when the gate switch occurs),
all intakes are toward the bottom, it has a short retention time of approximately 42 days whilestorage reservoirs have retention times of 200 days or greater, and there is minimal
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stratification in the late summer (difference of less than 6 degrees Celsius compared to the 20
degrees or more that typify storage reservoirs).
According to the results of this study HET submits that operating the hydro turbine from
gate two during the winter will not alter DO or temperature levels in the lake or
downstream during the winter and should be authorized. HET is willing to test the DOand temperature levels at the dam intake at varying depth intervals each fall to confirm full
mixing has occurred top to bottom prior to operating the turbine during the winter. If full
mixing has occurred (as determined by uniform DO and temperature levels top to bottom)HET proposes that full turbine operation is authorized for the winter from gate 2. If full
mixing has not occurred prior to switching to the lower gates, HET will not operate the
turbine until either full mixing occurs and is documented or until HET can provide other
sufficient documentation that there will be no negative impacts to water quality by operatingthe turbine from gate 2 during the winter.
Other general conclusions reached based on the results of this study include the following:
Lake Milton behaves like a Run of River Reservoir in terms of thermal
stratification during the late summer. Minimal stratification occurred in the late
summer during this study with a maximum temperature disparity of about a 6
degree Celsius from surface to bottom.
Although the turbine will release water more gently and provide less initial re-aeration, the shallow fast moving tailwaters below the Lake Milton dam provideample opportunity for re-aeration of discharge flows for several miles. So
although there may be some temporary decrease in DO levels within the stilling
basin during hydro operation compared the pre-hydro condition, it is anticipated
that levels remain within the pre-hydro range (min 6 mg/L or 70% saturation) andwill continue to re-aerate as flows travel down stream.
The methodologies used in this study are based on recommendations from the EPRI (1990)
report and are more than adequate for determining the pre-hydro DO levels. The proposedstandards to be maintained during hydro operation are well above the state average and
consistent with the data obtained during this study.
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6 REFERENCES
Aku, P. M. K., L. G. Rudstam and W. M. Tonn. 1997. Impact of hypolimnetic Oxygenation on
the vertical distribution of cisco (Coregonus artedi) in Amisk Lake, Alberta. Canadian Journal of Fisheries and Aquatic Sciences 54: 2182-2195.
Bodensteine, L. R. and W. M. Lewis. 1992. Role of Temperature, Dissolved Oxygen, and
Backwaters in the Winter Survival of Freshwater Drum ( Aplodinotus grunniens) in theMississippi River. Canadian Journal of Fisheries and Aquatic Sciences 49: 173-184.
Bowie, G. L. et al. 1985. Rates, Constants, and Kinetics Formulations in Surface Water QualityModeling (2nd Edition). EPA/600/3-85/040, Tetra Tech, Inc. for Environmental Research Lab,
Athens, GA.
Breitburg, D. L., T. Loher, C. A. Pacey and A. Gerstein. 1997. Varying Effects of Low
Dissolved Oxygen on Trophic Interactions in an Estuarine Food Web. Ecological Monographs
67(4): 489-507.
Caldwell, C. A. and J. M. Hinshaw. 1995. Communications: Tolerance of Rainbow Trout to
Dissolved Oxygen Supplementation and a Yersinia ruckeri Challenge. Journal of Aquatic
Animal Health 7: 168-171.
Dinsmore, W. P. and E. E. Prepas. 1997a. Impact of Hypolimnetic Oxygenation on Profundal
Macroinvertebrates in a Eutrophic Lake in Central Alberta. I. Changes in Macroinvertebrate
Abundance and Diversity. Canadian Journal of Fisheries and Aquatic Sciences 54: 2157-2169.
Dinsmore, W. P. and E. E. Prepas. 1997b. Impact of Hypolimnetic Oxygenation on Profundal
Macroinvertebrates in a Eutrophic Lake in Central Alberta. II. Changes in Chironomus spp.Abundance and Biomass. Canadian Journal of Fisheries and Aquatic Sciences 54: 2170-2181.
Electric Power Research Institute (EPRI). 1990. Assessment and Guide for Meeting Dissolved
Oxygen Water Quality Standards for Hydroelectric Plant Discharges. GS-7001
Electric Power Research Institute (EPRI). 2002. Maintaining and Monitoring Dissolved Oxygen
at Hydroelectric Projects: Status Report. Palo Alto, CA: 2002 1005194.
Ellis, C. R. and H. G. Stefan. 1989. Oxygen Demand in Ice-Covered Lakes as it Pertains to
Winter Aeration. Water Resources Bulletin 25(6): 1169-1176.
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Lake Milton Hydroelectric Project Hydro Energy Technologies, LLC
Pre-Hydro Water Quality Study November 11, 2010
53
Fast, A. 1994. Preventing Winterkill in Lakes and Ponds. Reviews in Fisheries
Science 2(1): 23-77.
Fang, X. and H. G. Stefan. 1993. Model Simulations of Dissolved Oxygen Characteristics in
Minnesota Lakes: Past and Future. Environmental Management 18(1): 73-92.
Jones, J. C. and J. D. Reynolds. 1999. Costs of Egg Ventilation for Male Common Gobies
Breeding in Conditions of Low Dissolved Oxygen. Animal Behaviour 57: 181-188.
Kennedy, R. H. and R. F. Gaugush. 1988. Assessment of Water Quality in Corps of
Engineers Reservoirs. Lake and Reservoir Management 4(2): 253-260.
Knights, B. C., L. B. Johnson and B. M. Sandheinrich. 1995. Responses of Bluegills and Black Crappies to Dissolved Oxygen, and Current in Backwater Lakes of the Upper Mississippi River
during Winter. North American Journal of Fisheries Management 15: 390-399.
Matthews, K. R. and N. H. Berg. 1997. Rainbow Trout Responses to Water Temperature andDissolved Oxygen Stress in Two Southern California Stream Pools. Journal of Fish Biology 50:
50-67.
Mathias, J. A. and J. Barcia. 1985. Gas Supersaturation as a Cause of Early Spring Mortality of
Stocked Trout. Canadian Journal of Fisheries and Aquatic Sciences 42: 268-279.
Makenthun, A. A. and H. G. Stefan. 1993. Experimental Analysis of Sedimentary OxygenDemand in Lakes: Dependence on Near-Bottom Flow Velocities and Implications for Aerator
Designs. University of Minnesota, St. Anthony Falls Hydraulic Laboratory Project Report No.
344.
Moss, D. D. and D. C. Scott. 1961. Dissolved Oxygen Requirements of Three Species of Fish.
Transactions of the American Fisheries Society 90(4): 377-393.
Nie, M., J. D. Crim and G. R. Ulrsch. 1999. Dissolved Oxygen, Temperature, and Habitat
Selection by Bullfrog ( Rana catesbeiana) Tadpoles. Copeia 1999(1): 153-162.
Ohio Environmental Protection Agency (OEPA), (2008). Biological and Water Quality Study of
the upper Mahoning River and Selected Tributaries 2006 . OEPA Technical Report EAS/2008-
10-8, Columbus, Oh.
Ohio Environmental Protection Agency (OEPA), (2008). Appendices to the Biological and
Water Quality Study of the upper Mahoning River and Selected Tributaries 2006 . OEPA
Technical Report EAS/2008-10-8, Columbus, Oh.
Patriarache, H. H. and J. W. Merna. 1970. A Resume of Winter Management of Midwestern
Winterkill Lakes. In: Symposium on the Management of Midwestern Winterkill Lakes. pp. 7-18.
E. Schneberger (Ed). Special Publication North Central Division, American Fisheries Society,Bethesda, MD.
8/6/2019 Appendix D - Pre-Hydro Water Quality Study
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Lake Milton Hydroelectric Project Hydro Energy Technologies, LLC
Pre-Hydro Water Quality Study November 11, 2010
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Peterson, M. J., G. F. Čada and M. J. Sale. 2001. Non-Structural Approaches for Addressing
Dissolved Oxygen Concerns at Hydropower Facilities. Waterpower 2000. HCI Publications.
Petrosky, B. R., and J. J. Magnuson. 1973. Behavioral Responses of Northern Pike, Yellow
Perch, and Bluegill to Oxygen Concentrations under Simulated Winterkill Conditions. Copeia1:125-133.
Piening, R. 1977. Potential Winterkill Lakes in Walworth, Kenosha, and Racine Counties,Wisconsin 1935-1975. Fish Management Report 92. Wisconsin Department of Natural
Resources, Madison, WI.
Thene, J. R., J. G. Stefan and E. I. Daniil. 1989. Low-Head Hydropower Impacts on StreamDissolved Oxygen. Water Resources Bulletin 25(6) 1189-1197.
Wetzel, R. G. 1983. Limnology 2nd Edition. Saunders College Publishing, Philadelphia.
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APPENDIX A –
Raw Study Data
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