Below is the most up to date Toccoa River info, along with the "Official DNR summary regarding the impacts of the Blue Ridge Lake drawdown". Get involved muchachos', our rivers and streams can't stand up for themselves!
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11-19-10 Via: Becky Hulsey / Unicoi Outfitters
According to the Fannin County News Observer, Tom Gilliland of Blairsville is going to ask TVA to help provide funds to restock trout in the tailwater. Tom is on the TVA Board.
He stated its a "good thing for TVA to do." Sounds like he might of heard the comment of Kevin McGrath to do the "neighborly thing."
Thanks to Duane Miller for speaking with Tom. And, thanks to Fannin County News Observer for keeping on top of the situation.
Big Kudos to John Damer and others to working hard to putting fish back in the river. We have had some major stocking lately.
We officially organized the Toccoa River Watershed Coalition yesterday!!!
Thanks to everyone that has stepped up to help the Toccoa. Your voice does make a difference!
12-20-10 Via: Becky Hulsey / Unicoi Outfitters
Recovery is going good!
DNR has put around 13,000 fish in the river.
The water continues to be a greenish sometimes a brown color. TVA does not say they are generating because they are working on the penstock. But, they are releasing from the another area so be sure to check the website for an accurate release. The river has changed since the heavy generations of the past months and the water is not clear so be careful wading or floating.
Fishing reports are great when you can fish. Reports of large fish and large numbers. We are asking folks to return large fish to the river so they can get bigger and help reproduction in the river. Some nice size browns were able to make it through the drawdown. And, we do have natural reproduction of browns and rainbows in the tailwater.
Tom Gilliland of the TVA board was in the shop today. He said TVA is working on getting us fish to put in the river.
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Assessment and Preliminary Restoration Plan for the Toccoa
River Trout Fishery Following A Deep Drawdown of Blue Ridge
Lake 2010
River Trout Fishery Following A Deep Drawdown of Blue Ridge
Lake 2010
John Damer
Fisheries Biologist
Georgia Department of Natural Resources
11/15/2010
Introduction
To ensure public safety and meet increased dam safety standards, TVA
conducted a deep drawdown of Blue Ridge Lake as part of a rehabilitation
project on Blue Ridge Dam. The objective of the project is to repair the penstock
and stabilize the intake tower and both faces of the dam. TVA began to draw
down the lake on July 15, 2010 to an elevation approximately 66 feet lower than
normal summer elevation and intends to hold that level for roughly 6-months.
During the drawdown period, water temperatures as high as 26.4ºC (79.5ºF)
were recorded in the Toccoa River below the dam, as warm water from the lake
passed through the dam into the tailwater (GADNR, unpublished data). Water
temperatures in the tailwater as measured at the dam remained above 22ºC
(71.6ºF) for 41 consecutive days (TVA, unpublished data). Prolonged exposure
to temperatures above 22ºC can stress trout severely and lead to trout mortality.
The purpose of this assessment was to determine the extent of any impact these
high temperatures had on the trout fishery below Blue Ridge Dam. The findings
can then be used as a baseline for rebuilding the trout population.
To ensure public safety and meet increased dam safety standards, TVA
conducted a deep drawdown of Blue Ridge Lake as part of a rehabilitation
project on Blue Ridge Dam. The objective of the project is to repair the penstock
and stabilize the intake tower and both faces of the dam. TVA began to draw
down the lake on July 15, 2010 to an elevation approximately 66 feet lower than
normal summer elevation and intends to hold that level for roughly 6-months.
During the drawdown period, water temperatures as high as 26.4ºC (79.5ºF)
were recorded in the Toccoa River below the dam, as warm water from the lake
passed through the dam into the tailwater (GADNR, unpublished data). Water
temperatures in the tailwater as measured at the dam remained above 22ºC
(71.6ºF) for 41 consecutive days (TVA, unpublished data). Prolonged exposure
to temperatures above 22ºC can stress trout severely and lead to trout mortality.
The purpose of this assessment was to determine the extent of any impact these
high temperatures had on the trout fishery below Blue Ridge Dam. The findings
can then be used as a baseline for rebuilding the trout population.
Methods
Nine evenly spaced stations were sampled on July 19-20, 2010 (at the beginning
of the drawdown period) using boat-mounted electrofishing gear. The same sites
were sampled again on October 13-15, 2010 (at the end of the drawdown
period). Personnel, equipment, and methods were the same for all samples.
Electrofishing equipment consisted of a 5.5 m tunnel-hulled aluminum boat
equipped with a Smith-Root Type VI-A electrofisher supplying power to two boom
mounted electrodes. Electrofishing occurred moving downstream near the
shoreline and 30 minutes of effort (pedal time) was expended at each station. All
trout observed were netted and placed in a recirculating livewell. Each fish
collected was weighed to the nearest gram (g), measured to the nearest
millimeter (mm) and returned to the river.
Nine evenly spaced stations were sampled on July 19-20, 2010 (at the beginning
of the drawdown period) using boat-mounted electrofishing gear. The same sites
were sampled again on October 13-15, 2010 (at the end of the drawdown
period). Personnel, equipment, and methods were the same for all samples.
Electrofishing equipment consisted of a 5.5 m tunnel-hulled aluminum boat
equipped with a Smith-Root Type VI-A electrofisher supplying power to two boom
mounted electrodes. Electrofishing occurred moving downstream near the
shoreline and 30 minutes of effort (pedal time) was expended at each station. All
trout observed were netted and placed in a recirculating livewell. Each fish
collected was weighed to the nearest gram (g), measured to the nearest
millimeter (mm) and returned to the river.
Results
A total of 347 trout were collected during the July 2010 sample, while only 57
trout were collected during the October sample. This represents a total decline
of 83.6%. Catch rates at all nine electrofishing stations were lower in October
than in July (Figure 1). In the July sample brown trout represented 41.8% of the
total catch, increasing to 71.9% in October.
Catch rates declined across nearly all sizes of trout from July to October 2010
(Figure 2). No trout larger than 483 mm (19 in.) were captured during the
October sample. In the July sample 10 fish larger than 483 mm were captured,
with the largest measuring 567 mm (22.3 in.).
Mean condition (relative weight, Wr) declined significantly (t = 9.21, df = 77, p <
0.0001) from 96.5 to 80.2 in July and October, respectively (Figure 3).
A total of 347 trout were collected during the July 2010 sample, while only 57
trout were collected during the October sample. This represents a total decline
of 83.6%. Catch rates at all nine electrofishing stations were lower in October
than in July (Figure 1). In the July sample brown trout represented 41.8% of the
total catch, increasing to 71.9% in October.
Catch rates declined across nearly all sizes of trout from July to October 2010
(Figure 2). No trout larger than 483 mm (19 in.) were captured during the
October sample. In the July sample 10 fish larger than 483 mm were captured,
with the largest measuring 567 mm (22.3 in.).
Mean condition (relative weight, Wr) declined significantly (t = 9.21, df = 77, p <
0.0001) from 96.5 to 80.2 in July and October, respectively (Figure 3).
Discussion/Conclusions
The decline in catch rates of trout over the 3-month drawdown is substantial. For
reference, sampling during a similar period in 2009 (a non-drawdown year) also
showed declining catches from July to October, but this decline was much less
severe than was observed in 2010 (15.3% decline in 2009 vs. 83.6% in 2010).
It is important to note that an 83.6% decline in catch rate does not translate
directly into an 83.6% mortality rate. Mortality certainly would have contributed to
this decline, but there are other factors that could have contributed as well.
Like many other tailwater trout fisheries in the Southeast, the Toccoa tailwater
fishery is supported mostly through stocking. As a result, the timing and
numbers of fish released during stocking events plays a large part in the
numbers of trout present in the system at any particular time. In both 2009 and
2010 trout were stocked between July and October sampling periods,
confounding any direct estimation of mortality. The last major stocking event in
2009 occurred on 9/2/09, while stocking ceased roughly one month earlier this
year (8/4/10) as a direct result of the drawdown. By itself, this certainly could
have contributed slightly to the relatively higher decline in numbers in 2010
relative to 2009.
On the other hand, 27,995 trout were stocked between sampling periods in 2010.
This was more than 6 times the number stocked between sampling periods in
2009 (4,153 stocked in 2009). In reality, the 83.6% decline may have been
higher had GADNR not stocked so many fish late in 2010.
Migration of trout into or out of the Toccoa tailwater could have also influenced
catch rates. When environmental conditions are not favorable, trout often move
to seek better conditions. Unfortunately, record high average air temperatures
meant water temperatures in Toccoa River tributaries were also high during part
of the critical period. Water temperature measurements taken in several major
tributaries in August routinely showed temperatures in excess of 22ºC with
individual readings as high as 26.4ºC (GADNR, unpublished data). Tributary
temperatures moderated somewhat during the latter part of the critical period,
allowing for an unknown amount of emigration into these cool refuges. It is
unknown how many trout may have left the river or if they will return.
The lack of larger fish in the October sample may suggest that mortality was
especially high for the larger size classes of trout. It is important to note that fish
larger than 20 inches have been routinely captured in electrofishing surveys in
the tailwater over the past two years, with trout measuring over 28 inches and
weighing 14lbs observed. Anglers also commonly reported trout of similar sizes.
These fish were conspicuously absent in the latest sample.
The low mean relative weight of trout collected in October was consistent with
the severe stress to which these fish were subjected. Although the main stressor
(temperature) has now been removed from the environment, some of the
remaining trout may still struggle to survive due to their poor condition. It is
possible that elevated mortality rates could continue to act on the remaining
population.
At first glance, it would appear that the brown trout population was better suited
to tolerate higher temperatures than the rainbow trout population. In mid-July
2010 (at the beginning of the drawdown) brown trout were outnumbered by
rainbow trout; comprising only 42% of the total trout community. By October
brown trout were in the majority comprising 72% of trout collected. While
rainbow numbers declined by 92%, browns only declined by 72%. It is important
to note that more catchable brown trout (averaging >9 inches) were stocked
between sampling periods in 2010 than were rainbow trout (5,035 and 2,560
catchable brown trout and rainbow trout, respectively). Once again, differences
in stocking regimes confound any direct estimation of brown and rainbow trout
mortality. From these data alone, it is difficult to separate superiority in thermal
tolerance from differences in stocking.
The decline in catch rates of trout over the 3-month drawdown is substantial. For
reference, sampling during a similar period in 2009 (a non-drawdown year) also
showed declining catches from July to October, but this decline was much less
severe than was observed in 2010 (15.3% decline in 2009 vs. 83.6% in 2010).
It is important to note that an 83.6% decline in catch rate does not translate
directly into an 83.6% mortality rate. Mortality certainly would have contributed to
this decline, but there are other factors that could have contributed as well.
Like many other tailwater trout fisheries in the Southeast, the Toccoa tailwater
fishery is supported mostly through stocking. As a result, the timing and
numbers of fish released during stocking events plays a large part in the
numbers of trout present in the system at any particular time. In both 2009 and
2010 trout were stocked between July and October sampling periods,
confounding any direct estimation of mortality. The last major stocking event in
2009 occurred on 9/2/09, while stocking ceased roughly one month earlier this
year (8/4/10) as a direct result of the drawdown. By itself, this certainly could
have contributed slightly to the relatively higher decline in numbers in 2010
relative to 2009.
On the other hand, 27,995 trout were stocked between sampling periods in 2010.
This was more than 6 times the number stocked between sampling periods in
2009 (4,153 stocked in 2009). In reality, the 83.6% decline may have been
higher had GADNR not stocked so many fish late in 2010.
Migration of trout into or out of the Toccoa tailwater could have also influenced
catch rates. When environmental conditions are not favorable, trout often move
to seek better conditions. Unfortunately, record high average air temperatures
meant water temperatures in Toccoa River tributaries were also high during part
of the critical period. Water temperature measurements taken in several major
tributaries in August routinely showed temperatures in excess of 22ºC with
individual readings as high as 26.4ºC (GADNR, unpublished data). Tributary
temperatures moderated somewhat during the latter part of the critical period,
allowing for an unknown amount of emigration into these cool refuges. It is
unknown how many trout may have left the river or if they will return.
The lack of larger fish in the October sample may suggest that mortality was
especially high for the larger size classes of trout. It is important to note that fish
larger than 20 inches have been routinely captured in electrofishing surveys in
the tailwater over the past two years, with trout measuring over 28 inches and
weighing 14lbs observed. Anglers also commonly reported trout of similar sizes.
These fish were conspicuously absent in the latest sample.
The low mean relative weight of trout collected in October was consistent with
the severe stress to which these fish were subjected. Although the main stressor
(temperature) has now been removed from the environment, some of the
remaining trout may still struggle to survive due to their poor condition. It is
possible that elevated mortality rates could continue to act on the remaining
population.
At first glance, it would appear that the brown trout population was better suited
to tolerate higher temperatures than the rainbow trout population. In mid-July
2010 (at the beginning of the drawdown) brown trout were outnumbered by
rainbow trout; comprising only 42% of the total trout community. By October
brown trout were in the majority comprising 72% of trout collected. While
rainbow numbers declined by 92%, browns only declined by 72%. It is important
to note that more catchable brown trout (averaging >9 inches) were stocked
between sampling periods in 2010 than were rainbow trout (5,035 and 2,560
catchable brown trout and rainbow trout, respectively). Once again, differences
in stocking regimes confound any direct estimation of brown and rainbow trout
mortality. From these data alone, it is difficult to separate superiority in thermal
tolerance from differences in stocking.
Management Approach
Although a precise estimate of trout mortality cannot be determined, this
assessment indicates the loss was severe. As mentioned previously, one goal of
these electrofishing samples was to formulate a recovery plan to rebuild the
population as quickly as possible within the constraints of available resources. At
the same time, these early restoration efforts are moderated by the realization
that a delay in this project and lake refilling could cause temperature problems
next summer. Thus, the approach taken must balance the risk of additional loss
against the value of a winter fishery and early start to rebuilding the population.
With these considerations in mind, GADNR’s short-term objectives are as
follows:
Objective 1: Using estimates of survival and supplemental trout stocking, target
a standing crop of roughly 1,000 trout per mile by mid-November 2010 to provide
a winter and spring fishery.
Objective 2: The Federal Hatchery system will stock available surplus broodfish
to add diversity and interest to the winter fishery. This contribution by the
Federal Hatchery system is outside current capabilities of GADNR and is greatly
appreciated.
Objective 3: Resume a normal stocking schedule in 2011. If spring 2011
electrofishing samples show moderately depressed numbers, consider the
tailwater for receipt of any surplus fish that hatchery inventories might identify.
Objective 4: Discontinue stocking if water temperatures in the tailwater exceed
20ºC during the refill period in 2011. Revise restoration strategy, taking into
account current conditions in the tailwater and available resources in the
hatchery system.
Although a precise estimate of trout mortality cannot be determined, this
assessment indicates the loss was severe. As mentioned previously, one goal of
these electrofishing samples was to formulate a recovery plan to rebuild the
population as quickly as possible within the constraints of available resources. At
the same time, these early restoration efforts are moderated by the realization
that a delay in this project and lake refilling could cause temperature problems
next summer. Thus, the approach taken must balance the risk of additional loss
against the value of a winter fishery and early start to rebuilding the population.
With these considerations in mind, GADNR’s short-term objectives are as
follows:
Objective 1: Using estimates of survival and supplemental trout stocking, target
a standing crop of roughly 1,000 trout per mile by mid-November 2010 to provide
a winter and spring fishery.
Objective 2: The Federal Hatchery system will stock available surplus broodfish
to add diversity and interest to the winter fishery. This contribution by the
Federal Hatchery system is outside current capabilities of GADNR and is greatly
appreciated.
Objective 3: Resume a normal stocking schedule in 2011. If spring 2011
electrofishing samples show moderately depressed numbers, consider the
tailwater for receipt of any surplus fish that hatchery inventories might identify.
Objective 4: Discontinue stocking if water temperatures in the tailwater exceed
20ºC during the refill period in 2011. Revise restoration strategy, taking into
account current conditions in the tailwater and available resources in the
hatchery system.
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