[Bristol-Birds] TVA over flowing Boone Dam spillways -- creating earlier bird habitat

From: "BBC Net" <jwcoffey@xxxxxxxxxx>
To: "'bristol-birds'" <bristol-birds@xxxxxxxxxxxxx>
Date: Wed, 19 Nov 2014 21:28:11 -0500
Boone Dam flowing over spillway Nov 2014.jpg

This is a photo taken earlier this week as the Boone Dam spillway was
flowing at 60 percent or more of its

designed capacity in the vicinity of Tri-City Airport in Sullivan County,
TN.   It is a very rare sight

since overflow of the five spillways is mainly used to control major
flooding due to weather.   In normal

operation, we have not seen the spillways flowing over these five channels.
Usually,  water flowing past

the dam is passed thru the internal generators shown at the bottom left
(photo by Wallace Coffey).

 

 

We are enjoying an earlier than normal exposed mudflat habitat in

the Austin Springs, Bluff City and Beaver Creek Embayment of Boone

Lake.  This has probably produced better migrant stopovers and birding.

 

BooneL lake operating guide 19 Nov 2014.pngTVA accelerated the annual 

drawdown at Boone Lake so 

engineers could conduct 

more detailed study and 

investigation of a sinkhole 

and a small amount of water 

seeping from the river bank 

below the dam.  

In the graph, the red line shows 

the actual elevation levels tracked

for  Boone Lake this year.  The blue 

line is a target plan of elevation TVA

wanted to achieve before the leak was found.  The black shows what the

elevation levels were last year during 2013.

 

The winter drawdown is out of an abundance of caution and public safety 

is TVA's priority. The dam is structurally sound and carefully monitored.

 

The dam and reservoir are maintained and operated with a surface area of 

about 4,400 acres  and a flood-storage capacity of 75,829 acre feet. 

 

Water levels in the reservoir fluctuate over a range of about 20 feet over 

the course of a year.   TVA can drop the reservoir elevation 2 feet per day 

and 7 feet for the week.

 

At 11 a.m. Wednesday (today- 19 Nov 2014), TVA was over flowing the 

spillways at a rate of 3,300 cubic feet per second.  The inflow from the 

South Fork Holston River and Watauga River was at 2,055 cubic feet 

per second.

 

The entire spillway has a maximum discharge capacity of about 7,000

cubic feet per second.  The five radial gates shown above each are

32 feet high and 40 feet wide.   

 

TVA  officials started the annual depth drawdown of Boone Lake about 

five weeks ahead of schedule.  When an Oct. 20 inspection of the dam 

revealed a sink hole, TVA workers repaired it quickly. 

 

Six days later, an uncommon occurrence happened when seepage was 

found near the location of the sink hole at the base of the dam.

 

The over flow at the spillways will probably continue for an extended

period.

 

As posted here earlier by Rick Phillips of Kingsport,  all access to birding

in the area above the main gate to the visitor center and above the dam

near the beach are closed to the public.  

 

Security officers are guarding this area to keep the public out.

 

Wallace Coffey

Bristol, TN
[Bristol-Birds] TVA over flowing Boone Dam spillways -- creating earlier bird habitat

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