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Tailwaters

Started by Onslow, December 12, 2018, 22:30:45 PM

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Onslow

December 12, 2018, 22:30:45 PM Last Edit: December 13, 2018, 21:03:19 PM by Onslow

Lets beat the bushes for data, and learn a few things.  Lets start with the Jackson River tailwater below Gathright.  Measuring location is just below the dam.

Drainage size at Gathright Dam: 345 sq. miles
Average flow/acre-feet ratio (full pool): .00389562
Mean flow: 436 cfs
Mean flow for July: 288 cfs
Mean flow for August: 277 cfs
Mean flow for September: 269
Average river channel width: ~120'
Max temp for 2017, July: 62 degrees. 62 for 2016
Max temp for 2017, August: 62 degrees.  63 for 2016
Max temp for 2017, September: 62 degrees.  64 for 2016
Estimated trout habitat: 17 miles
Average streambed gradient for aforementioned section: ~10 feet per mile
Lowest daily mean flow for 2017: 156 cfs (September)
Lowest daily mean/average stream width ratio: 1.3 cfs/1' of width streambed
Altitude of upper end of tailwater: 1400'
Lake depth: ~150'

Smith River

Drainage size at Philpott: 216 sq. miles
Average discharge/Acre-Feet ratio (full pool): .00255535
Mean flow: 277.5
Mean flow for July: 254 cfs
Mean flow for August: 259 cfs
Mean flow for September: 249 cfs
Average channel width around Bassett: ~80'
Average channel width below Martinsville: ~100' except in a few wide rapids
Max temp for 2016, July: 52 degrees
Max temp for 2016, August: 55.4 degrees
Max temp for 2016, September: 58.28
Estimated tailwater trout habitat: 25 miles.  Ends near Eggleston Falls.
Average Gradient: 8 FPM.  Some areas reach almost 20 FPM
Lowest daily mean for 2017 (September): 119 cfs
Lowest daily mean/average stream width ratio (Bassett): 1.49
Altitude at upper end: 804'
Lake depth: 170'

Highest mean temps for the Summer of 2018 @ Martinsville was 74.5 degrees.  This was a very brief spike.  No data for 2016.

Basset readings are not really available 2016.  The following numbers are for 2017

July max: 64.8
August max: 64.6
September max: 66.2

Thus far it appears the depth of Philpott and the lower rates of outflow vs. capacity affect discharge temps.  The Smith also has less streambed exposure to the sun, but temps are probably augmented by Martinsville Lake.

Cataloochee Creek

Max temp July, 2016: 69.8 degrees
Max temp for August 2016: 71.4
Max temp for September: 68.5

The looch temps were taken at the gage station which is nearing the transition point.

Pound River @ Flannagan Dam

Drainage size @ dam: 221 sq. miles
Average discharge: 291.7 cfs
Average discharge/Acre-feet ratio: .002002
Average July discharge: 131 cfs
Average August discharge: 114 cfs
Average September discharge: 104 cfs
Lowest daily mean for 2017 (April): 13.6 cfs
Lowest daily mean for Summer: 53.7 cfs
Altitude below dam: 1210'
Lake depth: 190'
Tailwater length: 2 miles.  Pound river enters Russell Fork 2 miles from the dam.  Russell Fork holds trout down to Breaks Interstate Park.
Average streambed width: ~75'
Temps at dam are not available.


Dougfish

"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? " -Oddball, 1970

"I don't wanna go to hell,
But if I do,
It'll be 'cause of you..."
Strange Desire, The Black Keys, 2006

Onslow

Going to add a few more tailwaters that are not trout worthy.  Unfortunately, I cannot procure good data for the Soho, Clinch, Pound, Watauga, Gauley, R.D. Baily.  Gonna throw some some streams for Cataloochee.  All content will be added to the first post, and not another.


Dougfish

December 13, 2018, 20:07:14 PM #3 Last Edit: December 13, 2018, 21:04:04 PM by Dougfish

Are both of your temp stats coming from the first gauge below each dam?

A fact we haven't addressed on these two tailwaters: feeders.
Outside of Townes Ck., the Smith has no coldwater feeders. And Townes is borderline. Yeah, The Smith has has some springs and seeps. But...
The Jackson below Gathright has numerous coldwater feeders. Some of them fairly substantial. Has to help.

"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? " -Oddball, 1970

"I don't wanna go to hell,
But if I do,
It'll be 'cause of you..."
Strange Desire, The Black Keys, 2006

Onslow

Yes.  But I'll post some up for Basset and Martinsville.  Coming atcha in a moment


ryguy

What about the temps right above Martinsville Dam?  The water at that point is warmed, thus the release over that dam will always keep downstream temps warmer.  Is that truly the case?

I don't follow it as much but with the changes in Philpott's releases, was there a significant shift in the Martinsville releases?

Sent from my iPhone using Tapatalk

Dougfish

Quote from: ryguy on December 13, 2018, 21:13:22 PM

What about the temps right above Martinsville Dam?  The water at that point is warmed, thus the release over that dam will always keep downstream temps warmer.  Is that truly the case?

I don't follow it as much but with the changes in Philpott's releases, was there a significant shift in the Martinsville releases

The shallow pond above Martinsville is what it is. The generations at Martinsville are what they are. When they have a back up of water, they generate.
When they don't, they don't. With only one generator at Philpott, the volume of cold water is halved.
The trout fishery below Martinsville is fukkered for a few, at least, more years. Yea, there will be some browns, there. But it's a shadow of what it was.
Pay your taxes. Pray the feds get the new turbines installed. Pray they don't ef it up. Pray for no droughts. Get a raft. Learn to fish high flows.
"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change? " -Oddball, 1970

"I don't wanna go to hell,
But if I do,
It'll be 'cause of you..."
Strange Desire, The Black Keys, 2006

Onslow

I still think wet Aug-Septembers the primary nemesis for the lower Smith.  Note the high water, and warm water.  The warm follows 12-24 hours after the surge.
Please review the hydrograph link below.

https://nwis.waterdata.usgs.gov/va/nwis/uv/?cb_00010=on&cb_00060=on&format=gif_default&site_no=02073000&period=&begin_date=2018-07-01&end_date=2018-10-01


Onslow

Quote from: Dougfish on December 13, 2018, 20:07:14 PM

Are both of your temp stats coming from the first gauge below each dam?

A fact we haven't addressed on these two tailwaters: feeders.
Outside of Townes Ck., the Smith has no coldwater feeders. And Townes is borderline. Yeah, The Smith has has some springs and seeps. But...
The Jackson below Gathright has numerous coldwater feeders. Some of them fairly substantial. Has to help.

Tailwater feeders are the Smith's problem.  By the time reaches Eggleston Falls, 40% of the flow is fed by warm tailwater feeders.  Add September tropical moisture, and the system crashes.  A wet spring and a dry Aug and Sept is good for the lower Smith.  This year we had a dry Spring and a very wet and warm fall.

Mudwall Gatewood 3.0

Quote from: Onslow on December 13, 2018, 22:20:10 PM

Quote from: Dougfish on December 13, 2018, 20:07:14 PM

Are both of your temp stats coming from the first gauge below each dam?

A fact we haven't addressed on these two tailwaters: feeders.
Outside of Townes Ck., the Smith has no coldwater feeders. And Townes is borderline. Yeah, The Smith has has some springs and seeps. But...
The Jackson below Gathright has numerous coldwater feeders. Some of them fairly substantial. Has to help.

Tailwater feeders are the Smith's problem.  By the time reaches Eggleston Falls, 40% of the flow is fed by warm tailwater feeders.  Add September tropical moisture, and the system crashes.  A wet spring and a dry Aug and Sept is good for the lower Smith.  This year we had a dry Spring and a very wet and warm fall.
The bottom-line is you're pushing the limits of an artificial managed ecosystem.  You can only go so far downstream before the nuances of mother nature attempts to restore what is standard or what used to be stock.     
"Enjoy every sandwich."  Warren Zevon


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