Norfork Minimum Flow Update from AGFC

As you all are probably aware, the siphon at Norfork has been offline since October 7th.  My apologies for not sending an e-mail sooner.

The current issue with the siphon is with the lakeside water sensor, which helps indicate fullness of the siphon.  It malfunctioned and caused the siphon to shut down.  The approximate time to get the replacement sensor will be 3-4 weeks.  In the mean-time, they are once again using the “speed-no-load” operation to achieve minimum flow.  Several folks have contacted AGFC personnel to express concerns about minimum flow, or a lack there of, over the last week or so.  I contacted the COE this a.m. to check into this situation.  It is my understanding that the Little Rock district COE folks assumed that “speed-no-load” has been operating at a cfs (cubic feet per second) level equivalent to that of minimum flow.  However, after contacting them this morning, they looked a little closer and found that it was actually operating (at times) at a cfs level up to ½ ft lower than minimum flow.  This was because the power house operators were trying to operate as close to 0 MWh (megawatt hours) as possible, and as a result, they were not achieving the minimum flow target of 300 cfs.  To rectify the situation, and get as close to minimum flow as possible, the power house operators will now try to achieve the minimum flow cfs, regardless of the mWh put out by speed-no-load.  In other words, you should not observe any more periods where flow is significantly lower than that of minimum flow.  If you do, please let me know ASAP.

Thank you all for your attention to this matter and for letting us know there was a problem. I’ll let you all know when the siphon has been repaired and is once again operating.  Please let me know if you have any questions.



Christy Graham

Trout Biologist Supervisor