2-20-16 "Interpreting TVA Preschedule"
Old man winter may have dug his heels in for a while longer, but warm weather is on the way. I hope everyone’s been busy tying flies, organizing gear and thinking spring. I first want to thank everyone that stopped by and said hello at the Derby City and Northern KY Fly Fishing Shows. It was a pleasure to speak with each of you. One of the questions I receive most often is 'How do I interpret the TVA Generation Preschedule on the Cumberland River’? I also get asked: What is a good flow to fish the river? Is wading possible on the Cumberland? When should I throw streamers etc., etc? I’ve talked with lots of people who've fished the Cumberland when they probably shouldn’t have due to unfavorable flows and have been left with a bad taste for the river because of it. There’s plenty of daily published information that can assist you with successfully fishing the Cumberland to ensure your drag stays screaming instead of dreaming. However, you have to know how to interpret this information. I’ll tackle this in two separate posts. First I’ll explain some of the basics regarding Wolf Creek Dam and the TVA Generation Preschedule below.
The first thing to remember is that the US Army Corps of Engineers (COE) publishes their schedules in local time which is Central Time. Pay attention to what time zone you are in and don’t be a victim of confusion concerning time zones.
Each day, the COE runs a hydrologic model to determine the amount of water to be released from Wolf Creek Dam. The COE then provides TVA with a total generation amount that corresponds to the amount of water they want to release from the dam the following day. TVA then schedules the hourly releases from Wolf Creek Dam and publishes them to the web as the generation preschedule. Tomorrow’s generation preschedule is usually available in the early afternoon. You will notice that peak generation at Wolf Creek Dam often coincides with when you would expect peak power use which is typically mid-morning and mid-afternoon.
There are (6) generators at Wolf Creek Dam. For some reason, many people are under the assumption that there are (4). Each generator when in use is capable releasing approximately 3,500 – 4,500 cubic feet of water per second (CFS). In addition to generators there are (6) sluice gates available for use at Wolf Creek Dam. Each sluice gate is basically a 6’x4’ concrete opening that when in use is capable of releasing approximately 1,500 CFS. The sluice gates are usually only used in late summer/early fall to supplement turbine releases with a higher dissolved oxygen concentration, or when generators are down for maintenance. It’s important to note that two of these sluice gates have restrictor plates which reduce the opening size of the gate in turn restricting flow. A sluice gate with a restrictor plate in place is known as an orifice gate. An open orifice gate equals approximately 250 CFS. Restrictor plates can be added to any of the six sluice gates, but it’s a big deal for this to be accomplished as release schedules have to be altered and specialized equipment as well as divers have to be used.
There are a few things to keep in mind regarding sluice gates. First, sluice gates produce a tremendous amount of dissolved oxygen which is very good for trout. Second, the water coming from sluice gates is very cold and may affect trout behavior located in the river closer to the dam. Third, and maybe most important in planning your trip to the Cumberland is that the TVA Generation Preschedule does not actively display when sluice gates are in use. This information is found elsewhere such as in the Project Operations Report (84’s). (84’s) will be covered in an upcoming second post. This information on sluice gates is vital, especially during summer months. I constantly see confusion on the river from anglers that didn’t realize a sluice gate has been operating causing higher water than expected. If you are close to the dam and a sluice gate is open you will see the unmistakable resulting 50-70 foot column of water being thrown in to the air below the dam.
The TVA Preschedule is for 24 hours. http://www.lrn-wc.usace.army.mil/tva_schedule.shtml
You can also call TVA fishing information at 1-800-238-2264 then option 4 for water release schedules then 34 for Wolf Creek Dam. Keep in mind that the published schedule is subject to change. I’ve been on the river several times over the years where this has happened. It’s frustrating, just accept it and keep fishing. If you look at the schedule above you can see that there are two columns you should be concerned with. Column one has an hourly listing of time for 24 hours and column 3 list the number of generators scheduled to be used at Wolf Creek Dam. When looking at the preschedule keep in mind that energy output from generators can change based on lake elevation. In the above preschedule, a single unit is 45 so with releases of 270 that’s six units (270 ÷ 45 = 6). However, if the lake gets higher or lower, the generators can become more or less efficient and can generate different amounts. A single generator can be anywhere between 35 - 55 MW each. Unfortunately, the current single generator output is not listed on the preschedule but knowing that it will be between 35-55 per unit, it’s usually pretty easy to decipher. Another thing to keep in mind is the hours listed are considered hour ending. For example, if the preschedule shows 45 at hour 14 and 90 at hour 15 and 0 at hour 16, one unit will run from 1:00-2:00 pm, then two units from 2:00-3:00 pm, then no generation from 3:00-4:00 pm. Also, If Lake Cumberland is high enough, spillways can be used by the COE to push water through the dam barrier. So, if you look at the preschedule the night before your visit to the river you can quickly determine how much water should flowing down the river the following day of your visit. The COE / TVA can come up with some dandy preschedules. You must keep in mind that the COE/TVA is managing Wolf Creek Dam for purposes other than making accommodations for a fisherman friendly generation schedule. So, do your homework before heading to the river. Figuring out where to put in and how to fish the river with a varying schedule can be tricky and properly interpreting the preschedule can make or break your trip.
In regards to what is a good flow to fish the river, I like very low water all the way up to one generator (55 or less on the preschedule) and a sluice gate when guiding clients. That equals out to about 5000 CFS. Trying to fish with two or more generators makes fishing very tough from a drift boat. With two generators running a drift boat or any other boat is floating too quickly to properly focus on fishing lies. However, there are those that brave the high swift water in bass boats to chase a variety of fish closer to the dam. During high water conditions drift boats must also pay very close attention to boat heading in order to stay clear from sweepers, boulders, etc.
Is wading possible on the Cumberland River? There are wading possibilities on the river, however there aren’t many. Slight generation from the dam can effectively knock out wading quickly. If you are fishing from a boat there are plenty of potential wading possibilities along the numerous islands and shoals, but a boat is necessary to access them.
When to throw streamers? I like to throw streamers when flows are coming from a sluice or one generator. Don’t limit yourselves to throwing streamers only at the banks like most people do. Mix it up and experiment with down and across swings, two handed stripping retrieves, and tandem rigs. Be very aggressive on your retrieves. Treat that streamer like you are daring that big brown trout to try and catch your fly. Also experiment with different color streamers. Believe it or not, white is not the only color for effective streamer fishing on the Cumberland.
Finally, the latest news on the Wolf Creek Dam Hatchery Creek is that it’s doing great. As of today the grand opening is slated for April 29th. This project is going to be in the spotlight without question. To me it’s obvious that with the completion of the Hatchery Creek project the Cumberland River is entering a new phase of life. The Cumberland will be a different river in 3-5 years and the quality of trout will show it. In my next post I will go in depth on how to interpret the 84’s which hold lots of other useful information about what’s coming down the Cumberland River. As a last note I would like to thank Robert Dillingham, PE Civil Engineer (Hydraulic) EC-H Water Management, U.S. Army Corps of Engineers; Nashville District for his assistance and advice with this report.
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