Featured Photo: Football Brown

Featured Photo: Football Brown

Thursday, August 03, 2023

At Long Last, the Water Control Manual Update for Center Hill Dam

Almost a year late but better late than never, the proposed water control manual (WCM) update is here from the Corps of Engineers. Find out more HERE. In short, it looks like they will continue the pattern they have been running (one hour of generation every 8 hours) to provide a minimum flow on the Caney Fork River. 

Unfortunately, as of right now, they are not going to provide a continuous minimum flow which would work wonders for this river. 2016, our last significant drought year, had a continuous minimum flow of 250 cfs and the trout population was better than it has been since the leaks in the dam were mitigated. Things quickly went downhill after that as they returned to long periods of dewatering the riverbed. 

At the link above, find a link to the proposed updated manual along with instructions on how to comment if you have something to say about it. In addition, the Corps of Engineers will be hosting a public meeting to update the WCM. If you're at all interested, below are my thoughts that I emailed to the Corps of Engineers. 



Hello,

I am writing to give my feedback on the water control manual (WCM) update proposal.

First, I would like to say that the preferred alternative of one unit every 8 hours is a vast improvement over the prior WCM. However, it unfortunately does not address the portion of the river that most needs a minimum flow. In your document, you acknowledge that the majority of fishing pressure is focused on the upper 5 miles of river. However, the preferred alternative regularly dewaters too much of the streambed in this section.

I would strongly urge you to consider alternative 10 which features one unit every 8 hours along with a 250 cfs continuous minimum flow. I'm not sure how you came to a value/ranking of "2" for the recreation category on alternative 10, but that doesn't really fit your own criteria. In fact, under the recreation category, alternative 10 should receive a rating of "4" due to frequent safe conditions for wading and swimming (I don't know if anyone swimming in the Caney and haven't seen this happening myself) AND even more importantly, it would "provide enough flow to support recreational boating and fishing at most locations downstream of Center Hill Dam."
During 2007-2010, I regularly waded at Happy Hollow and while some sections of riverbed are less accessible at these higher flows, the fish thrive and spread out to become more accessible with less wading. In fact, I caught one of my all time best fish on the Caney Fork ever, a brown trout, at Happy Hollow during this time period. The fish was sitting and feeding on a section of gravel bar that is now regularly completely dewatered. Fish were regularly feeding along the edges where they were very accessible. Now, they look for the little deep water they can find and concentrate into those spots. This requires MORE wading, even though flows are lower. In fact, back in 2007-2010, I would walk the gravel edges at Happy Hollow and catch fish in water that was a foot or two deep. Now, those fish are nowhere close to those locations. During higher flow times before the dam repairs, I could regularly find many large brown trout in very accessible locations, because the extra water in the streambed provided the habitat for those fish to live in shallower water. Now, they are left with only a few deep holes as their only retreat.

Lower flows are harder on fish because they are more easily located, meaning that harvest rates increase. These fish do not have any sanctuary in the upper river at these very low flows, meaning holdover fish (larger trout) have a harder time surviving. Unless stocking rates are going to significantly rise, fish need more opportunity for sanctuary. I've seen anglers wading sections of river FAR from any access point and harvesting large numbers of trout. This is because they are able to walk up or down the river to get there, often from a mile or more away. At slightly higher flows, this process is more difficult and gives the fish more chances to grow. Water management is important to fisheries management, and the Caney Fork can produce many more quality fish than it currently is. However, the fish must be given a chance to stay in the river for this outcome to happen.

Because the upper Caney Fork receives the most fishing pressure, I would suggest a continuous minimum flow to provide better habitat and conditions for the resident trout. I will add that the one hour of generation every 8 hours has done wonders for the middle to lower river and should be maintained as such. Because there is a distinct lack of wade access in this lower section, these flows strongly favor anglers with boats instead of wade anglers. While I have a boat and this doesn't directly impact me as much, it will be better for the entire river if we get a continuous minimum flow to not only keep the trout healthy, but also to spread out users on the upper river and reduce conflict between user groups. At current low minimum flows, I have to get out of my drift boat and drag it over several gravel shoals between the dam and Happy Hollow. This can easily be fixed with a continuous minimum flow and benefit the trout and macroinvertebrates they rely on in the process.

One thing I am interested in is a smaller minimum flow of 150-200 cfs. It has the potential to provide a better outcome for upper river fish and recreational users AND improve the amount of potential generation capacity from the 250 cfs constant minimum flow. I noticed that you eliminated the lower constant minimum flow alternative due to cost, but it was never actually stated what the cost would be to modify the existing orifice gate. Do you have those numbers? Or did I just miss it somewhere? I'm wondering if that is something that TU or some other organizations could get involved with in terms of fundraising. Are we talking thousands of dollars or millions?

Finally, I am disappointed that more is not being done to address dissolved oxygen (DO) issues. We are already seeing the results with stressed fish on the upper river over the last week. The big rain event a couple of weeks ago that necessitated higher releases has significantly impacted DO numbers and the fish have been showing the resulting stress. Has there been any discussion to run liquid oxygen into the forebay? I know this is done on TVA dams like Norris in the fall as necessary and has worked very well in mitigating dissolved oxygen issues. If not oxygenating the forebay, then how about mandating the use of the sluice as soon as DO readings start to drop below state mandated water quality standards? I would prefer that instead of just leaving it up to the discretion of the operators, since this can vary widely from one operator to the next.

In short, we need more done to help with both the trout, their food sources (macroinvertebrates), and recreational users of the river with more water and better water quality.

Thank you for considering my comments.

Sincerely,

David Knapp