records for, Norris Reservoir will not be filled up to 1,020 at any time during that winter, because there won't be water enough.

We have never had tremendous floods after the last of March, and so that the flood danger for the first there, for the year is very largely over by the 1st of April. Therefore, after the 1st of April we shall save all of the water that we can to fill Norris Reservoir, hoping generally to have it up to the elevation of 1,020 by the first of June or the first half of June. And then soon after that we will begin releasing it.

we

The first year that it was used, which was the summer of 1936, began releasing the water for navigation, I think, on the 19th of June, and it was released fairly regularly then through the summer. The next year, 1937, happened to be rather a wet summer, rains kept coming all summer, and we didn't use it out of the Norris Dam very fast.

This last summer I think was fairly typical, we had some heavy rains, and then we had some long dry periods, and the operation was very uncertain. The result is that in the last part of the summer we have been drawing Norris Reservoir down rather rapidly. While I was in Knoxville I knew the operations every day, but I don't know what it is now, I would have to guess at it, it is probably about 975 or 980 now, and during this next month we will draw it down another10 feet or something of that sort.

Now, that is an annual cycle. On the main river reservoirs, it is a simple cycle because we don't have the wide fluctuations, they will be kept down low all through the winter period from the holiday time until about the last of March, when the main flood danger is over.. None of these things, of course, are too precise. We have floods in April, but we have never had the biggest floods in April, they taper off during April. At some date, which may probably on the average be about April 1, we will fill all of the reservoirs a certain amount, perhaps not to the extreme amount that can be used for floods, but we will fill them 4 or 5 feet.

And then that water will be drawn down during the summer. Now, that particular operation is largely for mosquito control. The malaria people want us at the beginning of the season to have the water high to keep vegetation from starting along the edge of the water, and they say that the vegetation leaves won't come out if it is under water, so they would like to have us fill it up high just about as its leaves. start, and hold it there for perhaps 2 or 3 weeks. Then they want it drawn down rather steadily all summer, and we have a very complicated cycle that may have been explained to you.

We try to drawn down on an average of about a foot a month until the first of October, and the mosquitoes stop breeding about the first of October, but we don't draw down on a straight line, but we draw down on a saw-tooth line, up and down, during the week.

Each week we try to make a cycle, the reservoirs are drawn down over 2 days, and then held at the bottom level about 24 hours, and then raised again during the next 2 days, and held at the top about a day, and that makes only 6 days, but we spread it over 7 days, and we try to follow the same day of the week for draw-down and coming back.

That weekly fluctuation, as I understand it, tends to hamper the egg laying and perhaps destroys some of the eggs, or hampers more the larvae after they are hatched out by drawing them down a ways

from the bank, or leaving them stranded on the mud, and they die, and then the water comes back and the eggs have to be started all over again, by the mosquito, and if we can change it every week we kill a great bulk of the mosquito larvae.

When it comes back, we don't bring it back to the same level, but a tenth of a foot lower than it was before, so that in 4 weeks up and down, we are then in 1 month, we have lowered the crest and the water about half a foot, and that is different in the different reservoirs, because some of the reservoirs have only a small draw-down, and some of them are more.

At Pickwick we can fluctuate 6 or 8 feet during the summer, but on the Guntersville Reservoir, by only 2 or 3 feet, because of the conditions in that area.

Perhaps it is worth a word in saying how we can do this large amount of fluctuating, and this will illustrate it very well. When we have 6 or 8 reservoirs in succession, if we can take a certain amount of the water in the upper reservoir, which is like an extra amount of water, let that outside evenly through the gates to the reservoir below, that lowers the reservoir where we let it out, and raises it in the reservoir below-that is in addition to the ordinary river flow.

Then the next week that same amount of water will be released through the gates of that dam, and it will lower that reservoir and raise the next one below, so that the same amount of water can go through six or eight reservoirs and produce this weekly fluctuation and we don't have to, as we make one quantity of water produce the fluctuation all the way down.

It will perhaps require wasting water that we might otherwise use for power somewhat, but we are hoping to keep the waste of the water down reasonably; anyway we have made our power calculations conservatively to allow for such things.

The method by which our computations have been made has been this: These reservoir operation plans have been based on primarily flood control. The power calculations that have been made and we have estimated the amount of power that can be developed at every dam, those calculations are based on the amount of water that will result from these flood-control operations that I have tried to outline.

You are familiar with what we call primary power or firm power. That is the power that you can depend upon every year, and that is determined by the driest years.

Now, we have every 10 years or some such matter a very dry year. much dryer than the average year, so that our firm power calculations are based on those driest years. That means that in all of the other years we have a large excess of water.

Some of it will be used for secondary power. But the wettest years. we will have perfectly tremendous quantities of water; they aren't worth anything for power, and won't be used for power; they are very hard to get rid of, and our chief problem is how to get rid of it, and not save any water.

LACK OF CONFLICT IN MULTIPURPOSE-DAM SYSTEM

In the very driest years there will be no floods of any account, and our flood reservoirs won't be filled up, because it won't be wet enough. The years when water is most needed for power will be the years when there aren't any floods, and there is no flood problem. So, of

course, there is no conflict between trying to use the water for power and having to control it in floods.

There has been a good deal said about the conflict between flood control and power, and I don't think that there is much of any conflict. There is some overlapping, some slight amount of what might be called conflict, but I think any reasonably qualified engineer could make these plans and perform these operations just the same as we do. It is true that it is a rather new development in this country, there haven't been many cases of this sort. It is not so new in Germany, they built similar reservoirs 25 years ago, at least, and as far as I know, they have always operated them successfully, combining power use with whatever flood control they wanted or needed.

Our flood-control system, of course, is only partly completed, so that we can't speak from experience, very extensive experience as to just what it will do. It is interesting, though, we started to store water in Norris Reservoir on the 4th of March 1936, and a flood came along in that month, not a big flood, but it is the biggest that we have seen since we have been on the job. It would have produced about a 41-foot stage at Chattanooga, and 30 feet is where the water begins to get out of the river and do some damage, so that the 30-foot stage is what is called flood stage, and this would have been 11 feet higher and would have submerged a good deal of the city. It did submerge so as to surround some schoolhouses with water, so that the children couldn't get to it.

The effect of the Norris Reservoir alone on just its relatively small part reduced that height 4 feet, so that it reached only 37. And the area above Norris Reservoir is only one-seventh of the whole area above Chattanooga, and we don't claim that Norris controls more than a seventh of the area.

As I said earlier, to protect Chattanooga completely will require several more reservoirs, and we hope those will be built in the future, but we haven't outlined a completely definite program for that yet, and the reason for that is, as I suppose you all know-at least it looks to me the reason is-we have a rather definite annual sum of money to spend, provided by Congress, and we have used that on this navigation program which is the main river dams and reservoirs up to Knoxville, and until we have those substantially completed, we haven't prepared detailed plans as to what perhaps ought to be done next.

I think that the annual flood season is best illustrated by a diagram or a chart that you have in one of your exhibits. I don't know, that is. Mr. BIDDLE. We will get it. Go ahead.

Mr. WOODWARD. In that book is this diagram which indicates past records of floods at Chattanooga. I am sorry that you won't be able to see it very well but this copy is in the book, and it is properly labeled. The upper strip along the diagram shows the period by years from 1865 down to about the present year, and every year in which there was a flood a vertical line is drawn showing the height of that flood, and here is the 1867 flood at about the beginning of the record.

The next highest was in 1875, the third highest was in 1886, and we haven't since 1886 had any flood as big as those three which came within 20 years of each other. The largest recent flood, fairly recent, is 1917 and it is indicated by this.

Now, all of the floods of any importance are indicated here so that you can see the distribution by years and the size. On the bottom of the diagram is a similar strip, with those same floods in

115943-39-pt. 11-33

dicated, but they are not arranged by years but by the months of the year in which they come, and the same lines, and the same heights are drawn.

Now, January, February, and March are these three spaces, and you see how thick the floods are there, and how high, and April there are a few, and then May, June, July, and the other summer months there are occasional, very much smaller floods, and in December, at the end of December, why they begin to be larger floods. Now, here is a record of 70 years, and the same kind of record could be drawn for Florence or Johnsonville down on the lower river; it would be very similar and it is this kind of information that enables us to provide one kind of operation during the flood season in the winter, chiefly in the 3 months of January, Febru ary, and March, and then an entirely different kind of operation during the last 6 months of the year, and a transition in April and May, and you will all have copies of that available, if you want to use them.

I will add this bit of information. The 1867 flood in Chattanooga reached a stage on the gage of 57.9 feet. The maximum flood against which we say protection should be provided in order that Chattanooga will not be in any danger is a height of 77 feet on the gage, and our studies indicate that if we put in reservoirs that ought to be installed, on the various tributaries of the Tennessee River above Chattanooga, that we will reduce that superflood, if you want to call it that, it is not a real flood-just a flood used for planning safety that we have estimated, down to a gage of about 52 feet.

We could give you people a tremendous amount of figures if they would be of any use to you. I always have a feeling, unless a person wants them, I don't like to tell them all of these things, but I would be glad to be questioned on anything that you think would be useful. Chairman DONAHEY. It is suggested that we recess until 1 o'clock. (Whereupon, at 12 noon, the hearing was recessed until 1 p. m. of the same day.)

AFTERNOON SESSION, MONDAY DECEMBER 5, 1938

(Whereupon the hearing was resumed pursuant to recess at 1 p. m.)

TESTIMONY OF SHERMAN M. WOODWARD-Resumed

Chairman DONAHEY. You may proceed with the witness if he has finished his statement.

Mr. BIDDLE. Have you finished your statement?

Mr. WOODWARD. I think so.

Chairman DONAHEY. How long will you require Mr. Biddle? Mr. BIDDLE. I would like about not over an hour and a half, and I may be very much less.

Now, Mr. Woodward, your specialty is hydraulic engineering; isn't it?

Mr. WOODWARD. Yes, sir.

Mr. BIDDLE. Your job is to control the flow of the water of the Tennessee River chiefly; is that it?

Mr. WOODWARD. Yes, sir.

Mr. BIDDLE. For various purposes?

Mr. WOODWARD. Yes, sir.

Mr. BIDDLE. You have said, I think, that the main purpose was flood control and navigation?

Mr. WOODWARD. That is correct.

Mr. BIDDLE. Now, in addition to that, there are certain other purposes, such as the control of malaria?

Mr. WOODWARD. Yes.

Mr. BIDDLE. What else?

Mr. WOODWARD. You have not mentioned about the development of power. That is one of our purposes.

Mr. BIDDLE. Yes.

Mr. WOODWARD. Another

Mr. BIDDLE. I am speaking not of the purpose of the dam system, but of the purposes of the controlling of the watercourse; you understand that?

Mr. WOODWARD. Yes.

Mr. BIDDLE. Is that right?

Mr. WOODWARD. Another item that I did not think to mention this morning is the helping of wildlife, fish, and wild fowl.

And we give special attention to the fish during the spawning season. The State of Alabama is particularly interested in the fish industry, which is really a large industry on the part of the Tennessee River flowing through Alabama. Their special request is that over a 2 to 3 weeks' period in the month of May, we keep the level of these reservoirs just as steady as we can. They would very much prefer that we would not fluctuate the level over 1 foot, because any greater fluctuation tends to kill a great many fish eggs in the spawning

season.

Mr. BIDDLE. That of course is a minor consideration.

Mr. WOODWARD. That applies up on the Norris Reservoir to some degree also, but perhaps it is not so important there.

ORDERS ISSUED RE OPERATIONS FOR FLOOD CONTROL AND OTHER PURPOSES

Mr. BIDDLE. Now, has a study been made with respect a recent study-with respect to the various purposes for flood control, requests from the various parts of the system; have you got that there? Mr. WOODWARD. Yes, sir.

Mr. BIDDLE. What do you term it, what do you call it?

Mr. WOODWARD. I have an annual report that was made at the end of the fiscal year, just in our ordinary course.

Mr. BIDDLE. Annual report of one of your divisions?

Mr. WOODWARD. Yes; of what is called the river-control section. Mr. BIDDLE. That is a section under your department?

Mr. WOODWARD. Mr. Bowden heads that, and this was an annual report that he prepared.

Mr. BIDDLE. I am not interested in the whole report, but if you will turn to the schedule that I have in mind-that is-is it not?a statement of orders; is it?

Mr. WOODWARD. What we call water-control memoranda.

Mr. BIDDLE. Water-control memoranda. For what period of operation is that?

Mr. WOODWARD. That covers the fiscal year from July 1, 1937, to June 30, 1938?

Mr. BIDDLE. And that covers, I understand, all of the orders issued for various purposes over that period?

Mr. WOODWARD. Yes, sir; that is the complete file.