other purpose, but it is a big problem. The results of that investigation are embodied in the pamphlet that was transmitted with the Secretary's report.

This investigation was made under a board representing the Imperial Valley, the Reclamation Service, and the University of California, three members of the board, Mr. Grunsky, Mr. Schlecht, and Mr. Mead, and embodies the best and by far the most comprehensive knowledge that has ever been obtained on this subject. But, as a project, the investigation or the knowledge is by no means complete.

There is absolutely no feasible or advisable extension of irrigation in the Imperial Valley of any considerable magnitude without storage. The present irrigated lands have repeatedly been short of water, not seriously but frequently enough and to a sufficient extent to show that any large addition to the irrigated area means that either storage must be provided or its irrigation will be a menace to the irrigation interests in Imperial Valley and in the Yuma Valley. To divert from Laguna Dam would have the potentiality of taking the water supply from the lands already irrigated, and that in such a dry, hot country is disastrous.

The CHAIRMAN. What is the most that can be accomplished by the investigation contemplated by the bill?

Mr. DAVIS. There are two things that are most important. First is storage.

We have investigated a number of storage reservoirs in the Colorado Basin, and we believe from those investigations that that storage is feasible and have proceeded, in favoring legislation, on that supposition. We do not know exactly how much it will cost; we do not know approximately how much it will cost; we simply know that it is feasible, but where is the best place to construct storage has not been determined. Those investigations are still in progress but are greatly hampered for lack of funds, and this bill would materially help complete those investigations.

Mr. SMITH of Idaho. Do you think the amount would be sufficient, Mr. Director?

Mr. DAVIS. It would not be sufficient to absolutely complete them, but I think it will be sufficient to get information that Congress needs for legislation.

Mr. WELLING. I believe you said you have already expended $45,000?

Mr. DAVIS. Yes, sir.

Mr. WELLING. And this bill comprehends a total appropriation from the Imperial Valley and the Treasury of $40,000?

Mr. DAVIS. Yes, sir.

Mr. WELLING. Do you think that will give you enough money to make the investigation?

Mr. DAVIS. I was just coming to that. I think it would be wise, Mr. Chairman, although it is not in the Secretary's report, to put a proviso in that the Imperial Valley might contribute a larger amount if it chose. I don't think that that is absolutely necessary, because they probably can do that anyway.

The CHAIRMAN. Certainly they can. There is nothing to hinder them from doing that.

Mr. DAVIS. The requirement is that they must put up at least that much.

The CHAIRMAN. That implies that they may put up more, of course. They must put up at least that much.

Mr. DAVIS. And I think it would be very wise and very easy to get them to do that. Now, it is my belief that the most feasible point for storage of water for the Imperial Valley is in the Boulder Canyon, below the Grand Canyon, and it is the only reservoir of promise below the Grand Canyon.

The CHAIRMAN. How large is the capacity there for storage?

Mr. DAVIS. We have made surveys there for a high dam, and we were pursuing them until driven out partly by exhaustion of funds and partly by high water, and that survey needs completing. We have not made any investigation for foundation, which is the most important thing, and this bill would permit us to do that.

Mr. HAYDEN. Just where is that reservoir?

Mr. DAVIS. It is on the Colorado River, where it forms a boundary between Nevada and Arizona, about 20 miles below the mouth of Virgin River, just above the point where the river changes from a westerly course to a southerly course.

Mr. SUMMERS. About how far from the Laguna Dam is it?

Mr. DAVIS. From the Laguna Dam it is probably 300 miles. One of the very important features of that is that it is the nearest to the irrigated land of any large reservoir that we believe to be feasible. Mr. WELLING. Wouldn't it fill up with silt in time? Mr. DAVIS. In time it would, if not prevented.

The CHAIRMAN. You say it is how many miles distant from the dam?

Mr. DAVIS. About 300 miles, by the river's course.

Mr. TAYLOR. It is 300 miles from the dam, but only 12 miles from some creek?

Mr. DAVIS. From the Virgin River. It is, however, the nearest available site. Now, the other reservoirs that have been investigated are above the Grand Canyon and are 2,000 miles or more from the land to be irrigated, and that means that it would take several weeks, perhaps months, for the water, when it was turned out of the reservoir, to reach the land to be irrigated by it, and it would be necessary to foresee all the conditions that far ahead. That can not be done. and it would lead to large waste of water, and would also lead to more or less dissatisfaction with the service, undoubtedly. Our experience indicates that it is desirable to have a storage supply very much closer than it is possible to get it in this case, but it is nevertheless important to get it as close as possible.

Mr. WELLING. Mr. Davis, if you stored the water up there upon the headwaters of the Colorado, it surely would be proposed also to use that water for irrigation, would it not?

Mr. DAVIS. So far as it can be; yes, sir. One of the important features of having the reservoir below the canyon is that by having it there you do not interfere with very large possibilities of power development on the upper river; if you build a reservoir on the upper river for irrigation purposes, that water must be handled in accordance with irrigation, and must be stored in the winter and used in the summer. That is antagonistic to power purposes, but if

the principal storage for irrigation is on the lower river, then the water above all the water above-can be used for power; and there are vast possibilities for power, and it is going to be valuable in those mining regions. The water can all be used for power, turned on at the time when it is most convenient for power uses and caught in the reservoir below without injuring irrigation in the least.

The CHAIRMAN. That is, it would have time to travel down to the lands to be irrigated after it is used for power purposes?

Mr. DAVIS. Yes, sir.

Mr. HAYDEN. Then it is your purpose to make a thorough investigation of all possible reservoir sites on the lower Colorado River, below the Grand Canyon?

Mr. DAVIS. Yes, sir.

Mr. TAYLOR. And your present intention is to not make investigations up there in Colorado, Utah, or Wyoming, up at the headwaters?

Mr. DAVIS. Most of our investigations have been made up there, and we know some very good reservoir sites up there. They are important for irrigation in that region, and they are also valuable for power purposes.

Mr. TAYLOR. Of course, if our legislation ultimately contemplates reservoirs, of course we will have to have some adjustment or some understanding or some provisions that will be satisfactory to those States up there.

Mr. DAVIS. Yes, sir.

Mr. TAYLOR. For the use of that water in power and irrigation?

Mr. DAVIS. Yes, sir. And in consideration of the power value of those sites up there, it is important to have storage below the canyon, because there can be no question, no claim, on any water except what came down. Any water used above would unquestionably belong where it is used.

Mr. WELLING. Will not the hundreds of thousands of tons of silt that goes down there every year fill up your storage site?

Mr. DAVIS. It will in time, if not prevented.

Mr. TAYLOR. I was going to ask you, what about the sediment? To the members who have never seen that river I will say it is just a rolling mass of mud down there in that country a very large part of the time, and it must necessarily fill up a reservoir, even if the dam is a thousand feet high.

Mr. SMITH of Idaho. Has there never been any plan evolved to take silt out of these reservoirs?

Mr. DAVIS. Yes, sir. I will describe that here, if the committee wants to take the time.

The CHAIRMAN. Very well, Mr. Taylor's question also elicits that. Mr. DAVIS. All these questions are on the same subject. We have built a large reservoir on the Rio Grande. There is a picture of the dam on the wall.

Mr. HERNANDEZ. Elephant Butte Dam?

Mr. DAVIS. Elephant Butte Dam; yes. That is the largest structure so far built by the Reclamation Service.

Mr. LITTLE. That is at El Paso?

Mr. DAVIS. About 300 miles above El Paso. And the Rio Grande is one of the muddiest rivers that flows. The capacity of the reser

voir is over two and a half million acre-feet, and the solution of the mud problem that has been devised for that reservoir I consider applicable to the Colorado in the same way, and it is this:

In the first place we build a reservoir of large capacity so that it will be perhaps a century, at least half a century before sufficient mud is collected in the reservoir to seriously impair its value as a storage reservoir-that is, it has a surplus capacity built in advance. It is possible to build that dam higher, and that may be what will be done at that time. But the time will come, if the project is continued, when the accumulated sediment in that reservoir will reduce its capacity below the point that is necessary for the service of the lands below. That will mean in that case that there will be a long reservoir, 45 miles long, and most of the sediment will be deposited at the upper end, a large part of it, and a great deal of it above the water line, because when a river is in flood it backs up on account of the obstruction of the dam, and a very large capacity will be filled above the flow line of the reservoir.

Mr. LITTLE. Do I understand you to say that the mud, most of it, starts way above the dam?

Mr. DAVIS. All of it starts above the dam; yes, sir.

The CHAIRMAN. Where the water overflows-backs up?

Mr. LITTLE. Of course, it goes slowest when it gets to the dam, and isn't more mud deposited around the dam?

Mr. DAVIS. No; the large quantity is deposited all the way up and down there back of the dam.

Mr. TAYLOR. The water backs up there 5 or 6 miles where it is perfectly still, and the mud commences to drop as soon as it strikes that still water.

Mr. LITTLE. I had a lawsuit about it one time, and I found that most of the mud was deposited around the dam, according to the witnesses. Mr. DAVIS. It has been our experience that where a stream carries sediment it begins to deposit it some distance above the dam. I can show you on the Pecos River, and on the Salt River, and at various other places, where there are large deposits of sediment at a higher elevation than the spillway of a dam where the water runs over, as much as 11 feet, which means that the water has been 11 feet over the top of that spillway. The water at the head of the reservoir was a little higher, enough to make it run.

The CHAIRMAN. Isn't one explanation that there is much more sediment being carried; that the farther up you go, the more sediment is being carried, and that is being reduced all the time-the percentage to draw from?

Mr. DAVIS. Whenever turbid, running water is checked it begins to deposit sediment.

Mr. LITTLE. How do you account for the fact that in a lawsuit that I had, which went to the Supreme Court-in fact, I have had five or six of them, and all the witnesses testified that there was more mud down at the dam than there was anywhere else?

Mr. DAVIS. I don't know what the circumstances were. That might have been true in that case.

Mr. TAYLOR. Was that Kansas mud?

Mr. LITTLE. It was just a mill dam in Kansas, a couple of them. Mr. DAVIS. The time will come, of course, when the accumulated sediment in the reservoir, in spite of devices that will be used to dis

charge part of the sediment-several devices to postpone the day have been devised, and I think will be carried out, but when the time does come, when the reservoir does not accomplish its purpose by reason of lack of capacity, it will exhibit that by running dry when it is needed. Whenever the reservoir runs empty the stream will cut down through the thread of the reservoir, a distance in that case of 45 miles, and carry out that mud were it runs out of the opening through the dam. It will carry out a large amount of mud whenever it is in that stage; that is, there will be no pond in the reservoir when the water is runnig through, and when that happens, when that time comes, we will build another reservoir, a smaller one, on the headwaters, where the stream is clearer, and then in handling those two reservoirs in conjunction we will always draw on the lower one whenever there is water in it. We will draw on that until it is empty, and then turn water out from above, and as the water runs through it will wash out a great big channel there.

The accumulated mud contributes a large amount of seepage all the time. It is thoroughly watersoaked and there is a great mass of swamp land, seepage land, and whenever the water goes down below the level it cuts a channel through. Freshly deposited mud cuts very easily and rapidly by running water, and whenever the reservoir is empty and water is being drawn from the natural flow of the river or from the reservoir above, it will cut out the sediment. Now, if that reservoir being handled in connection with the main reservoir is not sufficient, another can be built. There are small reservoir sites on the headwaters of the Rio Grande, as there are on the headwaters of the Colorado. The time is long in the future when they will have to be built, but they can be built at less cost than the lower ones, and serve in that way and eventually we will get a system of operation and a quantity of storage capacity which will maintain its equilibrium by cutting out the sediment as rapidly, on an average, as it is brought in by the flow of the stream.

Mr. SMITH of Idaho. If you have reservoir sites your plan is all right, but if you do not have reservoir sites up the river then the reservoir eventually becomes useless.

Mr. DAVIS. Yes, sir; we must have reservoir sites on the upper river in order to make that possible. That would be comparatively clear water.

The CHAIRMAN. It may be a century or half a century before they will need that reservoir.

Mr. DAVIS. Yes, sir.

Mr. LITTLE. How do they avoid the collecting of so much mud from the dams on the Nile so that they become useless?

Mr. DAVIS. In the Assuan dam on the Nile it is handled in this way: There are 187 large openings-gates-in the dam, and whenever the river is in flood they open all those gates. When the river is in flood it carries most of the sediment and they let all that flood water run to the ocean and while that is running through it is carrying its heavy load of sediment and it also cuts out previously deposited sediment. Then when the river is on a decline and is not carrying so much mud they close the gates and they still have enough water with which to irrigate.

185833-20-37