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The CHAIRMAN. Are there any tributary streams of the land which would have to be condemned ?
Mr. Davis. There might be a little agricultural land probably in the vicinity of St. Thomas that would have to be purchased. There is only a small quantity, however, and for the height of the dam here proposed the amount that would be submerged would be negligible.
Senator KENDRICK. At a height of 550 feet, how long will the reservoir be, approximately? That is the height we have been discussing.
Mr. DAVIS. A little over 100 miles. That backs up a narrow canyon, however, and it does not reach anywhere near the Grand Canyon National Park. The upper part is in a very narrow canyon and the large capacity is in the lower part, where the canyon opens out between Boulder Canyon and the lower end of the Grand Canyon.
The river and its tributaries have been used for irrigation for many years. In the upper basin irrigation has proceeded to the extent of 1,500,000 acres, and in the lower basin to about 1,000,000 acres, making 2,500,000 acres now being irrigated in the valley of the Colorado above the mouth of the Gila.
The Gila, coming in just above Yuma and below Lagona Dam, contributes about 6 per cent of the water supply to the Colorado Basin; but it has torrential floods, about equal to those of the Colorado, lasting, however, for a very brief time, and the same kind of leveeing to protect against that is necessary. It does not, however, constitute the menace to the Imperial Valley that the Colorado does.
I have spoken about the Colorado River gradually building up its banks and its bed. It has built up a delta across the Gulf of California, and its course swings back and forth, as is always the case with those alluvial streams, sometimes running into the Imperial Valley and sometimes running the other way. When the country became known to the white people the river was running, a little west of south, from the point where it emerges from the hills at Yuma into the Gulf of California.
In 1905 and 1906 it overflowed and followed an old channel and ran down into the Salton Sea, and we had the spectacular closure of that break that was made by the Southern Pacific Co. in two attempts, one of which was unsuccessful. Finally, after running in there for more than a year, it was stopped. It broke the first closure and was stopped the second time and turned back into its old course.
That old course is, as I have said, very unstable. After a few yearstwo or three years-it again broke its banks, but there being levees to protect the Imperial Valley, it did
not go into the Imperial Valley, but followed what is called the Bee River, following a course to the southwestward, to Volcano Lake, and kept that course, running into Volcano Lake. It continued on that course until the sediment carried down had filled Volcano Lake and built up the channel between the upper part where it diverted from the main stream and Volcano Lake, and was running on that ridge and building it up for a period of about 14 years, and it built it up over 14 feet.
The interests in the Imperial Valley built large levees along that river to keep it from running northward again into the Imperial Valley and submerging that valley. This was comparatively easy. The river was running into Volcano Lake, but gradually and rapidly it built that up, and that bed kept building up higher and higher. As the river built up its bed it repeatedly came very near overtopping the levees, and one year it reached a point 6 inches higher than the levee and was only held out by piling sandbags on top of the levee and using the most strenuous means to keep the river out. That so alarmed the people of the valley that they cut a channel to throw the river into another of its old channels, called the Pescadero.
I forget to say that when the river cut into Bee River, knowing that that was so near the ridge line toward the Imperial Valley that it was dangerous, the United States made an appropriation of $1,000,000 to turn it back into its old course. That work was carried out by Mr. Ockerson and the river was turned back into its old course, but it was so unstable that the very first flood cut the levees away and it went into the Bee River, and into Volcano Lake.
Thus, the river has built a ridge up to the Gulf, on a course nearly south, where it was running when we found the river. It has also built a high ridge to Volcano Lake running about southwestward. Both of those are gentle slopes in both directions, but built up above the surrounding country and so high that the river became unstable. There is left a little triangle between those two courses which is relatively low ground, although the most of it is above sea level, and the river is now running into that. How long it will take to fill that up nobody knows. The guesses range from 7 to 15 years. But sure it is that within a few years, that place will be filled to such an extent that it will be rapidly approaching the danger line again, and when that is filled up there is no other place for the river to go except into the Imperial Valley.
Now, if we can desilt the river in the meantime by building a large reservoir and to a large extent stopping the silt deposit, that will be a safe place for the river to run for a long time to come. Of course it will pick up a little sand and carry it down there, but that will be relatively small. So the desilting of that river at the earliest possible date is very important for the future safety of all that large country, including not only the Imperial Valley but all that part of the country that is below the river level. All would be submerged if the river went in there. If that desilting process and the regulation of the river can be accomplished within the next six or eight years there will still be probably a considerable basin in which the river can run. But now, when there are floods of one hundred thousand to two hundred thousand second-feet it is extremely difficult, in fact, practically impossible, for man to do anything with it. You can fight it off in a certain way, but when the river once breaks loose and goes some place where it is not wanted you can not divert the river.
Senator KENDRICK. With a 35,000,000 acre-feet reservoir, will it not be possible absolutely to control and regulate the volume of the flow?
Mr. Davis. Not absolutely. It will be within certain limits. With a reservoir of that size we can have a maximum flow in the river of about 40,000 second-feet, or say one-fifth or one-sixth of its present flood volume and that will not be very common.
Senator ASHURST. If you can conveniently do so, will you kindly translate for us the term “second-feet” into acre-feet”?
Mr. Davis. Those are two terms that are used, one to state the rate of flow and the other to state the volume. A second-foot means a cubic foot passing a given point each second, and 1,000 second-feet means 1,000 cubic feet passing each second. That produces such a volume of water that in one hour it amounts to just about an acreinch, or in 12 hours an acre-foot.
Senator ASHURST. In the course of your statement you have referred frequently to "second-feet”. In stead of saying“ second-feet”, will you, if you can conveniently do so, say “ acre-feet”?
Mr. Davis. When I speak of a flow of 40,000 second-feet, that means it would carry 80,000 acre-feet per day.
The CHAIRMAN. Mr. Davis, I think that at this point we will adjourn for the lunch hour.
(Whereupon, at 12.50 o'clock p. m., a recess was taken until 2 o'clock p. m.)
The committee resumed its session at 2 o'clock p. m., pursuant to the taking of recess.
The CHAIRMAN. The committee will be in order. Mr. Davis, you may continue your statement.
STATEMENT OF ARTHUR P. DAVIS, CHIEF ENGINEER AND GEN
ERAL MANAGER EAST BAY MUNICIPAL UTILITY DISTRICT, OAKLAND, CALIF.-(Resumed)
Mr. Davis. I was speaking of the fact that the Colorado River has already occupied and built up to such height that it can not run upon the beds in stability, two ridges from the point where it leaves the hills near Yuma to the Gulf.
We have a map here that shows in a general way where they are [indicating on the map]. At this point near Pilot Knob, there is a hill on the one side and a hill on the other side, so that there is no very wide variation for the river to go there. And a short distance below, at about this point on the map
The CHAIRMAX. Where would that be?
Mr. Davis. About 4 miles below the Mexican line, on the west side, the river dropped through the levees in 1905 and ran down the old Alamo Channel into the Imperial Valley and threatened to submerge the Imperial Valley.
The CHAIRMAN. Will you point out the Imperial Valley on the map?
Mr. Davis. This is the Mexican line; Calexico is north of the Mexican line and Mexicali is south; El Centro being the largest city; and the Salton Sea is farther north than shown on this map. The bottom of the Imperial Basin is about 300 feet below the sea level.
The CHAIRMAN. Before you leave this river. Tracing the river, from Yuma it runs to the west and then down south?
Mr. DAVIS. Yes.
The CHAIRMAN. And at this point on the map the river at Log Jam seems to disappear, and then Pescadero River connects with it. I don't get that hiatus. What occurs at that point?
Mr. Davis. The reason is that at this point there is no definite channel. The river was running, as I explained, down Bee River to Volcano Lake, when it was filled up and the ridge built up so high as to be dangerous, and then the cut southwesterly was made by the Imperial reclamation district and the river was brought into this old channel called the Pescadero Channel.
The CHAIRMAN. Is that where the channel now is?
Mr. Davis. That is where the river is now running; yes. And the river had such a high velocity for a short distance here that it did a good deal of cutting, and carried a great deal of additional sediment down and deposited it down here where the land became more level, so it spreads out down in this region where there is no channel shown on the map.
The CHAIRMAN. This is down near the southern terminus of the Colorado River at Log Jam, and the balance of the stream is known as the Pescadero River, and empties into the Gulf of California.
Mr. Davis. It is so marked on this map; of course it is the same river.
The CHAIRMAN. Is it known by the two names?
Mr. Davis. Yes; this is called the Pescadero River all the way down, and the channel that it runs in here has always been called the Pescadero Channel, as this other channel shown here on the map is called the Bee River Channel. And there are other names. Here is the Algodones Channel. They are simply alluvial channels that the river has from time to time followed.
Senator KENDRICK. Mr. Davis, the river seems to follow a parallel direction with the coast line for more than 100 miles there, does it not?
Mr. Davis. The Pacific coast, do you mean, Senator?
Mr. Davis. It is only very roughly parallel. Running to the southwestward, while the coast line runs somewhat southeastward.
Senator KENDRICK. Is there any prospect of it getting clear across to the Pacific?
Mr. Davis. No, Senator; there are ranges of mountains between.
Senator KENDRICK. Then there would be no opportunity of increasing the flow and straightening the channel by turning it into the ocean?
Mr. Davis. No; the Gulf of California is the nearest ocean water. This yellow-shaded line on the map running a little west of south from the Colorado River is the old channel that the river was following, roughly speaking, at the time we discovered the river, and it continued to follow that channel until it filled up this channel and built up the ridge so high and became unstable, and finally left that channel in 1905 at a point not far below the Mexican line, and flowed into the Salton Sea. That was stopped in the way I have described, after several unsuccessful attempts; and then it broke in again near the same point, and was stopped a second time by the Southern Pacific Railway.
And then following its old built-up channel it was still unstable, and seeking to go somewhere else, and broke away from it at a point about 30 miles farther south, into an old Colorado River Channel called Bee River-that is the local name of it-and ran nearly due west into Volcano Lake; Volcano Lake being about southwest from Yuma; and the river continued to flow there until it filled up Volcano Lake with sediment, and built this ridge higher and higher, and ran in that direction about 14 years. The United States appropriated money to stop that and throw it into its old channel, and that was done, and for a short time it ran through the old channel, but it broke again from the old channel and again followed Bee River Channel to Volcano Lake, and that money was practically lost.
But about two years ago the Imperial district made a heavy cut to the southwestward from Bee River to the Pescadero Channel, because they knew there was low ground in here that the river would run into and remain stable for a period, and they put a dam into the river and turned the river successfully in that direction, and it is going there now.
The river carries a large amount of drift wood in times of flood, and when it was turned into this Pescadero Channel it followed that and eroded this channel as long as there was grade enough, but it soon got so low that it had very little grade, and it began spreading out, making shallow lakes and channels, and it deposited the timber which did not have deep enough water to carry it, and that formed this log jam and the other log jam through that region, and that accounts for this spreading out of the stream, as shown on the map here.
It finally concentrates through various little channels into the Pescadero River, and runs down into the Colorado and finally into the Gulf of California.
Senator JONES of Washington. Now, Mr. Davis, under what arrangement did we go down there and do work for Lower California ?
Mr. Davis. The United States did not do that, as such.
Senator Jones of Washington. Oh, I understood you to say that they did.
Mr. Davis. The United States made this effort to throw the river back into its old channel long ago by working through a corporation. The corporation that owns these works here is a subsidiary of the Imperial Valley irrigation district, the old corporation, and the Imperial Valley district operates through that Mexican corporation for all its work in Mexico. It is through that corporation they do everything on that side of the line.
Senator ASHURST. In 1910 nearly $1,000,000 of Federal funds were appropriated.
Mr. Davis. Yes; that was appropriated by the United States, and here is the level running southward by which the river was turned back into its own channel.
Senator Jones of Washington. Did we expend that money through that corporation?
Mr. Davis. Yes.
Senator JONES of Washington. We practically donated it to the corporation?
Nr. Davis. That is about the way it was handled. The Mexican authorities refused to allow the United States as such to work on that soil, but they did make a kind of a general agreement by which if they would put up the money their men could go down there, and I think it was ostensibly the corporation that carried the work out. At any rate, it was not officially recognized as United States work by the Republic of Mexico.