Early Floods in Los Angeles: Interview 140, William Mulholland: It is no difficulty to do things when the work is carried on in harmony with Nature
July 15, 2016 § 9 Comments
One of the best creek freak documents around is a series of interviews made by Los Angeles County Flood Control Engineer James Reagan, around 1914. The interviews give a vivid picture of the Los Angeles basin of more than 100 years ago. We will be posting other interviews from this document in the following months.
The following is a transcription of Mulholland’s interview by F. Z. Lee, on October 2, 1914.
As Mr. Mulholland said, he has never had anything to do with the river other than in connection with the water works, where their supply came from for many years.
There seems nothing strange or mysterious about handling the floods of the river if the lesson from nature was followed. It is no difficulty to do things when the work is carried on in harmony with Nature, but when man begins to obstruct the laws of Nature and to work against them, then there is great difficulty.
We had no trouble with the Los Angeles River until 1877-78. Up to that time the channel of the river was clear of willows and other growth that would cause the water to change about from one side of the river to the other. When the floods came they spread over the gravel beds of the river and ran along smoothly without obstruction. There were some willows along the banks of the streams but none out in the channel. The channels remained the same all the time.
Our trouble began as I say in 1877-78. The valley was grazed out to sheep and the sheep kept the willows back. There was nothing but grass in the channel when the floods came, and the waters flowed smoothly away.
Then when the sheep were moved away the willows grew up and formed obstructions which caused the water to cut into the banks and to wash away the farms.
Pure, clean earth is far more friable than banks of willows, for the willows give the water a footing, leverage which it uses to cut with. A bank of willows will wash away in a short time.
It is so with many obstructions in the river It creates a whirl and the water churns and bores, boils against obstruction, making great holes. That was the case with the piling and piers in the river, where roots and other drift was found buried deep at the foot of the piling. The water at its highest flood carried away the gravel and sand and as the velocity of the water slackened and the drift was caught underneath the debris as it began to fill in only at those places. If it were not so, out pipe line would be carried out entirely, were it that the entire center of the channel moved down stream during floods.
Occasionally a pipe would be broken but that was where the foundations of the piers were undermined and the entire structure let in. But the entire bed of the river does not move downstream.
To build dams for reservoirs in the mountains to hold the water back would be too expensive for the amount of good it would do. The pitch of the country is too steep to create any reservoirs of any size. They would be more wedges and not large enough to do any great good. The highest water that has ever been here and the highest water marks that old people who have lived here forty to fifty years and who have personally shown me, where the water came to, has had a run-off of 50,000 second feet. A very careful measurement was taken of the stream where the North Broadway concrete bridge now is. The present channel of the Los Angeles river is ample to carry away the water.
No man, no engineer, could invent or contrive such a wonderful system of water supply as this west coast has. There is no place in the world that I know of, which has the great amount of artesian or well water as this section of the country. It is called a semi-arid country and has only an average annual rainfall of fourteen or fifteen inches of rain. No one would think of trying to raise anything with that amount of water. This coast has had great upheavals and subsidences. Not in a folding and grinding sense of the strata, but a practical vertical lift and fall. There is a perfect coast line along the Palos Verdes hills. And the great deposits of gravel and sand, a porous material, has made a great reservoir of the coastal plains.
The varieties of water are due to this very change that has taken place– the reddish colored water at Long Beach comes from some part of the plain that was at one time a swamp. The [xx] waters coming from just such causes and the alkali waters from further-back in the mountains.
So it is this great bed of gravel, 600 feet or more deep, catches the water instead of allowing it to all run off into the sea.
Nature was wise in her plans for the delivery of the water from the high altitudes to the sea. When the waters reached the lower plains they began to wind back and forth, making the river longer and longer, and thus lessening the gradient of the river bed. The current of the stream being slower on the inside of the curve than on the outside, kept dropping its sediment and filling in, while on the outside of the curve the stream was cutting away, thus making the windings greater and greater.
Now, if a channel was cut straight through, it would cut out a great channel, there and leave the banks high above the water they need so badly.
Reagan, J.W. (1915). Early Floods in Los Angeles County: Notes by James P. Reagan. Los Angeles County Flood Control Engineer.