“So you want me to tell you something about the dam?” said Mr. Whitney, smiling at his rodman. The two were sitting on the side of a hill overlooking the construction work several days after Bob had been promoted from the office to the proud position of being the Chief’s aide. He had been on a message to the cofferdam gang and had returned to find the boss seemingly loafing. When he saw there might be a few free moments before he was set to work again he ventured some questions regarding the thing that was of most interest to him.  
The way Mr. Whitney answered was encouraging, so Bob came back, “Yes, sir, I’d like to know a lot more about it than I do. Anything you tell me is going to help. I’ve picked up a little here and there and know some of the details but I don’t really know anything about the general plan. Wasn’t there any irrigation on the Rio Grande before the Service took hold?”
 
“Indeed there was,” was the answer. “The Indians were the first irrigators. The or village Indians, as they were called, while it was in a crude way, all the land on which they raised corn. They were the first settlers of the Rio Grande Valley. We know this is so, for one of the Spanish Conquistadores, Coronado by name, wrote it down in the record of his travels. When he marched from the south into what is now New Mexico in search of the gold which was the aim and hope of all the adventurers of his time, he found the Indians the land by means of crude ditches dug with their . This was the first record we have, but it has been established beyond any reasonable doubt that such irrigation as he found was practiced here by this river that flows below us long before Columbus discovered America. The theory is that in all probability irrigation along the Rio Grande was in even before the Egyptians used the waters of the Nile for the same purpose. When the first Spanish settlers came along, and later the Americans, they adopted the same methods of making the ground productive as had the Indians. All we have done as time went on is to improve the general principles taken from the . Of course, as we made better tools, we have been able to build larger ditches and so increase the area of fertile land far beyond the dreams of the Indians.”
 
“But, Mr. Whitney,” Bob put in, “if irrigation was such a success, why weren’t more canals constructed before the Government took hold of the job?”
 
Mr. Whitney laughed. “The greatest drawback was a ridiculous thing. A long time ago a treaty was made with Mexico which prohibited the storing of flood water on the Rio Grande and it’s the flood water that is used in modern irrigation.”
 
“But how would that hurt the Mexicans?”
 
“The reason given was that the lack of water would with navigation, but when you realize that it isn’t until the Rio Grande flows a thousand miles on the other side of the Mexican boundary that any navigation begins, you can see how ridiculous that objection was. We were able to get this treaty broken at last and have substituted a new one in its place. Under this new treaty we guarantee to deliver to Mexico a certain minimum number of gallons of water a year and we are at liberty to do what we like with the remainder. By building this dam we will give Mexico only one-tenth of the total amount stored each year, yet that one-tenth is more than half as much again as they are getting now!”
 
“That new treaty clears up the biggest trouble, then, doesn’t it?” said Bob. “But in the early days of settlement I wouldn’t have thought that the Mexicans would have enforced the old treaty.”
 
“I don’t suppose they could,” returned Mr. Whitney, “but the kept many a from spending his time or energy in the work. Now, however, even Mexico is strong for the completion of the big dam, as it will a lot of her land which before was desert. Besides, it will cost them nothing and that always appeals to folks—including Mexicans!”
 
“It certainly is going to be some big dam,” said Bob, waving his hand over the work spread out below them. “How high is it going to be?”
 
“If I remember the figures exactly, it will be two hundred and twenty-five feet from the ............