"There are bad floods on the Ohio," was the reply, "and there is always danger when a flood tide comes down the Mississippi. You see, if part of a levee does give way, or as they say, if a 'crevasse' comes, thousands of square miles are inundated, hundreds of people made homeless, and the property loss is incalculable. All the land around the lower part of the Mississippi is just a flood plain which used to be covered with water every year. That land has been rescued from the river just as Holland has been rescued from the sea."
"Then there is danger every year?"
"There is always danger," was the reply, "and the levees are carefully patrolled. But during the high water of early summer there is more danger, and a week's rain means trouble. We're going to have a bad flood this year unless the rain stops soon."
"But the river isn't rising?"
"Not yet. Why should it? It isn't the water that flows directly into the Mississippi, but that which floods the tributaries that causes disaster. From the Rocky Mountains on the one side to the Alleghanies on the other, and from the Gulf of Mexico to Canada—nearly every drop of rain that
isn't evaporated or used by plants has to be carried to the sea by the Mississippi."
"It seems like a big job for one river bed," Colin agreed. "But how can it be made safer?"
"The way is easy," was the answer, "but costly. If big reservoirs are built on all the headwater streams so that—no matter what the rainfall may be—only a constant amount is allowed to flow out of these reservoirs, then floods will be avoided, there will be plenty of water for irrigation, and a steady depth of water in the channel will extend navigation that is now stopped during low-water periods. Besides which, it will make the Mississippi fish question a great deal easier."
"I don't quite see what it has to do with the fish!" the boy said.