WATER SUPPLY AND IRRIGATION 

 IN PORTO RICO. 



BY GUY E. MITCHELL. 



Although the island of Porto Rico has a less area than the dimin- 

 utive eastern state of Connecticut, yet its different sections are sub- 

 ject to as great a variation in rainfall as are the extremes of the 

 United States, ranging from practical aridity to very heavy precipi- 

 tation. As much as 140 inches of annual rainfall is reported in some 

 parts of the island, while at places on the south coast three years 

 have passed without rain. And it is on the south coast that opportu- 

 nity is offered for irrigation; but the area available is very small. 

 Some of the methods in use, however, are quite interesting. 



"The soil on this land," said Mr, Herbert M. Wilson, the engineer 

 of the geological survey, who has recently visited Porto Rico, "is in 

 every case the best kind for irrigation. It is fairly deep and under- 

 lain with a porous limestone or coral which affords good drainage and 

 probably insures safety from the danger of producing alkali. Much 

 of it is already under cultivation. 



"The perennial flow of the streams of this section is unusually 

 abundant for a land requiring irrigation. Moreover, the flood dis- 

 charges of these streams occur at frequent intervals during the year, 

 but are especially well distributed throughout the summer. 



"Are there any opportunities for the storage of water? 



"These frequent floods afford an abundant surplus for storage 

 -and the shapes of the smaller parting valleys and the lower canyons 

 through which the rivers emerge from the mountains may be found 

 opportunities for the construction of storage reservoirs at relatively 

 small cost. 



"The Spaniards, who in the past have been the principal land- 

 holders are thoroughly familiar with the requirements and processes 

 of irrigation as practiced in Spain. Quick to appreciate the advan- 

 tages of the artificial application of water, they have already con- 

 structed numerous ditches of moderate sizes, and much of the more 

 valuable sugar land is cultivated exclusively by the aid of irrigation. 



"Such work as I noticed," continued Mr. Wilson, "correspond in 

 general type to those seen in Mexico, but because of the greater in- 

 fluence of European ideas in this island, the construction is of a more 

 substantial character, and more nearly approaches that prevalent in 

 Spain and Italy. The diversion works are in every instance of the 

 crudest kind, simple wing dams of rocks and boulders thrown out into 

 the beds of the streams to direct a portion of the waters into the heads 



