DEPARTMENT OF THE JNTEB8IOR

WATER-SUPPLY

AND

IRRIGATION PAPERS

UNITED STATES GEOLOGICAL SURVEY

ISTo. 33

WASHINGTON

GOVERNMENT PRINTING OFFICE

1899
UNITED STATES GEOLOGICAL SIIEVEY

CHARLES D. WALCOTT, DIRECTOR

WATER RESOURCES OF PUERTO RICO

BY

HERBERT M. WILSON

WASHINGTON

GOVERNMENT PRINTITm OFFICE

1899
CONTENTS.

Letterof transmittaL.----... -..---..-..-_--_.._..--.--_----_--.__...._. 9

Topographic relief..., -.-... ................,.......^..................... ±1

Coastal topography...-- .._._ .._.__._._. .__.-.---. ------------------ 14

Physiography and scenery ..-..._..___._.._._-_...-.-_-......-.--.----. 15

Climatology..-----.---. ..^......................................... ------ 21

Precipitation.....-._-..__.._.._ -.-_--,..-..--..----._--------------- 22

Temperature .......--.-.-.........._...-...-.........._.......... ..- 24

Hydrography...-.-........-.._.--.--............-...---...--.....-....-.- 24

Irrigation ............................................................ 28

Agricultural lands and soil....---......--.......--..-......,..:..-......- 32

Old fields and fertilizers.-..._....--. .--.-...-.--...---..--------... .. 33

Agricultural products --.-_._-.__.-..._._....___.____,_---...--..-. _. 34

Forestry -...-.-.....--.......----...-........-...-....--....-..--..-..--- 41

Water power and supply... -_.-_........ ......-..--.---- ..---. --.--.-..-. 43

Transportation facilities...................... ............................ 44

Index....-...--.....-..,--. ..---...--..-......----.-.-..-,-..--.--..---- 47

5
ILLUSTRATIONS.

Page.

PLATE I. Drainage and hypsometric map of Puerto Rico ___._.___-._,.._-. 11

II. A, Carolina Plain with El Yunque in distance; B, Playa at mouth 

of Rio Loiza; C, Rio Canovanas; D, Foothills of Sierra de Luquilla, showing field and eocoanut trees_.._._-...---.--..-.-. 16

III. A, West from Cayey divide; B, Rio Jacaguas near Juana Diaz . _ 16

IV. A, Between Cayey and Aibonito summit; B, Caguas Valley and 

El Monte; 0, Hills along Rio Anasco; D, Near summit of Adjuntas Pass.-,.-------------.-._-.-.._-.-..-.-..---.----.-.--- 18

V. A, Scenery south of Aibonito summit; B, Bent mango trees, 

« San Juan. ...... ^............................................. 18

VI. Barren Mils near Juana Diaz _.__.__...,._.....-.------..---.,-.- 20

VII. A, Westward toward Lares from La Torre summit; U»Toward

Lares from the east; cocoanuts and bananas in foreground. ... £2

VIII. A, Parting Valley about and hills back of -Yauco; B, Arid flora 

near Lares; C, Fording Rio Loiza, near Carolina; D, Rio Portugues, at Ponce _.._._.._____.___-...---_.-.-_.-_-.-. -.-'--..- 26

IX. A, Rio Descalabrado; B, Rio ASasco; C', Regulator gate and

ditch; J), Wing dam...... ._..._._-___ -....... ............... 28

X. .4, River bed and masonry conduit; B, Irrigation ditch in earth;

C, Sugar land near Ponce; D, Guinea grass, Caguas Valley.... 32

XI. A, Mountain summits under cultivation; B, Ox cart; C, Saddle

and pack horse; D, Hogs led by rope..................._---_.. 34

XIL A, Sugar cane; B, Train of cars loaded with sugar cane drawn

by oxen; C, Coffee shade; D, Shelling coffee............ ...... 36

XIII. Map showing distribution of crops.-......--......-..--.---.-.,. 38

XIV. A, Cotton plant; B, Market scene, Ponce; C, Logs of ausubo en

route to market; D, Repairing military road ..........-..._... 40

XV. A, Mamey (bread fruit) tree in field of yautia, Rio Canovanas; 

B, Clump of bamboo; C, Near summit of Sierra de Luquilla; 

D, Ceiba tree in field of guinea grass ...-.....-.-..-.....--.... 42

XVI. A, Muddy cart road near Ad juntas; B, Muddy cart road near 

Aibonito; C, Rocky cart road near Lares; D, Rnttecl coral rock 

in cart road near San Sebastian __________-.-.._-_..-,-..---... 44

XVII. A, Bridge over Rio Cana near Caguas; B, Rocky cart road near

Lares..,--..-...............-...-..-...-. ...-..-.........---. 46

Fia. 1. Section north and south through El Yunque......----.-..-..,...-. 12

2. Section north and south through San Juan .......-.-..---.-.---..- 13

o. Section north and south through Ponce. _."-.....-.._-.-....---.---- 13

4. Cordillera Central, parting valley, coast limestone hills, and playa

at Ponce ...................-....._............... ..-.-....---- 15

5. Piloncilios, or conical coral hills; Lares.............----.-.-.-...-.. 20

6. Inverted siphon carrying ditch under military road ._........-.-... 30

7. Masonry conduit and retaining wall. ......-..-...^............,..- 31

8. Cultivated hilltops in Cayey tobacco district,.-.-...-.. ........... 37

9. Drying coffee on rolling platforms; Pietris plantation, Adjuntas . _. S8

10. Rockwork near Aibonito, summit of military road..... ........... 45

7
LETTER OF TRANSMITTAL.

DEPARTMENT OF THE INTERIOR, 

UNITED STATES GEOLOGICAL, SURVEY,

DIVISION OF HYDROGRAPHY,

Washington, My 31, 1899.

SIR: I have the honor to transmit herewith a manuscript relating 

to the water resources of Puerto Rico and to request that it be published as one of the series of Water-Supply and Irrigation Papers, 

The report is based on notes, sketches, and photographs gathered by 

Mr. Herbert M. Wilson during a brief journey made through the 

island of Puerto Rico in January^ 1899. The object of this trip 

was primarily to study the topographic characteristics and the water 

resources of the island, but incidentally numerous memoranda relative to the soil, agricultural products, and forests were obtained.

Mr. Wilson landed at the capital city of San Juan, whence a short 

trip was made by rail via Rio Piedras to .Carolina, whence saddle 

animals were taken still farther eastward to Canovanas and southward up the river of that name to its head waters, in the Sierra de 

Luquilla. After returning to San Juan he proceeded by ambulance 

over the military road, which crosses the island diagonally toward the 

southwest, via Caguas, Cayey, Aibonito, Coamo, and Juana Diaz, to 

Ponce, traveling by slow stages andt making the distance of 80 miles 

in four days.

At Ponce Mr. Wilson and his party were furnished with pack and 

saddle animals and civilian packers and set out the next day via 

Adjuntas and Lares, San Sebastian, and Anasco to Mayaguez, on the 

west coast. Thence the return journey to Ponce was made on horseback via Hormigueros and San German to Yauco, where rail was 

taken for Ponce.

Thus the trip included the country from the mountain tops near the 

eastern end of the island to near the southeast coast above Guayama 

and to the south coast at Ponce, a return to near the northwest coast 

at Lares, and a circuit of the southwestern coast from. Mayaguez to 

Ponce. The party crossed or visited the head waters of all the more 

important streams, saw nearly the entire country from the vantage 

points of the high summits, and visited nearly all of the larger cities 

except those at the eastern extremity of the island.
10 LETTER OF TEANSMITTAL.

This route led into the highest mountains at the eastern end of the 

island, within view of El Yunque, the highest peak; also into the 

Sierra de Cayey and the Cordillera Central, occupying the main length 

of the island, and, finally, into the low coral sugar loaves near Lares, 

and the limestone and volcanic foothills of the Tetas de Cerro Gordo 

and Las Sillas de Calderon, in the southwestern corner of the island. 

The data thus obtained concerning the water resources of this newly 

acquired portion of the United States are believed to be of sufficient 

importance to warrant early publication in this series of papers. 

Very respectfully, ^ F. H. NEWELL,

Hydrographer in Cliarge. 

Hon. CHARLES D. WALCOTT,

Director United States Geological Survey.
WATER RESOURCES OF PUERTO RICO.

By HERBERT M. WILSON.

TOPOGRAPHIC RELIEF.

Puerto Rico, as shown on the map (PI. I), is situated between latitudes 17° 54' and 18° 30' north and longitudes 65° 13' and 67° 15' west, 

thus lying well within the Torrid Zone. It is the easternmost as 

well as the southernmost of the Greater Antilles, though still farther 

to the east are the lesser of the West Indian islands belonging to the 

Windward Group. The shores are washed on the north by the waters 

of the Atlantic Ocean, on the south and east by those of the Caribbean Sea, and on the,west by Mona Passage, which separates the 

island from Haiti. According to the best information obtainable 

from measurement of existing maps, the area of Puerto Rico, exclusive of the dependent islands chief among which are Mona on the 

west and Viequas and Culebra on the east is 3,670 square miles. Its 

area is thus one-fourth, or 1,200 miles, less than that of the State of 

Connecticut, and is nearly three times as great as the area of Long 

Island. Its average width is 35 miles, or twice the width of Long 

Island, while its average length is 105 miles, or about the same as that 

of Long Island. Fourth of the Greater Antilles in size, it is roughly 

rectangular in form, its major axis lying almost exactly east and west.

The essential topographic characteristic of Puerto Rico is its exceedingly mountainous and highly eroded aspect, in spite of which none 

of its summits attain great altitude. The island is also notable for 

the abruptness with which the foothills of the mountain slopes plunge 

into the ocean, leaving practically no marginal coast plain, and for 

the variety in topographic form, resulting from great differences of 

erosive action at either extremity of the island and from changes in 

geologic structure. Extending irregularly through the entire length 

of the island from the extreme northeastern point, at Cabeza de San 

Juan, to the extreme western points, near Rincon and Cabo Rojo, is a 

series of connected mountain ranges forming the main divide between 

the drainage of the north and south coasts. At the eastern end of

11
U.S.GEOLOGICAL SURVEY WATER SUPPLY PAPER N9 32 PL.l.

ft»B£$$£'

-^kencontouisrqni^ent25Ofeet elevations.

Railroads 

Macadam* 

 Second class roads

DRAINAGE AND HYPSOMETRIC MAP OF PUERTO RICO

A.Ho«n * Cn. LLtb.B.llii,

BY HERBERT M.WILSON.
12 WATER RESOURCES OF PUERTO RICO. [NO. 32.

this island the most commanding range, the Sierra de Luquilla, terminates near its eastern extremity in the highest peak on the island, 

El Yunque, the elevation of which is given by Spanish authorities as 

1,520 meters, or approximately 4,940 feet. This appears to be an 

error, since, according to an aneroid reading by Mr. A. Hansard, its 

height is about 3,250 feet, while the maps of the United States War 

Department and charts of the United States Hydrographic Office and 

of the United States Coast and Geodetic Survey giTre its altitude as 

between 3,610 and 3,790 feet. Which of these elevations is most 

nearly correct it is at present difficult to ascertain. A north-south cross

SCALE

10 20 MILES

FIG. 1. Section north and south through El Yunque.

section through El Yunque (fig. 1) givejs some idea of the abruptness 

of the fall to the north, and is in striking contrast to the cross sections 

taken elsewhere on the island (figs. 2 and 3), which show the steepest 

slopes to the south.

A southern spur of the Luquillas connects this mountain range with, 

the northeastern spur of the Sierra de Cayey in a low divide but 5 

miles from the coast, near Humacao; thence the Sierra de Cayey 

extends westward to Aibonito Pass with comparatively uniform elevations between 2,200 feet in the lowest divides and 3,200 feet on the 

highest summits, none of which are especially pronounced. This portion of the main range of mountains skirts the eastern and southern 

coasts very closely, so that the greater portion of the drainage of the 

eastern third of the island is to the north, the southern and eastern 

coasts receiving the drainage from a narrow belt of country but 5 to 

10 miles in width. The length of the drainage to the north, measured 

in an air line, is from 25 to 30 miles.

At Aibonito the military road from San Juan to Ponce passes through 

the lowest divide in the central range of mountains, the elevation of 

this being approximately 1,840 feet above sea level. As a result of 

the closeness with which these mountains skirt the eastern and southern coasts, they suddenly fall off in a distance of but 2 to 3 miles hori-
WILSON.} - TOPOGRAPHIC RELIEF. 13

zontally from altitudes of 2,500 to 3,000 feet to the back coast border, 

at elevations of 200 to 300 feet. The abruptness of the escarpment to 

the south and east can thus be realized, and is illustrated by a northsouth cross section (fig. 2) constructed through Guayama and San 

Juan. This cross section also shows that the fall to the north, while 

not so great, is still quite abrupt, reaching the elevated basin about

SCALE 

to

PIG. a Section north and south through San Juan.

Cayey at an altitude of 1,200 feet, and is thence more gradual through 

the rolling country drained by the Rios Loiza and Guayanabo, in the 

neighborhood of Caguas, Aguas Buenas, and Comeiro.

To the west of Aibonito the main dividing range rises sharply in a 

broader and more strongly maintained sierra, which has here the name 

Cordillera Central. The passes through the Cordillera attain altitudes 

of 2,500 to 2,800 feet, but upon it there are no marked peaks, the 

highest summit scarcely reaching 3,300 feet in altitude. The Cordillera Central is interrupted to the north of Ponce in a pass 2,320 feet 

in altitude, leading to Adjuntas, at the head waters of the Rios PortuSCALE

FIG. 3. Section north and south through Ponca

gues and Arecibo. A cross section of Puerto Rico from Ponce to 

Arecibo (fig. 3) does not differ materially from that between Guayama 

and San Juan, the chief points of difference being that the slopes to 

the south do not fall away quite so abruptly as farther east, while to 

the north the slope is decidedly more gradual than in the neighborhood of Caguas.
14 WATER RESOURCES OP PUERTO RICO. [NO. 32.

West of Ad juntas the sierra rises abruptly to El Guilarte, altitude 

3,608 feet, which is the second mountain on the island in height. 

Here the character of the main dividing mountain range is abruptly 

changed. A number of rugged spurs branch northwestward toward 

Lares and Las Marias, westward toward Horrnigueros, and southwestward toward San German. These spurs have not the continuity of 

the main mountain range from which they spring, but are broken up 

into a number of irregular ridges and peaks of extremely rugged 

aspect.

The series of controlling mountain ranges as sketched above are of 

the same geologic time and origin; all are of mixed volcanic and sedimentary origin, consisting chiefly of hornblende-andesites, gneiss, and 

tuff, embedded in which, but found at altitudes generally below 2,000 

feet, is a compact blue limestone of Cretaceous time.

Abutting against the - foothills of these commanding sierras, and 

forming secondary topographic features of striking importance, are a 

number of varied forms found at different portions of the island and 

owing their shape and mode of weathering to their geologic origin. 

On the north coast, between Arecibo, San Juan, and Fajardo, the 

main summits fall away rather abruptly to elevations of between 

1,000 and 1,500 feet; they then continue as radial spurs, sloping 

gently to the northward and interrupted by numerous undulations, 

culminating often in peaks of considerable altitude and prominence.

These are separated by the principal rivers draining the interior, 

which flow generally to the north, but are deeply indented in the 

surface of the country. Thus within 5 or 6 miles to the north of the 

main summits the river bottoms are at altitudes of about 1,000 feet, 

while the summits of the ridges above are at elevations of 2,000 to 

2,500 feet. Again, within 5 miles of the coast, the river beds are at 

elevations of 50 to 100 feet above sea level, while the summits of the 

dividing ridges reach altitudes of 1,000 to 1,500 feet. These dividing 

ridges are often maintained to the ocean shore, are high, narrow, and 

A-shaped, and are separated one from the other by deep V-shaped 

valleys eroded by numerous streams flowing in every direction 

throughout the interior of the island.

COASTAL TOPOGRAPHY.

The topography of the coast border consists of narrow marginal 

plains extending here and there up the river valleys for from 3 to 5 

miles. These flat coast lands are called playas, and their continuity 

is broken on the northeast, southeast, and northwest by spurs of .the 

main mountain mass which plunge directly into the ocean. These 

encircling plains and playas are, moreover, irregularly broken by low 

coast hills. On the south these are all of limestone and are 200 to 400 

feet in height; on the north they are a series of old coral reefs eroded 

into detached hills of 50 to 150 feet in height. Thus the coast topog-
WILSON.] COASTAL TOPOGRAPHY. 15

raphy may be divided into three types, distinct from the central 

mountain mass, consisting of (1) the playas or plains; (2) coast hills 

and parting valleys which separate the latter from the foothill spurs 

of the central mountains; and (3) a highly eroded coral plateau, an 

intermediate topographic type beween the sierras and the coast topography, found in the northwest portion of the island between Arecibo, 

Lares, and Isabela. The ascent to this latter from the west in the 

neighborhood of Aguadilla is abrupt and the surface of the plateau is 

gently rolling. This is cut by the more important streams, which have 

eroded abrupt canyon walls 150 to 200 feet in height. To the south 

this is topped by a higher series of sugar-loaf shaped buttes of coral, 

the summit elevation of which is about 1,200 feet.

Still another topographic type, distinctive only in that it is an exaggeration of the limestone hills and parting valleys found elsewhere, is 

that between Mayaguez, Cabo Rojo, and Ponce, in the southwestern' 

corner of the island. Here the sea is bordered by a low ledge of coral, 

capped by a heavy stratum of hard limestone. This is tilted upward

FIG. 4. Cordillera Central, parting valley, coast limestone Mils, and playa at Ponce.

so as to rise from the southwest toward the center of the island, and is 

separated from the main sierra by two long and fertile parting valleys. 

Elsewhere on the island, and especially well developed from Ponce 

eastward to beyond Guayama, the low coast hills of limestone have 

their east-west continuity broken by the playas at the stream mouths. 

They are also separated front the main sierra by short, narrow parting 

valleys, eroded by branches of the streams which drain the main summits (fig. 4). Some of these hills terminate abruptly at the sea in 

bluffs 100 feet in height, while the parting valleys which border them 

on the north have elevations of 100 to 200 feet, their summits reaching 

altitudes of 500 to 1,000 feet.

PHYSIOGRAPHY AND SCENERY.

In order that the topographic forms of the island may be more clearly 

comprehended,'the following detailed description is given of some of 

the more striking surface characteristics along the route traveled.
16 WATER RESOURCES OP PUERTO RICO. [wo. 32.

The country traversed by railway eastward from San Juan as far as 

Carolina, and thence by military road to Rio Grande is typical of the 

larger playas reaching from the sea' margin to the back coast border. 

This is a comparatively flat alluvial plain (see PI. II, A) about the 

mouth of the Rio Loiza and its branches. It has been built up largely 

through the aid of mangrove growth, which has encroached upon the 

sea and retained the alluvium brought down by the streams. Between 

Rio Piedras and Carolina this alluvial plain is 5 miles in width from 

the seashore. Its greatest width, near the mouth of the river opposite 

the town of Loiza, is 9 miles. In the total air-line distance of 20 miles 

from near San Juan to beyond Rio Grande this plain is cut by three 

large lagoons, and the area of this magnificent stretch of agricultural 

land is about 100 square miles. The whole is well cultivated in a rich 

forage grass, called "Guinea grass," and in sugar cane. 

* To the south of the edge of this playa the hills rise rapidly in "broken 

spurs, which radiate from the summit of the Sierra de Luquilla. This 

playa land is, moreover, not an unbroken plain. It is comparatively 

level, however, rising from a few feet to about 60 to 75 feet above sea 

level. The apparently dead level of this playa is interrupted by occa 

sional low, bluff-topped hills of coral rock (see PI. II, J5), which have 

not been entirely eroded away.

A journey southward from Canovanas, up the river of that name to 

the summit of the Sierra de Luquilla, brings one immediately into the 

roughest of the highly eroded and rugged mountains which are so 

characteristic of the island. Cart roads extend up this river, as well 

as up all the other more level^ streams, until the diminished width of 

the gorge through which it flows and the roughness of the country 

cause them to be superseded by trails. The river flows over a rough, 

rocky bed and between steep slopes (see PI. II, (7), which are thickly 

covered with natural and cultivated vegetation. The cart road and 

the trail ford the river fifteen or twenty times in a distance of about 

6 miles, due to the sharp curves of the stream between the confining mountain slopes. At the end of that distance, at an elevation of 

about 250 feet, the gorge has become so narrowed that the trail leaves 

it and climbs abruptly, in 2 or 3 miles, to an altitude of 1,350 feet. In 

all directions branch trails lead up the steepest slopes to the habitations of the peasants, who are everywhere engaged in the cultivation 

of the various crops which thrive best in each particular locality. (See 

PI. II, D.)

The military road from San Juan to Caguas passes through a hilly 

depression, between the western terminus of the Sierra de Luquilla and 

the northern spurs of the Cordillera Central. The divide between the 

drainage basins of the Rios Loiza and Bayamon is crossed at an 

altitude of but 375 feet. At Caguas a broad mountain valley on 

the head waters of the various branches of the Rio Lo.iza is entered at 

an altitude of 230 feet. The slopes in every direction are not abrupt;
U. S, GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. Il

A, CAROLINA PLAIN, WITH EL YUNQUE IN DISTANCE i>, PLAYA AT MOUTH OF RIO LOIZA.

O, RIO CANOVANAS. D, FOOTHILLS OF SIERRA DE LUQUILLA, SHOWING FIELD AND 

COCOANUT TREES,
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. Ill

A, VIEW WEST FROM CAYEY DIVIDE.

B, RIO JACAGUAS NEAR JUANA DIAZ.
WILSON.] PHYSIOGRAPHY AND SCENERY. 17

their altitudes are not great, and all are well cultivated. The road 

southward to Cayey remains in the general depression at the head 

waters of the Bios Loiza and Plata, and is surrourided on the east 

and south by much higher and more rugged mountains, which slope 

upward to the summits of th^ main divide. To the northeast are 

numerous highly eroded ridges and peaks, the northward radial 

spurs of the Sierra de Cayey and of the Cordillera Central. Las Cruces, 

the highest pass between the head waters of the Rios Loiza and 

Plata, is crossed at an altitude of 1,310 feet. (SeePI. Ill, A.) Immediately thereafter the road descends abruptly to the " vegas," or plain, 

between altitudes 1,080 and 810 feet, extending for about 6 miles to 

and beyond Cayey. The valley about that city is .gently rolling, the 

country sloping away rather abruptly to the Rio Plata on the north, 

whence it rises rapidly to the higher summits of the northward radial 

spurs. To the south the summits of the main divides are nearly 2,000 

feet directly over the valleys. Abrupt as are the slopes all are heavily 

covered with soil and vegetation.

Beyond Cayey the road climbs rapidly to the main divide between 

the drainage areas tributary to the north and south coast. (See PI. IV, 

A.) This divide is crossed within 2 mile's of Aibonito at an altitude of 

1,860 feet. Thence there is a gradual descent of but 100 feet to the. 

rolling tableland about Aibonito, beyond which at an equal distance 

is a second summit with an altitude of 1,810 feet. The summits of 

the main sierra, as seen from the Aibonito uplands, have everywhere 

the same highly eroded forms, irregularly shaped mountain ridges, 

long spurs, and isolated peaks, jutting out in every direction to altitudes of 500 to 1,000 feet above the rolling upland on which their bases 

rest at elevations of 1,700 to 2,000 feet.

Beyond the second summit at Aibonito Pass the road descends with 

great abruptness in but 6 miles, as measured along its meanderings, 

and only 2 miles in an air line, for 1,400 feet, to an altitude 420 feet. 

Here is Some of the most magnificent mountain scenery. (See PL V, 

A.) The character of the topography, as well as of the flora, changes 

entirely as the semihumid side of the island is approached. The 

brilliant green here disappears from the vegetation, the damp moss 

and fern-covered slopes are gone, and all is covered with short, dry 

grass (see PI. VI), not unlike the bunch and buffalo grass of the 

West, with acacias and with other arid flora. At the same time the 

topographic forms do not exhibit the same high degree of erosion. 

Though exceedingly abrupt, the mountain slopes are more uniform 

and less intensely cut into separate spurs and peaks. The depth of the 

soil is much less than on the northern slopes, and rocky ledges and 

bluffs occasionally protrude.

The whole of the region from San Juan to Aibonito is picturesque 

in the extreme, and has an exceedingly pastoral and peaceful aspect. 

Caguas Valley is ideally beautiful. It is almost circular, about 3 by 

IRR d2 «
18 WATER RESOURCES OF PUERTO RICO. [NO.32.

4 miles in dimension, and through it winds in great serpentine curves 

the Rios Caguitas and Turabo. The former makes a long coil about 

El Monte, a lone hill 300 feet in height which occupies the center 

of the valley. (See PI. IV, B.) Among the higher summits about 

Aibonito the country still has the same picturesque aspect, the same 

pleasantly pastoral appearance, accentuated only by the immensity 

of the slopes. From the higher summits the Atlantic Ocean is in plain 

view to the north and the Caribbean Sea to the south. Every detail 

of topography may be seen for miles in all directions, as though one 

were viewing a model map.

Beyond Oayey and thence to Coamo the great mountain masses rise 

to such sheer heights or descend so abruptly to the bottoms of great 

gorges as to be imposing in the extreme. Between Coamo, Juana Diaz, 

and Ponce the aspect of the country is entirely dissimilar to that seen 

elsewhere on the route. The military road skirts the southern slopes 

of the Cordillera Central and remains at a fairly constant distance of 5 

miles back of the coast. It crosses six of the more important rivers 

which drain the southern slopes (see PI. Ill, B), yet at no place does 

it attain an altitude greater than 250 feet above sea level, nor at the 

stream crossings is it less than 100 feet above sea level.

To the north the masses of the main sierra rise abruptly in great 

jagged spurs, with fairly uniform slopes. In all other directions the 

country is a rolling plain, broken by numerous ridges and detached 

hills. (See PL VI.) These are separated by small and level parting 

valleys, relatively broad and all under cultivation, chiefly in sugar 

cane. (See PL X, (7.) The entire south coast is 1 to 7 miles in width, 

averaging about 5 miles, and from east of Guayama to a little west of 

Ponce is of this same general character. The sea is bordered by 

coral reefs, sometimes, especially near the river mouths, by small 

playas, and back of these, often quite close to the coast, rising northward there is a tilted limestone table-land.. This is eroded into 

detached hills and ridges both by the north-south primary drainage 

and by the east-west lateral drainage which forms the parting valleys. 

There is thus seen to be a large area of excellent agricultural land 

along the coast, but this is generally so arid as to require irrigation for 

the cultivation of such thirsty crops as sugar cane. Small fruits and 

vegetables are grown without irrigation and all the hills are covered 

with forage grass. The mountain slopes on this side, however, are 

not nearly so extensively cultivated as on the north side. In addition 

to the disadvantage of unfavorable soil and insufficient precipitation, 

comparatively little foothold is given to vegetation on their steep 

sides.

On the road from Ponce to Ad juntas, which ascends first the general course of the Rio Magueyes and near the summit crosses to the 

head waters of the Rio Portugues, one has an almost south-north cross 

section of the sierras, as compared with the diagonal section viewed
U. S. GEOLOGICAL SURVEY UPPLY PAPEft NO. 32 PL. IV

A, VIEW BETWEEN CAY EY AND AIBONITO SUMMIT. K, CAGUAS VALLEY AND EL MONTE.

C, HILLS ALONG RIO ANASCO. D, VIEW NEAR SUMMIT OF ADJUNTAS PASS,
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL- V

A, SCENERY SOUTH OF AIBONITO SUMMIT.

fi, BENT MANGO TREES. SAN JUAN.
WILSON.] PHYSIOGRAPHY AND SCENERY. 19

in traveling south westward from Aibonito to Ponce. The topographic 

characteristics are identical with those seen, however, on the latter 

route. Four miles to the north of Ponce the elevation is but 50 feet. 

The way climbs for the next 3 or 4 miles through sloping .foothills to 

an altitude of 400 feet. Thereafter, in 2 mites horizontally, the ascent 

to the main ridge dividing the two rivers is to an altitude of 1,720 feet. 

With equal abruptness the main summit (see PL IV, D) is reached 

about 15 miles from Ponce, at an altitude of 2,320 feet.

Adjuntas is on the northern slope and on the head waters of the 

Rio Arecibo. About it the topographic characteristics are in all 

respects similar to those observed at Aibonito. But a few miles to 

the southwest rises El Guilarte; to the north are seen long radial spurs 

of the main sierra, which are separated at Utuado by the valley of the 

Arecibo; northwestward another long spur extends to and beyond 

Lares and San Sebastian to the western sea at Aguadilla. This separates tli© head waters of the various rivers which empty into the northern ocean between Arecibo and Aguadilla and the drainage of the 

Rios Culebrina and Prieto, which flow into the western sea at Aguadilla and Anasco, respectively. The spur which extends to the southwest, and on which are El Guilarte, Las Sillas de Calderon, Tetas de 

Cerro Gofdo, and other prominent peaks, separates the waters of the 

Rios Prieto and Blanco from those of the Rio Guaaajibo.

It is thus seen that the neighborhood of Adjunfeas is, as^the name 

implies, the dividing point of the main sierra, which has extended 

with unbroken crest from its easternmost summit at El Yunque. At 

this point it is separated into a number of spurs of almost equal 

prominence, which r«ach' the western coast with several ramifications, 

the most prominent of which is necessarily that containing the group 

of summits above named.

The various trails leading westward from Adjuntas toward Las 

Marias and Lares follow the head waters of the Rio Blanco or Rio 

Prieto for a short distance. Thence they climb to altitudes of about 

2,000 feet at the summits of the divide separating the various drainage lines. These divides are high A-shaped ridges, separated by great 

V-shaped canyons with relatively smooth slopes 1,000 feet in depth, 

all well covered with vegetation. Everywhere throughout this region, 

on the highest summits and in the bottoms of the most profound 

gorges, are found the habitations of the peasantry, who gain a comfortable living from the cultivation of coffee and of fruits and vegetables.

From the summit above Lares (PI. VII, A), the altitude of which 

is 2,000 feet and which is called La Torre, a magnificent view is had 

of the surrounding landscape. To the east, south, an,d southwest are 

great masses of the most rugged mountain forms. In the first direction the high and serrated northward spurs of the Cordillera Central 

form the horizon line. To the south one looks across the gorge of the
20 WATER EESOURCES OF PUERTO RICO. [NO. 32.

Rio Blanco, 1,500 feet in depth and but a mile distant, whence the 

eye climbs a space of but a few miles to the highest summits of El 

Guilarte and Las Sillas de Calderon. To the north and northwest the 

country slopes away to the point, apparently but a few miles distant, 

Where the sea and sky meet in a dull gray line. The topographic 

aspects in this direction are entirely different from anything heretofore seen. The immediate foreground slopes away gradually to an 

altitude of about 1,000 feet in the neighborhood of Lares, beyond which, 

extending from the north through 80° toward the west, is a long 

line of sugar-loaf shaped coral hills (see fig. 5). These are but 250 to 

350 feet in height, their summits reaching altitudes of about 1,200 

feet. Some are covered with smooth green slopes and others have 

their surfaces broken by steep bluff ledges of coral. These " Piloncillos" or "Farallones," as the Spanish-American calls them, have 

the general appearance of a great group of conical-shaped Sibley

FIG. 5. Piloncillos, or conical coral hills; Lares.

tents and in this locality go under the general name of "Pepino hills," 

though similar topographic features in other portions of the West 

Indies are called by the English "cockpits."

Between Lares and San Sebastian the country is generally similar 

in topographic aspects to the region north of Cayey and Caguas toward 

San Juan. San Sebastian is at an elevation of 270 feet. From it fall 

away toward the west the gorges of the various rivers which drain 

that slope, and these are separated by high ridges having altitudes of 

but 500 to 800 feet, rising, however, to altitudes of nearly 1,000 feet 

as they approach the ocean. North of Anasco a high and serrated 

ridge maintains its bulk to the very margin of the sea, into which it 

plunges with abrupt slopes. The same is true of the ridges which 

approach the ocean to the north of Aguadilla, and in less degree of 

those north and south of Mayaguez. At the mouths of the principal 

rivers in the neighborhood of Aguadilla, Anasco, and Hormigueros
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. VI

BARREN HILLS NEAR JUANA DIAZ; PEASANT'S HOUSE AND ORANGE TREE IN FOREGROUND-.
WILSON.] CLIMATOLOGY. 21

are extensive alluvial playas similar to those already described, and 

highly cultivated in sugar cane.

The country traversed by the main highway from Mayaguez via 

San German and Yauco to Ponce has already been generally described 

as differing essentially in topographic characteristics from any of the 

other portions of the island passed over. The road skirts the southwestern slopes of the main sierra. Between it and the sea, distant in 

some places as much as 8 to 10 miles, are a series of low, rolling limestone hills tilted upward toward the interior and separated by two 

extensive parting valleys. The erosive action which has produced 

the long valleys marking the junction line between the foothills which 

parallel the main mountains promises, according to Mr. B. T. Hill, to 

reduce these valleys to sea level in the near geologic future, and thus 

to cut off from Puerto Rico a small island including the country round 

about Cabo Rojo and Lajas.

From Mayaguez, through Hormigueros and San German, to Sabana 

Grande is a great valley, through which flows the Rio Guanajibo. It 

is this which separates the main summits from the rolling foothills to 

the south, which are hereby dignified by the collective name of Cerro 

Gordo. Between Sabana Grande and Yauca is a low divide connecting the Cerro Gordo with the main sierra and separating the 

greater valley from a similar but smaller valley, which includes the 

lagoon of Guanica and extends from Guayanilla and Yauco to the 

port of Cabo Rojo. (PI. VIII, A.) Still south of the valley and separating it from the Caribbean Sea is a second well-defined ridge of 

low limestone and coral hills.

CLIMATOLOGY.

Situated as the island is, with a middle latitude of about 18° 15' N., 

which is well within the torrid zone, it is seen to be in the same 

approximate latitude as the City of Mexico, the Hawaiian Islands, the 

Sahara Desert, and Bombay, India. Because it is the easternmost of 

the Great Antilles, however, its climate is so tempered by the trade 

winds as to render it more moist and salubrious than that of any of 

the regions named, with the possible exception of the Hawaiian 

Islands.

To the trade winds primarily, and to the influence upon them of 

the high mountain summits in the interior of the island, are to be 

ascribed the moderate temperature and the peculiar distribution of 

precipitation which characterize this island. Though smaller in area 

by 1,000 square miles than the State of Connecticut, its extremes are 

subject to as great difference in rainfall, both in amount and occurrence, as are the extremes of the United States. The trade winds 

blow with unceasing regularity throughout the year, though not with 

such force as to be disagreeable. Their pressure is felt as wind movement but a short distance from the northern and eastern coastg, yet
22 WATER RESOURCES OF PUERTO RICO. [NO. 32.

their influence is exerted throughout the island, most perceptibly to 

the east and north of the mountain summits which form the watershed between the Atlantic Ocean and the Caribbean Sea. Their 

strength and persistence is witnessed in the shape of the trees on the 

north or windward coast (see PL V, B), where the trees are bent 

southwestward or away from the prevailing winds much as those on 

the southern coast of California bend eastward or landward away from 

the prevailing Pacific winds.

Heavily moisture laden from the warm ocean, the trade winds press 

against the mountains, which quickly condense the moisture they bear, 

and heavy showers of sudden occurrence but short duration result. 

Southward and westward the same winds continue to cause even more 

abundant precipitation at the sierra summits near the center of the 

island. Crossing these the winds are suddenly freed and expand, 

and being thus given power to carry in suspension a larger amount 

of moisture, they let fall but little rain over the southern and western 

slopes.

PRECIPITATION.

The above conditions are clearly recorded in such meteorologic data 

as has been collected by Prof. Mark W. Harrington; of the United States 

Weather Bureau, from existing Spanish records. According to a bulletin issued by the Weather Bureau, records for a period of twelve 

years show the average annual precipitation in San Juan to be 59.5 

inches. This is fairly well distributed throughout th& year, the greatest monthly mean (7.62 inches) occurring in November, but that amount 

is closely approached during the entire rainy season from April to 

November, inclusive. During the remainder of the year, in the 

so-called dry season, the mean monthly precipitation falls to a minimum of 1.8 inches in February. The persistence of rainfall throughout the year is still further accentuated by the fact that the least precipitation recorded at San Juan in any month was 0.3 of an inch in 

March of one year, while the greatest was 17.1 inches in August of 

another year.

While these figures give an indication of the range of precipitation 

in the neighborhood of San Juan and near the north coast, they form 

no criterion for the relative amounts falling elsewhere on the island. 

Records of observations made by Capt. Arthur C. Hansard at Hacienda Perla, published by the Weather Bureau, indicate quite different conditions there. This place is situated on the northeast coast, 

only about 20 miles east of San Juan, and about 3 miles from the 

sea, at an elevation of 460 feet. The records show an average annual 

precipitation of 123.4 inches during the two years 1896 to 1898, the 

maximum, 136.2 inches, occurring in 1897. The distribution of rainfall was similar to that at San Juan, the minimum monthly precipitation being 2.5 inches in February and the maximum 32.9 inches in 

May. During this period the greatest consecutive twenty-four-hour
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER MO. 32 PL. VII

A, VIEW WESTWARD TOWARD LARES FROM LA TORRE SUMMIT.

R, VIEW TOWARD LARES FROM THE EAST; COCOANUTS AND BANANAS IN 

FOREGROUND.
WILSON.] PRECIPITATION. 23

rainfall was 8.4 inches in August. In this period there averaged 

two hundred and fifty days a year in which over one-hundredth of 

an inch fell. The great differences in precipitation between two places 

so close together is partly accounted for by the fact that Hacienda 

Perla lies under the northern slope of El Yunque, the highest mountain on the island, and it feels therefore more strongly the effect of 

the compression of the trade winds than does San Juan, which is 

situated on the coast, and behind which the mountains rise more 

gradually and at a considerably greater distance to less altitudes than 

those behind Hacienda Perla. As shown by the accompanying profiles (figs. 1, 2, and 3), the highest summits back of San Juan, at the 

headwaters of the Rios Plata and Loiza, reach altitudes of 2,700 

feet in a horizontal distance of 30 miles.

Back of Hacienda Perla an altitude of over 3,700 feet is attained in 

less than 3 miles horizontally. Farther inland to the south and west 

of San Juan, under the summits of the main sierra in the neighborhood of Cayey, Aibonito, Barros, and Adjuntas, the precipitation is 

considerably greater than at San Juan, though not nearly so great as 

at Hacienda Perla. . This is because these points are at a much higher 

elevation and are nearer the mountain crests than is the capital city, 

and feel more directly their effect upon the trade winds.

Apparently great as are these extremes of precipitation, they are 

small as compared with those between points on the south and north 

coasts. According to data gleaned from Spanish records, it appears 

that the average annual precipitation on the southern slope of Puerto 

Rico is but 20 inches, against 55 to 123 inches on the northern slopes. 

This amount, however, is most irregularly distributed. There is said 

to be an authentic record at Guayama, immediately south of San 

Juan, of thirteen months, chiefly in the year 1893, when not an inch 

of rainfall was recorded. The records at Cabo Rojo show one period of 

three years in which no rain fell.

Such great changes in precipitation, as well as in geologic formation and soil composition, result in great differences in the flora of 

the two coasts. Puerto Rico may be said to have a humid as well as 

an arid side. This is evidenced not only by the perpetual muddiness 

of the roads on the north slope as compared with their dry and dusty 

surfaces on the south, but especially by the vegetation and the regimen of the rivers.

On the north, nearer the mountain summits, the flora is always 

bright and verdant and of true tropical luxuriance (see PI. IV, A), and 

the rivers carry large volumes of water. In the south, especially near 

the southwestern extremity of the island, the trees are dwarfed hardwoods; cacti, century plants, and acacias abound, and the vegetal as 

well as the topographic characteristics are similar to those of the semiarid Southwest of the United States. (See PI. VIII, B.) The river 

beds, moreover, are almost dry and are full of rocks and bowlders.
24 WATER RESOURCES OF PUERTO RICO. [NO. 32.

*

These two salient facts, the diversity of climate and of soil composition, must be kept prominently in mind in any consideration of 

agricultural or water resources or of highway construction, They 

make it clearly evident that any generalizations on these subjects for 

the whole island are valueless, and, small as is the area, each particular 

locality must be considered by itself in discussing the development of 

its products. It is scarcely necessary to add that while irrigation is 

not practiced on the northern side of Puerto Rico, all the wealth of 

sugar produced on the seniihumid side is dependent for its successful 

cultivation on water supplied by irrigation.

TEMPEEATURE.

The temperature is very evenly distributed in height and range, and 

is in marked contrast to the variations in precipitation. It need not 

be discussed in detail, as it has* little bearing upon problems connected 

with the agricultural resources, the development of irrigation, or the 

construction of highways. It is chiefly interesting because of its uniformity and the resulting healthfillness of the climate. The highest 

recorded temperature was that of 100.8° F., in the month of May, and 

the lowest but 56.1°, in the month of December. Rarely, indeed, has 

a temperature lower than 57° been recorded, and as rarely one above 

97°. The average annual temperature recorded in San Juan during 

twelve years was 78.1°, the lowest mean monthly temperature being 

74.7° in February of one year and the highest mean monthly temperature 81.1° in June of another year, a range of but 6.4° in extreme 

mean monthly temperatures.

At Hacienda Perla the average annual temperature is 76.9°, or but 

1° lower than at San Juan. At the same place the maximum recorded, 

95°, is lower by 5°, and the minimum is higher, 61°. Elsewhere in the 

mountains the range of temperature is about the same. On the south 

coast, as in the sierras, there are no authentic records, but there 

appears to be great uniformity of temperature everywhere on the 

island.

HYDROGRAPHY.

In spite of the smallness of the island, and the consequent short 

length of its rivers and restricted areas of their catchment basins, it 

is unusually well watered, because of the comparative humidity of the 

climate. Moreover, because of the steepness of the slopes, especially 

on the northern coast, and the impervious character of the clay soil 

which covers them, the proportion of precipitation which runs off 

makes these rivers of even larger volume than would otherwise be 

expected under corresponding conditions. Into the northern ocean 

flow 12 streams of considerable magnitude; toward the west coast flow 4 

of relatively equal size; into the eastern sea flow 5 of less magnitude, 

and into the southern sea flow 17 of considerable size but comparatively small perennial volume. In addition, there are between 1,200
WILSON.] HTDfcOGRAPHY. 25

and 1,300 streams and branches of less volume, but yet of sufficient 

size to bear separate names.

Since the average width of the island is but 35 miles and its extreme 

length but 105 miles, while its commanding summits range in altitude 

from 2,800 to 3,750 feet, it is evident that the slopes are steep, the fall 

of the rivers great, and the velocity of their waters high. Moreover, 

as the main summits of the dividing mountain ranges have been shown 

to be one-third nearer the southern and eastern coasts than the 

northern and western, it is also evident that such streams as flow to 

the north and west are three or four times as long and drain ten to 

fifteen times as great areas as those flowing to the south and east. The 

former have average lengths of 25 to 40 miles, measured along their 

stream beds; the latter have lengths of but 5 to 15 miles. For these 

and the reasons already given the streams flowing north and west 

necessarily have less abrupt slopes than do those which drain eastward and southward, which plunge from an altitude of 3,000 feet to 

sea level within a comparatively few miles.

It is thus seen that as the island is divided elirnatologically into two 

distinct portions, it is similarly divided hydrographieally, largely as a 

result of the same causes the trade winds and the topographic configuration of the surface. ^

Of the twenty-eight larger rivers above enumerated, each has its 

source high among the summits of the Cordillera Central. Those flowing to the north and west are characterized by precipitate descents 

of 1,000 to 2,000 feet in the first 5 miles of their headwaters. Thereafter they flow more leisurely and with consequent increased size to 

within 5 miles of the coast. There they emerge practically at sea 

level in long, meandering curves through the alluvial playas about 

their mouths. Because of the lowness of their grades near the coast 

and their resulting low velocity, all are of considerable width and 

moderate depth in the playa levels. A few miles inland, where they 

flow over steep, rocky beds, their channels are narrow and often confined by precipitous rocky walls, their width is of but comparatively 

few feet, their depth often less than a foot, and their velocities so 

high as to render them veritable mountain torrents (see PI. II, O).

On the southern coast the larger rivers have bed widths as great as 

those entering the northern and western coast. Their lengths, however, are so short for the same fall that they are not characterized by 

the long stretches of low, meandering grade found near the coast in 

the playas to the north. They emerge, on the contrary, from the mountains at but 3 to 5 miles from shore line at altitudes of 200 to 400 feet, 

and as a result this elevation is passed with comparatively steep 

slopes over rocky or bowlder-strewn channels. Above these coastal 

stretches and within the mountains the lengths of the rivers are so 

short for the relatively great heights which they fall that their dimensions are little greater than those of the smallest brooks which flow 

from the hill summits in the Rocky Mountains.
28 WATER BESQilfiCSS -OF FUEBTO TSICO. [NO. 32.

The rivers of the north and of the west are more like the streams of 

humid regions in the United States, as their perennial discharge is 

always fairly well maintained. The larger of these rivers have at 

low-water stage bed widths of 150 to 200 feet, average depths of 2 to 4 

feet, and minimum discharges of 250 to 1,500 second-feet. (See PI. 

VIII, C.) In time of flood, although these rivers attain maximum discharges of 10,000 to 20,000 second-feet, these volumes are not greatly 

in excess of the flood discharges of the rivers of the southern slope.

The width of stream bed of the southern rivers is often as great as 

that of those entering the northern coast, but owing to the infrequency 

and small amount of the precipitation and the relatively porous character of the soil reducing the percentage of run-off, as well as to the 

smallness of their catchment basins, they discharge minimum volumes 

of but 50 to 100 second-feet. These streams resemble the rivers of 

our Western plains in that their beds are nearly dry the larger part of 

the year (see PI. VIII, D), but are yet of sufficient capacity to discharge great volumes during the sudden floods to which they are subject. The beds of these rivers, even near the coast, are bowldei 

strewn and are from. 100 to 300 feet in width. The depth of their banks 

is 10 to 20 feet, yet the minimum, surface widths of such streams is 

but 50 to 100 feet and their average depth one-half to 1| feet during 

their minimum discharge, th maximum flood such streams reach discharges aggregating 5,000 to 10,000 second-feet, in some cases even 

more, as shown by their wide, rocky, dry beds.

To convey a clearer idea of the size and regimen of the rivers of 

Puerto Rico, the following results of rough gagings of such streams as 

were examined in the preliminary reconnaissance of the island are 

given. As these streams were observed in the middle of the dry season their discharges may be taken as showing the average minimum 

volumes which they carry.

The Rio Loiza, probably the largest on the island, was gaged near 

Carolina, about 15 miles east of San Juan. Its surface width was 220 

feet, its average depth 3 feet, and its minimum discharge 1,600 second-feet. (See PI. VIII, a)

The Rio Canovanas, above its junction with the Loiza, 5 miles east 

of Carolina, has a bed width of 60 feet, average depth 2 feet, average

velocity about 5 feet per second, and discharge 600 second-feet.

(See PI. II, C.) This amount is to be added to the discharge of the 

Loiza to give the volume of the latter at its mouth.

At Caguas, abdut 20 miles by road south of San Juan, and 230 feet 

above sea level, the Rio Caguitas, one of the principal branches of 

the Loiza, flows in long, meandering curves through a level alluvial 

valley, and carries a minimum volume of about 50 second-feet. A few 

miles beyond, and in the same valley, the Rio Turabo, another branch 

of the Loiza, is of similar character and discharges an equal volume.

The Rio Carite, at the crossing of the military road, 36 miles from 

San Juan, and in the Vegas or plain of Cayey, has an elevation of
U. S. GEOLOGICAL SURVEY

A, PARTING VALLEY ABOUT AND HILLS BACK OF YAUCO.

0,. FORDING RIO LOIZA NEAR CAROLINA.

WATER-SUPPLY PAPER NO. 32 PL. VIII

Ji, ARID FLORA NEAR LARES.

I). RIO PORTUGUES AT PONCE.
WILSON.] HYDROGRAPHY. 7

about 1,180 feet above sea levsl. This is a branch of the Rio Plata, 

and its discharge at this point is about the same as those of the two 

last-mentioned streams, namely, 50 second-feet, though because of 

its greater altitude, and consequently greater slope, the cross section 

of its channel is smaller.

The Rio Plata, at a point 4 miles northwest of Cayey, at an altitude of 810 feet, has a bed width of about 100 feet, a depth of 1£ feet 

and a discharge of 230 second-feet.

South of the main divide at Aibonito, the Rio Calabasas, 4 miles 

east of its junction with the Rio Coaino at Coamo and at an elevation 

of 480 feet, has a velocity of 3 feet per second and a discharge of but 

25 second-feet.

The Rio Coamo, at the city of that name, and at 360 feet above sea 

level, has a bed width of 100 feet, though its surface width is somewhat less. Its depth is but 4 inches and its discharge 100 second-feet.

The Rio Desealabrado, halfway between Coamo and Juana Diaz, at 

an elevation of 260 feet, has a comparatively dry bed of 120 feet width. 

Its velocity is but 2 feet per second and its discharge 40 second-feet. 

(See PL IX, A.)

The Rio Jacaguas at Juana Diaz, elevation 160 feet, has a bed width 

of 180 feet, a minimum surface width of 50 feet, and a discharge of 

50 second-feet. (See PI. Ill, B.)

The Rio Portugues at Ponce has a bed width of 175 feet, yet its 

minimum, discharge is but 60 second-feet. (See PL VIII, D.) Its 

total available discharge is considerably greater than this, but the 

remainder of its volume is diverted a few miles above for irrigation 

and for the water supply of Ponce. The same is in a measure true of 

the Rio Jacaguas, a portion of the discharge of which is utilized for 

irrigation above the military road.

The Rio Magueyes, at the crossing of the road from Ponce to Adjuntas, 5 miles nSrth of Ponce, elevation 400 feet, has a minimum discharge 

of 35 second-feet.

The Rio Portugues, at the crossing of the above-named road, near 

its' headwaters, 9 miles north of Ponce, elevation 1,000 feet, has a minimum discharge of 25 second-feet.

The Rio Arecibo, near its headwaters, at Ad juntas, altitude 1,440 

feet, has a minimum discharge of 40 second-feet. A few miles lower 

down, at Utuado, its discharge is 100 second-feet. This river, like 

the others described, discharges relatively increased volumes in its 

lower reaches near the coast.

The Rio Yahueca, one of the headwaters of the Rios Blanco and 

Pietro, or, as they are called near the coast, the Rio Anasco, has, at 

an elevation of 1,440 feet, about 5 miles west of Ad juntas, a minimum, 

discharge of 20 second-feet.

The Rio Blanco, into which the Rio Yahueca discharges, at an elevation of 1,350 feet, about 8 miles west of Adjuntas, has a mininmm 

volume of about 50 second-feet.
WATER RESOURCES OP PUERTO RICO. [NO. 32.

The Rio Culebrina, near the middle of its course at San Sebastian, 

elevation 140 feet, has a bed width of 125 feet, a considerably less 

surface width, a velocity of 4 feet per second; and a minimum discharge of 100 second-feet.

The Rio Anasco, halfway between San Sebastian and Anasco, at a 

point about 8 miles from the latter city, has, at an elevation of 80 feet, 

a bed width of 150 feet, a surface width of 75 feet, a depth of 1£ feet, 

and a discharge of nearly 600 second-feet. (See PI. IX, B.) The 

satne river below the city of Anasco flows through a level playa and 

has an easy, meandering course, its grade being so low as to render 

its velocity very slow. Its surface width is here about 200 feet, its 

depth 4 to 8 feet, and its discharge about 1,000 second-feet.

IRRIGATION.

It is evident that all the crops which the soil will produce can be 

grown over three-fourths of the extent of the island with the aid of 

the abundant rainfall alone. The other one-fourth, including all 

the region near the coast and from Cabo Rojo on the extreme west 

to beyond Guayama on the east, must be irrigated if the soil is to 

produce the full measure of crops of which it is capable. The total 

area of these irrigable lands is, however, relatively small. A portion 

of this one-fourth, or, in round numbers, of the 800 arid square 

miles,, is included within the steepest portions of the southern mountain slopes. Another portion consists of the rugged foothills which, 

as they rise in detached summits, it is impossible to reach with 

a gravity water supply. Still another portion of this area consists of 

the alluvial playas, which produce fairly abundant crops with the aid 

of the moisture which they draw through their roots from a soil which 

is but a few feet above the level of the sea. Of the 450 square miles 

included within the southern back-coast border, perhaps 150 consist 

of playa lands which need not be irrigated, and 300 more consist of 

detached and inaccessible hills and of the precipitous slopes of the 

sierra. There remain, accordingly, perhaps a total of 150 square 

miles which would add to the agricultural resources of the island if 

artificially provided with water.

The soil on these lands is in every case of the very best kind for 

agriculture with irrigation. It is usually an open, porous, limestone 

soil of sandy and gravelly texture, mixed with a little earthy loam. 

It is fairly deep and is underlain by a porous limestone or coral, which 

affords the best drainage and probably renders it safe from the danger of producing alkali. Much of it is already under cultivation in 

maize, beans, pease, and other lentils in the southwestern extremity of 

the island, and small vegetables and fruits elsewhere.

While the precipitation is insufficient, the perennial flow of the 

streams is unusually abundant for a land requiring irrigation. The 

minimum discharges of these streams where they would be diverted in
U. S. GEOLOGICAL SURVEY

A', RIO DESCALABRADO. S, RIO ANASCO.

0, REGULATOR GATE AND DITCH. D, WING DAM.
WILSON.] IRRIGATION. 29

the foothills are moderate in amount and yet nearly sufficient for the 

irrigation of such areas as they command. Moreover, the flood discharges of these streams occur at frequent intervals throughout, the 

year, but are especially well distributed throughout the summer or 

rainy season. They afford an abundant surplus for storage. The 

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

which the rivers emerge from the mountains give every indication 

that abundant opportunities will be found, on fuller investigation, for 

the construction of storage reservoirs at moderate expense and at relatively small cost.

The Spaniards, who in the past have been the principal landholders, 

are thoroughly familiar with the requirements and processes of irrigation as practiced in Spain. Quick to appreciate the advantages of 

the artificial application of water, they have already constructed 

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

sugar land, especially between Guayama and Ponce, is cultivated 

exclusively by the aid of irrigation. Much as has been done already 

in this direction, there is still room for further development. But a 

portion of the available water supply has been appropriated, and 

but a small portion of irrigable lands are artificially supplied with 

water.

Such works as were noted correspond in general type to those seen 

in Mexico, but because of the greater influence of European ideas in 

this island, their 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 rock and bowlders thrown out into the beds of the 

streams to direct a portion of the waters into the heads of the ditches. 

These are necessarily carried away by each flood, requiring to be 

immediately replaced. On the other hand, the headworks, falls, 

regulating gates, and other dividers are constructed in the most substantial manner of massive masonry.

In strong contrast to this type of construction are the minor distributaries observed in some of the cane fields. These were built by 

owners who had great grinding and boiling machinery for the treatment 

of their cane, and were imbued to a certain extent with American 

methods. They out-Americanized our Western irrigators. Their 

distributaries consist of a series of temporary trestles and shallow 

wooden troughs or gutters made of lumber brought from America. 

Thes,e tap the hillside ditches at such points as seem desirable, and 

are roughly placed so as to carry the water to such portions of the 

field as immediately require it. After irrigation in such localities 

the trestles and troughs are removed and utilized in irrigating other 

portions of the same fields. This practice is resorted to in order to 

reach the numerous little detached rolling hills 10 to 20 feet in maximum height, into which the surface of the sugar lands is broken. In
30 WATER RESOURCES OF PUERTO RICO. [NO. 32.

other localities, where practicable, these lands are irrigated by direct 

diversion from the main ditches of laterals dug in the earth and

ramifying to every 

portion of the field to 

which gravity will conduct the water.

Immediately to the 

west of Juana Diaz the 

most important irrigation work noted on the 

island is a ditch from 

the Rio Jacaguas. 

The point of diversion 

is in a narrow gorge, 

well up in the foothills, 

about 5 milesabove the 

military road. The 

ditch thence is about 

5 feet in width at the 

top, 3 feet in depth, 

and is excavated in the 

earth slopes of the hillsides, around which it 

is well graded. This 

ditch is divided into 

numerous distributaries, all of the simplest 

earth constru c t i o n, 

which convey its 

waters to every part of 

the cane fields.

Fartherwestanother 

irrigation ditch is carried under the military 

road in an inverted 

siphon of masonry (see 

fig. 6), which is similar 

in all respects to such 

structures seen in India and southern Europe.

The width of the 

masonry channel at 

the entrance of the 

siphon is but 2^ feet 

and its extreme depth

FIG. 6. Inverted siphon carrying ditch under military road. 18 inches. The
WILSON.] IRRIGATION. 31

slides down an incline at an angle of about 45° to a depth of about 6 feet 

below the level of the ditch bank, and is carried thence under the 

road in a rectangular masonry conduit. Near the entrance to this 

chute is a little masonry measuring box 3 inches in depth, from 

which water flows through a lip in the top of the conduit. The walls 

of the main conduit are a foot in thickness, and at their exit on the 

lower side are buttressed by square blocks 18 inches in cross section. 

In these are grooves for inserting flashboards, by which the amount 

of water passed into the canal beyond can be measured as over a

earth bank

o. Circular conduit

Bed of river

FIG, 7. Masonry conduit and retaining wall; longitudinal and transverse sections.

weir, while at the same time the supply is regulated. (See PL IX, 

C.) Below this a lateral is diverted through gates identical in type. 

Near this place was seen a rough wing dam of rock, which diverts 

a stream into a substantial masonry conduit (see PL IX, D), whence 

it is led along the banks of the river through a circular masonry 

pipe 30 inches in diameter and 10 inches thick (see fig. 7), in many 

places close to the river bank. To protect it from the erosive action
32 WATER RESOURCES OF PUERTO RICO. [NO. 32.

of floods, the conduit is supported on a heavy retaining wall of 

masonry until at some distance a sufficient grade is attained to 

carry it away from the banks of the stream. (See PI. X, A.)

AGRICULTURAL LANDS AND SOIL.

The parting valleys, and especially the playa plains, are often quite 

extensive, and constitute the chief portion of the more valuable sugar 

and grass lands which border the entire coast. The larger of these agricultural plains are to the eastward of San Juan as far as Luquilla, and 

include wide indentations which extend up the valley of the Rio Loiza. 

There are smaller playas between Fajardo and Humacoa and between 

Guayama and Ponce. (See PL X, O.) West of San Juan the playas 

are not so extensive until beyond the mouth of Rio Cibua, between 

which and Arecibo are some large areas of playa land. Thence westward there is no coast border of any moment until Aguadilla is 

reached, but there, as well as at Anasco, are two fairly extensive playas. 

The remaining sugar lands are those in the larger parting valleys, 

some of which are of great extent. Those between Yauco, Sabana 

Grande, and Hormigueros are the largest, but some of the others contain 1,000 to 5,000 acres each.

In addition to the cultivable areas which may be added by irrigation, much waste swamp land may be reclaimed by drainage. This 

is especially true of the playa lands about the coast lagoons and of 

some of the swampy valley lands near the head waters of the Rio 

Loiza and Rio Plata, which are now chiefly covered with guinea grass. 

(See PL X, D.) One such swamp alone, near Guanica, contains 8,000 

acres of reclaimable land belonging to the Government.

There are two other distinct types of agricultural lands on the 

island. These are found in a few small alluvial valleys on the upper 

courses of the rivers, as at Caguas (see PL IV, _B), Cayey, and Sabana 

del Palmar, and in the main mass of fruit and coffee land on the 

slopes, reaching even to the crests of the highest summits of the 

sierra. The mountain valleys appear frequently to have been old 

abandoned lake -beds, and are extensively cultivated in forage grass 

and in tobacco. The most interesting agricultural feature of the 

island is, however, the steep slopes of the main cordillera, which are 

everywhere cultivated and are mantled with sufficient depth of soil to 

give firm hold to the luxuriant vegetation with which they are covered. (See PL XI, A; text fig. 8, on page 37: and PL IV, O.)

The soil of Puerto Rico, in physical and chemical composition, is of 

two kinds. It is these differences which furnish the most radical 

changes in flora observed on the north and on the south side of the 

island, modified, of course, by altitude to a less extent and by precipitation to the greatest extent. Primarily the soils are either of calcareous or of clay origin, the result of decomposition of the underlying 

rock.
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. X

A, RIVER BED AND MASONRY CONDUIT. S, IRRIGATION DITCH IN EARTH.

(7, SUGAR LAND NEAR PONCE, Z>, GUINEA GRASS, CAGUAS VALLEY.
WILSON.] OLD FIELDS AND FERTILIZERS. 33

Geologically, the mountain portion of the island is, according to Mr. 

R. T. Hill, composed chiefly of basic igneous rocks, as tuffs, conglomerates, and ledges or dikes of diorites and hornblende-andesite, all 

of volcanic origin. Included within this mass and interbedded with 

it are two distinct limestone formations; one, found near the crest 

of the island, is a black shaly limestone of over 1,000 feet in thickness; the other is a light-gray crystalline limestone, which outcrops on 

the southern and western slopes between Ponce and Cabo Rojo. The 

soils which weather from the former of these limestones furnish the 

best tobacco lands. Those which have weathered out of the second 

of these limestones are of little agricultural value, and on them the 

indigenous flora is noticeably different from that grown on the former:

The main mountain masses are heavily covered with soil of a deepred arenaceous clay. This is the result of decay of the volcanic rocks 

which have been rapidly decomposed under the influences of perpetual 

moisture and heat. To the tenacity of this soil the interior of Puerto 

Rico owes its power to retain vegetable growth on its deep slopes even 

after they have been deforested.

The soils of the playas are entirely of alluvium washed down from 

the mountain formations and mixed with detritus from the adjacent 

limestone hills. These playa soils are reddish-black in color, except 

in the northwestern portion of the island, where they are derived 

from decay of the pepino hills and are black and calcareous. These 

playa soils are of sandy loam, well adapted to root penetration, and 

excellent for cultivation because they are open, porous, and therefore well drained.

OLD FIELDS AND FERTILIZERS.

In many portions of Puerto Rico the lands have been overcultivated 

without fertilization. Such lands are now abandoned and have somewhat the appearance of the "old fields" of the Southern States. On 

the limestone hills of the southern coast they are covered with a short 

grass and resemble the sheep-grazed hills of New Mexico and western 

Kansas. (PL VI.) These worn-out lands, or, as they are called in the 

British West Indies, "ruinates," are found scattered throughout the 

country, and furnish one of the most interesting problems connected 

with scientific agriculture in the opportunities they present for reclamation.

Excellent fertilizers are found well distributed throughout the 

island, and the value of these will ultimately be ascertained and their 

use extended. The most abundant of these is a greensand marl of 

Eocene age, found extensively in the northwestern portion of the 

island, between Lares and San Sebastian, and also in the neighborhood 

of Carolina, at the northeastern extremity of the island. This marl 

appears to be rich in phosphates and is not unlike in general appearance the marls of New Jersey. Next in value as fertilizers are large 

IRR 32 3
34 WATER RESOURCES OF PUERTO EICO. [NO. 32.

deposits of guano on Mona Island, just off the west coast, and smaller 

deposits in caverns on the west coast and near Ponce. Elsewhere 

throughout the island are great beds of shell and chalk marls and of 

lime phosphates. The lime marls are abundant everywhere around 

the coast, and gypsum marls occur in the neighborhood of Ponce.

AGRICULTURAL PRODUCTS.

The soil of Puerto Rico is so deep and fertile, the precipitation so 

abundant and well distributed, and the temperature, though tropic, 

so mild as to render it possible to cultivate almost all the land on the 

island. Moreover, almost every foot of it is now or has been under 

cultivation. It is essentially the land of the small farmer, because, 

limited as the island is in extent, the official records show that it is 

divided into 36,650 individual holdings. These are distributed as follows : Tobacco plantations, 66; cattle ranches, 240; coffee plantations, 

360; sugar plantations, 435; small coffee farms, 4,185; small farms of 

mixed coffee, fruit, and vegetables, 4,375; small fruit and vegetable 

farms, 16,990. At least 21,000 of these holdings are of the smallest 

kind, being owned by the poorer peasantry. Such holdings range in 

size from 5 to 50 acres, rarely reaching the latter amount. The remaining 5,000 holdings are from 100 to 5,000 acres or even larger. The 

greater proportion of these are relatively small and are devoted chiefly 

to the cultivation of coffee, the larger ones being mostly cultivated in 

sugar.

So fruitful are the soil and climate that the people pass an indolent 

and lazy existence, even to a greater extent than is observable elsewhere in Spanish America. Outside of the few large plantations the 

people are unacquainted with any agricultural implement other than 

the machete, a short thick sword, which serves all the purposes of 

scythe, brush hook, ax, hoe, and weapon of defense. Holes are 

scratched in the surface of the soil in which to plant seeds or transplant sprouts. Thereafter no attention is given to the crop until it 

becomes necessary to gather the product either for domestic consumption or for exchange in the nearest village for such household necessities as the farm does not produce.

Abundant and well distributed as are the various crops, the island 

produces to but a fraction of its capacity. (See PI. XIII.) Thus far 

there has been no incentive to grow such products as would have value 

for export, and no means have been available and no forces at work 

to incite the ambition of the people, and thus give them some inducement to gain a better living. They know nothing of the higher arts 

of civilization, and if they had more wealth than they now possess 

they would not know how to use it. With the higher aims which will 

come from association with the more active, liberal, and highly civilized people of the United States, increased energy may be exerted in
U. S. GEOLOGICAL SURVEY

A, MOUNTAIN SUMMITS UNDER CULTIVATION,

CY, SADDLE. AND PACK HORSE,

WATER-SUPPLY PAPER NO. 32 PL. xl

Z>, HOGS LED BY ROPE.
WILSON.] AGRICULTURAL PRODUCTS. 35

the near future in wresting from nature more bountiful and useful 

crops than are now cultivated.

At present such crops as are produced for exportation are limited 

almost exclusively to sugar and the by-products of the cane (molasses 

and rum), coffee, tobacco, and hides, in the order named. In value, 

however, coffee exceeds that of sugar in the ratio of three to one. 

According to the Spanish Estadistiea General, the total exports for 1897 

were valued at 118,574,678. These were distributed as follows:

Exports of principal articles from Puerto Rico, 1897.

Cane sugar. ........................ ..........^.

Coffee...---.---.-..-.---....-.......-..-.-.-.-.

Tobacco. ..----_.-..--..------.-....-------..---

Hides.... -._-_----- --.--....__.___-- -------

Total ....................................

Amount, in 

pounds.

125, 323, 589

25, 085, 069

51,097,823

6, 181, 771

823,108

Value.

$4, 007, 999

403, 519

12, 222, 598

1,194,318

71,852

674,392

$18,574,678

In addition to the above there are several other articles of export 

which, like these, are all of agricultural origin. In order of importance they are: Honey, the value of the exported product being 

$517,746; wax; cattle, of which 3,180 head were exported; chocolate; 

straw hats; and a very small amount of fresh fruit.

From the above it is evident that the most valuable crop of the 

island is coffee. Next in importance ranks sugar and then tobacco 

and cattle. In addition there are cultivated, chiefly for domestic 

consumption, various cereals, lentils, potatoes, small vegetables, and 

fruits, as well as forage grasses.

Of domestic animals cattle are first in importance. These are of 

unusually large size, being far more powerful and heavier than any 

seen in Central or tropic South America or elsewhere in the West 

Indies, and in fact exceed in size the cattle of our Southern States. 

They have widespreacling horns and in general appearance they 

resemble the range stock of Texas and the uplands of Mexico. (See 

PI. XII, jB.) Horses are abundant, but are so diminutive in size as to 

scarcely deserve any other name than pony. They resemble in general appearance the ponies of Cuba, but though small they are exceedingly hardy and are excellent pack animals. (See PI. XI, C.)

All the heavy draft work of the island is done by oxen, which are 

yoked, not by the neck but by the horns, to heavy two-wheeled bullock carts made of mahogany and similar hard woods. (See PI. XI, jB.) 

Off the roads, and these are but few and inferior in quality, all produce is hauled to the markets and purchases made there are carried
36 WATER RESOURCES OP PUERTO RICO. [NO. 32.

back to the mountain farms on the backs of the sturdy little pack 

horses which climb with sure foot the steep, wet, and slippery trails. 

(See PI. XI, (7.) The method of packing these animals is that commonly practiced in some portions of South America. Most burdens 

are carried, not by means of pack saddles or of aparejos and lash 

ropes, but in wicker-basket panniers, which are hung loosely over the 

backs of the animals. Sacks of coffee, however, are hung loosely by 

sling ropes. In this way they are loaded with 150 to 250 pounds of 

coffee or other burden and tramp with quick, short steps over the 

rugged trails.

In addition to cattle and horses a very few small mules are bred; 

the only other domestic animals are poultry, hogs, and dogs. Th® 

poultry are of inferior breed, being chiefly raised for the game cocks, 

which are used in the universal sport of the people. These and the 

hogs, which are also of small size and of poor breed (see PI. XI, D), 

thrive well, but are so few in number that fences are rarely built to 

restrain them. It is therefore a common sight to see hogs tethered by 

a string tied around one leg and attached to a tree or picket, and to 

see poultry tied in the same manner and forage much as do milch cews.

The various agricultural crops of importance are distributed in 

zones, depending on and clearly marking the variations in altitude, 

rainfall, and soil composition. Sugar cane is cultivated exclusively in 

the coast playas and in the parting valleys among the lower hills of the 

back-coast border. It grows luxuriantly, the stalks being 10 to 15 feet 

in height and often 2£ inches in diameter at the base. (See PI. XII, A.) 

The cane is cut during the months of January to March, inclusive, 

and produces an average yield of 3 tons to the acre. It is the only 

crop except coffee, the latter to a more limited extent, which is cultivated with modern methods and harvested by the use of modern 

machinery. Heavy, imported metal plows, drawn by six to ten yoke 

of oxen, are used in tilling the soil and making the furrows, through 

which irrigation water is flowed. The cane is cut down with a blow 

of a machete, and the longer stalks cut into lengths of 3 to 4 feet by 

the same process. It is carted from the field to the sugar mill either 

in ox carts (see PI. XI, B) or occasionally on trains of cars, hauled by 

oxen over railways placed temporarily in various avenues through the 

cane fields (see PL XII, B). The roadbed of these tramways is laid 

permanently, but the rails and ties are moved about as required. 

The sugar mills are invariably substantial brick structures containing 

the most modern machinery, in which the cane is crushed, boiled, and 

evaporated. From the mills cane sugar of muscovada grade, molasses, and rum are shipped, the last being usually distilled in the same 

mills.

Tobacco of excellent quality thrives well everywhere. The best 

varieties, cultivated in sufficient quantities for export, are grown 

chiefly in the valleys and the river bottoms on the head waters of the 

Kios Loiza and Plata. The culture of tobacco is especially exten-
U. S. 6EOL6GICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. xli

A, SUGAR CANE. J?, TRAIN OF CARS LOADED WITH SUGAR CANE DRAWN BY OXEN.

0. COFFEE SHADE. D, SHELLING COFFEE.
 WII/SON.] AGRICULTURAL PRODUCTS.

sive in the valleys and on the mountain slopes about Caguas, Oayey, 

Comeiro, and Juncos. (See PL IV, B. ) Especially interesting is its 

cultivation on the steepest slopes of the higher hills. (See fig. 8.) 

There groups of ten to twenty laborers may be seen clinging like ants to 

the steep mountain sides, hoeing and weeding or gathering the crop.

These tobacco fields are the best kept and the most industriously 

attended agricultural products observed on the island. The flavor of 

the tobacco grown in the region named is excellent. It is sold in Puerto 

Rico at about $25 to $30 per hundredweight. The larger portion of 

it is shipped to the United States and Europe, through Ciiba, where 

it passes as Habana tobacco of the highly prized Vuelto Abajo quality. 

In Habana it commands 1100 to $125 per hundredweight.

Coffee is grown everywhere, on the island at altitudes above 1,000

PIG. 8. Cultivated hill tops in Cayey tobacco district.

feet. Ordinarily it is at present cultivated at too low an altitude to 

yield the best variety and so little attention is given it in the way of 

cultivation and fertilization that the yield is relatively small. At altitudes of 1,000 to 1,500 feet the average product is about 500 to 600 

pounds per acre. Between 1,500 and 2,000 feet the yield is 600 to 800 

pounds per acre. Above 2,000 feet yields of 1,000 to 1,200 pounds per 

&cre are occasionally obtained, for at such altitudes coffee is generally 

grown by the larger planters and under more intelligent supervision. 

The product would be greatly increased and the quality improved if 

better methods of cultivation were employed and if the crop were more 

extensively grown on the higher summits. The coffee plant is very 

delicate and is invariably shaded by tall, wide-spreading trees, chiefly 

the guayava, guama, and inaga (see PI. XII, C), which are planted for 

this purpose, and only occasionally, as is the custom elsewhere in the 

West Indies, is the plant shaded by bananas and plaintains. These 

latter are, however, chiefly used as shade for the younger coffee plants 

before they reach the yielding age.
38 WATER RESOURCES OF PUERTO RICO. [NO. 32.

The coffee plant is not unlike a tall, slender currant bush in general 

appearance, though it is peculiarly devoid of leaves or branches. 

Several stems grow from one root, and these are but three-quarters 

to an inch in diameter at the base, although they are 8 to 12 feet in 

height. They put out little, short branches with small leaves, and on 

these branches grow the coffee beans with exceedingly short stems, so 

that they appear to cling closely to the wood. The coffee berry when 

ripe is not unlike a good-sized red cherry. The plant begins to bear 

after four years, and the berry is picked during the winter months, 

from October to February. It yields best in seven to eight years and 

continues to produce for about thirty years. The berry is gathered 

chiefly by women and children, who empty their small basketfuls into

FIG. 9. Drying coffee on rolling platforms, Pietris Plantation, AdjuntasJ

larger baskets or sacks, and these are carried by men to the drying 

platforms, where the coffee remains in the sunshine, but always protected from rain and night dew, until thoroughly dry. The drying 

platforms are of two general types. The first type consists of broad, 

level platforms of masonry, with smooth concrete surfaces on which 

the berries are spread out evenly and are hoed over, and from which 

they are gathered and placed under cover at night or when rain 

threatens. The second variety of platform, that used on the larger 

plantations, consists of large wooden trays about 8 by 12 feet. These 

rest on rollers which run on tracks in such manner that when it is 

necessary to place the coffee under shelter the trays are rolled under 

the coffee house; as the trays are but 5 to 7 inches in depth, they run 

one above another, so that usually three trays, and sometimes more,, 

are housed under one portion of the coffee house. (See fig. 9;) Not
U.S.GEOLOGICAL SURVEY WATER SUPPLY PAPER N° 32 PL. XIII.

Jfebztivefy correctonly. 

r* TUNA LEGEND

cm en

Coffee Sugar cane. Bananas,Oranges 

Grass Tobacco etc.

Sketch confcur inVarval 500 FeeK

MAP OF PUERTO RICO SHOWING DISTRIBUTION OF CROP LANDS.

BY HERBERT M.WILSON.
WILSON.] AGRICULTURAL PRODUCTS. 39

infrequently coffee is dried in the streets or plazas by spreading it out 

on burlap sacking, which can be quickly gathered up in the form of a 

bag and carried away.

After drying, the berry is crushed in great wooden mortars with 

heavy wooden pestles, so as to break away the dried husk which 

incloses the coffee bean. (See PI. XII, D.) Where better managed 

this crushing is performed in a circular trough not unlike an arastra, 

by means of heavy wooden wheels which are turned by animal power 

and sometimes by water power. After crushing, the coffee is washed 

and screened to separate the bean from the husk. The former is 

usually double that is, there are two half beans within one berry. 

Not infrequently, however, it consists of one deformed bean which is 

egg shaped and smaller than the two halves. This variety is called 

"caricolillas," and is especially prized in European markets. The 

washed coffee beans are placed in airy rooms in the drying houses 

and thoroughly seasoned and dried before shipping.

The variety grown generally is of excellent flavor. As yet little of 

it reaches the American market, chiefly because of the export duty 

now placed on it and because it commands a much higher price in the 

European than in the American market. The better varieties are 

sold by the sack by commission merchants in Puerto Rico at 13 

to 18 cents per pound. This is a higher price in Puerto Rico than is 

paid in New York by coffee importers for the best grades of Bogata, 

Caracas, and other fine Central American varieties. As it is not 

well known in the American market, importers will not offer more 

than 10 to 12 cents for it. Much of it, however, reaches the United 

States, chiefly that of the poorer grades, being shipped to Europe in 

transit. After it has remained some time in the bonded warehouses it is withdrawn under the names of Java and Mocha. The 

American coffee buyer purchases largely on the appearance of the 

bean, and accepts that which has a dull and lusterless appearance. In 

Europe, however, coffee having a bright gloss is preferred, and for 

this reason Puerto Rican coffee is at present extensively treated with a 

wash of gum arabic and charcoal or some similar preparation, which 

gives it this gloss. This process injures the sale of the article in the 

American market. Those who have used Puerto Rican coffee, however, insist that its flavor is equal to the best sold in the country, and 

that when better known it will command a higher price and will 

displace the very best of the Central American product.

Other valuable agricultural products are forage plants. The most 

important variety is guinea grass, a succulent plant having a blade 

or leaf 2 to 3 feet in height and fully one-half inch in width. It yields 

about 3 tons to the acre and grows quickly and luxuriantly. (See PI. 

XV, Z>, and PL X, Z>.) Cattle and horses thrive on it and on a nutritious, .leguminous plant called "malahojilla," which is a variety of 

the wild-pea pine. On the southern foothills the chief forage plant is
40 WATER RESOURCES OF PUERTO RICO. [NO. 32.

a short, dry-looking grass, not unlike the Southwestern bunch or 

buffalo grass. (See PI. VI.) The leaf and stalk of maize and the 

pods of various acacias, which are gathered green, are also used.

Maize is grown extensively in the wide parting valleys in the southwestern portion of the island. In the same region and in the beds of 

many of the streams which flow into the west coast, lentils are grown 

in large quantities. There are a number of varieties of these, chiefly 

beans, including the green string bean and the white and liver-colored 

bean, which when cooked are the "frijole" of Spanish America 

and the "Boston-baked bean" of the United States. A lentil-like 

berry, which in appearance is between a pea and a small bean, and yet 

grows on a bush belonging to the acacia tribe, is the guadure, and 

this is very extensively grown for domestic consumption on the semihumid side of the island. It occurs in a pod about 3 to 4 inches in 

length on a bush 6 to 8 feet in height. Yams and sweet potatoes are 

grown extensively, generally for home consumption, and Irish potatoes thrive well, but are grown to only limited extent in some portions 

of the uplands. Among other small vegetables are tomatoes and 

red pepper.

Cotton seems to flourish well, though it is not cultivated in commercial quantities. The cotton plants noted were almost as large as 

apple trees, being from 8 to 12 feet in height, with a stem 2 to 3 inches 

in diameter at the base. (See PL XIV, A.) The flowers and pods 

were numerous, and the latter well filled with a long staple cotton 

apparently as fine as the best grown in the Southern States.

A variety of upland rice peculiar to the island is cultivated in the 

interior hills, and grows without irrigation or inundation. At present 

but little is produced, because the Spanish have discouraged its cultivation in order to increase the importation of rice from Spain. A 

plant called the yautia is one of the staple vegetable foods of the 

people, and is grown on the humid side of the island in large fields, 

much as cabbage is cultivated in the United States. It is the 

Caladium esculentum, and grows to a height of 2 to 3 feet. It consists chiefly of wide-spreading, heavy, green leaves, 12 to 20 inches 

in length, in appearance not unlike those of the plantain. (See PI. 

XV, A.) These are stewed and eaten as is cabbage or spinach, or 

are boiled as is okra in soups.

Another staple food is the plantain, which is baked when green, and 

is the bread of the people. There are many varieties of plantains 

and bananas, both cultivated and wild. No attempt seems to have 

been made, however, to grow those varieties which are in favor in the 

markets of the United States or Europe, and none are, therefore, 

exported. This should become one of the greatest of the agricultural 

products of the island, both for home consumption and for export, 

when means of rapidly conveying the same to the coast are available 

through the construction of good highways, and when the people
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. XIV

A, COTTON PLANT. /?, MARKET SCENE, PONCE.

C, LOGS OF AUSUBO EN ROUTE TO MARKET, D, REPAIRING MILITARY ROAD,
 WILSON.] FORESTRY. 41

learn to produce such varieties as are in demand abroad. The seed 

stock at present used is poor and run out, the bananas yielding only 

2 or 3 hands deep instead of 10 to 15 hands, as they must for export.

Bananas and plaintains are grown generally throughout the island. 

They are cultivated most extensively on the hill slopes, being rarely 

seen on the alluvial lands and in the valley bottoms. On the humid 

side of the island these plants are, with cocoanut palms, the most 

prominent features of the landscape. (See PL VII, B.) They are 

scattered on every hillside, being grown sometimes ia orchards, but 

more generally in various portions of fields with other crops and in 

gardens. On the arid side of the island they are seen less frequently 

and at the lower altitudes quite rarely.

Another of the more abundant and valuable fruit trees is the cocoanut palm. The fruit is large sized and well flavored, and extensively 

consumed when green. But little is exported, though the husks are, 

to a moderate extent. This tree also flourishes everywhere and produces well.

Oranges, like bananas and cocoanuts, grow wild and cultivated 

everywhere with great luxuriance; so also do lemons and limes. A 

cultivated variety of oranges, which is used to a small extent in shading coffee, is unusually juicy and well flavored and is the equal of the 

best produced in the United States. Yet none are exported, and such 

few as are gathered are a drug on the home market and are sold at 

the rate of from two to three for one cent.

Pineapples are cultivated to a slight extent, chiefly in the southwest, about Cabo Ho jo. Guayavas also are chiefly grown in the southwestern portion of the island, though they are not cultivated to the 

extent one would expect. From them is made guayava jelly, which 

is a popular confection with the inhabitants and finds also ready 

market in the United States. Less abundant are the aguacate or 

alligator pear (Persea), the guanavana, called in Central America 

" chiramolla " and "custard apple" (Anona); the mango, the mamey 

or bread fruit (Marnmea), and a variety of others. All of these fruits 

and vegetables are extensively consumed by the people and are for 

sale in all the city markets. (See PI. XIV, B.)

FORESTRY.

The forest resources of the island have been practically exhausted. 

The country has been so long densely inhabited and under cultivation 

that practically all the virgin timber has been removed, and some of 

the native trees are so rare that specimens of them can scarcely be 

found. Practically all of the more valuable hard woods, which are 

abundant in Haiti and eastern Cuba, are indigenous on this island. 

The whole surface of the country, especially on the higher mountain slopes, is well covered with trees. The woods consist chiefly 

of the artificial and natural shade trees, under which coffee is
42 WATER RESOURCES OF PUERTO RICO. [NO. 32.

planted. (See PI. XII, C. ) The more important of these trees are the 

guama (Ingalaurinea), guava (Ingavera), bucare (Eryfhrina bu&are), 

and maga (TJiespesia grandiflora). These trees are of little value for 

their lumber, as their trunks are but 4 to 7 inches in diameter, are not 

straight, and branch about 10 to 15 feet from the ground, reaching a 

height of 30 to 50 feet. The maga has some value for timber; the 

wood is hard, can be worked without great difficulty, and is used to a 

limited extent in the construction of furniture and for similar purposes.

The most abundant of the precious hard woods is the ausubo, resembling teak or mahogany. Trees of this kind are found in many portions 

of tke island, and it is used extensively in making bullock carts, the 

spokes and poles of these being always of ausubo. It is also used for 

beams, rafters, and upright posts in buildings. Two varieties of Spanish cedar, the hard and soft cedar, occur, but both are rare a 12-inch 

plank, 1 inch thick and 12 feet long, being valued in the mountains 

at $1. Another of the more abundant woods is the guaraguao, which 

is used chiefly in making board flooring and is valued at about 50 

cents per plank. Another wood employed in board flooring is the 

capa prieta. An excellent furniture wood, strong and hard but very 

rare, is the capa blanca. The mauricio is a very durable yellow wood 

used for parts of machinery, for the hubs of carts, and for similar 

purposes. A wood which does not easily decay, and is therefore used 

for posts and such purposes as require insertion in the ground, is the 

higureillo. Among other of the native woods are the nonfragrant 

sandalwood, laurel, ucar, algarrobo, palosanto, and bamboo. (See 

PI. XV, B.}

All of these woods are so scarce, however, that the larger portion of 

the timber used in structures is imported. The most extensive import 

of wood is common spruce, hemlock, and pine from Nova Scotia. 

Many of the older buildings of the island are of native woods, but all 

of those which have been recently constructed have been built chiefly 

of imported lumber. Only two sawmills of any capacity were seen on 

the island, one in San Juan and the other in Ponce, and both were 

engaged in cutting up cedar wood for cigar boxes and in making parts 

of wagons and of machinery from ausobo. In the mountains in a 

few places old-fashioned whipsaw pits were seen, at which mahogany 

planks were being cut out of rough logs. These were then hauled by 

horses over muddy trails for many miles to the cities in which they 

were to be used. (See PI. XIY, C.)

Aside from the few scattered hard-wood trees which grow on the 

slopes of the more inaccessible mountains there are a few rather 

extensive pieces of woodland. The most important of these is on the 

eastern end of the Sierra de Luquilla, which is heavily covered with 

virgin forest. East of Ponce, about Santa Isabel and Salinas and in 

the extreme southwest near Cabo Rojo, are some extensive areas of
A MAMEY (BREAD FRUIT) TREE IN FIELD 

OF YAUTIA RIO CANOVANAS.

CLUMP OF BAMBOO. 60 FEET HIGH.

O, NEAR SUMMIT OF SIERRA DE LUQUILLA. D, CEIBA TREE IN FIELD OF GUINEA GRASS.
WILSON.] WATER POWER AND SUPPLY. 43

woodland. The amount of merchantable timber which is left, however, is too small to render this an important element among the 

natural resources of the island.

WATER POWER AND SUPPLY.

The volume of water available for utilization either as supply for 

domestic purposes in the various cities or for conversion into power 

through the agency of water wheels is relatively great. While this 

is especially true of the north side of the island, it applies also in a 

measurable degree to the south side, for, while on the latter side the 

streams do not discharge large volumes during the dry season, there 

is more water in them near their sources in the mountains than 

reaches the lowlands, because of loss through evaporation and percolation.

All of the cities of any size are provided with some form of domestic 

supply. At present, in San Juan, this is chiefly from rainfall. The 

same is true of most of the cities which are 011 the humid side of the 

island, though in some cases the rain water which is caught in tanks 

is supplemented by gravity supplies. In no city, however, ts there a 

water supply of modern type at all commensurate with the requirements of a tropic climate. Not only is the supply for domestic use 

insufficient in every case, but there is practically no supply available 

for fire engines, for the flushing of house plumbing, or for washing 

streets and flushing gutters.

A new water supply is being provided for the city of San Juan. 

This was commenced under the Spanish authorities and is now being^ 

pushed to completion by officers of the United States. It is well 

designed after several years of survey and investigation. The supply 

comes from the Rio Piedras, about 6 miles above San Juan, where it 

is diverted into a short canal, which carries it into settling reservoirs, 

each of which has a capacity of one and one-half days' supply, at 

the rate of 35 gallons per head. Thence the water flows into filter 

beds, whence it is pumped to a distributing reservoir 110 feet high. 

From this it will be conducted in underground mains and distributaries to the various houses in the ctty.

Ponce receives a gravity water supply from the Rio Portugues, 

whence it is diverted about 9 miles above the city and conducted in 

masonry conduits and underground iron distributaries to the more 

important streets. On a hill back of the hospital in the outskirts of 

Ponce is a small, covered, distributing reservoir. This has not been 

cleaned in many years and is so foul that its use has been abandoned. 

Mayaguez, which is in fact the best provided city on the island, also 

receives a gravity supply. This is from the Rio Mayaguez, the perennial discharge of which is sufficient for the present requirements of 

the inhabitants.
44 WATER RESOURCES OF PUERTO RICO. [NO. 32.

Most of the smaller cities, as Aibonito, Adjuntas, Lares, etc., have 

gravity supplies of water piped to them from neighboring streams, but 

the volume of water supplied is rarely greater than can be easily carried in a 2-inch pipe. No difficulty either of an engineering or financial 

nature should be encountered in supplying these cities with abundant 

quantities of wholesome, potable water. Near every city there is 

sufficient water available in one or more of the rivers, and this can 

invariably be diverted at sufficient altitude to permit its being carried 

by gravity into the cities. The natural conditions in nearly every 

case are such as should insure the procurement of such water supplies 

&t relatively small cost.

' The opportunities for the generation of power are also superabundant, and the use which has thus far been made of them is insignificant. The amount of water available for conversion into power is 

evident from a consideration of the discharge of the various streams, 

a»s already stated, and the great height from which the water falls in 

but comparatively few miles. Streams which have a minimum volume of 50 to 150 second-feet at an altitude of 1,000 to 1,500 feet fall 

to within 100 feet of sea level in a distance of 5 to 10 miles. Consequently there are many steep rapids, cascades, and high falls in their 

courses, and it is necessary to convey the water in flumes or ditches 

but relatively short distances to obtain such head as will produce all 

the power of which use can be made. Finally, the width of the 

banks of these streams within the mountain gorges is so small and 

their surfaces are composed so largely of rocks and bowlders that 

there will be little difficulty or expense connected with the diversion of 

the water through dams and head works. Already one American corporation has purchased and obtained control of one or more water 

powers on the Kios Plata and Arecibo. The amount of power 

which will be obtained from these has been estimated as from 500 to 

1,000 horse-power per concession.

TRANSPORTATION FACILITIES.

The development of the agricultural resources of the island is 

necessarily dependent largely on facilities for transporting products 

to the coast for shipment and of returning thence purchases made in 

the coast towns. At present the island is less adequately provided 

with good wagon roads than is the more sparsely inhabited and most 

inaccessible portion of the mountainous Western States. There is but 

one good road across the island and some pieces of fairly good road 

around the coast. The latter are, however, disconnected. In addition, 

there are about the coast several long but disconnected pieces of 

.railroad. The railroads are of French construction and operation. 

They are of very narrow gage, 1 meter or less. There are about 140 

miles of such railroad in operation, including a short stretch from 

San Juan eastward to Carolina; another from the same point westward
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. XVI

P. MUDDY CART ROAD NEAR AIBONITO.

O, ROCKY CART ROAD NEAR LARES. >, RUTTED CORAL ROCK IN CART ROAD NEAR SAN SEBASTIAN.
WILSON.] TRANSPORTATION FACILITIES. 45

to a little beyond Arecibo; a section between Aguadilla, Mayaguez, 

and Hormigueros; one between Saix Sebastian and Anasco, and another 

from Ponce to Yauco. The locomotives are light, the cars small and 

of trifling capacity, and the trains run but once in every day or two 

and consist of but two or three cars.

The roads are divided into three classes: First, military roads, of 

which there are about 285 miles. These are all well graded and well 

surfaced with macadam and are kept in fairly good repair. (PL XIV, 

D.) Moreover, they cross the various drainage channels on well-constructed masonry bridges and culverts (see PL XVII, A), often girdling 

the mountain sides in great cuts, blasted out of the sides of the 

precipitous slopes (see fig. 

10). Aside from the road 

from San Juan to Ponce, 

the other portions of this 

first-class road are near the 

coast, including a stretch 

between Arecibo, Aguadilla, and Mayaguez; another between Mayaguez 

and Yauco; and still others 

between Rio Piedras and 

Carolina and between Caguas, Juncos, Humacao, 

and Naguabo. A branch 

of the road which crosses 

the island extends from 

Cayey to Guayama. Aside 

from this limited amount 

of first-class road none on 

the island is worthy of 

being called even second 

class, though so designated 

by the Spanish.

There are said to be 

about 100 miles of secondgrade road, including 

stretches between Arecibo, Utuado, Adjuntas, and Ponce, of which 

only the latter portion is in condition to carry even the roughest cart 

traffic. (See PI. XVI, A.) Another bit of cart road, over which only the 

lightest loads can be drawn by bullock, is between Aguadilla, San 

Sebastian, and Lares. (See PL XVII, B.)

The third class of roads, called cart roads, are officially stated as 

aggregating over 500 miles in length. None of these, however, is fit for 

other traffic than that of pack animals. Even military roads furnish 

transportation facilities for only an extremely limited extent of counFlG. 10. Rockwork near Aibonito, summit of military 

road.
46 WATER RESOURCES OF PUERTO RICO. [NO. 32.

try to either side. The moment one leaves such roads he is compelled 

to enter at once on trails which climb the precipitous mountain sides 

with extremely steep grades or descend into the deep stream gorges.

The great amount of rainfall and the peculiarly slippery and sticky 

character of the red-clay soil on the humid side of the island renders 

all roads except those near the southern coast and those which are 

macadamized little better than impassable morasses. (See PI. XVI, B.) 

No wheeled conveyance can travel such roads unless they be provided 

with far better drainage than now. On the drier side of the island, 

especially over the coral formation at the western end, the roads are 

filled with great rocks and bowlders (see PI. XVI, (7), and in places 

the soft coral rock is worn into deep ruts, rendering the roads impassable now for carts. (See PI. XVI, D.) On these so-called cart roads 

even the sturdy pack animals have great difficulty in carrying relatively light burdens through clinging mud ankle deep, or over the 

bowlder and rock strewn surface.

As the bulk of the present transportation is on pack animals, which 

carry but 150 to 200 pounds a trip and return half laden, it is interesting to note the present price paid for handling freight in this manner. Between the more distant points over which pack journeys are 

made $1 per hundredweight is paid each way and 50 cents per hundredweight is the least rate, even for a very short haul. From the 

neighborhood of Adjuntas to Yauco and Ponce the rate is $1 per 

hundredweight. One of the largest coffee plantations on the island, 

that of Mariani Sons, pays from $1 to $1.50 per hundredweight for 

transportation. Those in the neighborhood of Lares pay as much as 

$2 per hundredweight for transportation to Mayaguez, and those of 

Tres Hermenos pay 75 cents per hundredweight. Sugar is conveyed 

from boiling houses to the nearest shipping points usually in 15-hundredweight hogsheads, which can be carried on bullock carts over the 

better roads found near the coasts. The cost for such haulage varies 

from 20 to 30 cents per hundredweight. Inferior as are the railroad 

facilities, the difference in price is shown by the fact that railroad 

carriage costs but two-thirds of a cent per hundredweight per mile.

The necessity for the development of a comprehensive system of 

first-class highways or railways is too evident to require further elaboration. Until such a system is in existence there is little hope for 

the development of any of the resources of the island except coffee 

and tobacco, which can be hauled at convenience, since they are not 

perishable, and sugar, which is grown only near the seacoast and at 

places convenient to shipping points. The most obvious direction in 

which improvement of internal means of communications should take 

place is in the construction of electric tramways as main arteries of 

traffic, supplemented by macadamized roads as feeders. Material for 

railway ballast and for road metaling is abundant in every part of 

the island. This consists chiefly of hard black limestone and of hard 

coral rock and bowlders.
U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER NO. 32 PL. XVII

A, BRIDGE OVER RIO CANA NEAR CAGUAS.

B, ROCKY CART ROAD NEAR LARES.
INDEX.

Page. 

Adjuntas, figure showing method of dryingcoffeeat..-.. 38

plate showing road near_. . 44 

topography near. ................ 19

Adfuatas Pass, plate showing view near

summit of ....... .......... 18

Agricultural land, types of _.......-... 33

Agricultural products. . 34-41 

Aibonito, figure showing military road

near............. ... .. .-.. 45

plate showing road near . ............. 44

topography and flora near........ _. 17,18

Aibonito summit, plate showing scenery

south of.............................. 18

plate showing view between Cayey 

and................................... 18

Afiasco, Rio, measurements of . . 28 

plate showing view of.... ........ . 28

plate showing hills along ..... .... 18

Area of Puerto Rico ..............._.__ 11

Areeibo, section north and south through. 13 

Arecibo. Rio, measurements of ......... 27

Ausubo, extent and use of........ ... 42

logs of, en route to market, plate showing .--...-.--.--__-..--. .-----.--- 40

Bamboo, plate showing clump of.. 42 

Bananas, cultivation of.. ...... -... 41

Blanco, Rio, measurements of............... 27

Caguas, plate showing bridge over Rio

Cananear.................. ... . 46

topography near....................... 16-17

Caguas Valley, plate showing El Monte and 18 

plate showing guinea grass in.... 32

Caguitas, Rio,measurements of....... 26

Calabasas, Rio, measurements of. ... 27 

Cana, Rio, plate showing bridge over, near

Caguas.._........._........ .. 46

Canovanas, Rio, measurements of.......... 26

plate showing character of *........ _. 16

plate showing field of yautia near... 42 

topography along the... -... .... ' 16

Carite, Rio,measurements of..... . 26-27

Carolina, plate showing view ot Rio Loiza

near........................ ......., . 26

Carolina Plain, plate showing ........... 16

Cattle, exports of............. .. .... 35

kinds of, and work done by....... 35-36

Cayey. plate showing view between Aibonito summit and......... ... . 18

topography near ...__.. .......... 17

Cayey divide, plate showing view west

from.____.. .._..._......... 16

Cayey tobacco district, figure showing cnl

 tivated hilltops in ... ....... .. 37

Cedar wood, value of....._................ 42

Ceiba tree, plate showing................... 42

Climatology of Puerto Rico............... 21-24

Page. 

Coamo, Rio, measurements of. .......... 27

Coastal topography of Puerto Rico 14-15 

Coast, south, width and topography of..... 18

Cocoanut palm, cultivation of ... 41 

Coffee,exports of...... .... .... 35

method of cultivating and drying, and 

value of ._......-------- . 37-39

figure showing method of drying, at 

Adjuntas.................-......- 38

plate showing method of shading . 36 

Coffee shelling, plate showing ........ 36

Conduit for irrigation, figure showing. 31 

Conduit, plate showing river bed and masonry ...... . . 32

Cordillera Central, coast limestone hills,

and playa at Ponce, view of, ..... 15

course and altitude of.. ...... 13,14

Cotton, cultivation of............. ....... 40

Cotton plant, plate showing. ... 40 

Crops in Puerto Rico, map showing distribution of-.................... -...- 38

Culebrina, Rio, measurements of ...... 28

Dam, wing, plate showing. .... 28

Descalabrado, Rio, measurements of . 27

plate showing view of.... ...... ... 28

Ditch, irrigation, plate showing . 32 

plate showing regulator gate and ..... 28

Drainage and hypsometric map of Puerto

Rico.................................. 11

ElGuilarte, height of..... .. .......... 14

El Monte, plate showing Caguas Valley and IS 

ElYunque, height of........................ 12

plate showing view of-.... . -... 16

section north and south through... 12 

Exports from Puerto Rico....... ... 35

Fertilizers in Puerto Rico . . 33,34

Flora, arid, near Lares, plate showing... -. 26

diversity of, in Puerto Rico.... ... 23

Foothills of Sierra de Luquilla, plate show^-

ing .................. .............. 16

Forestry of Puerto Rico ... ....... .. 41-43

Grass, varities grown in Puerto Rico 39-40 

Guayama, section north and south through 13 

Guinea grass,'Caguas Valley, plate showing ................................... 32

plate showing field of. ... 43 

Hacienda Perla, rainfall at.......... ..-. 22

temperature at ....... ... 24

Hansard, A. C,, observations made by... 22,23 

quoted on height of El Yunque......... 12

Harrington, M. W., meteorologic data collected by........- ..-- 22

Hides, exports of . ... ...'... 35 

Hill, R. T., quoted on erosion in Puerto

Rico.............- -. - -.-- 21

quoted on rocks of Puerto Rico ....._ 33

Honey, exports of... ... -- ........ 35

 47
48 INDEX.

Page. 

Hydrography of Puerto Rico............. 24-38

Hypsometric and drainage map of Puerto

Rico.................................. 11

Irrigation ditch, plate showing............. 32

Irrigation in Puerto Rico. ................ 38-33

Jacaguas, Rio, irrigation from the....... 30-33

measurements of.__.................. 37

plate showing view of, near Juana Diaz 16 

Juana Diaz, plate showing barren hills

near......-.-........-..-.-.-......... 20

plate showing view of Rio Jacaguas 

near--....-..--.............-.-....... 16

Land, agricultural, types of __ ._ __ ... 33 

Lares, plate showing arid flora near....... 38

plates showing roads near ....... __ 44,46

plate showing views near........_.... 33

topography near .....__............ 19-30

Las Cruces, altitude of...................... 17

LaTorre, altitude of........................ 19

plate showing view from summit of.... 33

Loiza, Rio, measurements of ... _ ......... 36

plate showing view of ......._........ 36

plate showing playa at mouth of....... 16

Luquilla, Sierra de. (See Sierra de Luquilla.) 

Magueyes, Rio, measurements of .......... 37

Mamey tree, plate showing................. 42

Mango trees bent by wind, plate showing. 18 

Map, drainage and hypsometric, of Puerto

Rico.-.----.-.....-.....---........... 11

Map showing distribution of crops in

Puerto Rico.-_-_.__---.........-..... 38

Market scene, Ponce, plate showing ....... 40

Mayagnez, water supply of................. 43

Military road. (See Road, military.) 

Molasses, exports of ....._..._..__.... 35

Mountain ranges of Puerto Rico. _..... 11-14

Mountain summits under cultivation, plate

showing... ............ .. 34'

Orangos in Puerto Rico...._.,. ........ 41

Ox cart, plate showing.. ... ____....... 34

Pack animals, cost of transportation by... 46 

Pack horse, plate showing.....--..---.-.... 34

Parting valley about and hills back of

Yauco,plate showing......... .... 36

Piedras, Rio, water supply furnished by... 43 

PUoneillos, near Lares, view of..... 30

Pineapples,cultivation of........ ... 41

Plantain, cultivation of........._........ 40-41

Plata, Rio, measurements of................ 27

Playa at mouth of the Rio Loiza, plate

showing.... ..... ............ 16

Playa, description of.................... 16

Ponce, plate showing market scene at...... 40

plate showing sugar land near.. ..... 32

plate showing view of Rio Portugues 

at..................................... 26

section north and south through... 13 

topography near ...................... 18-19

water supply of.......... ............. 43

Portugues, Rio, plate showing view of..... 36

measurements of........................ 37

Portugues, Rio, water supply furnished 

by............ .............................. 43

Precipitation in Puerto Rico............. 33-34

Products, agricultural, of Puerto Rico... 34-41 

Railroads in Puerto Rico ....... ....... 44-4S

Rainfall in Puerto Rico................... 32-24

Regulator gate and ditch, plate showing . - 28 

Rice,cultivation of........._._'.......... 40

Rio. (See next word of name.) 

Road, military, near Aibonito, figure showing ..........................._..... 45

from San Juan to Ponce, course of and 

topography along. ................. 16-18

plate showing method of repairing..... 40

Road near Adjuntas, plate showing....._ 44

Road near Aibonito, plate showing ........ 44

Road near San Sebastian, plate showing... 44 

Roads in Puerto Rico . ........... ...... 45-46

Roads near Lares, plates showing........ 44,46

San Juan, plate showing bent mango trees

at-.-.-......-.. .--.---.-......-.., 18

rainfall at...........................----- 23

section north and south through ....... 13

water supply of ......... ............. 43

San Sebastian, plate showing road near.... 44

Section north and south through El

Yunque ........._ .................. 12

Section north and south through Ponce ... 13 

Section north and south through San Juan. 13 

Sierra de Cayey, cotirse and elevation of .. 12 

Sierra de Luquilla, extent and course of... 12 

plate showing foothills of............... 16

plate showing view near summit of.... 48

topography of .......................... 16

Siphon, figure showing inverted, carrying

ditch under military road .......... 30

Soils of Puerto Rico....................... 33-33

Streams, number and measurements of.. 24-28 

Sugar, exports of. .............. .......... 35

method of cultivating.-...--.---.-----.- 36

Sugar cane, plate showing.... ........-..-.. 36

trains of cars loaded with, plate showing ................................... 86

Sugar land near Ponce, plate showing.. 33 

Temperature of Puerto Rtoo.... . .-.. 24

Tobacco, cultivation and. value of. .-.. Sf 

^ exports of ........__ ._ ___........ 35

figure showing' cultivation, oa hflltops 

in Cayey district ................... 37

Topographic features of Pnerta Eico.... 11-21

Trade winds, influence of........ ...... 21-32

Transportation facilities in Puerto Rico. 44-46 

Turabo, Rio, measurements of............. 26

"Water power and supply in Pnerto Eico. 43-44 

"Winds, trade, influence of ................ 21-33

"Wing dam, plate showing.......--.-.... 28

Woods of Puerto Rico ......-.......-_-.-. 43-43

Yahueca, Rio, measurements of............ 27

Yauco, plate showing parting valley about,

and hilts back of..................... 28

Yautia, plate showing field of .... ......... 43

cultivation of................... ........ 40
1895.

Sixteenth Annual Report of the United States Geological Survey, 1894-95, Part II, 

Papers of an economic character, 1895; octavo, 598 pp.

Contains a paper on the public lands and their water supply, by P. H. Newell, illustrated 

by a large map showing the relative extent and location of the vacant public lands; also a 

report on the water resources of a portion of the Great Plains, by Robert Hay.

A geological reconnoissance of northwestern Wyoming, by George H. Eldridge, 

1894; octavo, 72 pp. Bulletin No. 119 of the United States Geological Survey; 

price, 10 cents.

Contains a description of the geologic structure of portions of the Bighorn Range and 

Bighorn Basin, especially with reference to the coal fields, and remarks upon the water 

supply and agricultural possibilities.

Report of progress of the division of hydrography for the calendar years 1893 and 

1894, by F. H. Newell, 1895; octavo, 176 pp. Bulletin No. 131 of the United 

States Geological Survey; price, 15 cents.

Contains results of stream measurements at various points, mainly within the arid region, 

and records of wells in a number of counties in western Nebraska, western Kansas, and 

eastern Colorado.

1896.

Seventeenth Annual Report of the United States Geological Survey, 1895-96, Part 

II, Economic geology and hydrography, 1896; octavo, 864 pp.

Contains papers on "The underground water of the Arkansas Valley in eastern Colorado," by G. K. Gilbert; "The water resources of Illinois," by Frank Leverett; and "Preliminary report on the artesian areas of a portion of the Dakotas," by N. H. Darton.

Artesian-well prospects in the Atlantic Coastal Plain region, by N. H. Darton, 

1896; octavo, 230 pp., 19 plates. Bulletin No. 138 of the United States Geological Survey; price, 20 cents.

Gives a description of the geologic conditions of the coastal region from Long Island, 

N. Y., to Georgia, and contains data relating to many of the deep wells.

Report of progress of the division of hydrography for the calendar year 1895, by 

F. H. Newell, hydrographer in charge, 1896; octavo, 356 pp. Bulletin No. 140 

of the United States Geological Survey; price, 25 cents.

Contains a description of the_ instruments and methods employed in measuring streams 

and the results of hydrographic investigations in various parts of the United States.

1897.

Eighteenth Annual Report of the United States Geological Survey, 1896-97, Part 

IV, Hydrography, 1897; octavo, 756 pp.

Contains a "Report of progress of stream measurements for the year 1896," by Arthur 

P. Davis; "The water resources of Indiana and Ohio," by Frank Leverett; "New developments in well boring and irrigation in South Dakota," by N. H. Darton; and " Reservoirs 

for irrigation," by J. D. Schuyler.

1898.

Nineteenth Annual Report of the United States Geological Survey, 1897-98, Part 

IV, Hydrography, 1899; octavo, 814 pp.

Contains a "Report of progress of stream measurements for the calendar year 1897," by 

F. H. Newell and others; " The rock waters of Ohio," by Edward Orton; and " Preliminaryreport on the geology and water resources of Nebraska west of the one hundred and third 

meridian," by N. H. Darton.

1899.

Twentieth Annual Report of the United States Geological Survey, 1898-99, Part 

IV, Hydrography, 1900; octavo, pp.

Contains a "Report of progress of stream measurements for the calendar year 1898," by 

F. H. Newell, and "Hydrography of Nicaragua," by A. P. Davis.

WATER-SUPPLY AND IRRIGATION PAPERS, 1896-1899.

This series of papers is designed to present in pamphlet form the results of stream measurements and of special investigations. A list of these, with other information, is given on 

the outside (or fourth) page of this cover.

Survey bulletins can be obtained only by prepayment of cost, as noted above. 

Postage stamps, checks, and drafts can not be accepted. Money should be transmitted by postal money order or express order, made payable to the Director of 

the United States Geological Survey. Correspondence relating to the publications 

of the Survey should be addressed to The Director, United States Geological 

Survey, Washington, D. C.

IRR32
WATER-SUPPLY AND IRRIGATION PAPERS.

1. Pumping water for irrigation, by Herbert M. Wilson, 1896.

2. Irrigation near Phoenix, Arizona, by Arthur P. Davis, 1897.

3. Sewage irrigation, by George W. Rafter, 1897.

4. A reconnoissance in southeastern Washington, by Israel C. Russell, 1897.

5. Irrigation practice on the Great Plains, by E. B. Cowgill, 1897.

6. Underground waters of southwestern Kansas, by Erasmus Haworth, 1897.

7. Seepage waters of northern Utah, by Samuel Fortier, 1897.

8. Windmills for irrigation, by E. C. Murphy, 1897.

9. Irrigation near Greeley, Colorado, by David Boyd, 1897.

10. Irrigation in Mesilla Valley, New Mexico, by F. C. Barker, 1898.

11. River heights for 1896, by Arthur P. Davis, 1897.

12. Water resources of southeastern Nebraska, by Nelson Horatio Darton, 1898.

13. Irrigation systems in Texas, by W. F. Hutson, 1898.

14. New tests of pumps and water lifts used in irrigation, by O. P. Hood, 1898.

15. Operations at river stations, 1897, Part I, 1898.

16. Operations at river stations, 1897, Part II, 1898.

17. Irrigation near Bakersfield, California, by C. E. Grunsky, 1898.

18. Irrigation near Fresno, California, by C. E G-runsky, 1898.

19. Irrigation near Merced, California, by C. E. Grunsky, 1899.

20. Experiments with windmills, by Thomas O. Perry, 1899.

21. Wells of northern Indiana, by Frank Leverett, 1899.

22. Sewage irrigation, Part II, by George W. Rafter, 1899.

23. Water-right problems of Bighorn Mountains, by Elwood Mead, 1899.

24. Water resources of the State of New York, Part I, by G-eorge W. Rafter, 1899.

25. Water resources of the State of New York, Part II, by George W. Rafter, 1899.

26. Wells of Southern Indiana (continuation of No. 21), by Frank Leverett, 1899.

27. Operations at river stations, 1898, Part 1,1899.

28. Operations at river stations, 1898, Part II, 1899.

29. Wells and windmills in Nebraska, by Erwin Hinckley Barbour, 1S99.

30. Water resources of the Lower Peninsula of Michigan, by A. C. Lane, 1899.

31. Lower Michigan mineral waters, by Alfred C. Lane, 1899.

32. Water resources of Puerto Rico, by Herbert M. Wilson, 1899.

In addition to the above, there are, in various stages of preparation, other papers 

relating to the measurement of streams, the storage of water, the amount available 

from underground sources, the efficiency of windmills, the cost of pumping, and 

other details relating to the methods of utilizing the water resources of the country. Provision has been made for printing these by the following clause in the 

sundry civil act making appropriations for the year 1896-97:

Provided, That hereafter the reports of the Geological Survey in relation to the 

gaging of streams and to the methods of utilizing the water resources may be 

printed in octavo form, not to exceed 100 pages in length and 5,000 copies in number; 1,000 copies of which shall be for the official use of the Geological Survey, 

1,500 copies shall be delivered to the Senate, and 2,500 copies shall be delivered to 

the House of Representatives, for distribution. (Approved, June 11,1896; Stat. L., 

vol. 29, p. 453.)

The maximum number of copies available for the use of the Geological Survey 

is 1,000. This quantity falls far short of the demand, so that it is impossible to 

supply all requests. Attempts are made to send these pamphlets to persons who 

have rendered assistance in their preparation through replies to schedules or who 

have furnished data. Requests made for a certain paper and stating a reason for 

asking for it are granted whenever practicable, but it is impossible to comply with 

general demands, such as to have all of the series sent indiscriminately. 

Application for these papers should be made either to members of Congress or to 

THE DIRECTOR,

UNITED STATES GEOLOGICAL SURVEY, 

IRR 32 Washington, D. C,