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CM

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Principal

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Diversión

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La Sequia

Guajataca

Guajataca

Cedros

Aguadilla

5.6

5.5

5.4

5.3

5.2

5.1

5.0

5.0

4.0

5.7

5.9

5.5

3.0

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124.00

123.00

122.00

Introduction
 

18°28'35"
 

PUERTO RICO ELECTRIC POWER AUTHORITY

67°04'10"

EXPLANATION

67°04'05"
 67°04'00"
 

By Luis R. SolerLópez

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION0
 

2
 

4
 

6
 

2001
 8 2006 Section 4

RESERVOIR BOTTOM CONTOUR – Depth of the reservoir bottom, 5.6 5.8

March 2006, in meters below spillway elevation of 125.73 meters Lago Guerrero is located in Aguadilla, northwestern Puerto Rico (fig. 1). The 2001 conditions. As of May 30, 2001, Lago Guerrero had a calculated storage 

reservoir has a surface area of about 32,000 square meters and is excavated in capacity of 127,376 cubic meters, and a spillway elevation of 125.73 meters 5.4

above mean sea level. Contour interval variable. Shoreline shown Aymamón Limestone of Miocene age. This bedrock consists of chalk interbed- above mean sea level (Puerto Rico Electric Power Authority, written commun., as red line equal to spillway elevation or zero depth. The pumphouse 

ded with solution-riddled hard limestone (Monroe, 1969). The reservoir was 2001). The storage capacity determined from the March 9, 2006, bathymetric structure location is approximate

constructed in the 1930s as part of the Isabela Hydroelectric System to regulate survey was about 121,100 cubic meters, which represents a water storage Pumphouse structure

flows to two hydroelectric plants–Central Isabel No. 2, at an elevation of about capacity loss or sediment accumulation of 6,276 cubic meters. The reservoir has Selected cross section

110 meters above mean sea level, and Central Isabel No. 3, at about 55 meters lost about 5 percent of its storage capacity over 5 years, which is equivalent to 

10 above mean sea level. Hydroelectric power generation was discontinued during an annual loss rate of 1 percent per year from 2001 to 2006 or about 1,255 cubic Dam 0 20 40 60 80 100 120 140 160 180 200
 the early 1960s, although the exact date is unknown (Puerto Rico Electric Power meters per year. The relation between water volume and pool elevation of Lago 

Authority, written commun., 2007). The principal use of the reservoir since then Guerrero for 2006 is listed on table 1. DISTANCE FROM THE LEFT BANK, IN METERS
 

has been to regulate flow to two public-supply water filtration plants and supply 

irrigation water for the Aguadilla area. Flow into the reservoir is derived from Table 1. Lago Guerrero capacity table for March 9, 2006, at 0.305 meter (about 

Lago Guajataca through a 26-kilometer-long Canal Principal de Diversion 0 1 foot) elevation intervals.
 0 concrete canal (Puerto Rico Electric Power Authority, written commun., 2001). 

Additional inflow occurs on an incidental basis only during intensive rainfall Pool elevation, in meters Storage capacity,
 2
 

2

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION

from the immediate drainage area. The present Lago Guerrero drainage area is above mean sea level in cubic meters

undetermined, due to the irregular and complex topography of the limestone 125.73 121,100 

4
 

4
 

6
 

6 terrain and anthropogenic modifications to the stormwater drainage system. 125.58 111,659 2001 Stormwater runoff, however, is presumed to be negligible compared to the almost 125.27 102,378 8
 2006 2001 Section 1
 constant inflow to the reservoir of about 59,300 cubic meters per day from Lago 8 124.97 93,258 2006 Section 5 10 Guajataca (CSA Group, 2000). 0 20 40 60 80 100 120 140 160 180 200 124.66 84,339 10
 

0 20 40 60 80 100 120 140 160 180 200 124.36 75,722 DISTANCE FROM THE LEFT BANK, IN METERS On March 9, 2006, the U.S. Geological Survey (USGS), Caribbean Water 124.05 67,405 DISTANCE FROM THE LEFT BANK, IN METERS
 Science Center, in cooperation with the Puerto Rico Electric Power Authority 123.75 59,394 18°28'30" (PREPA), conducted a bathymetric survey of Lago Guerrero to determine the 123.44 51,773 storage capacity of the reservoir and sedimentation amount since a previous 

survey conducted on May 30, 2001. The March 2006 survey was made to develop 

a bathymetric map of the reservoir, establish baseline data for future reservoir 

123.14 44,546

122.83 37,708

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION

0
 

122.53 31,202 2 capacity comparisons, and to estimate the average sedimentation rate over the 

122.22 24,977 preceding 5 years.

121.92 19,034

Method of Survey
 121.62 13,704

121.31 8,986

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION

4
 

6
 

0
 

2
 

4
 

6
 

2001
 8
 2006 121.01 4,837 Section 2

The March 2006 bathymetric survey was conducted using a differential global 10 120.70 1,628 positioning system (DGPS) coupled to a digital depth sounder similar to the one 0 20 40 60 80 100 120 140 160 180 200

used for the May 2001 survey (Soler-López, 2002). The bathymetric data were 120.40 181 2001

DISTANCE FROM THE LEFT BANK, IN METERS
 8 2006 Section 6 120.09 1 then stored and transferred into a geographic information system (GIS), where 

119.83 0 10 final analysis and volume calculations were made following procedures similar 0 20 40 60 80 100 120 140 160 180 200
 

to those used to develop a bathymetric map of Lago Guerrero reservoir in May 

2001 (Soler-López, 2002). The GIS was used to analyze the bathymetric data for A comparison between the May 30, 2001, and March 9, 2006, bathymetric 

surveys of 2001 and 2006. maps indicates that sediment accumulation in Lago Guerrero from 2001 to 

2006 has been minimal and has occurred primarily on the upper reach of the 

For this study, 30 survey navigation lines were established at a spacing of about reservoir, nearest to the Canal de Diversion del Lago Guajataca intake (fig. 2, 

5 meters parallel to the northwestern perimeter of the reservoir and continuing sections 3-6). In this reach, sediment accumulation has raised the reservoir 

upstream. Geographic position and water depths were acquired simultaneously bottom by an average of about 25 centimeters over 5 years. The source of the 

using a DGPS interfaced to a depth sounder. The pool elevation of the reservoir sediment (including debris such as trash and plant matter) is most likely washwas measured at the existing PREPA reservoir staff gage before and after the data off into the irrigation canal where the channel is bordered by steep embank0 DISTANCE FROM THE LEFT BANK, IN METERS

2
 

4
 

6
 

2001
 8 2006 Section 3

DEPTH, IN METERS BELOW

SPILLWAY ELEVATION

10
 

0 20 40 60 80 100 120 140 160 180 200
 collection process. The soundings were subsequently adjusted to represent water 

depths below the spillway elevation. A bathymetric map representing the reservoir bottom in March 2006 was then generated from the field data (fig. 2). A 

triangulated irregular network (TIN) surface model of Lago Guerrero was 

created from the bathymetric map, and the reservoir volume was calculated using 

the GIS. A stage-storage curve (fig. 3) and selected cross sections representing 

the reservoir bottom (fig. 2) were generated using the TIN surface model and the 

digital data from the 2001 and 2006 surveys.

Storage Capacities, Bathymetry, and Sedimentation Rates

The May 2001 and March 2006 bathymetric data indicate the storage capacity of 

Lago Guerrero has changed slightly between surveys. Because construction 

records for Lago Guerrero reservoir and original bathymetry were not available, 

the volumetric changes and bottom contour morphology are referenced to May 

126.00

Spillway elevation = 125.73 meters above mean sea level

125.00

ments. This sediment is transported into Lago Guerrero by the sustained flow in 

the channel from Lago Guajataca reservoir. (fig. 4). Figure 5 shows part of the 

Lago Guerrero flooded area and the vegetation surrounding it which contributes 

plant matter. 

Summary and Conclusions

Lago Guerrero is a reservoir with a surface area of 32,000 square meters, 

constructed as part of the Isabela Hydroelectric System in the 1930s. The reservoir consists of an excavation into the limestone bedrock constructed primarily 

to regulate flows to two hydroelectric plants. The bathymetric survey conducted 

on March 9, 2006, indicated a storage capacity of about 121,100 cubic meters. 

Prior to this survey, a storage capacity of 127,376 cubic meters was determined 

from a similar survey conducted on May 30, 2001. The difference in storage 

capacities represents a storage loss of about 6,276 cubic meters between 

surveys. Based on this storage loss, the inter survey (2001-2006) sedimentation 

rate of Lago Guerrero is about 1,255 cubic meters per year or about 1 percent of 

the original storage capacity (127,376 cubic meters) per year. A bathymetric 67°10'38" map developed for the current (2006) survey indicates that most of the sedimentation in the reservoir has occurred in the upper part of the reservoir adjacent to 

the inlet channel. The lost storage capacity is probably sediment and debris 

washed into the Canal de Diversión del Lago Guajataca from the steep embankments along parts of the canal during stormwater runoff. Based on the current 

DISTANCE FROM THE LEFT BANK, IN METERS

0 100 200 Meters 18°28'25"

0 250 500 Feets

Figure 2. Bathymetric map of Lago Guerrero, Aguadilla, Puerto Rico, March 2006. Shoreline modified from U.S. Geological Survey quadrangle Moca, Puerto Rico, from planetable surveys in 1922 and 1937.

Revised in 1964. Lambert conformal conic projection. Puerto Rico state plane coordinate system. (Puerto Rico datum, 1940 adjustment).

66°53'38"

67°04'39" 67°04'00"

ATLANTIC OCEAN

18°28'45" (2006) sedimentation rate of about 1,255 cubic meters per year, Lago Guerrero 

has an estimated useful life of about 96 more years or the year 2102.

ELEVATION, IN METERS ABOVE MEAN SEA LEVEL

ISABELA

Canal 0114 CAMUY

QUEBRADILLAS REFERENCES CITED
 Lago Canal

Guerrero

18°27'30" Moca

CSA Group, 2000, Evaluación de los canales del sistema de riego de la región Canal

noroeste de Puerto Rico: Resumen de Promedios Anuales de Descarga para AGUADILLA

Cada Estación: Sección 5, Tabla 9. Canal

Monroe, W.H., 1969, Geologic map of the Moca and Isabela quadrangles, Puerto 

Rico: U.S. Geological Survey Miscellaneous Geologic Investigations Map 

I-565, 1 pl.
 MOCA 0108

0112

Lago

Soler-López, L.R., 2002, Sedimentation survey of Lago Guerrero, Puerto Rico, 

May 2001: U.S. Geological Survey Water-Resources Investigations Report 02-

de

Guajataca

EXPLANATION

4169, 12 p., 1 pl. Diversión Río Guajataca drainage

basin boundary SAN 

SEBASTIAN

0112 Surface-water

18°28'15" 2006 station and number

2001

0108 Lake-level

station and number

20,000 40,000 60,000 80,000 100,000 120,000 140,000 Map location Town or city LARES

STORAGE CAPACITY, IN CUBIC METERS

Figure 5. Lago Guerrero upstream view -- Upstrem view photograph of the Lago Guerrero flooded area taken from the top of the 0 1 2 3 4 5 Kilometers

Figure 3. Relation between water storage capacity and pool elevation for Lago Guerrero, Aguadilla, excavation dam. The photograph shows the typical vegetation that surrounds Lago Guerrero, which consists mainly of Puerto 

Puerto Rico, for 2001 and 2006. 0 1 2 3 4 5 Miles Rican almond tree Prunus amygdalus. Photograph taken by Luis Soler of the USGS on January 2, 2003.

18°15'00"

Base from 1997 CRIM aerial photo. 1:10,000

Figure 1. Location of Lago Guerrero in Aguadilla in northwestern Puerto Rico. Figure 4. Aerial photograph view of Lago Guerrero, Puerto Rico, and part of the Canal Principal de Diversión of Lago Guajataca. 

SEDIMENTATION SURVEY OF LAGO GUERRERO, AGUADILLA, PUERTO RICO, MARCH 2006

By 

Luis R. Soler-López

2007

0

121.00

120.00

119.00

118.00