Sedimentation Survey of Lago Toa Vaca, Puerto Rico, June-July 2002

By Luis R. Soler-López


In cooperation with the


U.S. Geological Survey Scientific Investigations Report 2004-5035


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The Lago Toa Vaca dam is located in the municipality of Villalba in southern Puerto Rico, and is owned and operated by the Puerto Rico Aqueduct and Sewer Authority. Construction was completed in 1972 as the first phase of a multi-purpose project that contemplated four possible diversions from other basins to mitigate the rapid storage capacity loss of Lago Guayabal, located immediately downstream of the Toa Vaca dam. The latter phases of the intra-basin diversions were cancelled, and currently, the reservoir receives runoff from only 56.8 square kilometers of its drainage area.

Lago Toa Vaca reservoir when constructed was to be used for irrigation of croplands in the southern coastal plain. The reservoir had an original storage capacity of 68.94 million cubic meters. Sedimentation has reduced the storage capacity by only 7 percent between 1972 and 2002 to 64.08 million cubic meters. This represents a long-term sedimentation rate of about 162,000 cubic meters per year.

Based on the 2002 sedimentation survey, Lago Toa Vaca has a sediment trapping efficiency of about 98 percent and a drainage area-normalized sedimentation rate of about 3,086 cubic meters per square kilometer per year between 1972 and 2002. At the current long-term sedimentation rate the reservoir would lose its storage capacity by the year 2400.




Dam, Reservoir, and Basin Characteristics

Method of Survey

Field Techniques

Data Processing

Storage Capacity and Sediment Accumulation

Sediment Trapping Efficiency and Water Renewal Rates

Sediment Yield and Reservoir Life Expectancy

Summary and Conclusions

References Cited


1. Lago Toa Vaca, Puerto Rico, Bathymetry, 2002

2. Lago Toa Vaca, Puerto Rico, Topography, 1972


The citation for this report, in USGS format, is as follows:


Soler-López, L.R., Sedimentation survey of Lago Toa Vaca, Puerto Rico, June-July 2002, U.S. Geological Survey Scientific Investigations Report 2004-5035, 32 p.


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