Lago Dos Bocas at Damsite - 50027100

View towards downstream right-side of Lago Dos Bocas Spillway.  Photo by Matthew Larsen, USGS.

Lago Dos Bocas is located in the municipio of Utuado, and was constructed in 1942 by the Puerto Rico Electric Power Authority (PREPA).  The dam was originally intended as hydroelectricity source.

Lago Dos Bocas has a drainage area of 170.0 square miles (440.5 square kilometers).  Originally, the reservoir had a water-storage capacity of 30,401 acre-feet (37.5 million cubic meters), but by 1999 the capacity had been reduced by sediment infilling to 14,625 acre-feet (18.0 million cubic meters).

Real-time Reservoir Level

During 1995, about 240 million gallons per day (908 million liters per day) of in-stream fresh water were used to generate around 26 gigawatt-hours of electricity.  An in-stream water use is water that is used within the stream channel for such purpose as hydroelectric, power generation, navigation, fish propagation, and recreation.

Lago Dos Bocas will be an important source of potable water as part of the Superaqueduct system.  The Superaqueduct system will capture water from Dos Bocas and Caonillas reservoirs, and transport it eastward along the northern coast to San Juan area.  The pipeline system is expected to supply 100 million gallons per day (378.5 million liters per day) of water to the San Juan metropolitan area, and to about fifteen communities along the pipeline system.  The Superaqueduct system will be supplying potable water to about 1,300,000 people living in the north coast region of Puerto Rico.

The Superaqueduct system includes the construction of a 72-inch (1.83 meters) diameter high- pressure pipeline; a 300-million gallon (1,136 million liter) retention reservoir located between Río Grande de Arecibo and Río Tanamá; a water filtration plant in Arecibo that is expected to produce 100 million gallons per day (378.5 million liters per day); two 10-million gallon (37.9 million liters per day) storage tanks in Arecibo; and two smaller connectors.

The U.S. Geological Survey, in cooperation with PREPA and Puerto Rico Aqueduct and Sewage Authority (PRASA), has produced a number of reports regarding effects of sediment infilling on storage capacity of Lago Dos Bocas, including:

Soler-López, L.R., 2001, "Sedimentation survey of Lago Dos Bocas, Puerto Rico, October 1999": U.S. Geological Survey Water-Resources Investigations, Report 00-4234, 18 p., 1 pl.

In addition, the U.S. Geological Survey, in cooperation with local government agencies, has produced a number of reports regarding the effects of sediment infilling on the storage capacity of principle water-supply reservoirs of Puerto Rico.  The results of these surveys are summarized in "Sedimentation survey results of the principal water supply reservoirs of Puerto Rico,"

These reports can be purchased at a nominal cost by contacting Information Desk at the U.S. Geological Survey, GSA Center, 651 Federal Drive, Suite 400-15, Guaynabo, PR 00965, 787-749-4346 ext. 296.  Please contact Water-Use Information, 787-749-4346 ext. 259, if you have other questions regarding water supply in Puerto Rico.

The table below shows the relationship between reservoir level and available water. This information is presented in graphical format in the figure above. Note that an acre-foot is a volume of water that would cover an acre (43,560 square feet) to a depth of 1 foot.

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