Sedimentation survey of Lago Loco, Puerto Rico, March 2000

Lago Loco, a small reservoir property of the Puerto Rico Electric Power Authority and part of the Southwestern Puerto Rico Project, has lost 64 percent of its original storage capacity. In 1951, the original storage capacity was about 2.40 million cubic meters, decreasing to 1.43 million cubic meters in 1986 and to 0.87 million cubic meters in March 2000. The storage loss or longterm sedimentation rate increased from 27,714 cubic meters per year from the period of 1951 to 1986 to 31,224 cubic meters per year for the period of 1951 to 2000. This represents a capacity loss of about 1.1 percent per year for the period of 1951 to 1986 and 1.3 percent per year for 1951 to 2000. The trapping efficiency of the reservoir was about 92 percent in 1951, decreasing to about 87 percent in 1986, and to about 80 percent in March 2000. The sediment yield of the net sediment- contributing drainage area increased from 1,504 megagrams per square kilometer per year between 1951 and 1986 to 1,774 megagrams per square kilometer per year between 1951 and 2000, or about 18 percent. At the current sedimentation rate of the reservoir, the life expectancy of Lago Loco is about 28 more years or until the year 2028.