 It is located between the municipalities of Ciales and Orocovis, west of the Doña Juana Recreation Area, on PR-143 at km 25.4.The lowest temperatures recorded on the Puerto Rico—some 40 °F (4 °C) -- were measured at Lake Guineo.Lake Matrullas is located at 18.2064°N 66.4798°W (), at an altitude of 2,464 feet above sea level.