This dataset contains the selected physical properties and chemical constituents that were measured at Levittown Lake, Toa Baja, Puerto Rico during a diurnal cycle. Diel studies were conducted at the lake to estimate the community net primary productivity, the respiration rate, and the gross productivity rate. Two diel studies were conducted on November 18, 2010, and May 18, 2011, near the respective annual periods of highest and lowest tides for the northern coast of Puerto Rico. The community primary productivity is defined as the rate at which organic matter is created by photosynthesis and is important for supporting the food web in aquatic ecosystems. The field data collection included the measurement of physicochemical parameters such as temperature, dissolved oxygen, and percent of oxygen saturation. Measurements were obtained at about 1 hour-intervals.