Team members took notes, measured water pH, and evaluated water temperature data

Team members took notes, measured water pH, and evaluated water temperature data for each sample collected. Water temperatures up to 60 degrees Celsius (140 degrees Fahrenheit) were recorded but are an underestimate due to equilibration time issues with the temperature sensor. Remote measurements of the water's surface temperature via a thermal camera have consistently indicated temperatures of 70-80 degrees Celsius (roughly 160-175 degrees Fahrenheit). Field measurements of pH indicated values of 4.3 for the surface water, 4.2 for the yellow-orange water, and 3.9 for the yellow-green water (pH of the October 26, 2018, sample was 4.2). Additional laboratory analyses by USGS California Volcano Observatory colleagues revealed that the three January samples, while more dilute (perhaps due to recent heavy rainfall), are chemically similar to the water sampled in October, which indicates ongoing reactions between the lake water, volcanic gases, and the surrounding basaltic rocks. HVO's work in a culturally sensitive area closed to the general public is done with permission of Hawai‘i Volcanoes National Park. The purpose of the UAS flights was to collect water samples and gas data to assess ongoing volcanic hazards. USGS photo by S. Warren.