Hydrologist Jim Roche manages Yosemite's water quality monitoring program and works to protect the park's water resources, including two Wild & Scenic rivers: the Merced and the Tuolumne rivers. He came to Yosemite from Death Valley National Park in 2003 and had worked previously in Yellowstone and Great Basin national parks, Big Cypress National Preserve, and as a Peace Corps volunteer in Gabon, Central Africa. (3 minutes 20 seconds)

View Yosemite's other "Study the Scientist" videos to watch resource rangers describe their jobs.

• See wildlife biologist Sarah Stock, who specializes in ornithology  
• See social scientist Bret Meldrum, who studies the quality of a visitor's park experience
• See fire archeologist Jun Kinoshita, who functions as both a firefighter and an archeologist
• See botanist Martin Hutten, who specializes in lichens and invasive plants
• See historical architect George Jaramillo, who preserves the park's historical structures