Instrument Maintenance in Sierra Nevadas (IMAGE) American Society of Agronomy Caption Critical Zone Observatory staff maintain instruments at a site in the southern Sierra Nevadas. Credit Photo credit Erin Stacy. Usage Restrictions Use with story only License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.