Hammering out concessions contracts across the National Park System is not an easy, or quick, job. Failure to reach new contracts before existing ones expired at the end of 2014 prompted the National Park Service to propose extended dozens of contracts for up to a year to keep visitor services operating without interruption.

Yellowstone National Park officials, in a draft report to the World Heritage Committee regarding the health of the national park, say they are making strides in reducing impacts tied to pollution and visitation.

Over the past century and more, tourists to Yellowstone National Park have marveled at the colors in the park's hot springs. Unfortunately, some of those visitors can't resist tossing coins, trash and other foreign objects into the thermal pools. Scientists have wondered how all that activity may have changed the composition and appearance of those springs, and a recently-released study offers some answers to those questions.

With over half the world's geysers, Yellowstone National Park offers tremendous opportunities to see these geologic wonders in action. Explore the mechanics of geysers, their role in the park's history and what they teach us about the world in which we live. Produced by Steven Bumgardner.