The water that flows through Crystal Cave in Sequoia National Park (CA) is Yucca Creek which flows into Cascade Creek. As soon as you move into the entrance of Crystal Cave and pass through the spiderweb gate, you can here the gurgling of Yucca Creek as it passes through the cave:
Yucca Creek also reveals that Crystal Cave is a rare marble cave (only about 5% of the caves in the world are marble caves) like at Oregon Caves National Monument and the river bed reveals the marble of Crystal Cave:
Yucca Creek is evident well into the cave even after passing Emerald Pools: