This stream drama comes straight from a fresh Montana Fish, Wildlife & Parks press release: the upper Shields River is officially host to a local reality show, and the invasive brook trout just got voted off the island. Here is how the eviction process works:The Rescue Mission: Crews head into Dugout Creek and surrounding streams to scoop up the native cutthroats and move them to temporary safe housing. Crews head into Dugout Creek and surrounding streams to scoop up the native cutthroats and move them to temporary safe housing. The Secret Weapon: Staff treat the water with rotenone—a fast-decomposing, plant-based toxicant—to clear out the invasive brook trout. Staff treat the water with rotenone—a fast-decomposing, plant-based toxicant—to clear out the invasive brook trout.