Yellowstone is taking another step this week in efforts to eradicate brook trout from its streams and restore native Yellowstone cutthroat trout to the park’s waters. Spokesman Dan Hottle says Elk Creek and its tributaries including Lost and Yancey creeks near Tower Junction in the Yellowstone River drainage are to be treated with a fish toxin over the next couple weeks. Hottle says biologists will introduce the chemical Rotenone will be introduced in small quantities, visitors are advised not to swim in or drink from the streams now through October 7. Hottle says the action is part of Yellowstone’s Native Fish Conservation Plan to correct a situation that was brought about by an ill-advised move some decades ago. Hottle says at that time, streams were stocked with non-native brook trout. Their presence has contributed to a decline in native cutthroat trout in park lakes, rivers and streams. Brook trout compete with cutthroat trout and often completely displace them and other native fish species. Hottle says results will not be seen for several weeks and may require another application or two before the brook trout population is removed and the park can reintroduce genetically pure native Yellowstone cutthroat to the streams.