Eradication of non-native fish in Yellowstone National Park and the restoration of native cutthroat trout continues with the poisoning of three creeks to rid the area of brook trout. Beginning Monday, the fish toxin is being introduced into Elk, Lost and Yancey Creeks where non-native brook trout were introduced decades ago. 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. While the chemical Rotenone will be introduced in small quantities, park officials advise visitors not to swim in or drink from the streams now through September 30th. Warning signs will be posted at all treated areas. Meanwhile, the project will not impact the nearby Yellowstone River. Such treatments will be repeated until brook trout have been completely removed from Yellowstone’s streams.