Chicago Gulch Creek is a headwater tributary to Fords Creek which drains the eastern aspect of the Judith Mountains. Approximately 3 miles of Chicago Gulch is on private lands, about 1 mile state lands and 1 mile on BLM lands. Chicago Gulch currently supports non native brook trout (Salvelinus fontinalis). The proposed action is to remove all of the non-native fish in Chicago Gulch and its tributaries on approximately 4.5 miles of stream. Treatment will occur upstream from a dry reach using the piscicide CFT Legumine™ (5% liquid rotenone). We then proposed to restock Chicago Gulch Creek with locally obtained, non-hybridized westslope cutthroat trout (WCT). It is predicted the population of WCT would be very robust (>2500 individuals). Based on the Draft Environmental Assessment, public comment and the currently high risk of extinction of WCT in the Missouri Drainage, it is my decision to proceed with Alternative 2, the proposed action. Alternative 2 involves removal of an existing fish population of brook trout. Removals will involve piscicides. The Draft Environmental Assessment, together with this decision notice, will serve as the Final Environmental Assessment document for this proposal. No significant impact on the human or physical environment except to help ensure the long-term persistence of pure WCT in the Missouri River drainage occurs with this project and the Environmental Assessment is the appropriate level of analysis.