6-Month Extension of Final Determination for the Proposed Listing of the Headwater Chub and Distinct Population Segment of the Roundtail Chub as Threatened Species; Proposed rule; reopening of the comment period.

We, the U.S. Fish and Wildlife Service (Service), announce a 6-month extension of the determination of whether the headwater chub (Gila nigra) and a distinct population segment of the roundtail chub (Gila robusta) are threatened species, and we announce the reopening of the comment period on the proposed rules to add these species to the List of Endangered and Threatened Wildlife. We are taking this action based on our finding that there is substantial disagreement regarding the sufficiency or accuracy of the available data relevant to our proposed regulations to add these species to the List of Endangered and Threatened Wildlife, making it necessary to solicit additional information by reopening the comment period for 30 days.