History and Background

  • The US Highway 160 from Durango to Bayfield Record of Decision (ROD) was signed November 2006. The Selected Alternative included an interchange 0.6 miles east of the current US 160/US 550 intersection.
  • In February 2008, the first construction phase of the interchange was advertised and construction began in July. This $34.4 million project included a second westbound lane, 4 major bridge structures and ramps.
  • In September 2007, CDOT began detailed design work on the next phase of the interchange that included the US 550 connection. During this work, it was discovered that there was a gas well within the alignment selected in the ROD. The US 550 connection was redesigned to avoid this gas well.
  • This alignment shift required revisiting the environmental process. As part of this process, the Webb Ranch was evaluated under Section 106 of the National Historic Preservation Act. In consultation with the State Historic Preservation Officer (SHPO), CDOT determined that a portion of the Webb Ranch is eligible for listing on the NRHP and that the preferred alternative would result in an adverse effect to the ranch, as defined in 36 CFR 800.5.
  • In July 2008, FHWA received a letter from the owners of the Webb Ranch identifying potential archeological sites not identified in the US 160 FEIS. This necessitates an additional evaluation under the Section 106 process to determine if these archaeological sites are eligible to the NRHP.
  • The NRHP eligibility of a portion of the Webb Ranch and the determination that the proposed action will result in an adverse effect has also necessitated an evaluation of that property under Section 4(f) of the Department of Transportation Act. The Section 4(f) evaluation process requires FHWA and CDOT to evaluate alignments that avoid the NRHP-eligible portion of the Webb Ranch.
  • The results of the Section 4(f), Section 106, and NEPA re-evaluation processes will determine the alignment of US 550 and where it will connect to US 160.