I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Affected Environment and Environmental Impacts October 2005
Proposed improvements to Twin Peaks Road, Linda Vista Boulevard, and El
Camino de Mañana would impact vegetation in area of suitable habitat. Vegetation
impacts in suitable habitat would be limited to riparian vegetation along the Santa
Cruz River and desertscrub vegetation in upland areas along Linda Vista
Boulevard and El Camino de Mañana. Prior to removal of vegetation during
construction, the Town of Marana would develop a revegetation plan that would
comply with the Arizona Native Plant Law (ANPL), and Native Plant Protection
Ordinances (NPPO) of the Town of Marana and Pima County. In addition, the
revegetation plan would include Corps’ recommendations from the TRDN
Feasibility Study (see Mitigation below). As a result of the revegetation plan, the
value of the vegetation in the disturbed area of the project area would be improved
by construction of the preferred alternative.
The preferred alternative is not likely to adversely affect CFPO or its habitat
because: 1) although pygmy-owls do occur within mean dispersal distance of the
study area, USFWS is not aware of any nesting pairs within this distance; 2)
impacts to riparian vegetation would be temporary and would not permanently
impede use of the Santa Cruz River as a movement corridor; 3) loss of desertscrub
vegetation does not occur in areas used by pygmy-owls for nesting; 4) width of the
proposed Twin Peaks Road and noise from traffic should not prevent movement of
pygmy-owls across it; and, 5) the bridges over the Santa Cruz River would be of
sufficient height to allow unimpeded wildlife movement underneath.
The preferred alternative would result in disturbances to suitable habitat to the
yellow-billed cuckoo. In addition, the species has been documented in the study
area; therefore, the project may impact individual cuckoos, but is not likely to
jeopardize the continued existence of yellow-billed cuckoos.
The Section 7 of the ESA requires federal agencies to ensure that the actions they
authorize, fund, or carry out do not jeopardize the continued existence of
endangered species. To comply with Section 7 requirements, FHWA requested
concurrence with the USFWS on August 4, 2004 which resulted in the USFWS
concurring that the Preferred Alternative would not jeopardize the endangered
CFPO nor the yellow-billed cuckoo in a letter dated December 21, 2004 (see
Appendix B).
Mitigation
Prior to construction, the Town of Marana would develop a revegetation plan that
would incorporate the mitigation discussed below. This revegetation plan would be
provided to the contractor. Mitigation measures would include revegetation of
impacted areas along the roadway and the riparian vegetation along the Santa Cruz
River. Mitigation would include:
• Disturbed soils would be re-seeded using species native to the project vicinity
and would mirror the current plant composition to the extent possible.
• Within upland areas, trees greater than 4 inches diameter at breast height and
Saguaro cactus that are removed would be replaced within the overall
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
4-31
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D