I-10 Twin Peaks Traffic Interchange, Environmental Assessment

Affected Environment and Environmental Impacts October 2005
conducted to determine the types of species and number of individual plants that
would be impacted.
Mitigation
To protect vegetation resources in the project area, a revegetation plan would be
developed prior to construction activities. The Town of Marana would develop a
Native Plant Protection Plan (NPPP) in accordance with local ordinances.
Protected native plants within the construction limits would be impacted by the
preferred alternative; therefore, the ADOT Roadside Development Section would
notify the Arizona Department of Agriculture (ADOA) at least 60 days prior to the
start of construction to afford commercial salvagers the opportunity to remove and
salvage these plants.
Conclusion
One Salvage Restricted plant species listed under the ANPL, the Tumamoc
globeberry, has been documented by AGFD as occurring within 2 miles of the
study area. Tumamoc globeberry were not observed during a pedestrian survey of
the study area and existing land use has disturbed suitable habitat for the Tumamoc
globeberry. In addition, native plants protected by the ANPL, Marana NPPO and
Pima County NPPO are present within the project area and would be impacted by
construction of the preferred alternative. A revegetation plan would be developed
prior to construction activities and a NPPP would be developed by the Town of
Marana to address impacts to native vegetation and develop mitigation measures.
Vegetation, Riparian Habitat, and Wetlands
Existing Conditions
Vegetation in the study area is a mosaic of natural upland vegetation, small dry
ephemeral washes, disturbed and re-established riparian areas, wetland vegetation
of the Santa Cruz River, and disturbed and landscaped vegetation associated with
residential housing, commercial businesses, and light industry. Most of the natural
vegetation in the study area occurs: 1) within the high flow channel of the Santa
Cruz River; and, 2) along Linda Vista Boulevard, particularly between El Camino
de Mañana (west) and Hartman Lane (east).
Natural vegetation in the study area is representative of three vegetation
communities: 1) Arizona Uplands; 2) Riparian Scrub; and, 3) Cottonwood/Willow
Riparian Forest. Arizona Uplands vegetation exists in the upland areas along Linda
Vista Boulevard and is characterized by foothills palo verde, saguaro, velvet
mesquite, triangle-leaf bursage, and cholla cactus. The most intact Arizona
Uplands Vegetation occurs along Linda Vista Boulevard west of Hartman Lane.
Arizona Uplands vegetation along Linda Vista Boulevard east of Hartman Lane
has been fragmented as a result of residential development. No natural landscapes
of Arizona Upland vegetation remain on the west side of the study area because of
the Continental Ranch housing development. Small and scattered remnant Sonoran
Interstate 10 Traffic Interchange at
Twin Peaks/Linda Vista
4-36
Project No.: NH-010-D (AIW)
TRACS No.: 10 PM 236 H5838 01D