Four adjacent ranges define the western edge of the Avra and Altar valleys. Even though desert ironwood has dark green, lush foliage much of the year, this tree is almost exclusively a Sonoran Desert species. The same is true of the distribution of saguaros, foothill palo verdes, fishhook barrel cacti, and most of the hundreds of other plants growing here. These rugged ranges also provide natural refuges for a variety of wildlife, including desert bighorn and migratory pollinators. In addition to the biological resources, the area has abundant rock art sites and other archaeological sites.

During the planning process for the SDCP, concerns were raised regarding loss of property tax revenue as well as adverse tax base impacts of Pima County purchasing parcels for open space. This report assesses impacts in two ways. First, the net assessed values of the open space parcels before purchase are compared to the sum of the net assessed values of all parcels in Pima County and in each applicable school district. Second, the property taxes assessed by Pima County and applicable school districts on each open space parcel before purchase is compared to the sum of the property taxes assessed on all parcels within Pima County and applicable school districts.