Scottsdale, Arizona, population 215,000, lies directly east of Phoenix. The City limits encompass 184.5 square miles, including a large portion of the McDowell Mountains, which provide a backdrop for the City.

A diamondback rattlesnake in the McDowell Sonoran Preserve.

Strawberry hedgehog cactus blossoms in the McDowell Sonoran Preserve.

As reported in Beyond Takings and Givings, Scottsdale has been working since the 1970s to protect the McDowell Mountains. In 1977, the City adopted a Hillside Zoning District that prohibited development in Conservation Areas but allowed transfers on a one-to-one basis to Development Areas. In 1991, the City replaced the Hillside Ordinance with the Environmentally Sensitive Lands Ordinance (ESLO), which placed an overlay zone on 134 square miles of land. The ESLO limited development to a density as low as one unit per 40 acres on steeper slopes and also strictly regulated development in the mountains to minimize grading, protect ridges and restrict the use of non-indigenous plants. However, the ESLO also allowed density to be transferred from land with greater environmental sensitivity to land with less environmental sensitivity. As well as transfers within a single property, or clustering, the original ESLO allowed off-site transfers particularly from sites that are severely constrained by the ordinance. To accommodate the transferred density, applicants could be granted reduced lot size and setback requirements via an administrative process or additional density via a public hearing process. There was no predetermined limit on additional density allowed on the receiving site. The City Council could determine the appropriateness of the density proposed on the receiving site based on environmental conditions and general plan goals.

Since 1991, Scottsdale has refined its ESLO three times, in 2001, 2003 and 2004. It may be too soon to judge whether these changes will lead to use of the off-site transfer option. In the past, significant preservation has occurred on site in conjunction with major developments. For example, the 3,500-acre McDowell Mountain Ranch preserved 891 acres of open space using the cluster process. Likewise, a master plan process preserved one square mile of open space at a development known as Scottsdale Mountain. However, as reported in Beyond Takings and Givings, developers had not used the off-site transfer option as of the publication of that book in 2003, largely because of the ability to achieve the desired density through other techniques such as clustering. In April 2004, Donald Meserve, City Planner, confirmed that non-contiguous transfers still have not occurred.

However, Scottsdale does not rely solely on TDR and clustering to preserve open space. In 1995, City voters approved a 0.2-percent sales tax to be used for land acquisition. (As of 2003, this tax increase generated $115 in revenues for open space preservation.) In 1996, the voters also approved revenue bonds using the proceeds of the sales tax increase. In 1997 and 1998, the City issued more than $97 million in revenue bonds to acquire key parcels. In 1998, the voters expanded the acquisition area to include an additional 19,940 acres, bringing the total land area proposed for preservation to more than 36,000 acres. In 1999, the voters approved the use of up to $200 million in general obligation bonds to be paid by the increased sales tax. As of 2003, Scottsdale had issued $134.6 million in general obligation bonds to preserve land. Because of the bonds, the City was able to front load $269 million in acquisition as of 2003. As a result, the McDowell Sonoran Preserve now encompasses 11,023 acres of protected lands.