Scottsdale’s McDowell Sonoran Preserve spans more than 30,000 acres of Sonoran desert, and its funding is now being challenged in two separate court cases. The disputes coincide with the preserve’s 32nd anniversary this month. It stretches from around 136th Street and Shea Boulevard north to the Tonto National Forest and is often called the nation’s largest urban preserve, according to ABC15 Arizona.
Scottsdale voters approved sales-tax increases over the years to pay for land purchases and conservation in the preserve. Those taxes are central to the two court challenges, according to ABC15 Arizona.
Former Scottsdale City Councilman David Smith filed a lawsuit earlier this year in Maricopa County Superior Court seeking to sunset the preserve tax, ABC15 reports. Separately, the Goldwater Institute is challenging the tax in a case with arguments scheduled for Wednesday before the Arizona Court of Appeals in Tucson, according to the station.
Goldwater Institute Says the Math Doesn't Add Up
Goldwater Institute argues that the tax increase needed at least 60% voter approval and says the measure received 58%, below the threshold it says applies to taxes approved by referendum, according to the Goldwater Institute. The organization’s complaint and motion for a preliminary injunction in Stamper v. Scottsdale were filed May 30, 2025. They ask the court to declare the city’s sales and use tax unconstitutional and bar officials from enforcing it. Scott Day Freeman, a senior attorney at the institute, is representing the challenge.
The tax dispute has a longer history. Scottsdale voters approved a 0.20% tax in 1995 and a 0.15% tax in 2004 for land acquisition and improvements in the preserve, according to Arizona Digital Free Press. The outlet reports that the sales tax for land purchases and new trailheads is slated to sunset. City officials have estimated that a proposed replacement tax could generate $25 million annually for 30 years. The Arizona Court of Appeals also previously reversed a Superior Court dismissal of a related Goldwater challenge concerning the city’s use of public resources to promote a proposed sales-tax measure.
Scottsdale's own election materials describe the current 0.20% tax rate as designated solely to fund improvements, maintenance and protection of citywide parks and recreational facilities, as well as maintenance and protection of the preserve, as determined by ordinance, per the city's 2025 tax-rate documentation.
What Proposition 490 Proposed—and What the Courts Must Decide
Scottsdale’s official Proposition 490 ballot text described a 0.15% transaction privilege and use tax for 30 years, taking effect when the existing 0.20% rate expired in 2025. The tax was designated for specified citywide parks and recreational facilities and for maintenance and protection of the preserve, according to the City of Scottsdale. Goldwater says the measure received 58% of the vote and argues that a 60% threshold applied. The materials cited here do not establish which Arizona constitutional provisions or court precedents control, or resolve whether the threshold distinguishes referendums from initiatives; that legal question remains disputed.
The city’s FY 2026/27 capital plan lists $2.3 million for its preservation program, including a feasibility study for the Rio Verde Wildlife Crossing and various trailhead improvements, according to the City of Scottsdale.
'The Mother of the Preserve' Reflects on Its Growth
ABC15’s anniversary report also included a brief reflection from Carla, whom the station identified as the “mother of the preserve.” She declined to comment on either lawsuit.
The station reported that Carla described the McDowell Sonoran Preserve as a preserve rather than a park and recommended that newcomers take a guided hike to learn about it.
The preserve, which by one account from the Arizona Digital Free Press includes 12 trailheads and 235 miles of trails, has scheduled a number of activities for this fall to mark the anniversary. Among those exploring it recently were Chad Larsen and John Kass, who hiked near Tom's Thumb in the preserve; Kass told the outlet the hike offered a great experience and views.
A Vast Desert Landscape With an Uncertain Funding Future
The preserve has been protected since 1994 and spans more than 30,500 acres, according to the City of Scottsdale. Its scale, stretching from suburban Scottsdale to the edge of the Tonto National Forest, has made its tax-funded upkeep a recurring subject of legal scrutiny even as the land itself keeps drawing hikers to its trailheads.
