Thyra Ryden-Diaz is building Scottsdale’s future, one project at a time

After nearly three decades helping shape the infrastructure of Scottsdale, Thyra Ryden-Diaz is stepping into a new role at a pivotal moment for water in the Southwest.

Recently named interim senior director of Water Resources for the city, Ryden-Diaz brings technical expertise, institutional knowledge and a long history of public service to one of Scottsdale’s most critical departments.

For Ryden-Diaz, engineering was never just a career path. It was part of the family business.

“I am a third-generation engineer,” she said. “My father was a civil engineer; my grandfather was an electrical engineer. Engineering is the family business.”

As a child, she spent weekends visiting construction sites with her father and experimenting with electrical breadboards and erector sets encouraged by her grandfather. Those early experiences shaped the problem-solving mindset that would guide her career.

Although she once considered chemical engineering because of her love for chemistry, a summer engineering program before her senior year of high school changed everything.

“The day we spent making and testing concrete—that was it,” she said. “I chose civil engineering before my senior year of high school and never wavered.”

Ryden-Diaz earned a bachelor’s degree in civil engineering from Arizona State University and later completed a master’s degree in public management from Northern Arizona University while working full time for the city.

She joined Scottsdale in 1999 after seeing an article highlighting employee satisfaction within the organization.

“Scottsdale was expanding, building and had challenges I wanted to help solve,” she said.

What began as a role reviewing civil plans evolved into a career managing some of Scottsdale’s most visible and complex infrastructure projects. Over the years, Ryden-Diaz has overseen projects ranging from sewer and water system improvements to trailheads, drainage systems and major transportation work.

Among the projects she points to with particular pride are the development of ASU Scottsdale SkySong and the expansion of Scottsdale’s Advanced Water Treatment facility.

“The expansion of the Advanced Water Treatment facility was an incredible project expanding the realm of possibilities and setting a world-class example,” she said.

Her résumé reflects the scale of that work. Ryden-Diaz has managed nearly $500 million in city projects over more than 20 years without legal claims.

Colleagues describe her as highly organized, technically skilled and deeply committed to public service. She has also authored internal project management guides and served in leadership roles with professional engineering organizations.

Still, Ryden-Diaz says what kept her in Scottsdale all these years is simple: loyalty.

“Knowing my efforts, skill and technical knowledge help make Scottsdale a great place to live,” she said. “The history of who, what and why of almost three decades of experience is valuable to the organization.”

That institutional knowledge could prove especially valuable as Scottsdale navigates ongoing uncertainty surrounding the future of the Colorado River and regional water supplies.

“This is a challenging time for water,” Ryden-Diaz said. “We have very smart professionals at Scottsdale Water who are dedicated, work tirelessly and are poised to carry out the mission to serve the water needs of Scottsdale residents through this difficult time of Colorado River negotiations.”

Her approach to leadership and decision-making remains grounded in engineering fundamentals: define the problem carefully, work through the variables and remain open to iteration, "especially when the solution involves the public,” she added.

Outside the office, Ryden-Diaz volunteers with Scouts BSA, mentoring young people through Eagle Scout projects, including projects benefiting Scottsdale’s Preserve system.

As she steps into the interim senior director role, Ryden-Diaz carries with her not only decades of technical experience, but also a personal investment in the city she has helped build — project by project, pipeline by pipeline and neighborhood by neighborhood.