Sienna Hills sits in the foothills east of the original Washington City grid, on the bench rising toward the base of the Hurricane Cliffs uplift. The community is a post-2000 master-planned subdivision typical of the Washington City buildout era — stucco-and-tile single-family homes, integrated trail and park amenities, and a residential character that is more recent than the older Washington core. The neighborhood is one of several master-plans on the east side of I-15 that have together pushed Washington City's population from a few thousand to over 30,000 since 2000.

A foothills master-plan

Sienna Hills was begun in the 2000s on what had been ranching and grazing ground east of the original Washington townsite. The foothills location gives the community elevation views toward the Pine Valley Mountain massif to the northwest and toward Sand Hollow and the Hurricane Cliffs to the southeast. The build-out has continued steadily through the 2010s and 2020s, with newer phases moving further up the foothill bench.

What the neighborhood is for

Sienna Hills is one of the post-2000 master-plans that defines modern Washington City — newer than the Telegraph Street historic core, on the foothill bench rather than the river bottom, and oriented toward family-and-school residency rather than the older agricultural economy. The community sits adjacent to the Coral Canyon golf-anchored neighborhood, and the two together form a continuous residential zone on the east side of I-15. The neighborhood is one of the more rapidly developing pieces of Washington County as of 2026.