Natural Area Open Space (NAOS)

Scottsdale's Environmentally Sensitive Lands Ordinance (ESLO) protects the city's Sonoran Desert hillsides, washes, ridgelines, and native vegetation by carving out Natural Area Open Space, abbreviated NAOS: desert that a development must preserve in its natural state forever. When a lot is developed under the ESLO, a portion of it is set aside and recorded as NAOS, and inside that area you cannot build, grade, clear, or install conventional landscaping. It stays raw desert.

NAOS is not a fixed percentage for every lot. Scottsdale calculates the required amount from the land's slope and landform, so steeper, more sensitive terrain must preserve more of the lot. A relatively flat parcel might owe a smaller share, while a hillside lot can owe a large fraction of its area as undisturbed NAOS. The required area is then placed on the recorded plat as an easement-like preservation area, so it binds future owners too.

For a custom home, NAOS directly shrinks your buildable area. It works alongside, but separately from, setbacks and lot coverage limits. A lot can look big on paper, but once you subtract the recorded NAOS, the part you may actually disturb and build on is smaller. That drives where the house, driveway, and pool can go, and it is why desert hillside sites need careful early planning.

For example, a Scottsdale hillside lot in the ESL overlay might be required to keep a substantial percentage of its area as NAOS. The home, driveway, and graded yard all have to fit in the remaining disturbable footprint, with the protected desert left untouched around them.

If you are buying or building on a sensitive Scottsdale lot, confirm the NAOS requirement before you design. Knowing how much of the lot must stay wild, and where, tells you the true size of the canvas you have to work with.