Water utilities are required to develop, implement, and maintain a backflow prevention plan. Each utility's plan is individual to the system. And this is what the city states, “If you have or are planning on installing an irrigation system, you must first comply with Oregon and City of Bend Ordinances. These Rules and Regulations require that all irrigation systems have approved backflow protection.” Note that they say “approved” because some aren’t, while others are to certain degrees but not always.
At any rate, that install up on the butte should have pulled a permit, should have installed the device, and should have had it inspected.
Riverwoods, eh? You’re just around the corner from me. Yeah… small town, almost. I do like that new DRW sign out by 97. Wonder who paid for that?