Simplot Waste Lagoon #1, also known as Simplot Buttercreek Lagoon, is a private-owned structure located in Umatilla, Oregon. The lagoon is regulated by the Oregon Water Resources Department and holds a significant hazard potential, with a moderate risk assessment rating. It stands as an Earth-type dam with a height of 46 feet and a storage capacity of 535 acre-feet.

Despite its uncontrolled spillway, the lagoon has not been modified in recent years and its condition remains unrated. The last inspection was carried out in March 2018 and is scheduled for every three years. With its off-channel position and a drainage area of zero, the lagoon serves a primary purpose of "Other," making it an intriguing site for water resource and climate enthusiasts to monitor and study in the Hermiston area.