State engineer issues order after long‑running Tropic–Otter Creek storage agreement lapsed; council discusses responses

Local water users and the State Engineer’s Office are engaged in a dispute over storage at Tropic Reservoir after a long-standing informal arrangement between Tropic and Otter Creek Irrigation lapsed and a change application expired.

Meeting participants described a sequence in which an informal or “napkin” agreement governed expanded storage at Tropic for decades. According to a timeline discussed in the meeting, Tropic’s reservoir was documented around 1898–1901, increased storage in 1936, a rejected storage request in 1942, an informal temporary storage arrangement in 1961, and a formal change application filed in 1977. The State Engineer approved the change in February 2005; that approval later lapsed in February 2010, and participants said Tropic continued to operate under the prior understanding until 2025. In early 2025 the State Engineer’s Office filed an enforcement referral and a distribution order requiring Tropic to open the reservoir; council members reported the reservoir was opened in April 2025.

Council members said Otter Creek Irrigation chose not to renew the earlier agreement or refile a change application and has let water pass downstream. Several speakers told the council that the operation of the reservoir and the timing of downstream releases affected downstream users’ ability to store April water and created local tensions this year.

Legal and technical context: Participants discussed the historical Cox decree and an adjudication process on the river. Jody Gale, Utah State University Extension Service, said the council should be careful about legislative intervention: “The one thing that should not be done by the legislature is to mess around with the Cox decree,” she said, adding that the Cox decree resulted from water users stipulating rights that a judge signed. Council members also referenced a recent study they said shows groundwater and surface water in parts of the basin are interconnected; participants said that connectivity is relevant to arguments about whether releases from Tropic contribute to downstream flows.

Enforcement and near‑term steps: The council was told the State Engineer’s Office issued a distribution order and that Otter Creek and Tropic planned a meeting on July 22 to discuss whether to rework an agreement. Council members discussed outreach and education options, including drafting a letter from the watershed council to the state watershed council and to local associations of governments (AOGs) to explain the local impacts and to urge that water-rights adjudication remain an administrative, not a political, process. Members asked staff to compile local economic and agricultural statistics for use in such correspondence.

What remains unresolved: Meeting participants flagged several open items for technical follow-up: whether Tropic fully emptied to the distribution order, how releases were impeded by debris and constrictions downstream, the exact accounting of any 10% sharing arrangement referenced in the historical agreement, and whether the reservoir’s physical spillway and outlet structures match the historical storage rights. The council requested a fact sheet and technical brief to support outreach and recommended letting the State Engineer’s Office complete its administrative process while the council pursues public education and AOG coordination.

—Ending note: Council members agreed to compile input for a draft letter backing administrative adjudication and to route that draft to members and regional AOGs for early fall review. A July 22 meeting between Otter Creek and Tropic was identified as the immediate next forum for local negotiation.