Wyoming State Engineer Brandon Gebhart announced that on May 5, 2026, the State of Montana placed a call under Article V(A) of the Yellowstone River Compact to fill Tongue River Reservoir in Montana. As a result, priority administration is in effect on post-1950 water rights in Wyoming that divert water from the Tongue River and its tributaries and are not excluded from the compact.
A public meeting will be held from 5:30 to 6:30 p.m. Monday, May 18, in the dining room of The Hub on Smith. Attendees are asked to enter on the north side of the building.
The Tongue River Basin has been experiencing drought conditions over the past year with historically low winter snowpack and streamflow conditions. According to the release, those conditions led to Montana’s interstate call and prompted the administration of the Tongue River Basin in Wyoming.
The priority administration will affect post-1950 water rights within the Tongue River Basin, including reservoir storage, stream diversions and groundwater withdrawals, all of which affect river flows. Post-1950 water rights will be regulated off or prevented from turning on. Wyoming hydrographer-commissioners will continue to administer reservoir storage and post-1950 diversions throughout the spring and work with affected water users until the administration is lifted.
As provided in the compact, domestic uses less than one-half acre in area and livestock uses, including stock reservoirs less than 20 acre-feet in capacity, are excluded from this administration. The release noted these excluded rights could be subject to future regulation to satisfy priority calls by senior Wyoming water rights.
Beginning May 5, 2026, Wyoming hydrographer-commissioners have worked to record the current storage levels of reservoirs with post-1950 water rights. Going forward, those reservoirs can continue to accrue storage so long as post-1950 storage gained after the interstate call on May 5 remains in storage until either the water is released to satisfy the Montana call or Montana lifts the call because Tongue River Reservoir will fill.
Reservoirs with unfulfilled pre-1950 water rights can continue to store water and that storage will not be subject to release to satisfy Montana’s call. However, that storage and other direct flow rights could be subject to regulation to satisfy priority calls by senior Wyoming water rights.
The priority administration will be carried out pursuant to state law by hydrographer-commissioners assigned to various portions of the Tongue River Basin, working under the direction of Division II Superintendent David Schroeder.
The Wyoming State Engineer’s Office can be contacted at:
Jack Morey, deputy state engineer, 307-777-5032, jack.morey2@wyo.gov
David Schroeder, Division II superintendent, 307-674-7012, d.schroeder@wyo.gov
Jeff Cowley, interstate streams administrator, 307-777-1942, jeff.cowley@wyo.gov
