Wyoming Framework Water Plan - Living Rivers Home Page

3.0 SETTING
administered on a straight priority basis (irrespective of the state line). Water uses developed after the
Compact’s signing are administered to equally share the available water supply.
Upper Niobrara River Compact (1962)
The compact dividing the waters of the Niobrara River between the States of Nebraska and
Wyoming was negotiated by the two states in 1962 and approved by Congress in 1969. Stock water
reservoirs in Wyoming not exceeding 20 acre-feet in capacity are not restricted except by Wyoming law,
and no restrictions were placed on diversion or storage of water in Wyoming. The exception to this
occurs on the main stem east of Range 62 West and on Van Tassel Creek south of Section 27, Township
32 North, Range 60 West. In this area, direct diversions are regulated on an interstate priority basis with
lands in Nebraska west of Range 55 West. Storage reservoirs with priority dates prior to August 1, 1957,
may store water only during the period of October 1 to June 1, unless water is available after meeting
direct flow appropriations in Wyoming and Nebraska west of Range 55 West. Storage reservoirs with
priority dates after August 1, 1957, may store a maximum of 500 acre-feet in any water year from
October 1 to May 1, unless water is available after meeting direct flow appropriations in Wyoming and
Nebraska west of Range 55 West. Groundwater development was recognized to be a significant factor,
and the compact provides for investigation of this resource and possible apportionment at a later date.
Snake River Compact (1949)
The compact dividing the waters of the Snake River and Salt River between the states of Idaho
and Wyoming was negotiated by the two states in 1949 and ratified by them and the federal government
in 1950. The compact recognizes, without restrictions, all existing rights in Wyoming as of the date of the
compact. It permits Wyoming unlimited use for domestic and stock uses provided that stock water
reservoirs shall not exceed 20 acre-feet in capacity. It permits Wyoming to divert (or store) for new
developments, for supplemental or original supply, 4 percent of the Wyoming-Idaho state line flow of the
Snake River.
Yellowstone River Compact (1950)
The Yellowstone River Compact dividing the waters of the tributaries (Clarks Fork, Big Horn,
Tongue, and Powder) of the Yellowstone among the states of Wyoming, Montana, and North Dakota was
negotiated in 1950 and ratified by the three states and the federal government in 1951. Existing rights as
of January 1, 1950, maintain their status in accordance with the laws governing the acquisition and use of
water under the doctrine of prior appropriation. In addition, existing and future domestic and stock water
uses including stock water reservoirs up to a capacity of 20 acre-feet are exempted from provisions of the
Compact. The unappropriated or unused total divertible flow of each tributary, after needs for
supplemental supply for existing rights are met, is allocated to Wyoming and Montana as follows:
Clarks Fork of the Yellowstone River:
Wyoming . . . . . . . . . . . . . . 60%
Montana . . . . . . . . . . . . . . . 40%
Big Horn River (exclusive of Little Big Horn River):
Wyoming . . . . . . . . . . . . . . 80%
3-16