The Wyoming Constitution defines that all natural waters within the boundaries of the state are declared to be the property of the state. The Wyoming State Engineer's Office is charged with the regulation and administration of the water resources in Wyoming.

Wyoming water law operates under the prior appropriation doctrine, or "first in time-first in right". Those holding an earlier priority water right are allowed to receive their full portion of water before those with junior rights may receive water under their right.

Water rights can be issued to anyone who plans to make beneficial use of the water. Recognized beneficial uses include: irrigation, municipal, industrial, power generation, recreational, stock, domestic, pollution control, instream flows, and miscellaneous. Water rights holders are limited to withdrawals necessary for the purpose. For example, irrigators are allowed to divert up to 1 cfs (cubic foot per second) for each 70 acres under irrigation.

Surface Water:

The Surface Water and Engineering Division is responsible for reviewing permit applications for any request for putting surface waters of the state to a beneficial use. Permits are issued for, 1) transporting water through ditch or pipelines; 2) for storage in reservoirs; 3) storage in smaller (under 20 acre-feet of capacity and a dam height less than 20 feet) reservoir facilities for stockwater or wildlife purposes; 4) enlargements to existing ditch or storage facilities; and 5) for instream flow purposes.

This Division also carries out the Safety of Dams Program for Wyoming. The State Engineer is responsible for ensuring the safety and structural integrity of water storage facilities in the state. On-site inspections of facilities are made and any new or rehabilitation construction plans must be reviewed and approved by the State Engineer's Office.

The Instream Flow Law was passed by the 1986 Wyoming Legislature which allowed for the maintenance of stream flows to be considered a beneficial use. Unlike other water rights which may be applied for by the general public, only the Water Development Commission (WWDC) may apply for an instream flow water right.

The Wyoming Game and Fish Department completes biological studies of a stream reach to determine what flows are required from a fisheries habitat perspective. The WWDC then completes hydrologic analyses to determine the amount of water available in that particular stream segment. The State Engineer then holds a public hearing prior to making his decision regarding the amount for the instream flow.

Groundwater:

The Ground Water Division has been registering ground water rights for all uses except stock and domestic since 1947. In 1955, legislation was passed requiring that a permit be obtained from the State Engineer's Office prior to the drilling of all wells, except stock and domestic wells. Since May 24, 1969 a permit is required prior to the drilling of any water well. Ground water rights are issued for the same beneficial uses as for surface water rights.

Due to the large scale development of ground water for irrigation use in some areas of the state, three groundwater management districts called Control Areas have been established. An Advisory Group is elected in each of the Control Areas to review new permit applications, requests for water right changes, and advise the State Engineer's Office regarding such items.

The State Engineer is empowered to require driller's reports, water use reports, create well spacing requirements, well construction standards, and require wells to be sealed. The Ground Water Division maintains a statewide observation well network, conducts interference investigations and water right adjudication (finalization) inspections. Cooperative investigations of the occurrence and availability of the State's groundwater resources are conducted by the Ground Water Division and the United States Geological Survey.

Board of Control:

Wyoming is divided into four water Divisions for administration purposes. Each of these Divisions is headed by a Superintendent. These four Superintendents, located in Torrington, Sheridan, Riverton, and Cokeville, in addition to the State Engineer comprise the Wyoming Board of Control.

The Board of Control is responsible for the adjudication process for each permit. The Adjudication procedure involves a field inspection to assure that the water is being put to a beneficial use as specified under the permit.

The Board of Control is also responsible for any changes to adjudicated rights, such as changes in point of diversion, change in use, change in the area of use, or abandonment of a water right.

As a headwaters state, Wyoming is party to seven interstate compacts and 2 U.S. Supreme Court decrees. In addition to participating in the Commissions that have been established to administer these compacts, the State Engineer also participates in a number of basin- or region-wide water resource groups and associations.

Compacts:

Colorado River Compact, 1922--Divides the basin at Lee Ferry, AZ. Provides that the upper basin states may use 7.5 million acre feet annually.

Upper Colorado River, 1948--Apportions 14% of the water allocated in the Colorado River Compact to Wyoming.

Amended Bear River, 1978--Provides for administration of flows and storage between Utah, Idaho, and Wyoming.

Belle Fourche River, 1943--Allocates new uses after 1943, 10% to Wyoming and 90% to South Dakota.

Snake River, 1949--Wyoming may divert 4% of the ID-WY stateline flow for post-1949 uses.

Upper Niobrara River, 1962--Restrictions on storage in larger (over 500 acre feet) facilities.

Yellowstone River Compact, 1950--Allocates the flows of the Powder, Tongue, Bighorn and Clarks Fork Rivers between Montana and Wyoming.

Court Decrees:

North Platte River, 1945--The Supreme Court ruled that Wyoming could irrigate up to 168,000 acres. Natural flow split at the state line 25% to Wyoming and 75% to Nebraska.

Laramie River, 1911, 1922--Allows Colorado to divert up to 39,750 acre feet per year.

Teton Creek and South Leigh Creek ("Roxanna" Decree), 1941--When the flow naturally available at the state line in either stream declines below specified thresholds, it is split between Wyoming and Idaho apportionment diversions.