TWIN FALLS • All water in Idaho is owned by the public; holding a water right does not give the water user ownership of the water. A water right simply gives the user the right to divert water.
All water rights in Idaho exist for beneficial uses. Whether the water is diverted from a river or creek, or pumped from an aquifer, the user must declare a beneficial use for it.
Irrigation, commercial, municipal, industrial, livestock, hydropower, recreation, aquaculture, native fish and wildlife — and, of course, domestic use — are all considered beneficial uses.
Domestic water rights include water for personal household use, including drinking, bathing, laundry, sprinkling a lawn or garden (up to one-half acre), washing a car, and small-scale livestock. Domestic water rights include up to 13,000 gallons per day.
A water right might be lost if not used, thus the “use it or lose it” concept comes into play. There are, however, statutory conservation defenses against forfeiture, including making deposits — credits for unused water — in the state’s water bank.
Water uses are broken into two types: consumptive and non-consumptive.
Consumptive use is when water is consumed or lost during its use. The largest consumptive use of water is irrigation, through evapo-transpiration. Water is spread over the ground; some evaporates, and some transpires during plant growth. Other consumptive uses include dairies and manufacturing.
Non-consumptive use is when water is diverted but not consumed during its use; the Idaho Department of Water Resources classifies hydropower production as the only non-consumptive use.
Senior vs. Junior
Each water right is assigned a number and a priority date that determines who gets water during a shortage. This constitutes the “first in time, first in right” rule. Senior (oldest) water rights are fully satisfied before junior (newer) water rights, until there is no water left. When there is not enough water to satisfy all the water rights, junior water-rights holders get little or no water.
Enlarged Water Rights
Prior to 1963, diversions were allowed without filing for rights. After 1963, water rights became the law. During Idaho’s 1990s water adjudication, the state gave “enlarged” water rights to users who had not followed the 1963 rules, but gave them junior water rights with a 1994 priority date.
Can I Get a New Water Right?
Because of perennial water shortages, a moratorium in 1963 was placed on new consumptive-use water diversions on the Eastern Snake Plain Aquifer. If you want to farm land that has no water rights attached, or want to build a new dairy, you have to purchase an existing water right and transfer the rights to your property, unless you have a mitigation plan.