How water rights work in Idaho

Administered by Idaho Department of Water Resources (IDWR) · sources checked October 8, 2026

Doctrine
Prior appropriation (first in time is first in right)
Largest adjudication
Snake River Basin Adjudication, final decree August 25, 2014
Domestic use
Up to 13,000 gallons a day, including up to half an acre of irrigation
Forfeiture
Five continuous years of nonuse
Ownership change
Notify IDWR within 120 days
Right numbers
Basin-sequence-suffix, e.g. 95-1234A

Four kinds of record

Most rights in IDWR's files are one of four things. A permit is issued after an application is approved and sets a deadline to finish the project. A license follows once the owner proves beneficial use and IDWR completes a field examination.

A decree is a court's confirmation of a right, usually through an adjudication. A claim records an existing use, either as a statutory claim or as a filing in an adjudication.

Each right has a number made of the administrative basin, a sequence number and sometimes a suffix. In 95-1234A, for example, 95 is the basin.

The adjudications

The Snake River Basin Adjudication began in 1987 to determine every water right in the Snake River drainage. Its Final Unified Decree was signed on August 25, 2014, covering more than 158,000 rights. The decree can be viewed at srba.idaho.gov.

North Idaho has its own adjudications for the Coeur d'Alene-Spokane, Palouse, Clark Fork-Pend Oreille and Kootenai basins, and the Bear River basin is listed as well. If you deferred a small domestic or stockwater claim in the SRBA, you now file a Motion for Determination of Deferred De Minimis Domestic or Stock Water Use to get a decreed right.

Household water without a permit

Idaho Code 42-111 defines domestic use as water for homes, livestock and related purposes, including irrigation of up to half an acre, as long as total use stays under 13,000 gallons a day. Another route qualifies any use under 2.8 acre-feet a year.

The definition excludes mobile home and RV parks, apartments, most subdivisions of five or more lots, and mainly commercial uses unless they fit under the 2.8 acre-foot limit. Several domestic rights can't be stacked to serve a larger use that would otherwise need a permit.

Five years of nonuse

A right can be lost if it goes unused for five continuous years. When buying property, ask for evidence the water has been used, such as crop or meter records, rather than relying on the paper record alone.

Telling IDWR about a sale

Idaho Code 42-248 requires anyone who owns or claims a right to notify IDWR of any change in ownership, or in mailing address, within 120 days. The notice needs deeds or other evidence of the conveyance and, if the right is being split, how it is divided.

If the person filing doesn't own the land where the water is used, they must show they notified the landowner of record. IDWR sends official notices to whoever is in its records, so a stale address can mean missing an adjudication deadline. Updating the record does not confirm the right is valid.

Looking up a right

IDWR's Water Right & Adjudication Search shows the record and associated documents for any right or claim. The Map-Based Water Rights Search finds rights by location, and the Irrigation Water Rights Finder searches by address. A water-rights attorney can help when a purchase depends on an old or split right.

Sources

A plain-language summary, not legal advice. Rules change; the agency and a water-rights attorney are the people to ask about a specific right.