Water law in Idaho and all of the arid West is based on a simple idea known as the prior appropriation doctrine. This principle of "first in time is first in right" means that the first farmers, canal companies and miners that diverted water for irrigation and industry owned the first rights to use the water.
When the system was tied solely to surface water, it was relatively easy to administer: As water flows dropped during the summer, the users with the newest rights were turned off first. There were exceptions, but even in droughts, the prior appropriation doctrine laid out a clear priority system.
In the 1940s, new pumping technology and low electrical rates made it economical to use groundwater for irrigation.
Groundwater appropriation rules were written in 1951. Yet groundwater was administered separately from surface water into the 1990s. Legally, the two were not connected. Spring water - water that seeped out of the Eastern Snake Plain Aquifer from American Falls Reservoir west to King Hill - was treated as surface water.
KNOWLEDGE OF AQUIFER, RIVER LINK BROUGHT CHANGES
Starting in the 1960s, engineers recognized there were clear connections among the aquifer, the springs and the river.
When spring flows began to drop, scientists realized groundwater pumping was reducing spring stream flows. But not until the 1990s did the state develop what is called "conjunctive management" of groundwater, spring and surface water use. Under the law, senior water right holders - those with the oldest rights - can make a "call" requiring the Idaho Department of Water Resources director to shut down groundwater pumping so the senior users can get water.
If the pumpers don't want to shut down their pumps, they can lease water from others for the senior users or pay them for the lost water. Elaborate mitigation settlements have evolved involving the purchase and transfer of fish farms by groundwater districts.
But senior users must be able to prove they are "injured" by the pumping. Determining injury means determining how much the lower flows are due to drought, pumping and other factors.
To administer these policies, groundwater pumpers have created groundwater districts that work together to manage aquifer resources.
When senior water rights holders call for water and prove injury, the districts meet their demands either by leasing water or paying the senior users.
These disputes can take years in court but usually are worked out through negotiation. If they get to court, the doctrine of "first in time is first in right" is balanced against another doctrine of water law: full economic development.
In one of the landmark decisions in Idaho expressing this balance, the Idaho Supreme Court ruled in 1907 that a farmer could not dam an entire stream simply to raise the level of water high enough to flood-irrigate.
In other words, a senior user cannot use unreasonable means to get water. What is unreasonable is a judgment call.
'USE IT OR LOSE IT' EVOLVES
Another basic concept of Idaho water law is that a water user forfeits a water right if he quits using water over a period of time, usually five years. This idea, "use it or lose it," is designed to prevent hoarding of water.
But in Idaho, "use it or lose it" has become complicated. Several changes in water law and court decisions over the past decade have weakened this doctrine.
The Idaho Supreme Court ruled in 1908 that a canal company or irrigation district could not divert water if it were not put to use. "If it should cease to have water users or consumers, and cease to apply the water to beneficial use, its right to divert the water would cease," the court wrote.
First, a user can place water stored in a reservoir in a water bank, making it available for leasing to other farmers or other uses such as increasing salmon flows. Placing water in the water bank is considered the same as putting it to beneficial use.
A law passed in 2003 exempted water conserved by users from forfeiture. That means if a farmer shifted from flood irrigation, which requires much more water, to sprinklers, the user retains the right to the larger water right.
Another change is the most complicated.
Legal title to water often is held by a canal company or an irrigation district even though the water is directly tied to land owned by farmers in the district or service area. The basic doctrine would seem to say if a farmer quit irrigating a field for five years under state law, the water right would be forfeited.
LAW LIMITS ABILITY TO SELL OR TRANSFER WATER RIGHTS
Historically, water has been tied to the land it irrigated. The water rights transfer when property is sold. Canal companies, irrigation districts and others who owned storage space in reservoirs could sell or lease their water.
Water rights are held in the form of shares in canal companies, and the shares can be sold. In an irrigation district, the water remains tied to the land.
Where an individual owns water rights he can transfer or sell the rights. But selling rights is limited to the amount of water actually consumed, such as the amount crops use.
Most water rights also include an amount of water necessary for delivering them that includes expected losses from seepage and evaporation, which cannot be sold.
Other water users can challenge transfers if they believe they will reduce or injure their own rights. For instance, if a farmer transferred a water right to another field, and less water would run in the ditch to the farmer down the line from the old field, that farmer could stop the transfer.
Idaho law also doesn't allow the transfer of water to boost stream flows. So a rancher who reduced water use couldn't sell part of the water right to a group that wanted more water in a stream for salmon.
However, Idaho law does allow ranchers to put part of their surface water rights in a water bank for lease to increase flows for salmon.
United Water Idaho, for example, bought water from a farmer whose land was turned into wildlife habitat. The water was exchanged for water in Lucky Peak Reservoir, where it is now used to serve United Water's customers.
Rocky Barker: 377-6484