Pumping ground water linked to declining spring flow

By DAVE WILKINS

Capital Press

Idaho water users can expect some pivotal court decisions this year.

The Idaho Supreme Court will wade into the long-running battle between fish farms that use natural springs and crop producers who rely on ground-water wells.

The court heard oral arguments Dec. 3. Both sides are eagerly awaiting a decision, which is expected to come before March 1.

Aquaculture companies involved in the case contend that ground-water pumpers who hold junior, or lower-ranked water rights, have depleted the natural springs they use to raise trout and other freshwater fish.

The ruling could affect how the Idaho Department of Water Resources manages the Eastern Snake River Aquifer and connected resources such as natural springs.

"It could be a foundational ruling for the future of conjunctive management," said Travis Thompson, an attorney representing Buhl, Idaho-based Clear Springs Foods Inc., one of the nation's largest trout producers. "It may set some foundational criteria for what is required all along the Snake River Plain."

State water officials have already determined that ground-water pumping has contributed to reduced spring flows in the region. The big question remaining is by how much.

The ruling is expected to influence what happens in two other important water cases that could come before the state Supreme Court later this year. One pits a surface water coalition comprised of canal companies and irrigation districts against junior ground-water pumpers. The other pits the A&B Irrigation District, which relies heavily on deep wells, against junior ground-water pumpers.

The case that will be decided this winter dates back to 2005, when spring users filed a "water call" against junior ground-water pumpers. At issue is the method used by the Idaho Department of Water Resources to calculate how many junior ground-water wells should be subject to curtailment.

Department officials believe a special computer model is the best available tool for measuring aquifer flows and their potential impact on natural springs and river flows, but have also recognized that it could be in error by as much as 10 percent.

That error factor, or so-called "trim line," is at the center of the case.

Spring users contend that use of the error factor has excluded too many junior ground-water pumpers from potential curtailment. Ground-water pumpers, on the other hand, argue that it's appropriate and that shutting down hundreds of wells would cripple Southern Idaho's economy.

Some of the spring water rights in the case were established as early as 1955. Curtailing all ground-water wells developed after that date would mean shutting off water to about 800,000 acres, said Lynn Tominaga, executive director of the Idaho Irrigation Pumpers Association.

"It would cause havoc," he said.

Ground-water pumpers acknowledge that their wells have had some impact on spring flows, but they argue that other factors have also played a big role. Since the 1950s, farmers have adopted more efficient irrigation practices, including a shift away from flood irrigation to sprinklers. The changes have resulted in a significant reduction in incidental recharge to the aquifer, ground-water users contend.

Spring water users "are never going to get back to the flows they got in the '50s," Tominaga said.

Idling thousands of acres of productive farmland in order to restore spring flows to fish farms isn't an equitable tradeoff, he said.

Annual crop and livestock production in south-central Idaho is valued at more than $2 billion a year, compared to commercial trout sales of about $50 million to $60 million.

Spring users, Tominaga said, "are trying to get the tail to wag the dog."