Two Magic Valley canal companies have appealed the terms of a water-right license for Milner Dam, arguing that it includes substantial changes from the permit the dam's power plant has operated under for about 15 years.

On Oct. 20, the Idaho Department of Water Resources approved a license for about 5,700 cubic feet per second of water for the North Side and Twin Falls canal companies to use at Milner.

IDWR hearing officer and former Idaho Chief Justice Gerald Schroeder will hear the companies' appeal, IDWR Director Dave Tuthill said Wednesday. Schroeder will set a hearing date at a future point.

Perhaps the biggest issue, and the one Tuthill spent the most time explaining in his order, is the removal of language that kept the state from taking some of the water for recharging the Eastern Snake Plain Aquifer. It's a complex argument, and rests on the fact that the Snake River is essentially treated as two rivers above and below Milner Dam.

The state allows for the river to be completely diverted at Milner, replenishing itself downstream through springs providing water from the aquifer. No water-right holders above Milner can affect rights below the dam.

That means downstream users rely on the aquifer and what water comes back from the canals. As the aquifer has shrunk over the years, the Legislature and state water officials have made putting water back into it a priority, Tuthill argued - one not just suggested, but legally required.

At the same time, he wrote, the exemption in the permit for recharge projects also allowed the canal companies to make demands they shouldn't be able to on upstream water. So, to satisfy the state's recent priorities and remove the problem, he removed the language.

Tuthill's decision, however, means that for the first time, the state can deduct some water from the Milner flows to use farther upriver. That could harm the hydropower plant, reducing the power it can generate.

According to the petition, the canal companies are also questioning language allowing IDWR to review the water license when the hydropower project's FERC license expires in 2038, as well as an "annual diversion volume" limitation they argue was never previously mentioned. An attempt to ask for more time to consult the water rights examiner and Idaho Power Co. on the matter was ignored, they argue.

Both the review language and the volume limitation are now standard in such water licenses, Tuthill said. He pointed to a court decision from earlier this year that upheld his ability to change the license language from that of the permit.

Travis Thompson, a Twin Falls attorney who is representing the canal companies, said he had little comment to add at the moment, as the appeal is in its early stages.

The license, Tuthill said, could have been issued since 1993 but hadn't been because of a backlog in licensing and the fact that the Milner license required extensive legal analysis. It also depended on a review of the Swan Falls Agreement, a 24-year-old deal between Idaho Power and the state in which Idaho Power surrendered water rights for guarantees it would receive average daily minimum flows at its power plant near the falls.