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Water Plan Comments Sought by Patricia R. McCoy, Idaho Staff writer Capital Press, October 31, 2003

A proposed mitigation plan to improve water delivery for both ground and spring water users is on file with the Idaho Department of Water Resources, and available for public review and comment until Nov. 24.

Threatened litigation over water rights filed in 2001 triggered discussions that led to the proposed plan, said Lynn Tominaga, executive director of the Idaho Groundwater Appropriators.

The plan, jointly filed by the North Snake and Magic Valley ground water districts, is a five-year program intended to address past conflicts between users of water from aquifer springs, and groundwater pumpers.

The groundwater rights are for irrigation water for some 220,000 acres of farmland in Gooding, Jerome, Minidoka, Blaine and Cassia counties. Most of the land is north of the Snake River. They also include water rights for domestic, municipal, commercial and industrial uses, according to a legal notice calling for public comment published by IDWR.

Drought

The plan was developed in response to several factors, including three successive years of severe drought, declines in the amount of water flowing from springs in the Thousand Springs reach of the mid-Snake River, and calls by some spring water users to shut off junior ground-water rights in the Snake Plain aquifer, Tominaga said.

"Neither spring users nor groundwater users want to see such a shut-off happen. It would cause massive disruption to the region's economy, and offer only uncertain benefits to spring water users," he said.

"While spring discharge levels will never again reach historic highs, there's enough water to go around, and our plan will begin a process whereby all users can enjoy a stable, secure water supply. This is a water management issue, not a water shortage issue," Tominaga said.

In the IDWR legal notice, a summary of the proposed plan states the North Snake and Magic Valley groundwater districts propose delivering an average 40,000 acre-feet of water per year to the Thousand Springs Reach of the Snake River annually for five years, beginning in 2004.

The replacement water would come from rental of storage water from the Water District 01 Rental Pool, management of operational spill or tailwater, conversion or idling of groundwater-irrigated acres, and recharge to the Eastern Snake River Plain Aquifer, the legal notice said.

Plan Goals

"The goals of our plan are to improve aquifer conditions above the springs, protect groundwater pumpers, improve distribution for all users, avoid litigation, and build trust among all water users," said Tominaga, whose organization represents farmers, ranchers, local governments and industries.

Human use of the aquifer for the past 100 years caused the current situation, Tominaga said. It won't be rectified overnight, or simply by denying others the opportunity to use groundwater.

The Snake River aquifer is a 15,600 square-mile underground system of lava, caves, gravel and water that contains between 500 million and 1 billion acre feet of water.

A century of human use changed the natural character of the aquifer, he said. Aquifer discharge measured 4,200 cubic feet per second in 1902 along the Snake River at springs between Milner and King Hill.

Over the next 50 years, people built hundreds of miles of canals and flood-irrigated the plain above. Massive amounts of water seeped into the aquifer. By 1953, spring flows were near their high of 6,800 cfs. Farms and fish producers sprang up to take advantage of the natural springs. In the meantime, farms and dairies on the plain above drilled more wells.

By the mid-1980s, spring flows began to taper off steeply, dropping in 1986 to their 1917 level, about 5,000 cfs. Drought, conversion to sprinkler systems from flood irrigation, and lining canals all contributed to the change. It conserved water, but meant much less surface water flowed into the aquifer, Tominaga said.