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Aquifer sets Stage for Rest of State

by Cindy Snyder
Farm & Ranch Guide, January 14, 2008

BURLEY, Idaho - If you want to know what the future of water looks like in Idaho, the Eastern Snake Plain Aquifer is a good place to start.

And despite the frustration felt by water users across that aquifer, Idaho is actually further ahead than many other western states in trying to come to grips with the intricacies of managing ground water conjunctively with surface water.

"Other states are looking to Idaho," said Dave Tuthill.

The director of the Idaho Department of Water Resources was in Burley on Jan. 10 to speak during the Idaho Irrigation Association Equipment Show.

"In Arizona the state Supreme Court is still wrangling with the definition of what ground water is," he added.

That may not be much comfort to surface and spring water users who believe ground-water pumpers are lowering the aquifer and overall water supply.

Colorado is the only state with more experience managing surface and ground water conjunctively, Tuthill said. The state was forced by the court system to deliver ground and surface water together in two basins.

Those basins are relatively small and contained, compared to the Eastern Snake Plain Aquifer, he said.

Still the state of Idaho is moving forward. Tuthill issued an order in late December calling on ground-water pumpers to supply Twin Falls Canal Company with replacement water by Jan. 21. According to IDWR calculations, the only canal company or irrigation district injured in 2007 was the Twin Falls Canal Company.

Letters warning irrigators of possible curtailment in 2008 were sent to ground-water pumpers last October. Pumpers can avoid curtailment by providing adequate mitigation water.

"We prefer not to curtail, but ground-water users must compensate surface water users," Tuthill said.

If 2008 turns out to be similar to 1977, Tuthill estimates the need for mitigation water could be as much as 850,000 acre-feet of water. If 2008 turns out to be more like last year, the need could be closer to 500,000 acre-feet.

Where the ESPA is serving as a harbinger of things to come is in illustrating the mismatch between a system that was developed to deliver water in the 20th century and 21st century needs.

In the 20th century, dams, reservoirs and canals were built to provide irrigation water, hydro power and flood control. But four new concerns are emerging to drive 21st century needs, Tuthill said.

The first of those new concerns comes in the form of Endangered Species Act requirements. Even with below-normal runoff in 2007, nearly 500,000 acre-feet of water was sent downstream for fish flow augmentation. A federal judge in Oregon is expected to rule later this winter on the adequacy of a draft plan to manage the Upper Snake reservoir system, and he has indicated he doesn't think that's enough water.

"That need was not thought of when they built the reservoir system," Tuthill said.

Increasing urbanization is another new driver. Agriculture was the impetus for building the water infrastructure in Idaho, but agriculture will come in last place for the ability to pay for water.

"It is incumbent for those in this room to come up with additional water," Tuthill said, adding that he thinks it's the perfect time to explore options for additional storage in the state.

He is sometimes criticized for not stressing water conservation enough but said conservation alone won't meet the need.

"There's not an irrigator or an irrigation company here that's not thinking about conservation, but when you look at ET (evapotranspiration), conservation can't get there."

Ground-water mitigation is another new use that must be factored into the 21st century water needs. About 1 million acres of land is irrigated by ground-water sources in eastern Idaho which draws about 2 million acre-feet of water from the aquifer. The total inflow of water to the aquifer is projected to be about 8 million acre-feet.

"The infrastructure was not built with that two million acre-feet draw on the system in mind," he said.

Finally, there's climate change. Whether that change means hotter temperatures or just extreme variation - higher highs and lower lows - is unknown, but Tuthill said he thinks it could be the biggest driver of water use in coming years.

He said municipal water needs will be met in the future but providing water for agriculture and other economies can only come from new sources of water.

"It's time to look at some new surface-water storage. It's not a panacea, but it is important," Tuthill said.

Cindy Snyder, Ag Weekly correspondent
Aquifer sets Stage for Rest of State
Farm & Ranch Guide, January 14, 2008

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