Looking at '09 Irrigation

Questions to be answered on irrigation supplies

Published in the February 2009 Issue Published online: Feb 28, 2009 Irrigation
Viewed 973 time(s)

Questions about Eastern Idaho's Snake River Plain aquifer are piling up and the demand for answers to satisfy Idaho's irrigators and water users is intensifying as the 2009 irrigation season comes into view.

Idaho's Department of Water Resources (IDWR) has been struggling for answers to the pressure building each year to meet historic downstream water rights. From Twin Falls to the Upper Snake River Valley the matter is of extreme concern to growers.

In fact, the eyes of the users from trout farmers to potato growers are lit up as the IDWR sorts through a draft Comprehensive Aquifer Management Plan (CAMP) in an attempt to come up with answers.

Each year the search seems to deepen as water shortages are becoming the norm for not only use of the Snake River stream flow but now the aquifer below it. Last September the IDWA issued 1,700 letters to groundwater users explaining they could face curtailment this spring.

The letters are a continuation of water delivery calls made three years ago by senior water rights holders. These include seven water-delivery groups known as the Surface Water Coalition and spring-water users, Blue Lakes Trout Company and Clear Springs Foods' Snake River Farm facility. This water call could affect pumping rights after Jan. 4, 1973.


While snowfall was within averages into early December, and questions about stream flow appeared answered for another irrigation season, based on snowfall totals of last year, carryover reservoir supplies and weather forecasts, it is aquifer recharges that now draw the attention.

The IDWR authorized $150,000 for recharge projects to benefit the Eastern Snake Plain Aquifer last fall. The Board approved the cost of lease and conveyance up to $3 an acre foot offered by the Eastern Idaho Water Right coalition for recharge.

This coalition is composed of Upper Snake River storage contract holders who leased their carryover storage water. The fall recharge pilot project was for several sites above the American Falls Reservoir.

Holding off the quest for Snake River water appears to be a never-ending battle. Idaho Senators Mike Crapo and Larry Craig fought off efforts to designate a 42-mile river segment below Jackson Lake Dam as Wild and Scenic in the Snake Headwaters bill, part of a larger Senate legislative package.

The Idaho Water Users Association Inc. was opposed to the designation because it feared the designation would eventually put at risk Idaho Snake River irrigation water rights and storage supplies in Jackson Lake Reservoir above Jackson, Wyo.


Many water users thought the loss of the Teton Dam at Newdale, Idaho, in 1976 would mark the end of dam-building by the Bureau of Reclamation (BOR). However, with completion of Ridges Basin Dam in southwestern Colorado this year, there is hope for Idaho water users.

No one knows how political water projects will become under new Pres. Barrack Obama's administration but it was doubtful Secretary of Interior and former Idaho Governor Dirk Kempthorne-who favors western state water projects-would be kept by a new administration.

Kempthorne applauded the southwestern Colorado project along with Colorado Senator Ken Salazar, a southern Colorado seed potato grower. The project will supply much needed water to the Ute and Southern Ute tribes and the Navajo Nation.

The Ridges Basin Dam and Lake Nighthorse Reservoir will begin filling this spring and will hold about 120,000 acre feet.

Completion of the Animas-La Plata Project of a pipeline to transport culinary water to the Navajo Nation should be finished in 2012.

The Idaho Water Resources Board toured the Minidoka Dam near Rupert, Idaho, in September and discussed the engineering needed to raise the height of the dam up to 5 feet. This would increase the storage capacity of Lake Walcott by 55,000 acre feet-much needed additional storage space that would help bolster storage water for downstream stream flow rights holders.

The Board signed an agreement with the BOR to perform a feasibility study of the project. The dam, located near Rupert, Idaho, is situated on the Snake River below the American Falls Reservoir. Lake Walcott holds 95,180 acre feet in comparison to American Falls' 1.7 million acre feet.

In comparison, Palisades Reservoir holds 1.2 million acre feet and Jackson Lake Reservoir 847,000. It is this pair of storages at the highest point in the Snake River System that keep southern Idaho irrigators turned to weather reports and snowfall totals throughout the winter.

In early December, the entire Snake River storage system of 4.2 million acre feet was at 52 percent of capacity.

The Board is also asking the BOR for matching 50-50 funds for a study on the possibility of rebuilding the Teton Dam near Newdale, Idaho.


A weather modification program was planned in the Upper Snake River Basin again this year to increase snowpack. Called an experimental project, silver iodine crystals are put into cloud cover to "milk" moisture from passing storm fronts. Several entities are involved in sharing costs of the project.

Another effort to increase irrigation water amounts is to take land out of production. The state and federal governments each offer minimum amounts per acre for land put into the Conservation Reserve Environmental Protection (CREP) program.

The water board hoped more financial incentives could be found to bolster the program in 2009. The Board will approach the state legislature to ask for increased funding from $7 to $10 million over the first five years of the program.


Snake River Watermaster Lyle Swank was asked about the recharge situation. Swank, who oversees diversions for the largest irrigation district in the country, says each irrigation district or canal company has to provide its own answers for loss of discharge-an annual event-and which is not considered "additional" recharge to the Snake River Plain Aquifer.

He said water is more commonly moved within the canal system, than transferred. If land did have canal shares and was irrigated the shares may have been moved to other ground within the canal system. He said there is no reporting requirement to the IDWR for that situation.

"If water is transferred, it goes through a legal notice advertisement process which allows any protestant to file objections, and it is well documented when and where the water right is moved to a different legal description location," Swank said.

As for natural recharge from the canal and irrigation districts, he says all canals in Idaho have been leaking water into the aquifer to some degree since they were established.

"For most of the past century, the leakage was considered more of a problem. . For some of the canals, they may have been a big enough problem that they took measures to reduce the leakage."

Mentioning the Aberdeen-Springfield Canal at Aberdeen, Idaho, Swank said the company was allowed to drill wells to recover the water lost due to leakage.

"It has been only recently, when the surface water/ground water conflicts started, that this leakage has been considered to have a `recharge value.' The recharge location, hydrology and geology are all variables which make recharge at one location different than others.

"When water returns and whether it returns more quickly or is longer lasting may be better or worse depending on whether we have a short- or long-term outlook. But canals do have the option to reduce their leakage by lining canals," he continued.

However, Swank says what would normally be recharged during the irrigation season is considered normal operation that occurred for decades, and would not be considered an amount that could be a recharge credit.

"If the aquifer has been declining at some locations, it may not have been enough or at the best location to stabilize the Eastern Snake Plain Aquifer (ESPA). What we are looking at for recharge would be in addition to what normally would be recharged during the irrigation season."

IDWR director David Tutill explained to his board that a recharge at the end of the irrigation season last year could not be noticed in trend lines of increased spring flow.

He explained that since the 1950s the spring flow trend line has been down. Map data from the USGS show that flow declines are seasonal, matching the irrigation seasons above the springs. He said this will probably mask groundwater diversions.


Jerry Rigby of Rexburg, Idaho, and attorney and chairman of the IDWR, said the move from flood to sprinkler irrigation in the decades of the 1950s-1960s was one of the largest factors in decreasing the Snake River Plain Aquifer.

He said no one can force surface irrigators to continue to flood irrigate. "Therefore," Rigby said, "there are many who want to have incentives developed which would encourage surface users to continue to floor irrigate or at least continue the incidental recharge.

"However, until the laws are changed, the current law won't allow one to receive recharge credit for true `incidental' recharge and therefore one cannot demand credit or other benefits.

"We are presently working on a methodology which would determine a reasonable amount of `incidental' recharge. However, in order to get any real benefit, one's system would need to recharge a substantial amount of water beyond that amount determined to be incidental.

"Some systems easily meet this higher test and would be given mitigation credit for wells within their systems with the `excess over incidental' recharge. These wells would be considered `call proof' from calls made by surface users from down stream."

Rigby continued, "If we don't do something, then those who are having a substantial amount of loss from their systems will begin to develop a sealing mechanism to avoid their system losses, which will only aggravate the lowering aquifer levels and cause more water calls to be made by downstream surface users.

"However, to date, surface water users have not been willing to provide any incentive, claiming that if any group provides these incentives, it should be the ground water users."

Rigby indicated it may be a matter of "who blinks first." Or, in the minds of all water users, how much naturally seeps back into the aquifer based on dry or wet years.

Swank adds that the scientific community has a basic understanding of the ESPA. "We know that the historical canal diversions `recharged' the ESPA over time and contributed to the rising spring flows at Thousand Springs and elsewhere. We are looking at ways and places to recharge while also gathering information to determine if those efforts are having the desired impact. CAMP is an effort to stabilize the ESPA by a combination of both increasing supply and reducing demand."