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Tucked in one corner of Shoshone Falls are two small turbines, installed a century ago when the Magic Valley was young.

Now the oldest turbines in Idaho Power’s hydropower network, the company plans to replace them with modern technology that would boost generating power while changing the falls themselves.

The utility company’s effort to upgrade its facility marks the latest chapter in how Magic Valley balances energy demands with its most famous landmark.

Since the region’s earliest days, visitors to Shoshone Falls have been stunned by the sight. In high water seasons, billions of gallons of Snake River water roar daily over the 212-feet rocky heights.

“There was a notion that it was a wondrous place, the canyon,” said College of Southern Idaho history professor Russ Tremayne.

But a number of other interests had their eyes on the river, Tremayne said, including those pursuing power. In 1907 and 1909, the Greater Shoshone and Twin Falls Water Power Company installed two car-sized turbines that together can produce 1 megawatt — the first in the Magic Valley, and still in operation today.

“These were plenty to power Twin Falls at that time,” said Dennis Bramon, the current plant operator for Idaho Power.

Now they’re antiques, along with the system controlling them. By 2015, a $100 million plan to replace the turbines with one large 64-megawatt unit would once again alter the face of the falls, ensuring a show in the spring but possibly draining them for much of the rest of the year.

The project is currently in the hands of the U.S. Federal Energy Regulatory Commission, which may grant a license for it sometime this year, said Jim Leonard, Idaho Power’s lead engineer. It would be the last new or expanded hydropower project in the foreseeable future for the company, which has traditionally relied on hydro as its primary source of generation.

The proposal, Leonard said, was put together about 20 years ago when Idaho Power upgraded its Milner and Twin Falls dam facilities. The plan took a back seat in the 1990s during the national push for deregulation, but resurfaced as Idaho Power sought ways to meet rising demands for energy.

After public meetings and other preparations, Idaho Power filed its final application to FERC for a license amendment in August 2006, just two years after the feds renewed Shoshone Falls’ existing 30-year license.

The plant would still be operated as run-of-the-river, meaning it wouldn’t use any water from the reservoir behind the falls. But the upgrade would leave the plant capable of diverting five times as much water as it can today, a new maximum of 4,800 cubic feet per second. (For comparison, 1 cfs equals about 7.5 gallons per second.)

Idaho Power’s current license requires it to spill at least 300 cfs over the falls during daylight hours from April 1 through Labor Day. The company’s initial project description in 2005 didn’t call for anything more than that. But over time, a new plan emerged from conversations with the city of Twin Falls and state and federal parks agencies.

A draft application released in February 2006 suggested keeping the minimum flows and shutting down the power plant on Memorial Day, Independence Day and Labor Day weekends. The final application later that year instead proposed extra releases every weekend from April 15 to June 16.

Under the final version, Idaho Power would release the larger weekend flows on Fridays from 4 to 8 p.m. and Saturdays, Sundays and Memorial Day from 9 a.m. to 8 p.m. The actual amount over the falls would vary depending on the river. The plant would be limited to 950 cfs until the falls reached 9,000 cfs, at which point the plant would gradually increase its diversions.

Leonard noted that under the proposed plan, more water would run over the falls in the spring and summer, peak visitor seasons, than the current license requires. But the larger flows will come with a cost — even during the peak season, when the number of days that the falls get more than 300 cfs would nearly be halved at best.

The effect would be even more pronounced during the rest of the year. During the remaining seven and a half months, the falls would be bone-dry:

* 208 days in a low water year, compared to 53 days under the current license.

* 208 days in a median water year, compared to 108 days now.

* 81 days in a high water year, compared to zero days now.

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Aesthetics are only one of many concerns when someone plans to divert a sizeable part of the Snake.

Since 2006, groups ranging from the U.S. Fish and Wildlife Service to Idaho Rivers United have outlined a range of issues to FERC, including the expansion’s effects on water quality, wildlife and historic sites.

The commission’s latest environmental review recommends adopting most of the monitoring and species-protection plans put forward by Fish and Wildlife, the Idaho Department of Fish and Game and the Idaho Department of Environmental Quality.

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So the main problem that remains for many is the view.

The city of Twin Falls’ concerns were resolved by the changes to the final application, City Manager Tom Courtney said. But two other public agencies — the Idaho Department of Parks and Recreation and the National Park Service — have told FERC in official filings that they’re still concerned about the falls’ future. Officials from agencies said they appreciate the changes Idaho Power has made, but want to make sure federal regulators know the arrangement may not go far enough.

“It’s a balance,” said Susan Rosebrough, the NPS northwest hydropower coordinator. “Just looking at the process — from no proposals to mitigation — and seeing what’s come up out of that, we’re really happy with that.”

In the federal agency’s most recent comments, submitted in January 2008, the agency noted that weekday visitors to the falls during the spring run-off season may still expect higher flows than they’ll actually see. The proposed weekend hours would also hamper photographers and other visitors who rely on the light available during the early mornings and late evenings.

NPS proposed in the letter that visitors should be surveyed and tallied to monitor the effects of the project. Its state counterpart also questioned that month whether the environmental review recommended enough measures to make up for the diverted river.

State officials are also OK with the compromise, but still wanted FERC to be aware of their concerns, said Mary Lucachick, IDPR’s water recreation analyst. It’s “just appropriate to let them know that this is a public resource, and allowing a private company to have even more control over shaping flows over it is a decision that the FERC needs to make,” she said.

Leonard dismissed most recent aesthetics criticisms as “a lot of posturing and really not a lot of substance.” He added that the utility will take other steps to improve the view, including cutting back the number of power lines strung across the canyon.

The lines were one of several concerns listed by the plant’s neighbors, homeowners in the Country Club Estates, who are also nervous that the narrow road leading down to their homes will be unsafe and clogged during construction.

Some of the residents’ concerns won’t be sorted out until the feds approve the project and engineering work begins, Leonard said. But he said Idaho Power has assured local highway officials that the road will be in equal or better condition after the project wraps up.

Country Club residents remain unconvinced. Keith Kulm, the current vice president of the homeowners’ board, said residents were told the project was delayed about three years back and haven’t heard an update since.

“I don’t know that any of those concerns have been addressed,” he said of the filings.

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One other issue may affect the project’s future more than the aesthetics concerns.

Just about everyone who commented criticized Idaho Power’s request for a 50-year plant license rather than the current 30 years. Shoshone Falls’ recent license renewal came at the same time as the rest of the hydro projects along the mid-Snake, coordinating how the whole stretch of river operates.

“It allows you to look at the cumulative effects,” Rosebrough said. “That is still important.”

Leonard defended the request for the longer license, arguing it assures Idaho Power that the plant will be in operation for the next half-century and will be worth the investment. If FERC doesn’t grant it, the company would have to decide if the expense still seemed worthwhile.

It’s not clear if the FERC process will actually wrap up this year. The timeline’s already been put back: Idaho Power had originally predicted that construction would wrap up this November, at a total cost of $75 million.

FERC spokeswoman Celeste Miller said last week that regulators have completed their environmental review and a decision is pending. But just last month, the commission granted a late motion for the Shoshone-Bannock tribes to intervene in the case.

“We hope to act as soon as possible,” Miller said.

While the company waits, it’s getting the rest of the project ready. That includes an application to the Idaho Department of Water Resources for a 3,580-cfs water right. IDWR is accepting protests to the application through March 22.

How much of that right the power plant can use is up for debate. Idaho Power’s hydropower network has dealt with dry conditions for 10 of the last 11 years, and Snake River stream flow projections for this spring don’t look promising. FERC’s review states Shoshone Falls’ electrical output would only triple.

The utility is part of a comprehensive effort to repair the Eastern Snake Plain Aquifer and stabilize water supplies across southern Idaho. But Leonard noted the water picture still has management “a little on edge.” And the company’s annual projections of what it’ll get out of the expansion are conservative — just 60 percent of what the new turbine could generate if it ran at full capacity for a year.

Officials aren’t deterred.

“We in the engineering and power-production side are 100 percent convinced this is a project that should be built,” Leonard said.

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