Dry spring lowers Idaho Power hydroelectric forecast

May 16, 2013

BOISE, Idaho — Streamflow forecasts for the Snake River continue to decline as the window of opportunity for much-needed spring rainfall narrows, and that lack of water will have an impact on power production.

Addressing a recent meeting regarding the company’s long range Integrated Resource Plan, Idaho Power Operations Hydrology Leader Kresta Davis-Butts said the flows into Brownlee Reservoir this year will be among the lowest since Brownlee Dam was completed in 1959.

Brownlee is the largest of Idaho Power’s 17 hydroelectric facilities, which typically generate over half of the electricity the company produces for more than 500,000 customers in southern Idaho and eastern Oregon. Mediocre winter snowpack, combined with an extremely dry late winter and spring in the Snake River Basin and low carryover in the Upper Snake reservoir system, will sharply reduce the amount of water available for hydroelectric generation. The lack of water may also impact irrigators, anglers and other recreationists as flows dwindle.

How dry is it? Current projections estimate 2.7 million acre-feet of water will flow into Brownlee Reservoir in Hells Canyon during the run-off season (April- July) this year – ranking in the bottom 10 percent of April through July volumes since 1960. An acre-foot is the amount of water it would take to cover an acre of land to a depth of one foot, or about 326,000 gallons.

Idaho saw the fifth-lowest precipitation in 119 years during the key January-March period, according to the National Climate Data Center. Based on records from 1960-2012, the average flow into Brownlee Reservoir during the month of April is 28,457 cubic feet per second (cfs). During April of 2013, the average flow into Brownlee Reservoir was just 11,092 cfs, or 39 percent of average.

“Water in the Snake River fuels Idaho Power’s hydroelectric system,” said Phil DeVol, Resource Planning Leader for Idaho Power. “This situation underscores the importance of having a diverse resource portfolio. Our gas- and coal-fired generating resources are critical to our system, particularly during low water conditions such as those being experienced. With the reduced water, we’ll also have to rely more on power purchased on the market in order to provide the electricity our customers need and want.”

Those higher-cost options are reflected in the annual Power Cost Adjustment (PCA) recently filed with the Idaho Public Utilities Commission (IPUC). The PCA is a cost-recovery tool that passes on the majority of the benefits and costs of supplying energy to Idaho Power customers. The projected drop in hydroelectric generation is a significant factor in the 15.3 percent overall rate increase being sought in this year’s Idaho PCA filing. Given that amount, Idaho Power has proposed that the IPUC consider deferring part of the rate increase to the following PCA collection period in order to mitigate the impact on customer rates.

Protecting young salmon emerging from redds below Hells Canyon Dam is a primary concern for Idaho Power during the spring. Idaho Power maintains flows out of Hells Canyon Dam above 8,700 cfs through mid-May, when emergence is generally complete. The poor water outlook makes it imperative that Idaho Power manage the water carefully to ensure customer demand for electricity can be reliably met during the summer months. This may lead to flows dropping below 8,500 cfs after Memorial Day. Although Idaho Power does not currently anticipate flows dropping below 6,500 cfs, that is a possibility if Brownlee inflows continue to decline. Idaho Power will continue to provide updates on Snake River water conditions.

For the latest Brownlee water information, visit www.idahopower.com/ourenvironment.

About Idaho Power Company: Idaho Power employs approximately 2,000 people who serve more than 500,000 customers throughout a 24,000-square-mile area in southern Idaho and eastern Oregon. With 17 low-cost hydroelectric projects as the core of its generation portfolio, Idaho Power’s residential, business and agricultural customers pay among the nation’s lowest rates for electricity. IDACORP, Inc. (NYSE: IDA) is the investor-owned utility’s parent company based in Boise, Idaho.