The US power company has applied to the state’s Public Utilities Commission (IPUC) for an average increase in rates of 14.5%, which equates to about US$77.5M.

Under the Power Cost Adjustment (PCA) system the company can file for a rate rise to help cover the extra cost of meeting electricity demand in the summer by having to use more expensive thermal capacity and purchasing wholesale energy. The company relies more on its lower cost hydro assets during the mid-year peak demand season.

Idaho Power said its flows from snowmelt over April-July are expected to be only 40% of the runoff in the same period in 2006. The forecast is almost half the 30-year average stream flow, according to the US Weather Service’s Northwest River Forecast Center

In a statement, the company said: ‘Our PCA filing this year reflects just how bad the winter snow pack was for Idaho Power and ultimately our customers.’

The company added: ‘The PCA addresses both the strengths and weaknesses of hydropower.’ In years when runoff is relatively high the rates are adjusted downward, it said.

IPUC recently approved the company’s 20-year growth plan which calls for 1.3GW of additional installed capacity – but not from hydro, to come instead from other renewables (wind and geothermal) as well as coal and nuclear. Through the efficiency measures of demand-side management initiatives, the company also aims to reduce the call for energy by 187MW from present levels. It also plans to upgrade transmission links to gain access to a further 285MW.

The company has a system of 17 dams in its hydro assets.