Idaho Power FWP Free writing prospectus

Filed pursuant to Rule 433

Registration No. 333-166774

April 10, 2012

Final Term Sheet

4.30% First Mortgage Bonds due 2042

Secured Medium-Term Notes, Series I

IDAHO POWER COMPANY

Issuer: Idaho Power Company Trade Date: April 10, 2012 Original Issue Date/Settlement Date: April 13, 2012, which is the third business day following the Trade Date Principal Amount: $75,000,000 Price to Public: 99.934% of Principal Amount, plus accrued interest from the Original Issue Date Purchasers’ Discount: 0.75% Proceeds to the Company: 99.184% Interest Rate: 4.30% per annum Anticipated Ratings:*
Standard & Poor’s Ratings Services: “A-”
Moody’s Investors Service: “A2” Anticipated Use of Proceeds: Together with the net proceeds of First Mortgage Bonds due 2022 offered concurrently with the notes offered hereunder, to pay at or prior to maturity $100 million of Idaho Power Company’s 4.75% First Mortgage Bonds due 2012 and to fund a portion of Idaho Power Company’s capital requirements. If Idaho Power Company does not use the net proceeds immediately, it will temporarily invest them in short-term investments Interest Payment Dates: April 1 and October 1, commencing October 1, 2012 Redemption: As specified in Pricing Supplement No. 4 dated April 10, 2012
Make-whole Call: Prior to October 1, 2041, the greater of (i) 100% of the principal amount to be redeemed and (ii) an amount to be determined using a discount rate equal to the Treasury Rate plus 20 basis points
Par Call: On or after October 1, 2041, 100% of the principal amount to be redeemed Maturity Date: April 1, 2042 CUSIP: 45138LBA0 Purchasers:
J.P. Morgan Securities LLC ($20,625,000)
Merrill Lynch, Pierce, Fenner & Smith
                      Incorporated ($18,750,000)
Wells Fargo Securities, LLC ($18,750,000)
KeyBanc Capital Markets Inc. ($5,625,000)
Mitsubishi UFJ Securities (USA), Inc. ($3,750,000)
RBC Capital Markets, LLC ($3,750,000)
U.S. Bancorp Investments, Inc. ($3,750,000)

* A securities rating is not a recommendation to buy, sell or hold securities and may be subject to review, revision, suspension or withdrawal at any time.

The issuer has filed a registration statement (including a prospectus) with the SEC for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering. You may get these documents for free by visiting EDGAR on the SEC Web site atwww.sec.gov. Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling J.P. Morgan Securities LLC, collect at 1-212-834-4533, Merrill Lynch, Pierce, Fenner & Smith Incorporated, toll free at 1-800-294-1322, or Wells Fargo Securities, LLC, toll free at 1-800-326-5897.