Filed Pursuant to Rule 424(b)(5)
	Registration No. 333-166774
PROSPECTUS SUPPLEMENT
To Prospectus dated May 25, 2010
$500,000,000
Idaho Power Company
First Mortgage Bonds,
Secured Medium-Term Notes, Series I

This prospectus supplement may be used to offer and sell the notes only if accompanied by the accompanying prospectus.

Idaho Power Company may use this prospectus supplement to offer from time to time its first mortgage bonds, secured medium-term notes, series I.

Terms of Sale

The following terms may apply to the notes which we may sell at one or more times. We will include final terms for each note you purchase in a pricing supplement.

§	Mature 9 months to 30 years from date of issue
§	Fixed interest rate
§	Interest payable on March 1 and September 1
§	Held in book-entry form by The Depository Trust Company
§	Settlement in immediately available funds
§	May be subject to mandatory redemption or redemption at our option
§	Minimum denominations of $1,000 increased in multiples of $1,000

You should carefully consider the risk factors that we have disclosed in our public filings under the Securities Exchange Act of 1934, as amended, before purchasing the notes.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these notes or determined that this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We may sell the notes directly or indirectly through one or more agents or dealers, including the agents listed below. The agents are not required to sell any specified number or amount of notes. The agents will use their reasonable best efforts to sell the notes offered.

If we sell the notes at 100% of their principal amount, we will receive between $496,250,000 and $499,375,000 of the proceeds from the sale of the notes, after paying the agents’ commissions of between $625,000 and $3,750,000.

BofA Merrill Lynch

BNY Mellon Capital Markets, LLC

J.P. Morgan

KeyBanc Capital Markets

Mitsubishi UFJ Securities

RBC Capital Markets

SunTrust Robinson Humphrey

US Bancorp

Wells Fargo Securities

Prospectus Supplement dated June 17, 2010

We take responsibility only for the information contained in this prospectus supplement and the accompanying prospectus and any pricing supplement, including the information that we incorporate by reference, and any free writing prospectus that we prepare and distribute. We have not, and the agents have not, authorized any other person to provide you with information that is different. If anyone provides you with different or inconsistent information, you should not rely on it. The information contained in or incorporated by reference in this prospectus supplement, the accompanying prospectus and any applicable pricing supplement is accurate only as of its respective date, regardless of the time of delivery of such document or any sale of the securities offered hereunder. We are not making an offer of these notes in any state where the offer is not permitted.

___________________

TABLE OF CONTENTS
	Page
Prospectus Supplement
Description of the Notes	S-3
Supplemental Plan of Distribution	S-4
Prospectus
Risk Factors	2
Forward-Looking Statements	2
About Idaho Power Company	4
Ratios of Earnings to Fixed Charges	4
Description of First Mortgage Bonds	5
Description of Debt Securities	11
Book-Entry System	18
Use of Proceeds	20
Plan of Distribution	20
Incorporation of Certain Information by Reference	22
Where You Can Find More Information	23
Legal Matters	23
Experts	24

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DESCRIPTION OF THE NOTES

General

          We are issuing these notes as part of a series of first mortgage bonds under our Indenture of Mortgage and Deed of Trust, dated as of October 1, 1937, as amended and supplemented. You should read the following information, which summarizes certain terms of the notes, in conjunction with the general terms and conditions of the notes and the indenture described under “Description of First Mortgage Bonds” in the accompanying prospectus.

          For each note we offer and sell, we will prepare a pricing supplement to this prospectus supplement and the accompanying prospectus. The pricing supplement will include the specific terms of the note to which it relates and may include modifications of or additions to the more general terms described in this prospectus supplement and the accompanying prospectus.

          The pricing supplement relating to a note will contain the following important information:

• purchase price of the notes, which may be a percentage of the aggregate principal amount

• issue date

• maturity date, which will be from nine months to 30 years from the date of issue

• interest rate

• interest accrual date

• redemption provisions, if any, and

• other material terms not inconsistent with the indenture.

          The following information applies to the notes that we are offering, unless we specify otherwise in the pricing supplement.

          Except as discussed under “Book-Entry System” in the accompanying prospectus, each note will be in book-entry form and not certificated form. The initial depositary for book-entry notes will be The Depository Trust Company.

          You may buy the notes in denominations of $1,000 or any larger amount equally divisible by $1,000.

          Unless we specify otherwise in a pricing supplement and make additional related disclosure, we will not offer the notes to non-United States holders. You are a non-United States holder if you are, for United States federal income tax purposes:

• a nonresident alien individual

• a foreign corporation

• a foreign partnership or

• an estate or trust that in either case is not subject to United States federal income tax on a net income basis on income or gain from a note.

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Interest and Payment on the Notes

          Each note will bear interest at a fixed rate stated on the face of the note. Interest will be computed on the basis of a 360-day year of twelve 30-day months. We will make interest payments to noteholders on March 1 and September 1 of each year or on the interest payment dates specified in the pricing supplement, and at maturity or upon earlier redemption.

          If any interest payment date, redemption date or maturity date does not fall upon a business day, we will make the payment on the next business day. A business day is any day, other than a Saturday or Sunday, on which banks in The City of New York are not required or authorized by law to close. If we pay or provide for payment on the next business day, no interest will accrue on those amounts for the period from and after the interest payment date, redemption date or maturity date, as the case may be, to the next business day.

          We will make payments of principal, premium, if any, and interest in respect of the notes in immediately available funds. We will make payments on book-entry notes to Cede & Co., the partnership nominee of The Depository Trust Company.

          The record date for the March 1 payment will be February 15, and the record date for the September 1 payment will be August 15. If we change the interest payment dates, we will indicate in the pricing supplement the new record dates. In order to receive interest payments on a note, you must hold the note on the applicable record date, whether or not the record date is a business day. We will begin paying interest on the first interest payment date after the notes have been issued, provided that the notes are issued before the applicable record date.

Redemption of the Notes

          The notes may be subject to redemption, either mandatory or at our option, before they mature. The pricing supplement will indicate whether or not a note is subject to redemption and the terms of redemption, if any. If we decide to redeem the notes, you will receive at least 30 days’ notice.

Tax Defeasance

          Under current United States federal income tax law, defeasance under the indenture should be treated as a taxable exchange of the notes to be defeased for an interest in the defeasance trust. Accordingly, you would recognize gain or loss equal to the difference between your cost or other tax basis of the notes and the fair market value of your interest in the defeasance trust. In addition, you might also thereafter be required to include in income your share of the income, gain or loss of the defeasance trust, which could be a different amount and includible in income at different times than would be the case in the absence of defeasance under the indenture. You should consult your own tax advisors as to the specific potential consequences to you of defeasance under the indenture.

SUPPLEMENTAL PLAN OF DISTRIBUTION

          We are offering the notes on a continuing basis through the agents listed on the cover, each of which has agreed to use to its reasonable best efforts to solicit purchases of the notes.

S-4

          We have the right to accept offers to purchase notes and may reject any offer to purchase notes. The agents may also reject any offer to purchase notes. We will pay the agents a commission on any notes sold through the agents. The commission will range from 0.125% to 0.750% of the principal amount of the notes depending on the maturity of the notes.

          We may also sell notes to the agents who will purchase the notes as principal for their own accounts. Any such sale will be made at a discount to be agreed upon at the time of sale. Any notes the agents purchase as principal may be resold at a fixed public offering price, the market price or other prices determined by the agents at the time of resale.

          The agents may resell any notes they purchase as principal to other brokers or dealers at a discount which may include all or part of the discount the agents received from us. Unless the applicable pricing supplement states otherwise, the agents will purchase the notes, as principal, at a price equal to 100% of the principal amount less a discount that equals the applicable commission on an agency sale of notes of the same maturity.

          We may also sell notes directly to investors on our own behalf in those jurisdictions where we are authorized to do so. We will not pay any commissions on sales made directly by us.

          We may sell notes through agents other than the agents listed on the cover, subject to conditions described in the selling agency agreement that we have entered into with the agents listed on the cover. The commission applicable to agency sales through any other agents will be the same as that applicable to agency sales through the agents listed on the cover.

          The agents, whether acting as agent or as principal, may be deemed to be “underwriters” within the meaning of the Securities Act of 1933, as amended. We have agreed to indemnify each agent against certain liabilities, including liabilities under the Securities Act of 1933, or to contribute to payments made in respect of such liabilities. We have also agreed to reimburse the agents for certain of their expenses, including the reasonable fees and expenses of their counsel.

          The agents may sell to dealers who may resell to investors and the agents may pay all or part of the discount or commission they receive from us to the dealers. Such dealers may be deemed to be “underwriters” within the meaning of the Securities Act of 1933. Any discounts or commissions that an agent receives in purchasing a note as principal and reselling such note, and any profit on the resale of such note by the agent, may be deemed to be underwriters’ discounts or commissions under the Securities Act of 1933.

          Payment of the purchase price of the notes must be made in immediately available funds.

          In addition to offering the notes through the agents described in this prospectus supplement, we may sell other debt securities. The sale of other debt securities will reduce the maximum aggregate amount of notes that we offer by this prospectus supplement.

          The notes are a new issue of securities with no established trading market and will not be listed on a securities exchange. The agents have advised us that they intend to establish a trading market for the notes. However, the agents are not obligated to do so and may discontinue any

S-5

market making at any time without notice. No assurance can be given as to the liquidity of the trading market for the notes.

          In connection with the offering, the agents may purchase and sell notes in the open market. These transactions may include short sales, stabilizing transactions and purchases to cover positions created by short sales. Short sales involve the sale by the agents of a greater number of notes than they are required to purchase in the offering. Stabilizing transactions consist of certain bids or purchases made for the purpose of preventing or retarding a decline in the market price of the notes while the offering is in progress.

          The agents also may impose a penalty bid. This occurs when a particular agent repays to agents a portion of the underwriting discount received by it because the agents have repurchased notes sold by or for the account of such agent in stabilizing or short covering transactions.

          These activities by the agents may stabilize, maintain or otherwise affect the market price of the notes. As a result, the price of the notes may be higher than the price that otherwise might exist in the open market. If these activities are commenced, they may be discontinued by the agents at any time.

          We estimate that our share of the total expenses of the offering, excluding underwriting discounts and commissions, will be approximately $2.45 million.

          Each agent and its affiliates may from time to time engage in transactions with, and perform investment banking, general banking and other financial services for, us and our affiliates in the ordinary course of business.

S-6

PROSPECTUS
$500,000,000
IDAHO POWER COMPANY
First Mortgage Bonds
Debt Securities
	We may offer from time to time, in one or more series:
	•	our first mortgage bonds and
	•	our unsecured debt securities.
We may offer these securities in any combination in one or more offerings up to a total amount of $500,000,000. This prospectus provides you with a general description of the securities we may offer. Each time we sell securities, we will provide a prospectus supplement that will contain specific information about the terms of that offering. The prospectus supplement may also add, update or change information contained in this prospectus. Before you invest, you should carefully read this prospectus and any supplements, as well as the information that we incorporate by reference in this prospectus.
We may offer these securities directly or through underwriters, agents or dealers, as described in the “Plan of Distribution.” The supplements to this prospectus will describe the terms of any particular plan of distribution, including any underwriting arrangements.
Our principal executive offices are located at 1221 West Idaho Street, Boise, Idaho 83702-5627, and our telephone number is (208) 388-2200.
Investing in our securities involves risks. Please see “Risk Factors” on page 2 of this prospectus as well as the risk factors in our most recent Annual Report on Form 10-K and in any other reports we file pursuant to the Securities Exchange Act of 1934 that we incorporate by reference in this prospectus.
Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.
May 25, 2010

TABLE OF CONTENTS

	Page
Risk Factors	2
Forward-Looking Statements	2
About Idaho Power Company	4
Ratios of Earnings to Fixed Charges	4
Description of First Mortgage Bonds	5
Description of Debt Securities	11
Book-Entry System	18
Use of Proceeds	20
Plan of Distribution	20
Incorporation of Certain Information by Reference	22
Where You Can Find More Information	23
Legal Matters	23
Experts	24

ABOUT THIS PROSPECTUS

          We take responsibility only for the information contained in this prospectus and any accompanying prospectus supplement, including the information that we incorporate by reference in this prospectus and any free writing prospectus that we prepare and distribute. We have not authorized any other person to provide you with information that is different. If anyone provides you with different or inconsistent information, you should not rely on it. We are offering to sell securities and seeking offers to buy securities only in states where offers and sales are permitted.

          The information contained in or incorporated by reference in this prospectus is accurate only as of the date of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered hereunder.

          Unless we indicate otherwise, or the context otherwise requires, references in this prospectus to the “Company,” “we,” “us” and “our” or similar terms are to Idaho Power Company.

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RISK FACTORS

          Investing in our securities involves risks. You should carefully consider the risk factors described in our most recent Annual Report on Form 10-K and in any other reports we file pursuant to the Securities Exchange Act of 1934 that we incorporate by reference in this prospectus as well as those included in any prospectus supplement hereto. Our subsequent filings with the Securities and Exchange Commission may contain amended and updated discussions of significant risks.

FORWARD-LOOKING STATEMENTS

          In addition to the historical information contained in this prospectus, this prospectus includes forward-looking statements. In connection with the safe harbor provisions of the Private Securities Litigation Reform Act of 1995, we are hereby filing cautionary statements. You should read these cautionary statements with the cautionary statements and risk factors under “Risk Factors” in this prospectus and in any prospectus supplement and with those included in our most recent Annual Report on Form 10-K and in any other reports that we file pursuant to the Securities Exchange Act of 1934 that we incorporate by reference in this prospectus.

          These cautionary statements identify important factors that could cause our actual results to differ materially from those projected in forward-looking statements made by us or incorporated by reference in this prospectus or any prospectus supplement. Any statements that express or involve discussions about expectations, beliefs, plans, objectives, assumptions or future events or performance are not statements of historical facts and may be forward-looking. These statements often, but not always, use words or phrases such as “anticipates,” “believes,” “estimates,” “expects,” “intends,” “plans,” “predicts,” “projects,” “may result,” “may continue” or similar expressions. Forward-looking statements involve estimates, assumptions and uncertainties and are qualified in their entirety by reference to, and are accompanied by, the following important factors. These factors are difficult to predict, contain uncertainties, are beyond our control and may cause actual results to differ materially from those contained in forward-looking statements:

• the effect of regulatory decisions by the Idaho Public Utilities Commission, the Oregon Public Utility Commission and the Federal Energy Regulatory Commission affecting our ability to recover costs and/or earn a reasonable rate of return including, but not limited to, the disallowance of costs that have been deferred;

• changes in and compliance with state and federal laws, policies and regulations, including new interpretations by oversight bodies, which include the Federal Energy Regulatory Commission, the North American Electric Reliability Corporation, the Western Electricity Coordinating Council, the Idaho Public Utilities Commission and the Oregon Public Utility Commission, of existing policies and regulations that affect the cost of compliance, investigations and audits, penalties and costs of remediation that may or may not be recoverable

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	through rates;
•	changes in tax laws or related regulations or new interpretations of applicable law by the Internal Revenue Service or other taxing jurisdictions;
•	litigation and regulatory proceedings, including those resulting from the energy situation in the western United States, and penalties and settlements that influence business and profitability;
•	changes in and compliance with laws, regulations and policies including changes in law and compliance with environmental, natural resources and endangered species laws, regulations and policies and the adoption of laws and regulations addressing greenhouse gas emissions, global climate change, and energy policies;
•	global climate change and regional weather variations affecting customer demand and hydroelectric generation;
•	over-appropriation of surface and groundwater in the Snake River Basin resulting in reduced generation at hydroelectric facilities;
•	construction of power generation, transmission and distribution facilities, including an inability to obtain required governmental permits and approvals, rights-of-way and siting, and risks related to contracting, construction and start-up;
•	operation of power generating facilities, including performance below expected levels, breakdown or failure of equipment, availability of electrical transmission capacity and the availability of water, natural gas, coal, diesel and their associated delivery infrastructures;
•	changes in operating expenses and capital expenditures, including costs and availability of materials, fuel and commodities;
•	blackouts or other disruptions of our transmission system or the western interconnected transmission system;
•	population growth rates and other demographic patterns;
•	market prices and demand for energy, including structural market changes;
•	increases in uncollectible customer receivables;
•	fluctuations in sources and uses of cash;
•	results of financing efforts, including the ability to obtain financing or refinance existing debt when necessary or on favorable terms, which can be affected by factors such as credit ratings, volatility in the financial markets and other economic conditions;
•	actions by credit rating agencies, including changes in rating criteria and new interpretations of existing criteria;
•	changes in interest rates or rates of inflation;
•	performance of the stock market, interest rates, credit spreads and other financial market conditions, as well as changes in government regulations, which affect the amount and timing of required contributions to pension plans and the reported costs of providing pension and other postretirement benefits;
•	increases in health care costs and the resulting effect on medical benefits paid for employees;
•	increasing costs of insurance, changes in coverage terms and the ability to obtain insurance;

3

• homeland security, acts of war or terrorism;

• natural disasters and other natural risks, such as earthquake, flood, drought, lightning, wind and fire;

• adoption of or changes in critical accounting policies or estimates; and

• new accounting or Securities and Exchange Commission requirements, or new interpretation or application of existing requirements.

          Any forward-looking statement speaks only as of the date on which we make the statement. New factors emerge from time to time; we cannot predict all factors or assess the impact of any emerging factors on our business, or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statement.

ABOUT IDAHO POWER COMPANY

          We are an electric utility incorporated under the laws of the State of Idaho in 1989 as successor to a Maine corporation organized in 1915. In 1998, we reorganized into a holding company structure and became the principal subsidiary of IDACORP, Inc. IDACORP, Inc. owns all of our outstanding common stock.

          We are engaged in the generation, transmission, distribution, sale and purchase of electric energy. Our service territory covers approximately 24,000 square miles in southern Idaho and eastern Oregon, with an estimated population of one million. We hold franchises in 71 cities in Idaho and nine cities in Oregon and hold certificates from the respective public utility regulatory authorities to serve all or a portion of 25 counties in Idaho and three counties in Oregon. We are the parent of Idaho Energy Resources Co., a joint venturer in Bridger Coal Company, which supplies coal to the Jim Bridger generating plant that we own in part. As of March 31, 2010, we supplied electric energy to approximately 490,000 general business customers. We own and operate 17 hydroelectric generation projects and two natural gas-fired plants and share ownership in three coal-fired generating plants. We rely heavily on hydroelectric power for our generating needs and are one of the nation’s few investor-owned utilities with a predominantly hydroelectric generating base.

RATIOS OF EARNINGS TO FIXED CHARGES

	Twelve Months Ended December 31,					Three Months Ended March 31, 2010
	2005	2006	2007	2008	2009
Ratio of Earnings to Fixed Charges	2.83x	3.12x	2.56x	2.61x	3.04x	1.98x
Supplemental Ratio of Earnings to Fixed Charges(1)	2.78x	3.06x	2.52x	2.57x	3.01x	1.97x

(1) Includes interest on the guaranty of the American Falls Reservoir District bonds and Milner Dam, Inc. notes.

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DESCRIPTION OF FIRST MORTGAGE BONDS

          We will issue the first mortgage bonds offered in this prospectus under our Indenture of Mortgage and Deed of Trust, dated as of October 1, 1937. Deutsche Bank Trust Company Americas, formerly known as Bankers Trust Company, is the corporate trustee, and Stanley Burg serves as individual trustee. We have amended and supplemented the indenture in the past and will supplement it again by one or more supplemental indentures relating to these first mortgage bonds.

          This section briefly summarizes the material provisions of the indenture and supplemental indentures, which we refer to collectively as the indenture in this section, and uses some terms that are not defined in this prospectus but are defined in the indenture. This summary is not complete and we qualify it by reference to the indenture. The indenture is on file with the Securities and Exchange Commission, and we incorporate it by reference in this prospectus. You should read the indenture for a complete understanding of its provisions and for the definitions of some terms used in this summary. In the summary below, we include references to section numbers of the indenture so that you can easily locate those provisions.

          Issuance in Series. We issue bonds in series. Each series of bonds may have different terms. We will include all of the following information about a specific series of bonds in the prospectus supplement relating to those bonds:

• the designation and series of the bonds

• the aggregate principal amount of the bonds

• the offering price of the bonds

• the date or dates on which the bonds will mature

• the interest rate or rates for the bonds, or how we will determine the interest rate or rates

• the dates on which we will pay the interest on the bonds

• the denominations in which we may issue the bonds

• the terms pursuant to which we may redeem the bonds, if any

• whether we will issue all or a portion of the bonds in global form and

• any other terms or provisions relating to the bonds that are not inconsistent with the provisions of the indenture.

          Form and Exchange. Unless we state otherwise in the prospectus supplement:

• we will issue the bonds in fully registered form without coupons

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• a holder of bonds may exchange bonds, without charge, for an equal aggregate principal amount of bonds of the same series, having the same issue date and with identical terms and provisions and

• a holder of bonds may transfer bonds, without charge, other than applicable stamp taxes or other governmental charges.

          See “Book-Entry System” for a description of additional requirements as to the form and method of exchange of bonds. We will describe any additional requirements as to the form and method of exchange of bonds in the prospectus supplement.

          Interest and Payment. We will pay principal, premium, if any, and interest in U.S. dollars at Deutsche Bank Trust Company Americas in New York City, and, at our option, at our office in Boise, Idaho. Indenture, Section 35

          Maintenance Requirements. We will file a certificate with the corporate trustee within 90 days after the close of each calendar year stating that:

• we have made the necessary expenditures to maintain our property in good condition as an operating system or

• we will designate an additional amount that should be spent for this purpose.

If we designate an additional amount, we must deliver to the corporate trustee, within 30 days, cash equal to that amount less the following deductions:

• expenditures made after the close of the year to maintain the property and

• any allowances for waiver of our right to issue additional bonds under the indenture.

Indenture, Section 38

We may withdraw this cash for reimbursement for later expenditures on:
•	property maintenance, repairs, renewals and replacements
•	waiver of our right to issue additional bonds under the indenture or
•	the purchase or redemption of bonds of any series, unless a supplemental indenture provides otherwise for a particular series of bonds.

We must spend or appropriate 15% of our annual gross operating revenues for maintenance, retirement or amortization of our properties. We may, however, anticipate or make up these expenditures or appropriations within the five years that immediately follow or precede a particular year. Indenture, Section 38; Second Supplemental, Section 15

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          Improvement or Sinking Fund. There is no sinking or improvement fund requirement. Twenty-seventh Supplemental, Section 14

          Security. The indenture secures all bonds issued under the indenture equally and ratably, without preference, priority or distinction. We may issue additional first mortgage bonds in the future, and those first mortgage bonds will also be secured by the indenture. In the opinion of our general counsel, the lien of the indenture constitutes a first mortgage on all the properties that we own, except as discussed below, subject only to liens for taxes and assessments that are not delinquent and minor excepted encumbrances. Certain of our properties are subject to easements, leases, contracts, covenants, workmen’s compensation awards and similar encumbrances and minor defects and clouds common to properties. In the opinion of our general counsel, none of these interferes with our operations.

          The indenture does not create a lien on the following excepted property:

• revenues or profits, or notes or accounts receivable, contracts or choses in action, except as permitted by law during a completed default

• securities or cash, except when pledged or

• merchandise or equipment manufactured or acquired for resale.

          The indenture creates a lien on our interest in property that we subsequently acquire other than excepted property, subject to limitations in the case of consolidation, merger or sale of substantially all our assets. Indenture, Section 87 We have covenanted to execute and deliver instruments that are necessary to carry out the purposes of the indenture and to create a lien on after-acquired property that the indenture covers. Granting Clauses

          The indenture does not contain any covenants or other provisions to provide holders of the first mortgage bonds special protection in the event of a highly leveraged transaction.

          Issuance of Additional Bonds. The indenture limits the aggregate principal amount of bonds at any one time outstanding to $2.0 billion. We may amend the indenture and increase this amount without consent of the holders of first mortgage bonds. Indenture, Sections 22 and 121; Forty-fifth Supplemental, Article I The indenture contains some restrictions on increasing the amount of prior lien bonds, which are bonds, obligations or principal indebtedness secured by any mortgage or other lien upon any property additions prior to the lien of the indenture. Indenture, Sections 6 and 46

          We may issue additional bonds that rank equally with the bonds in principal amount equal to:

• 60% of the cost or fair value, whichever is less, of property additions made after December 31, 1943, less the amount of prior lien bonds thereon Indenture, Article V, Second Supplemental, Sections 10 and 13

• the principal amount of first mortgage bonds or prior lien bonds referred to above, retired or then to be retired Indenture, Articles V and VI or

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• the amount of cash that we deposit with the corporate trustee for the purpose, which we may withdraw on the same basis as bonds may be issued. Indenture, Article VII

          We may not issue bonds as provided above, with certain exceptions, unless we meet a net earnings requirement. Generally, the indenture requires that our net earnings must be at least twice the annual interest requirements on all outstanding debt of equal or prior rank, including the bonds that we propose to issue. Under certain circumstances, the net earnings test does not apply, including the issuance of refunding bonds to retire outstanding bonds which mature in less than two years or which are of an equal or higher interest rate, or prior lien bonds.

We calculate net earnings before deduction of:
•	property retirement expenses, depreciation or depletion
•	interest expense on indebtedness
•	amortization of debt discount and expense and
•	any taxes measured by or dependent on net income.

We may include only a limited amount of revenue from property not subject to the lien of the indenture in net earnings. Indenture, Sections 7, 27 and Article VI

          Property additions consist of electric or gas property, or property used in connection therewith. Property additions exclude securities, contracts or choses in action, merchandise and equipment for consumption or resale, materials and supplies, property used principally for production or gathering of natural gas, or any power sites and uncompleted works under Idaho state permits. In determining net property additions, we deduct all retired funded property from gross property additions except to the extent of certain credits with respect to released funded property. Indenture, Section 4 The indenture restricts issuance of bonds and taking other credits under the indenture based on property additions subject to prior liens to no more than 15% of all bonds outstanding. However, the prior liens must not exceed 50% of the cost or fair value, whichever is less, of these property additions. Indenture, Section 26

          As of March 31, 2010, we could issue under the indenture approximately $462 million of additional first mortgage bonds based on unfunded property additions and $612 million of additional first mortgage bonds based on retired first mortgage bonds.

          We estimate that at March 31, 2010, unfunded property additions were approximately $770 million.

          Release of Properties. Generally, we may release property from the lien of the indenture by doing the following:

• depositing cash with the corporate trustee

• substituting property additions or

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• waiving our right to issue additional bonds on the basis of retired bond credits, without application of the net earnings test.

Indenture, Section 59

          Actions Without Trustees’ Release or Consent. Unless we are in default in the payment of interest on any outstanding bonds or one or more of the completed defaults described under the caption “Events of Default” below have occurred and are continuing, we may, without the trustees’ release or consent, and without providing a report to the trustees or depositing with them the consideration we receive:

• sell or otherwise dispose of any machinery, equipment, tools, implements or other property, which has become old, inadequate, obsolete, worn out, unfit or unadapted for use in our operations, after we replace that property with other property which has at least equal value and is subject to no additional liens

• cancel or make changes or alterations in or substitutions of any contracts, leases or rights of way grants or

• surrender or assent to the modification of any right, power, franchise, license, governmental consent or permit under which we may be operating, if, in the opinion of our board of directors, stated in a resolution filed with the corporate trustee, the surrender or modification is desirable in the conduct of our business and does not impair the security of outstanding bonds.

Indenture, Section 58

          Amendment of the Indenture. Generally we may modify or amend the indenture with the consent of the holders of 60% in principal amount of all outstanding first mortgage bonds. However, when an amendment does not affect all series of first mortgage bonds, holders of 60% of the principal amount of all outstanding first mortgage bonds of each series affected must also consent to the amendment.

          Unless each bondholder consents, we cannot make the following modifications:

• impair the right of any bondholder to receive payment on its bond when due or to sue for any overdue payment

• create any lien equal or prior to the lien of the indenture

• deprive any bondholder of a lien upon the mortgaged and pledged property or

• reduce the bondholder vote necessary to amend the indenture.

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Indenture, Sections 113, 121; Twenty-third Supplemental, Section 9; Thirty-sixth Supplemental, Section 9

          Events of Default. The following are defaults, sometimes called completed defaults, under the indenture:

• failure to pay the principal of any bond when due and payable whether at maturity or otherwise

• failure to pay interest on any bond for 60 days

• failure to pay principal of or interest on any outstanding prior lien bond beyond the grace period, if any, in the prior lien bond

• failure to observe a covenant not to, without the corporate trustee’s written approval,

• go into voluntary bankruptcy or insolvency, apply for or consent to the appointment of a receiver or trustee for us or our property in any judicial proceedings or make any general assignment for the benefit of creditors or

• suffer to be made and remain unvacated for a period of 90 days any order for the appointment of a receiver or trustee for us or our property in any proceeding instituted by a creditor, or any final order appointing such a receiver or trustee in any other proceeding or any order adjudicating us to be bankrupt or insolvent or

• failure to perform other covenants, agreements or conditions contained in the indenture for 90 days after the corporate trustee gives us notice.

Indenture, Section 65

          Discharge. The indenture will be cancelled and discharged when all indebtedness secured by the indenture is paid, including charges of the trustees.

          In addition, first mortgage bonds will be considered paid and not to be outstanding for any purpose under the indenture when we have irrevocably deposited with the trustee

• sufficient cash or

• an amount of direct obligations of, or obligations guaranteed by, the United States government or obligations which are collateralized by obligations of the United States government which, in the opinion of an independent accountant and the opinion of our officers, will provide sufficient funds, without regard to reinvestment thereof, together with any deposited cash

to pay when due the principal of, and premium, if any, and interest to the maturity date or redemption date of such first mortgage bonds, provided that in the case of redemption, proper

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notice shall have been given or appropriate arrangements have been made with the corporate trustee for the giving of notice.

Indenture, Section 106 and Twenty-seventh Supplemental, Section 10

          Miscellaneous. The indenture provides that the corporate trustee, upon request of the holders of a majority in interest of the outstanding first mortgage bonds, if properly indemnified to its satisfaction, must take action to enforce the lien of the indenture. Indenture, Section 92; Sixth Supplemental, Article XXIII

          We covenant in the indenture to deliver a certificate to the trustee annually, within 90 days after the close of the fiscal year, to show that we are in compliance with the terms of the indenture and that we have not defaulted under the indenture. Various supplemental indentures

          Concerning the Corporate Trustee. We and our affiliates may conduct banking transactions with the corporate trustee in the normal course of business.

DESCRIPTION OF DEBT SECURITIES

          We will issue the debt securities offered in this prospectus under our Debt Securities Indenture, dated as of August 1, 2001. Deutsche Bank Trust Company Americas is the trustee under the indenture. We may amend and supplement the indenture and will supplement it by one or more supplemental indentures relating to these debt securities.

          This section briefly summarizes the material provisions of the debt securities indenture and uses some terms that are not defined in this prospectus but are defined in the indenture. This summary is not complete and we qualify it by reference to the indenture. The indenture is on file with the Securities and Exchange Commission, and we incorporate it by reference in this prospectus. You should read the indenture for a complete understanding of its provisions and for the definition of some terms used in this summary. In the summary below, we include references to section numbers of the indenture so that you can easily locate these provisions.

          Other Indebtedness. The indenture does not limit the amount of debt securities that we may issue; it does not restrict the amount or type of other debt that we may issue or contain any other provisions that would afford holders of the debt securities protection in the event of a highly leveraged transaction. We may use other indentures or documentation containing provisions different from those included in the indenture under which we are offering these debt securities in connection with future issues of debt securities. We may also offer our first mortgage bonds, which are secured indebtedness and which are described above under the caption “Description of First Mortgage Bonds.” As of March 31, 2010, there were $1,381,100,000 in aggregate principal amount of our first mortgage bonds outstanding.

          Security, Ranking and Subordination. The debt securities that we may issue under this indenture will be unsecured. The debt securities that we are offering in this prospectus will rank equal in right of payment to our other unsecured indebtedness that is outstanding now or that we may issue in the future, except for any indebtedness that, by its terms, is subordinate to these debt securities.

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          Issuance in Series. We will issue debt securities in series. Each series of debt securities may have different terms and, in some cases, debt securities of the same series may have different terms. The prospectus supplement relating to a particular series of debt securities will contain the following information about those debt securities:

•	the title of the series
•	any limit on the aggregate principal amount of the series
•	the date or dates on which we will issue the debt securities of that series and on which we will pay the principal amount and any premium
•	the rate or rates at which the debt securities of that series will bear interest, or how we will determine the rate or rates
•	the date or dates from which interest will accrue
•	the dates on which we will pay interest on the debt securities of that series and the regular record dates for the interest payment dates
•	the place or places where we will pay the principal of, premium, if any, and interest, if different from those we describe in this prospectus
•	any redemption terms, including mandatory redemption through a sinking fund or otherwise, redemption at our option and redemption at the option of the holder
•	the denominations in which we will issue the debt securities of that series, if other than denominations of $1,000 and any integral multiple of $1,000
•	the provisions for the satisfaction and discharge of the indenture if different from those we describe in this prospectus and
•	any other terms of the debt securities of the series.
Form and Exchange. Unless we state otherwise in the prospectus supplement:
•	we will issue the debt securities in fully registered form without coupons
•	a holder of debt securities may exchange debt securities, without charge, for an equal aggregate principal amount of debt securities of the same series, having the same issue date and with identical terms and provisions and
•	a holder of debt securities may transfer debt securities, without charge, other than applicable stamp taxes or other governmental charges.

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Indenture, Sections 3.1, 3.2 and 3.6

          Unless we state otherwise in the prospectus supplement, the transfer of debt securities may be registered and exchanged at the corporate trust office of the trustee, in New York, New York, as security registrar. We may change the place for registration of transfer and exchange. We may designate one or more additional places for registration and exchange, all at our discretion.

          We are not required to execute or to provide for the registration of transfer or exchange of any debt security

• during a period of 15 days prior to giving any notice of redemption with respect to that debt security or

• that has been selected for redemption in whole or in part, except the unredeemed portion of any debt security being redeemed in part.

Indenture, Sections 3.6 and 4.2

          See “Book-Entry System” for a description of additional requirements as to the form and method of exchange of debt securities. We will describe any additional requirements as to the form and method of exchange of debt securities in the prospectus supplement. Indenture, Section 3.1

          Payment of Interest. Unless we state otherwise in the prospectus supplement, we will pay interest on each debt security to the person in whose name the debt security is registered as of the close of business on the regular record date for that interest payment date. If we have defaulted in the payment of interest on any debt security, we may pay the defaulted interest to the holder of the debt security as of the close of business on a special record date that is not less than 10 days prior to the date we propose to pay the defaulted interest. Notice of the special record date will be given by mail at least 15 days before the special record date. We may also pay defaulted interest in any other lawful manner permitted by requirements of any securities exchange on which the debt security may be listed, if the trustee deems that manner of payment practicable. Indenture, Section 3.8

          Unless we state otherwise in the prospectus supplement, we will pay the principal of and premium, if any, and interest at maturity at the corporate trust office of the trustee, in New York, New York, as our paying agent. We may change the place of payment. We may appoint one or more additional paying agents and may remove any paying agent, all at our discretion. Indenture, Section 4.2

          Redemption. We will describe any terms for the optional or mandatory redemption of a particular series of debt securities in the prospectus supplement. Unless we state in the prospectus supplement that the debt securities of that series are redeemable at the option of a holder, debt securities will be redeemable only at our option. In order to exercise our right to redeem any debt security, we must give the holder notice by mail at least 30 days prior to the date fixed for redemption. If we want to redeem fewer than all the debt securities of a series, the trustee will choose the particular debt securities to be redeemed by a method of random

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selection, substantially pro rata, that the trustee believes is fair and appropriate and which complies with the requirements of the principal national securities exchange, if any, on which the debt securities of that series are listed. If the debt securities to be redeemed have different terms and different maturities, we may select the particular debt securities to be redeemed.

          Unless we state otherwise in the prospectus supplement, if we are redeeming the debt securities at our option, the redemption will be conditional upon the paying agent or agents receiving from us, on or prior to the date fixed for redemption, enough money to redeem all of the debt securities called for redemption, including accrued interest, if any. If sufficient money has not been received, the notice will not be effective and we will not be required to redeem the debt securities. Indenture, Section 14.2

          Consolidation, Merger or Sale. The indenture provides that we will not consolidate with, merge with or into any other person, whether or not we are the survivor, or sell, assign, transfer or lease all or substantially all of our properties and assets as an entirety or substantially as an entirety to any person or group of affiliated persons, in one transaction or a series of related transactions, unless:

• the successor person, if we are not the survivor, is a person organized under the laws of the United States or any state thereof or the District of Columbia and expressly assumes in writing, by a supplemental indenture, all of our obligations under the outstanding debt securities and the indenture

• immediately before and after giving effect to the transaction or series of transactions, no event of default, and no default, shall have occurred and be continuing and

• we deliver to the trustee an officer’s certificate and an opinion of counsel stating that the transaction and the supplemental indenture comply with the indenture.

Indenture, Article Eleven

          Events of Default. The following are events of default with respect to any series of debt securities:

• failure to pay the principal of, or premium, if any, on, any debt security of that series when due and payable at maturity, and upon redemption, and the time for payment has not been extended or deferred, but excluding any failure by us to deposit money in connection with any redemption that is at our option

• failure to pay interest on any debt security of that series when due and our failure continues for 30 days, and the time for payment has not been extended or deferred

• failure to make a sinking fund payment when due with respect to debt securities of that series

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• failure to observe or perform any other covenant, warranty or agreement contained in the debt securities of that series or in the indenture, other than a covenant, agreement or warranty included in the indenture that is specifically dealt with in another event of default, and our failure continues for 60 days after the trustee or holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series have given us written notice

• a court enters a decree or order for relief that remains unstayed and in effect for 60 consecutive days in respect of us in an involuntary case under any applicable bankruptcy, insolvency or similar law

• appointing a receiver, liquidator, assignee, custodian, trustee, sequestrator or similar official for us or for any substantial part of our property or

• ordering the winding up or liquidation of our affairs

• we commence a voluntary case under any applicable bankruptcy, insolvency or similar law

• we consent to the entry of an order for relief in an involuntary case under any applicable bankruptcy, insolvency or similar law

• we consent to the appointment or taking possession by a receiver, liquidator, assignee, custodian, trustee, sequestrator or similar official for us or for any substantial part of our property

• we make any general assignment for the benefit of creditors and

• any other event of default with respect to debt securities of that series specified in the applicable prospectus supplement.

Indenture, Section 6.1

          An event of default with respect to the debt securities of any series does not necessarily constitute an event of default with respect to any other series of debt securities issued under the indenture. Unless we cure the default, the trustee is required to give notice of any default known to it within 90 days after the default has occurred; the term “default” includes any event which after notice or passage of time or both would be an event of default. Except in the case of a default in payment, the trustee is protected in withholding notice if and so long as the board of directors, the executive committee or a trust committee of directors or responsible officers of the trustee in good faith determine that the withholding of notice is in the interest of the holders. Indenture, Section 6.11

          If an event of default with respect to debt securities of any series, other than due to events of bankruptcy, insolvency or reorganization, occurs and is continuing, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice in writing to us, and to the trustee if given by the holders, may declare the unpaid principal of and accrued interest to the date of acceleration on all the outstanding debt securities of that

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series to be due and payable immediately. The holders of a majority of the principal amount of the outstanding debt securities of that series, upon the conditions provided in the indenture, may rescind an acceleration and its consequences with respect to that series.

          If an event of default occurs due to bankruptcy, insolvency or reorganization, all unpaid principal of and accrued interest on the outstanding debt securities of all series will become immediately due and payable without any declaration or other act on the part of the trustee or any holder. Indenture, Section 6.1

          The holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee, or exercising any trust or power conferred on the trustee, with respect to the debt securities of that series, subject to the right of the trustee to decline to follow instructions that would be unlawful, expose the trustee to personal liability or be unduly prejudicial to the interests of holders who do not join in the direction. Indenture, Section 6.9

          Subject to the provisions of the indenture relating to the duties of the trustee, if an event of default shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under the indenture at the request or direction of any of the holders, unless the holders have offered to the trustee reasonable indemnity. Indenture, Section 7.2

          The indenture provides that we must periodically file statements with the trustee regarding compliance by us with all conditions and covenants contained in the indenture. Indenture, Section 4.6

          Modification of Indenture. We may modify the indenture, without notice to or the consent of any holders of debt securities, with respect to certain matters, including:

• to add one or more covenants or other provisions for the benefit of holders of debt securities of one or more series or to surrender any of our rights or powers and

• to cure any ambiguity, defect or inconsistency or to correct or supplement any provision which may be inconsistent with any other provision of the indenture.

Indenture, Section 10.1

          In addition, we may modify certain of our rights and obligations and the rights of holders of the debt securities with the consent of the holders of at least a majority in aggregate principal amount of the outstanding debt securities affected by the modification. Indenture, Section 10.2

          No amendment or modification may, without the consent of each holder of any outstanding debt security affected:

• change the stated maturity of any debt security

• reduce the principal amount of, or the rate of interest on, or the amount of any premium on, or any amount payable on redemption of, or extend the time for payment or change the method of calculating interest on, any debt security, or

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	reduce the amount of principal of an original issue discount security that would be due and payable upon acceleration of maturity
•	impair the right to institute suit for the enforcement of any payment with respect to any debt security
•	reduce the percentage in principal amount of outstanding debt securities of any series necessary to modify or amend the indenture, or to waive compliance with certain provisions of the indenture or defaults or events of default and their consequences or
•	subordinate any debt securities to any other of our indebtedness.

Indenture, Section 10.2

          Waiver. The holders of not less than a majority in aggregate principal amount of the outstanding debt securities of any series may waive any default or event of default with respect to that series, except payment and bankruptcy defaults. Indenture, Section 6.10

          Defeasance. Unless we state otherwise in the prospectus supplement relating to the debt securities of a particular series, the indenture provides that we shall be discharged from our obligations under the indenture with respect to any series of debt securities at any time prior to the maturity date or redemption of that series when we meet certain requirements specified in the indenture, including

• when we have irrevocably deposited with the trustee, in trust,

• sufficient funds to pay the principal of and premium, if any, and interest to the maturity date or redemption on, the debt securities of that series or

• an amount of direct obligations of, or obligations guaranteed by, the United States government as will be sufficient, without consideration of any reinvestment of any accrued income on those obligations, to pay when due the principal of and premium, if any, and interest to the maturity date or redemption on, the debt securities of that series and

• when we have paid all other sums payable with respect to the debt securities of that series.

          Upon the discharge of the indenture with respect to a particular series, the holders of debt securities of that series shall no longer be entitled to the benefits of the indenture, except for purposes of registration of transfer, exchange and replacement of lost, stolen or mutilated debt securities. Indenture, Sections 12.1 and 12.2

          Concerning the Trustee. We and our affiliates may conduct banking transactions with the trustee in the normal course of business.

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BOOK-ENTRY SYSTEM

          We may issue all or some of the first mortgage bonds and debt securities in book-entry form, which means that global notes, not certificates, will represent the securities. If we issue global notes representing any securities, the following provisions will apply to all book-entry securities:

          The Depository Trust Company, New York, NY, which we refer to as “DTC”, will act as securities depository for the securities. We will issue the securities as fully-registered securities registered in the name of Cede & Co., DTC’s partnership nominee, or such other name as an authorized representative of DTC may request. We will issue one fully-registered security certificate for each issue of the securities, each in the aggregate principal amount of the issue, and we will deposit the certificate with the corporate trustee to hold as agent for DTC. We and the trustee will treat Cede & Co. as the holder of the securities for all purposes.

          DTC, the world’s largest securities depository, is a limited-purpose trust company organized under the New York Banking Law, a “banking organization” within the meaning of the New York Banking Law, a member of the Federal Reserve System, a “clearing corporation” within the meaning of the New York Uniform Commercial Code, and a “clearing agency” registered pursuant to the provisions of Section 17A of the Securities Exchange Act of 1934, as amended. DTC holds and provides asset servicing for over 3.5 million issues of U.S. and non-U.S. equity, corporate and municipal debt issues, and money market instruments from over 100 countries that DTC’s direct participants deposit with DTC. DTC also facilitates the post-trade settlement among direct participants of sales and other securities transactions in deposited securities through electronic computerized book-entry transfers and pledges between direct participants’ accounts. This eliminates the need for physical movement of securities certificates. Direct participants include both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, clearing corporations, and certain other organizations. DTC is a wholly-owned subsidiary of The Depository Trust & Clearing Corporation, or DTCC. DTCC is the holding company for DTC, National Securities Clearing Corporation and Fixed Income Clearing Corporation, all of which are registered clearing agencies. DTCC is owned by the users of its regulated subsidiaries. Access to the DTC system is also available to others such as both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, and clearing corporations that clear through or maintain a custodial relationship with a direct participant, either directly or indirectly. DTC has Standard & Poor’s highest rating: AAA. The DTC rules applicable to its participants are on file with the Securities and Exchange Commission. More information about DTC can be found at www.dtcc.com and www.dtc.org.

          Purchases of securities under the DTC system must be made by or through direct participants, which will receive a credit for the securities on DTC’s records. The ownership interest of each actual purchaser, the beneficial owner, is in turn to be recorded on the direct and indirect participants’ records. Beneficial owners will not receive written confirmation from DTC of their purchase. Beneficial owners are, however, expected to receive written confirmations providing details of the transaction, as well as periodic statements of their holdings, from the direct or indirect participant through which the beneficial owner entered into the transaction. Transfers of ownership interests in the securities are to be accomplished by entries made on the books of direct and indirect participants acting on behalf of beneficial owners. Beneficial

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owners will not receive certificates representing their ownership interests in the securities, except in the event that use of the book-entry system for the securities is discontinued.

          To facilitate subsequent transfers, all securities deposited with DTC are registered in the name of DTC’s partnership nominee, Cede & Co., or such other name as an authorized representative of DTC may request. The deposit of securities with DTC and their registration in the name of Cede & Co. or such other DTC nominee do not effect any change in beneficial ownership. DTC has no knowledge of the actual beneficial owners of the securities. DTC’s records reflect only the identity of the direct participants to whose accounts the securities are credited, which may or may not be the beneficial owners. The direct and indirect participants will remain responsible for keeping account of their holdings on behalf of their customers.

          Conveyance of notices and other communications by DTC to direct participants, by direct participants to indirect participants, and by direct participants and indirect participants to beneficial owners will be governed by arrangements among them, subject to any statutory or regulatory requirements that may be in effect from time to time.

          Redemption notices will be sent to DTC. If less than all of the securities within an issue are being redeemed, DTC’s practice is to determine by lot the amount of the interest of each direct participant in the issue to be redeemed.

          Neither DTC nor Cede & Co., nor any other DTC nominee, will consent or vote with respect to the securities unless authorized by a direct participant in accordance with DTC’s money market instrument procedures. Under its usual procedures, DTC mails an omnibus proxy to the issuer as soon as possible after the record date. The omnibus proxy assigns Cede & Co.’s consenting or voting rights to those direct participants to whose accounts the securities are credited on the record date, identified in a listing attached to the omnibus proxy.

          Redemption proceeds and distributions on the securities will be made to Cede & Co., or such other nominee as an authorized representative of DTC may request. DTC’s practice is to credit direct participants’ accounts upon DTC’s receipt of funds and corresponding detail information from us or the trustee on the payable date in accordance with their respective holdings shown on DTC’s records. Payments by participants to beneficial owners will be governed by standing instructions and customary practices, as is the case with securities held for the accounts of customers in bearer form or registered in street name. Payment by participants to beneficial owners will be the responsibility of the participants and not of DTC, the trustee or us, subject to any statutory or regulatory requirements as may be in effect from time to time. Payment of redemption proceeds and distributions to Cede & Co., or such other nominee as may be requested by an authorized representative of DTC, is our responsibility or the responsibility of the trustee. Disbursement of these payments to direct participants will be the responsibility of DTC, and disbursement of these payments to the beneficial owners will be the responsibility of direct and indirect participants.

          In case of any optional tender for or mandatory purchase of securities, pursuant to their terms, a beneficial owner shall give notice to elect to have its securities purchased or tendered through its participant to the tender/remarketing agent and shall effect delivery of the securities by causing the direct participant to transfer the participant’s interest in the securities, on DTC’s

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records, to the tender/remarketing agent. The requirement for physical delivery of securities in connection with an optional tender or a mandatory purchase will be deemed satisfied when the ownership rights in the securities are transferred by direct participants on DTC’s records and followed by a book-entry credit of tendered securities to the tender/remarketing agent’s DTC account.

          DTC may discontinue providing its services as depository with respect to the securities at any time by giving reasonable notice to us. Under such circumstances, in the event that a successor depository is not obtained, security certificates are required to be printed and delivered.

          We may decide to discontinue use of the system of book-entry-only transfers through DTC, or a successor securities depository. In that event, security certificates will be printed and delivered to DTC.

          Neither we, the trustee, any paying agent, nor the registrar for the securities will have any responsibility or liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in a global security or for maintaining, supervising or reviewing any records relating to these beneficial ownership interests.

          The information in this section concerning DTC and DTC’s book-entry system has been obtained from sources that we believe to be reliable, but we take no responsibility for the accuracy thereof.

USE OF PROCEEDS

          Unless we state otherwise in the prospectus supplement, we will add the net proceeds from the sale of the securities to our general funds. We may use our general funds for any of the following purposes:

• to acquire property

• to construct, complete, extend or improve our electric facilities

• to improve or maintain our service

• to redeem, pay at maturity or purchase outstanding first mortgage bonds and debt securities and

• to repay short-term borrowings.

If we do not use the proceeds immediately, we may temporarily invest them in short-term instruments.

PLAN OF DISTRIBUTION

          We may sell the securities offered by this prospectus:

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• through underwriters or dealers

• through agents

• directly to a limited number of purchasers or to a single purchaser or

• through a combination of any of those methods of sale.

          Through Underwriters or Dealers. If we use underwriters in the sale, the underwriters will buy the securities for their own account. The underwriters may resell the securities in one or more transactions, including negotiated transactions, at a fixed public offering price or at varying prices determined at the time of the sale. The underwriters may sell the securities directly or through underwriting syndicates that managing underwriters represent. Unless we state otherwise in the prospectus supplement, the obligations of the underwriters to purchase the securities will be subject to certain conditions, and the underwriters will be obligated to purchase all of the securities if they purchase any of them.

          If we use a dealer in the sale, we will sell those securities to the dealer as principal. The dealer may then resell the securities to the public at varying prices determined at the time of resale.

          Any initial public offering price and any discounts or concessions allowed or reallowed or paid to dealers may be changed from time to time.

          Through Agents. We may from time to time designate one or more agents to sell the securities. Unless we state otherwise in the prospectus supplement, any agent will agree to use its best efforts to solicit purchases for the period of its appointment.

          Directly. We may sell the securities directly to one or more purchasers. In this case, there will be no underwriters or agents.

General Information.

          The prospectus supplement will state:

• the names of any underwriters, dealers or agents, and the amounts of securities underwritten, purchased or sold by each of them

• the terms of the securities offered

• the purchase price of the securities and the proceeds we will receive from the sale

• any initial public offering price

• any discounts or commissions and other items constituting underwriters’ or agents’ compensation and

• any discounts or concessions allowed or reallowed or paid to dealers.

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          We may authorize underwriters, dealers or agents to solicit offers from certain institutions. We may sell the securities to these institutions for delayed delivery at a specified date in the future. At that time, they will pay the public offering price on the terms we describe in the prospectus supplement.

          We may agree to indemnify underwriters, dealers and agents against certain civil liabilities, including liabilities under the Securities Act of 1933.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

          The Securities and Exchange Commission allows us to incorporate by reference information into this prospectus, which means that we can disclose important information to you by referring you to other documents filed separately with the Securities and Exchange Commission. The information incorporated by reference is considered to be part of this prospectus. We incorporate by reference the following documents that we filed with the Securities and Exchange Commission (SEC file number 1-3198):

• Annual Report on Form 10-K for the year ended December 31, 2009 filed on February 23, 2010

• Quarterly Report on Form 10-Q for the quarter ended March 31, 2010, filed on May 6, 2010 and

• Current Reports on Form 8-K filed on January 22, 2010, February 8, 2010, March 4, 2010, March 24, 2010, April 2, 2010, April 16, 2010, April 23, 2010, May 10, 2010 and May 21, 2010.

          We also incorporate by reference all documents we subsequently file pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934 (i) after the date of the initial registration statement and prior to the effectiveness of the registration statement and (ii) after the date of this prospectus and before we terminate the offering. We are not incorporating by reference any documents or portions of documents that are not deemed “filed” with the Securities and Exchange Commission, including any information furnished pursuant to Items 2.02 and 7.01 of Form 8-K.

          Any statement contained in a document incorporated or deemed to be incorporated by reference or deemed to be part of the prospectus shall be deemed to be modified or superseded for purposes of the prospectus to the extent that a statement contained in the prospectus or in any other subsequently filed document which also is or is deemed to be incorporated by reference or deemed to be part of the prospectus modifies or replaces such statement. Any statement contained in a document that is deemed to be incorporated by reference or deemed to be part of the prospectus after the most recent effective date may modify or replace existing statements contained in the prospectus. Any statement so modified shall not be deemed in its unmodified form to constitute part of the prospectus for purposes of the Securities Act of 1933. Any statement so superseded shall not be deemed to constitute part of the prospectus for purposes of the Securities Act of 1933.

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          We will provide to each person, including any beneficial owner, upon request, to whom this prospectus is delivered, a copy of any or all of the information that has been incorporated by reference in this prospectus but not delivered with this prospectus. You may obtain a copy of this information at no cost, by written or oral request to us at the following address:

Shareowner Services
Idaho Power Company
1221 W. Idaho Street
Boise, ID 83702
Telephone 208-388-2200

          You may also access these documents at http://www.idacorpinc.com.

WHERE YOU CAN FIND MORE INFORMATION

          We file annual, quarterly and current reports and other information with the Securities and Exchange Commission. The public may read and copy any materials we file with the Securities and Exchange Commission at the Securities and Exchange Commission’s public reference room located at 100 F Street, N.E., Washington, D.C. 20549. The public may obtain information on the operation of the public reference room by calling the Securities and Exchange Commission at 1-800-SEC-0330. The Securities and Exchange Commission maintains an internet site that contains reports, proxy and information statements, and other information regarding issuers that file electronically with the Securities and Exchange Commission. The address of that site is http://www.sec.gov. Information about us is also available at our website at http://www.idahopower.com and on IDACORP, Inc.’s website at http://www.idacorpinc.com. However, the information on our website and on IDACORP, Inc.’s website is not a part of this prospectus.

          This prospectus is part of a registration statement on Form S-3 that we filed with the Securities and Exchange Commission relating to the securities covered by this prospectus. This prospectus does not contain all the information included in the registration statement. You may review a copy of the registration statement at the Securities and Exchange Commission’s public reference room or on the Securities and Exchange Commission’s internet site referred to above.

LEGAL MATTERS

          Rex Blackburn, our Senior Vice President and General Counsel, and Dewey & LeBoeuf LLP, New York, New York, will pass upon the validity of the securities and other legal matters for us. Sullivan & Cromwell LLP, New York, New York, will pass upon the validity of the securities for any underwriter, dealer or agent. Dewey & LeBoeuf LLP and Sullivan & Cromwell LLP may, for matters governed by the laws of Idaho, rely upon the opinion of Mr. Blackburn. As of May 1, 2010, Mr. Blackburn owned 13,223 shares of IDACORP, Inc. common stock, including shares that may be acquired within 60 days pursuant to the exercise of stock options. Mr. Blackburn is acquiring additional shares of IDACORP, Inc. common stock at regular intervals through employee stock plans.

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EXPERTS

          The consolidated financial statements of Idaho Power Company and its subsidiary for the year ended December 31, 2009, and the related financial statement schedule, incorporated in this prospectus by reference from the Company’s Annual Report on Form 10-K for the year ended December 31, 2009, and the effectiveness of the Company’s internal control over financial reporting as of December 31, 2009, have been audited by Deloitte & Touche LLP, an independent registered public accounting firm, as stated in their reports (which reports (1) express an unqualified opinion on the financial statements and financial statement schedule and include an explanatory paragraph relating to the adoption of guidance for accounting for uncertainty in income taxes and (2) express an unqualified opinion on the effectiveness of internal control over financial reporting), which are incorporated herein by reference. Such financial statements and financial statement schedule have been so incorporated in reliance upon the reports of such firm given upon their authority as experts in accounting and auditing.

          With respect to the unaudited interim financial information for the periods ended March 31, 2010 and 2009, which is incorporated herein by reference, Deloitte & Touche LLP, an independent registered public accounting firm, have applied limited procedures in accordance with the standards of the Public Company Accounting Oversight Board (United States) for a review of such information. However, as stated in their report included in the Company’s Quarterly Report on Form 10-Q for the quarter ended March 31, 2010, and incorporated by reference herein, they did not audit and they do not express an opinion on that interim financial information. Accordingly, the degree of reliance on their report on such information should be restricted in light of the limited nature of the review procedures applied. Deloitte & Touche LLP are not subject to the liability provisions of Section 11 of the Securities Act of 1933 for their report on the unaudited interim financial information because the report is not a “report” or a “part” of the registration statement prepared or certified by an accountant within the meaning of Sections 7 and 11 of the Securities Act of 1933.

          Rex Blackburn, our Senior Vice President and General Counsel, has reviewed the statements under “Description of First Mortgage Bonds” relating to the lien of the indenture and the statements as to matters of law and legal conclusions in the documents incorporated by reference. We make these statements in reliance upon his opinion and authority as an expert.

24

$500,000,000

IDAHO POWER COMPANY

First Mortgage Bonds
Secured Medium-Term Notes, Series I

PROSPECTUS SUPPLEMENT

June 17, 2010

BofA Merrill Lynch
BNY Mellon Capital Markets, LLC
J.P. Morgan
KeyBanc Capital Markets
Mitsubishi UFJ Securities
RBC Capital Markets
SunTrust Robinson Humphrey
US Bancorp
Wells Fargo Securities