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                                                                     Exhibit 4.6

                          REGISTRATION RIGHTS AGREEMENT

                  THIS REGISTRATION RIGHTS AGREEMENT is made and entered into as
of February 14, 2003 by and between Sierra Pacific Resources, a Nevada
corporation (the "Company"), and Merrill Lynch & Co., Merrill Lynch, Pierce,
Fenner & Smith Incorporated (the "Initial Purchaser") pursuant to the Purchase
Agreement, dated February 11, 2003 (the "Purchase Agreement"), between the
Company and the Initial Purchaser. In order to induce the Initial Purchaser to
enter into the Purchase Agreement, the Company has agreed to provide the
registration rights set forth in this Agreement. The execution of this Agreement
is a condition to the closing under the Purchase Agreement.

                  The Company agrees with the Initial Purchaser for the benefit
of the Initial Purchaser and for the benefit of the beneficial owners (including
the Initial Purchaser) from time to time of the Registrable Securities (as
defined herein) (each of the foregoing a "Holder" and together the "Holders"),
as follows:

                  Section 1. Definitions. Capitalized terms used herein without
definition shall have their respective meanings set forth in the Purchase
Agreement. As used in this Agreement, the following terms shall have the
following meanings:

                  "Affiliate" means, with respect to any specified person, an
"affiliate," as defined in Rule 144, of such person.

                  "Amendment Effectiveness Deadline Date" has the meaning
specified in Section 2(d) hereof.

                  "Business Day" means each Monday, Tuesday, Wednesday, Thursday
and Friday that is not a day on which banking institutions in The City of New
York are authorized or obligated by law or executive order to close.

                  "Common Stock" means any shares of Common Stock, par value
$1.00 per share, of the Company and any other shares of common stock as may
constitute "Common Stock" for purposes of the Indenture, including the
Underlying Common Stock.

                  "Conversion Price" has the meaning assigned to that term in
the Indenture.

                  "Damages Accrual Period" has the meaning specified in Section
2(e) hereof.

                  "Damages Payment Date" means each February 14 and August 14 in
the case of Securities and the Underlying Common Stock.

                  "Deferral Notice" has the meaning specified in Section 3(j)
hereof.

                  "Deferral Period" has the meaning specified in Section 3(j)
hereof.

                  "Effectiveness Deadline Date" has the meaning specified in
Section 2(a) hereof.


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                  "Effectiveness Period" means the period of two years from the
Issue Date or such shorter period that will terminate upon the earliest of the
following: (A) when all the Securities covered by the Shelf Registration
Statement have been sold pursuant to the Shelf Registration Statement or when
all shares of Underlying Common Stock have been sold pursuant to the Shelf
Registration Statement and (B) when, in the written opinion of counsel to the
Company, all outstanding Registrable Securities held by persons which are not
affiliates of the Company may be resold without registration under the
Securities Act pursuant to Rule 144(k) under the Securities Act or any successor
provision thereto.

                  "Event" has the meaning specified in Section 2(e) hereof.

                  "Event Termination Date" has the meaning specified in Section
2(e) hereof.

                  "Event Date" has the meaning specified in Section 2(e) hereof.

                  "Exchange Act" means the Securities Exchange Act of 1934, as
amended, and the rules and regulations of the SEC promulgated thereunder.

                  "Filing Deadline Date" has the meaning specified in Section
2(a) hereof.

                  "Holder" has the meaning specified in the second paragraph of
this Agreement.

                  "Indenture" means the Indenture dated as of the date hereof
between the Company and the Trustee, pursuant to which the Securities are being
issued.

                  "Initial Purchaser" has the meaning specified in the first
paragraph of this Agreement.

                  "Initial Shelf Registration Statement" has the meaning
specified in Section 2(a) hereof.

                  "Issue Date" means February 14, 2003.

                  "Liquidated Damages Amount" has the meaning specified in
Section 2(e) hereof.

                  "Material Event" has the meaning specified in Section 3(j)
hereof.

                  "Notice and Questionnaire" means a written notice delivered to
the Company containing substantially the information called for by the Selling
Securityholder Notice and Questionnaire attached as Annex A to the Offering
Memorandum of the Company issued February 11, 2003 relating to the Securities.

                  "Notice Holder" means, on any date, any Holder that has
delivered a Notice and Questionnaire to the Company on or prior to such date.

                  "Principal Amount" means, with the respect to the Securities,
the principal amount due on the maturity date as shown on such Securities.


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                  "Prospectus" means the prospectus included in any Registration
Statement (including, without limitation, a prospectus that discloses
information previously omitted from a prospectus filed as part of an effective
registration statement in reliance upon Rule 415 promulgated under the
Securities Act), as amended or supplemented by any amendment or prospectus
supplement, including post-effective amendments, and all materials incorporated
by reference or explicitly deemed to be incorporated by reference in such
Prospectus.

                  "Purchase Agreement" has the meaning specified in the first
paragraph of this Agreement.

                  "Record Holder" means, with respect to any Damages Payment
Date relating to any Securities or Underlying Common Stock as to which any
Liquidated Damages Amount has accrued, the registered Holder of such Securities
or Underlying Common Stock, as the case may be, 15 days prior to the next
succeeding Damages Payment Date.

                  "Registrable Securities" means the Securities, until such
Securities have been converted or exchanged, and the Underlying Common Stock and
any securities into or for which such securities have been converted or
exchanged, and any security issued with respect thereto upon any stock dividend,
split or similar event until, in the case of any such security, the earliest of
(i) its effective registration under the Securities Act and resale in accordance
with the Registration Statement covering it, (ii) expiration of the holding
period that would be applicable thereto under Rule 144(k) were it not held by an
Affiliate of the Company or (iii) its sale to the public pursuant to Rule 144.

                  "Registration Expenses" means the expenses described in
Section 5 hereof.

                  "Registration Statement" means any registration statement of
the Company that covers any of the Registrable Securities pursuant to the
provisions of this Agreement, including the Prospectus, amendments and
supplements to such registration statement, including post-effective amendments,
all exhibits, and all materials incorporated by reference or explicitly deemed
to be incorporated by reference in such registration statement.

                  "Restricted Securities" has the meaning assigned to that term
in Rule 144.

                  "Rule 144" means Rule 144 under the Securities Act, as such
Rule may be amended from time to time, or any similar rule or regulation
hereafter adopted by the SEC.

                  "Rule 144A" means Rule 144A under the Securities Act, as such
Rule may be amended from time to time, or any similar rule or regulation
hereafter adopted by the SEC.

                  "SEC" means the U.S. Securities and Exchange Commission and
any successor agency.

                  "Securities" means the 7.25% Convertible Notes due 2010 of the
Company to be purchased pursuant to the Purchase Agreement.

                  "Securities Act" means the Securities Act of 1933, as amended,
and the rules and regulations promulgated by the SEC thereunder.


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                  "Shelf Registration Statement" has the meaning specified in
Section 2(a) hereof.

                  "Subsequent Shelf Registration Statement" has the meaning
specified in Section 2(b) hereof.

                  "TIA" means the Trust Indenture Act of 1939, as amended.

                  "Trustee" means The Bank of New York (or any successor
entity), the Trustee under the Indenture.

                  "Underlying Common Stock" means the Common Stock into which
the Securities are convertible or issued upon any such conversion.

                  Section 2. Shelf Registration. (a) The Company shall prepare
and file or cause to be prepared and filed with the SEC, as soon as practicable
but in any event by the date (the "Filing Deadline Date") ninety (90) days after
the Issue Date, a Registration Statement for an offering to be made on a delayed
or continuous basis pursuant to Rule 415 of the Securities Act (a "Shelf
Registration Statement") registering the resale from time to time by Holders
thereof of all of the Registrable Securities (the "Initial Shelf Registration
Statement"). The Initial Shelf Registration Statement shall be on Form S-3 or
another appropriate form permitting registration of such Registrable Securities
for resale by such Holders in accordance with the methods of distribution
elected by the Holders and set forth in the Initial Shelf Registration
Statement. The Company shall use its reasonable efforts to cause the Initial
Shelf Registration Statement to be declared effective under the Securities Act
as promptly as is practicable but in any event by the date (the "Effectiveness
Deadline Date") that is one hundred and eighty (180) days after the Issue Date,
and to keep the Initial Shelf Registration Statement (or any Subsequent Shelf
Registration Statement) continuously effective under the Securities Act until
the expiration of the Effectiveness Period; provided, however, that no Holder
shall be entitled to have the Registrable Securities held by it covered by such
Shelf Registration Statement unless such Holder shall have provided a Notice and
Questionnaire in accordance with Section 2(d) and is in compliance with Section
4. From and after the date hereof, the Company will not grant any existing or
future holders of the Company's securities the right to include any of the
Company's securities in the Shelf Registration Statement. The Company will use
its reasonable efforts to seek and obtain waivers from its security holders with
pre-existing registration rights to effectively waive any such rights with
respect to the Shelf Registration Statement; provided that no assurance can be
given that any such third-parties shall waive their rights.

                  (b) If the Initial Shelf Registration Statement or any
Subsequent Shelf Registration Statement ceases to be effective for any reason at
any time during the Effectiveness Period (other than because all Registrable
Securities registered thereunder shall have been sold pursuant thereto or shall
have otherwise ceased to be Registrable Securities), the Company shall use its
reasonable efforts to obtain the prompt withdrawal of any order suspending the
effectiveness thereof, and in any event shall within thirty (30) days of such
cessation of effectiveness amend the Shelf Registration Statement in a manner
reasonably expected to obtain the withdrawal of the order suspending the
effectiveness thereof, or file an additional Shelf Registration Statement
covering all of the securities that as of the date of such filing are
Registrable Securities (a "Subsequent Shelf Registration Statement"). If a
Subsequent Shelf


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Registration Statement is filed, the Company shall use its reasonable efforts to
cause the Subsequent Shelf Registration Statement to become effective as
promptly as is practicable after such filing and to keep such Registration
Statement (or another Subsequent Shelf Registration Statement) continuously
effective until the end of the Effectiveness Period.

                  (c) The Company shall supplement and amend the Shelf
Registration Statement if required by the rules, regulations or instructions
applicable to the registration form used by the Company for such Shelf
Registration Statement, if required by the Securities Act or, to the extent to
which the Company does not reasonably object, as reasonably requested by the
Initial Purchaser or by the Trustee on behalf of the registered Holders.

                  (d) Each Holder agrees that if such Holder wishes to sell
Registrable Securities pursuant to a Shelf Registration Statement and related
Prospectus, it will do so only in accordance with this Section 2(d) and Section
3(j). Each Holder wishing to sell Registrable Securities pursuant to a Shelf
Registration Statement and related Prospectus agrees to deliver a Notice and
Questionnaire to the Company at least ten (10) days prior to any intended
distribution of Registrable Securities under the Shelf Registration Statement.
From and after the date the Initial Shelf Registration Statement is declared
effective, the Company shall, as promptly as is practicable after the date a
Notice and Questionnaire is delivered, and in any event within five (5) Business
Days after such date, (i) if required by applicable law, file with the SEC a
post-effective amendment to the Shelf Registration Statement or prepare and, if
required by applicable law, file a supplement to the related Prospectus or a
supplement or amendment to any document incorporated therein by reference or
file any other required document so that the Holder delivering such Notice and
Questionnaire is named as a selling security holder in the Shelf Registration
Statement and the related Prospectus in such a manner as to permit such Holder
to deliver such Prospectus to purchasers of the Registrable Securities in
accordance with applicable law and, if the Company shall file a post-effective
amendment to the Shelf Registration Statement, use its reasonable efforts to
cause such post-effective amendment to be declared effective under the
Securities Act as promptly as is practicable, but in any event by the date (the
"Amendment Effectiveness Deadline Date") that is forty-five (45) days after the
date such post-effective amendment is required by this clause to be filed; (ii)
provide such Holder copies of any documents filed pursuant to Section 2(d)(i);
and (iii) notify such Holder as promptly as practicable after the effectiveness
under the Securities Act of any post-effective amendment filed pursuant to
Section 2(d)(i); provided, that if such Notice and Questionnaire is delivered
during a Deferral Period, the Company shall so inform the Holder delivering such
Notice and Questionnaire and shall take the actions set forth in clauses (i),
(ii) and (iii) above upon expiration of the Deferral Period in accordance with
Section 3(j), provided, further, that if under applicable law the Company has
more than one option as to the type or manner of making any such filing, it will
make the required filing or filings in the manner or of a type that is
reasonably expected to result in the earliest availability of the Prospectus for
effecting resales of Registrable Securities. Notwithstanding anything contained
herein to the contrary, the Company shall be under no obligation to name any
Holder that is not a Notice Holder as a selling security holder in any
Registration Statement or related Prospectus; provided, however, that any Holder
that becomes a Notice Holder pursuant to the provisions of this Section 2(d)
(whether or not such Holder was a Notice Holder at the time the Registration
Statement was declared effective) shall be named as a selling security holder in
the Registration Statement or related Prospectus in accordance with the
requirements of this Section 2(d).


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                  (e) The parties hereto agree that the Holders of Registrable
Securities will suffer damages, and that it would not be feasible to ascertain
the extent of such damages with precision, if (i) the Initial Shelf Registration
Statement has not been filed on or prior to the Filing Deadline Date, (ii) the
Initial Shelf Registration Statement has not been declared effective under the
Securities Act on or prior to the Effectiveness Deadline Date, (iii) the Company
has failed to perform its obligations set forth in Section 2(d) hereof within
the time period required therein, (iv) the aggregate duration of Deferral
Periods in any period exceeds the number of days permitted in respect of such
period pursuant to Section 3(j) hereof or (v) the number of Deferral Periods in
any period exceeds the number permitted in respect of such periods pursuant to
Section 3(j) (each of the events of a type described in any of the foregoing
clauses (i) through (v) are individually referred to herein as an "Event," and
the Filing Deadline Date in the case of clause (i), the Effectiveness Deadline
Date in the case of clause (ii), the date by which the Company is required to
perform its obligations set forth in Section 2(d) in the case of clause (iii)
(including the filing of any post-effective amendment prior to the Amendment
Effectiveness Deadline Date), the date on which the aggregate duration of
Deferral Periods in any period exceeds the number of days permitted by Section
3(j) hereof in the case of clause (iv), and the date of the commencement of a
Deferral Period that causes the limit on the number of Deferral Periods in any
period under Section 3(j) hereof to be exceeded in the case of clause (v), being
referred to herein as an "Event Date"). Events shall be deemed to continue until
the "Event Termination Date," which shall be the following dates with respect to
the respective types of Events: the date the Initial Shelf Registration
Statement is filed in the case of an Event of the type described in clause (i),
the date the Initial Shelf Registration Statement becomes effective under the
Securities Act in the case of an Event of the type described in clause (ii), the
date the Company performs its obligations set forth in Section 2(d) in the case
of an Event of the type described in clause (iii) (including, without
limitation, the date the relevant post-effective amendment to the Shelf
Registration Statement is declared effective under the Securities Act),
termination of the Deferral Period that caused the limit on the aggregate
duration of Deferral Periods in a period set forth in Section 3(j) to be
exceeded in the case of the commencement of an Event of the type described in
clause (iv), and termination of the Deferral Period the commencement of which
caused the number of Deferral Periods in a period permitted by Section 3(j) to
be exceeded in the case of an Event of the type described in clause (v).

                  Accordingly, commencing on (and including) any Event Date and
ending on (but excluding) the relevant Event Termination Date (a "Damages
Accrual Period"), the Company agrees to pay, as liquidated damages and not as a
penalty, an amount (the "Liquidated Damages Amount"), payable on the Damages
Payment Dates to Record Holders, accruing for each portion of such Damages
Accrual Period beginning on and including a Damages Payment Date (or, in respect
of the first time that the Liquidation Damages Amount is to be paid to Holders
on a Damages Payment Date as a result of the occurrence of any particular Event,
from and including the Event Date) and ending on but excluding the first to
occur of (A) the date of the end of the Damages Accrual Period or (B) the next
Damages Payment Date, at a rate per annum equal to one-quarter of one percent
(0.25%) for the first 90-day period from the Event Date, and thereafter at a
rate per annum equal to one-half of one percent (0.5%), of the aggregate
Principal Amount of such Securities or, if the Holder has converted such
Securities into Underlying Common Stock and such shares of Common Stock then
constitute Registrable Securities, the Conversion Price of such Securities in
effect at the time of such conversion, in each case, determined as of the
Business Day immediately preceding the next Damages Payment Date;


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provided, that in the case of a Damages Accrual Period that is in effect solely
as a result of an Event of the type described in clause (iii) of the immediately
preceding paragraph, such Liquidated Damages Amount shall be paid only to the
Holders that have delivered Notice and Questionnaires that caused the Company to
incur the obligations set forth in Section 2(d) the non-performance of which is
the basis of such Event; provided further, that any Liquidated Damages Amount
accrued with respect to any Securities or portion thereof called for redemption
on a redemption date or converted into Underlying Common Stock on a conversion
date prior to the Damages Payment Date, shall, in any such event, be paid
instead to the Holder who submitted such Securities or portion thereof for
redemption or conversion on the applicable redemption date or conversion date,
as the case may be, on such date (or promptly following the conversion date, in
the case of conversion). Notwithstanding the foregoing, no Liquidated Damages
Amounts shall accrue as to any Registrable Security from and after the earlier
of (x) the date such security is no longer a Registrable Security and (y)
expiration of the Effectiveness Period. The rate of accrual of the Liquidated
Damages Amount with respect to any period shall not exceed the applicable rate
provided for in this paragraph and shall not exceed one-half of one percent
(0.5%), notwithstanding the occurrence of multiple concurrent Events. Following
the relevant Event Termination Date, the accrual of Liquidated Damages Amounts
will cease (without in any way limiting the effect of any subsequent Event
requiring the payment of Liquidated Damages Amount by the Company).

                  The Trustee shall be entitled, on behalf of Holders of
Securities or Underlying Common Stock, to seek any available remedy for the
enforcement of this Agreement, including for the payment of any Liquidated
Damages Amount. Notwithstanding the foregoing, the parties agree that the sole
monetary damages payable for a violation of the terms of this Agreement with
respect to which liquidated damages are expressly provided shall be such
liquidated damages. Nothing shall preclude a Notice Holder or Holder from
pursuing or obtaining specific performance or other equitable relief with
respect to this Agreement.

                  All of the Company's obligations set forth in this Section
2(e) that are outstanding with respect to any Registrable Security at the time
such security ceases to be a Registrable Security shall survive until such time
as all such obligations with respect to such security have been satisfied in
full (notwithstanding termination of this Agreement pursuant to Section 8(k)).

                  The parties hereto agree that the liquidated damages provided
for in this Section 2(e) constitute a reasonable estimate of the damages that
may be incurred by Holders of Registrable Securities by reason of the failure of
the Shelf Registration Statement to be filed or declared effective or available
for effecting resales of Registrable Securities in accordance with the
provisions hereof.

                  Section 3. Registration Procedures. In connection with the
registration obligations of the Company under Section 2 hereof, the Company
shall:

                  (a) Before filing any Registration Statement or Prospectus or
any amendments or supplements thereto with the SEC, furnish to the Initial
Purchaser copies of all such documents proposed to be filed and use its
reasonable efforts to reflect in each such document when so filed with the SEC
such comments as the Initial Purchaser reasonably shall propose within three (3)
Business Days of the delivery of such copies to the Initial Purchaser.


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                  (b) Prepare and file with the SEC such amendments and
post-effective amendments to each Registration Statement as may be necessary to
keep such Registration Statement continuously effective for the applicable
period specified in Section 2(a); cause the related Prospectus to be
supplemented by any required Prospectus supplement, and as so supplemented to be
filed pursuant to Rule 424 (or any similar provisions then in force) under the
Securities Act; and comply with the provisions of the Securities Act applicable
to it with respect to the disposition of all securities covered by such
Registration Statement during the Effectiveness Period in accordance with the
intended methods of disposition by the sellers thereof set forth in such
Registration Statement as so amended or such Prospectus as so supplemented.

                  (c) As promptly as practicable give notice to the Notice
Holders and the Initial Purchaser (i) when any Prospectus, Prospectus
supplement, Registration Statement or post-effective amendment to a Registration
Statement has been filed with the SEC and, with respect to a Registration
Statement or any post-effective amendment, when the same has become effective,
(ii) of any request, following the effectiveness of the Initial Shelf
Registration Statement under the Securities Act, by the SEC or any other federal
or state governmental authority for amendments or supplements to any
Registration Statement or related Prospectus or for additional information,
(iii) of the issuance by the SEC or any other federal or state governmental
authority of any stop order suspending the effectiveness of any Registration
Statement or, to the Company's knowledge, the initiation or threatening of any
proceedings for that purpose, (iv) of the receipt by the Company of any
notification with respect to the suspension of the qualification or exemption
from qualification of any of the Registrable Securities for sale in any
jurisdiction or, to the Company's knowledge, the initiation or threatening of
any proceeding for such purpose, (v) of the occurrence of (but not the nature of
or details concerning) a Material Event (provided, however, that no notice by
the Company shall be required pursuant to this clause (v) in the event that the
Company either promptly files a Prospectus supplement to update the Prospectus
or a Form 8-K or other appropriate Exchange Act report that is incorporated by
reference into the Registration Statement, which, in either case, contains the
requisite information with respect to such Material Event that results in such
Registration Statement no longer containing any untrue statement of material
fact or omitting to state a material fact necessary to make the statements
contained therein not misleading) and (vi) of the determination by the Company
that a post-effective amendment to a Registration Statement will be filed with
the SEC, which notice may, at the discretion of the Company (or as required
pursuant to Section 3(j)), state that it constitutes a Deferral Notice, in which
event the provisions of Section 3(j) shall apply.

                  (d) Use its reasonable efforts to prevent the issuance, and if
issued to use its reasonable efforts to promptly obtain the withdrawal of any
order suspending the effectiveness of a Registration Statement or the lifting of
any suspension of the qualification (or exemption from qualification) of any of
the Registrable Securities for sale in any jurisdiction in which they have been
qualified for sale.

                  (e) If reasonably requested in writing by the Initial
Purchaser or any Notice Holder, promptly incorporate in a Prospectus supplement
or post-effective amendment to a Registration Statement such information as the
Initial Purchaser or such Notice Holder shall, on the basis of an opinion of
nationally-recognized counsel experienced in such matters (a copy of


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such opinion to be delivered to the Company together with such request),
determine to be required to be included therein by applicable law and make any
required filings of such Prospectus supplement or such post-effective amendment;
provided, that the Company shall not be required to take any actions under this
Section 3(e) that are not, in the reasonable opinion of counsel for the Company,
in compliance with applicable law.

                  (f) Furnish to each Notice Holder and the Initial Purchaser,
upon their request and without charge, at least one (1) conformed copy of the
Registration Statement and any amendment thereto, including financial statements
but excluding (i) schedules, (ii) all documents incorporated or deemed to be
incorporated therein by reference and (iii) all exhibits (in each case, unless
requested in writing to the Company by such Notice Holder or the Initial
Purchaser, as the case may be).

                  (g) During the Effectiveness Period, deliver to each Notice
Holder in connection with any sale of Registrable Securities pursuant to a
Registration Statement, without charge, as many copies of the Prospectus or
Prospectuses relating to such Registrable Securities (including each preliminary
prospectus) and any amendment or supplement thereto as such Notice Holder may
reasonably request; and the Company hereby consents (except during such periods
that a Deferral Notice is outstanding and has not been revoked) to the use of
such Prospectus or each amendment or supplement thereto by each Notice Holder in
connection with any offering and sale of the Registrable Securities covered by
such Prospectus or any amendment or supplement thereto in the manner set forth
therein.

                  (h) Prior to any public offering of the Registrable Securities
pursuant to the Shelf Registration Statement, register or qualify or cooperate
with the Notice Holders in connection with the registration or qualification (or
exemption from such registration or qualification) of such Registrable
Securities for offer and sale under the securities or Blue Sky laws of such
jurisdictions within the United States as any Notice Holder reasonably requests
in writing (which request may be included in the Notice and Questionnaire);
prior to any public offering of the Registrable Securities pursuant to the Shelf
Registration Statement, use its reasonable efforts to keep each such
registration or qualification (or exemption therefrom) effective during the
Effectiveness Period in connection with such Notice Holder's offer and sale of
Registrable Securities pursuant to such registration or qualification (or
exemption therefrom) and do any and all other acts or things necessary or
advisable to enable the disposition in such jurisdictions of such Registrable
Securities in the manner set forth in the relevant Registration Statement and
the related Prospectus; provided, that the Company will not be required to (i)
qualify as a foreign corporation or as a dealer in securities in any
jurisdiction where it would not otherwise be required to qualify but for this
Agreement or (ii) take any action that would subject it to general service of
process in suits or to taxation in any such jurisdiction where it is not then so
subject.

                  (i) Upon (A) the issuance by the SEC of a stop order
suspending the effectiveness of the Shelf Registration Statement or the
initiation of proceedings with respect to the Shelf Registration Statement under
Section 8(d) or 8(e) of the Securities Act, (B) the occurrence of any event or
the existence of any fact (a "Material Event") as a result of which any
Registration Statement shall contain any untrue statement of a material fact or
omit to state any material fact required to be stated therein or necessary to
make the statements therein not


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<PAGE>

misleading, or any Prospectus shall contain any untrue statement of a material
fact or omit to state any material fact required to be stated therein or
necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading, or (C) the occurrence or existence
of any pending corporate development that, in the discretion of the Company,
makes it appropriate to suspend the availability of the Shelf Registration
Statement and the related Prospectus, (i) in the case of clause (B) above,
subject to the next sentence, promptly prepare and file a post-effective
amendment to such Registration Statement or a supplement to the related
Prospectus or any document incorporated therein by reference or file any other
required document that would be incorporated by reference into such Registration
Statement and Prospectus so that such Registration Statement does not contain
any untrue statement of a material fact or omit to state any material fact
required to be stated therein or necessary to make the statements therein not
misleading, and such Prospectus does not contain any untrue statement of a
material fact or omit to state any material fact required to be stated therein
or necessary to make the statements therein, in the light of the circumstances
under which they were made, not misleading, as thereafter delivered to the
purchasers of the Registrable Securities being sold thereunder, and, in the case
of a post-effective amendment to a Registration Statement, subject to the next
sentence, use its reasonable efforts to cause it to be declared effective as
promptly as is reasonably practicable, and (ii) give notice to the Notice
Holders that the availability of the Shelf Registration Statement is suspended
(a "Deferral Notice") and, upon receipt of any Deferral Notice, each Notice
Holder agrees not to sell any Registrable Securities pursuant to the
Registration Statement until such Notice Holder's receipt of copies of the
supplemented or amended Prospectus provided for in clause (i) above, or until it
is advised in writing by the Company that the Prospectus may be used, and has
received copies of any additional or supplemental filings that are incorporated
or deemed incorporated by reference in such Prospectus. The Company will use its
reasonable efforts to ensure that the use of the Prospectus may be resumed (x)
in the case of clause (A) above, as promptly as is practicable, (y) in the case
of clause (B) above, as soon as, in the sole judgment of the Company, public
disclosure of such Material Event would not be prejudicial to or contrary to the
interests of the Company or, if necessary to avoid unreasonable burden or
expense, as soon as reasonably practicable thereafter and (z) in the case of
clause (C) above, as soon as, in the sole judgment of the Company, such
suspension is no longer appropriate. The period during which the availability of
the Registration Statement and any Prospectus is suspended (the "Deferral
Period") without the Company incurring any obligation to pay liquidated damages
pursuant to Section 2(e) shall not exceed forty-five (45) days in any three (3)
month period and ninety (90) days in any twelve (12) month period.

                  (j) In the event of a Qualified Underwritten Offering, make
available for inspection during normal business hours by a representative for
the Notice Holders of such Registrable Securities and any broker-dealers,
attorneys and accountants retained by such Notice Holders, all relevant
financial and other records, pertinent corporate documents and properties of the
Company and its subsidiaries, and cause the appropriate executive officers,
directors and designated employees of the Company and its subsidiaries to make
available for inspection during normal business hours all relevant information
reasonably requested by such representative for the Notice Holders or any such
broker-dealers, attorneys or accountants in connection with such disposition, in
each case as is customary for similar "due diligence" examinations; provided,
however, that such persons shall first agree in writing with the Company that
any information that is reasonably and in good faith designated by the Company
in writing


                                       10
<PAGE>

as confidential at the time of delivery of such information shall be kept
confidential by such persons and shall be used solely for the purposes of
exercising rights under this Agreement, unless (i) disclosure of such
information is required by court or administrative order or is necessary to
respond to inquiries of regulatory authorities, (ii) disclosure of such
information is required by law (including any disclosure requirements pursuant
to federal securities laws in connection with the filing of any Registration
Statement or the use of any Prospectus referred to in this Agreement), (iii)
such information becomes generally available to the public other than as a
result of a disclosure or failure to safeguard by any such person or (iv) such
information becomes available to any such person from a source other than the
Company and such source is not bound by a confidentiality agreement; and
provided further that the foregoing inspection and information gathering shall,
to the greatest extent possible, be coordinated on behalf of all the Notice
Holders and the other parties entitled thereto by the counsel referred to in
Section 5. For the purposes of this paragraph, "Qualified Underwritten Offering"
shall mean an underwritten public offering of Registrable Securities in an
aggregate amount of at least $25 million.

                  (k) Comply with all applicable rules and regulations of the
SEC and make generally available to its securityholders earning statements
(which need not be audited) satisfying the provisions of Section 11(a) of the
Securities Act and Rule 158 thereunder (or any similar rule promulgated under
the Securities Act) commencing on the first day of the first fiscal quarter of
the Company commencing after the effective date of a Registration Statement.

                  (l) Cooperate with each Notice Holder to facilitate the timely
preparation and delivery of certificates representing Registrable Securities
sold pursuant to a Registration Statement, and cause such Registrable Securities
to be in such denominations as are permitted by the Indenture and registered in
such names as such Notice Holder may request in writing at least two Business
Days prior to any sale of such Registrable Securities.

                  (m) Provide a CUSIP number for all Registrable Securities
covered by each Registration Statement not later than the effective date of such
Registration Statement and provide the Trustee for the Securities and the
transfer agent for the Underlying Common Stock the with printed certificates for
the Registrable Securities that are in a form eligible for deposit with The
Depository Trust Company.

                  (n) Use its reasonable best efforts to provide such
information as is required for any filings required to be made with the National
Association of Securities Dealers, Inc.

                  (o) Upon (i) the filing of the Initial Shelf Registration
Statement and (ii) the effectiveness of the Initial Shelf Registration
Statement, announce the same, in each case by release to Reuters Economic
Services and Bloomberg Business News.

                  (p) Enter into such customary agreements and take all such
other necessary actions in connection therewith (including those requested by
the holders of a majority of the Registrable Securities being sold) in order to
expedite or facilitate disposition of such Registrable Securities.

                  (q) Cause the Indenture to be qualified under the TIA not
later than the effective date of any Registration Statement; and in connection
therewith, cooperate with the


                                       11
<PAGE>

Trustee to effect such changes to the Indenture as may be required for the
Indenture to be so qualified in accordance with the terms of the TIA and
execute, and use its reasonable efforts to cause the Trustee to execute, all
documents as may be required to effect such changes, and all other forms and
documents required to be filed with the SEC to enable the Indenture to be so
qualified in a timely manner.

                  Section 4. Holder's Obligations. Each Holder agrees, by
acquisition of the Registrable Securities, that no Holder shall be entitled to
sell any of such Registrable Securities pursuant to a Registration Statement or
to receive a Prospectus relating thereto, unless such Holder has furnished the
Company with a Notice and Questionnaire as required pursuant to Section 2(d)
hereof (including the information required to be included in such Notice and
Questionnaire) and the information set forth in the next sentence. Each Notice
Holder agrees promptly to furnish to the Company all information required to be
disclosed in order to make the information previously furnished to the Company
by such Notice Holder not misleading and any other information regarding such
Notice Holder and the distribution of such Registrable Securities as may be
required to be disclosed in the Registration Statement under applicable law.

                  Section 5. Registration Expenses. The Company shall bear all
fees and expenses incurred in connection with the performance by the Company of
its obligations under Sections 2 and 3 of this Agreement whether or not any of
the Registration Statements are declared effective. Such fees and expenses shall
include, without limitation, (i) all registration and filing fees (including,
without limitation, fees and expenses (x) with respect to filings required to be
made with the National Association of Securities Dealers, Inc. and (y) of
compliance with federal and state securities or Blue Sky laws (including,
without limitation, reasonable fees and disbursements of the counsel specified
in the next sentence in connection with Blue Sky qualifications of the
Registrable Securities under the laws of such jurisdictions as the Notice
Holders of a majority of the Registrable Securities being sold pursuant to a
Registration Statement may designate), (ii) printing expenses (including,
without limitation, expenses of printing certificates for Registrable Securities
in a form eligible for deposit with The Depository Trust Company), (iii)
duplication expenses relating to copies of any Registration Statement or
Prospectus delivered to any Holders hereunder, (iv) fees and disbursements of
counsel for the Company in connection with the Shelf Registration Statement and
(v) reasonable fees and disbursements of the Trustee and its counsel and of the
registrar and transfer agent for the Common Stock. In addition, the Company
shall bear or reimburse the Notice Holders for the reasonable fees and
disbursements of one firm of legal counsel for the Holders, which shall
initially be Shearman & Sterling, but which may, upon the written consent of the
Initial Purchaser (which shall not be unreasonably withheld), be another
nationally recognized law firm experienced in securities law matters designated
by the Company. In addition, the Company shall pay the internal expenses of the
Company (including, without limitation, all salaries and expenses of officers
and employees performing legal or accounting duties), the expense of any annual
audit, the fees and expenses incurred in connection with the listing of the
Registrable Securities on any securities exchange on which similar securities of
the Company are then listed and the fees and expenses of any person, including
special experts, retained by the Company.

                  Section 6. Indemnification; Contribution. (a) The Company
agrees to indemnify and hold harmless the Initial Purchaser and each Holder and
each person, if any, who


                                       12
<PAGE>

controls the Initial Purchaser or any Holder within the meaning of either
Section 15 of the Securities Act or Section 20 of the Exchange Act, as follows:

                        (i) against any and all loss, liability, claim, damage
            and expense whatsoever, as incurred, arising out of any untrue
            statement or alleged untrue statement of a material fact contained
            in the Registration Statement (or any amendment thereto), or the
            omission or alleged omission therefrom of a material fact necessary
            in order to make the statements therein, in light of the
            circumstances under which they were made, not misleading or arising
            out of any untrue statement or alleged untrue statement of a
            material fact included in any preliminary prospectus or the
            Prospectus (or any amendment or supplement thereto), or the omission
            or alleged omission therefrom of a material fact necessary in order
            to make the statements therein, in the light of the circumstances
            under which they were made, not misleading;

                        (ii) against any and all loss, liability, claim, damage
            and expense whatsoever, as incurred, to the extent of the aggregate
            amount paid in settlement of any litigation, or any investigation or
            proceeding by any governmental agency or body, commenced or
            threatened, or of any claim whatsoever based upon any such untrue
            statement or omission, or any such alleged untrue statement or
            omission, provided that (subject to Section 6(d) below) any such
            settlement is effected with the prior written consent of the
            Company; and

                        (iii) against any and all expense whatsoever, as
            incurred (including the fees and disbursements of counsel),
            reasonably incurred in investigating, preparing or defending against
            any litigation, or any investigation or proceeding by any
            governmental agency or body, commenced or threatened, or any claim
            whatsoever based upon any such untrue statement or omission, or any
            such alleged untrue statement or omission, to the extent that any
            such expense is not paid under (i) or (ii) above;

provided, however, that this indemnity shall not apply to any loss, liability,
claim, damage or expense to the extent arising out of any untrue statement or
omission or alleged untrue statement or omission made in reliance upon and in
conformity with written information furnished to the Company by the Initial
Purchaser or such Holder (which also acknowledges the indemnity provisions
herein) and each person, if any, who controls the Initial Purchaser or any such
Holder expressly for use in the Registration Statement (or any amendment
thereto), or any preliminary prospectus or the Prospectus (or any amendment or
supplement thereto), and provided further that any amounts payable by the
Company to the Initial Purchaser or the Holders shall be net of any insurance
proceeds actually recovered by the Initial Purchaser or the Holders in
connection therewith.

                  (b) In connection with any Shelf Registration in which a
Holder, including, without limitation, the Initial Purchaser, is participating,
in furnishing information relating to such Holder to the Company in writing
expressly for use in such Registration Statement, any preliminary prospectus,
the Prospectus or any amendments or supplements thereto, such Holders agree,
severally and not jointly, to indemnify and hold harmless the Initial Purchaser
and each person, if any, who controls the Initial Purchaser within the meaning
of either Section 15 of the Securities Act or Section 20 of the Exchange Act and
the Company, and each person, if any, who


                                       13
<PAGE>

controls the Company within the meaning of either such Section, against any and
all loss, liability, claim, damage and expense described in the indemnity
contained in subsection (a) of this Section, as incurred, but only with respect
to untrue statements or omissions, or alleged untrue statements or omissions,
made in the Registration Statement (or any amendment thereto), or any
preliminary prospectus or the Prospectus (or any amendment or supplement
thereto) in reliance upon and in conformity with written information furnished
to the Company by such Holder (which also acknowledges the indemnity provisions
herein) and each person, if any, who controls any such Holder expressly for use
in the Registration Statement (or any amendment thereto) or such preliminary
prospectus or the Prospectus (or any amendment or supplement thereto).

                  The Initial Purchaser agrees to indemnify and hold harmless
the Company, the Holders, and each person, if any, who controls the Company or
any Holder within the meaning of either Section 15 of the Securities Act or
Section 20 of the Exchange Act against any and all loss, liability, claim,
damage and expense described in the indemnity contained in subsection (a) of
this Section, as incurred, but only with respect to untrue statements or
omissions, or alleged untrue statements or omissions, made in the Registration
Statement (or any amendment thereto), or any preliminary prospectus or the
Prospectus (or any amendment or supplement thereto) in reliance upon and in
conformity with written information furnished to the Company by the Initial
Purchaser expressly for use in the Registration Statement (or any amendment
thereto) or such preliminary prospectus or the Prospectus (or any amendment or
supplement thereto).

                  (c) Each indemnified party shall give notice as promptly as
reasonably practicable to each indemnifying party of any action commenced
against it in respect of which indemnity may be sought hereunder, but failure to
so notify an indemnifying party shall not relieve such indemnifying party from
any liability hereunder to the extent it is not materially prejudiced as a
result thereof and in any event shall not relieve it from any liability which it
may have otherwise than on account of this indemnity agreement. An indemnifying
party may participate at its own expense in the defense of any such action;
provided, however, that counsel to the indemnifying party shall not (except with
the consent of the indemnified party) also be counsel to the indemnified party.
In no event shall the indemnifying parties be liable for fees and expenses of
more than one counsel (in addition to any local counsel) separate from their own
counsel for all indemnified parties in connection with any one action or
separate but similar or related actions in the same jurisdiction arising out of
the same general allegations or circumstances. Counsel for the indemnified party
shall be legal counsel acceptable to the indemnifying party; provided that the
indemnifying party shall not unreasonably object to the legal counsel selected
by the indemnified party. With respect to any action commenced, the parties
hereto agree that it shall not be deemed to be an "unreasonable objection" if
the indemnifying party objects to the choice of legal counsel selected by the
indemnified party if such legal counsel is unable, for any reason, to also act
as legal counsel to the indemnifying party; provided that the indemnifying party
shall not raise such objection with respect to more than two legal counsels
selected by the indemnified party. No indemnifying party shall, without the
prior written consent of the indemnified parties, settle or compromise or
consent to the entry of any judgment with respect to any litigation, or any
investigation or proceeding by any governmental agency or body, commenced or
threatened, or any claim whatsoever in respect of which indemnification or
contribution could be sought under this Section 6 hereof (whether or not the
indemnified parties are actual or potential parties thereto), unless such
settlement,


                                       14
<PAGE>

compromise or consent (i) includes an unconditional release of each indemnified
party from all liability arising out of such litigation, investigation,
proceeding or claim and (ii) does not include a statement as to or an admission
of fault, culpability or a failure to act by or on behalf of any indemnified
party.

                  (d) If at any time an indemnified party shall have requested
an indemnifying party to reimburse the indemnified party for fees and expenses
of counsel, such indemnifying party agrees that it shall be liable for any
settlement of the nature contemplated by Section 6(a)(ii) effected without its
written consent if (i) such settlement is entered into more than 45 days after
receipt by such indemnifying party of aforesaid request, (ii) such indemnifying
party shall have received notice of the terms of such settlement at least 30
days prior to such settlement being entered into and (iii) such indemnifying
party shall not have reimbursed such indemnified party in accordance with such
request prior to the date of such settlement.

                  (e) If the indemnification provided for in this Section 6 is
for any reason unavailable to or insufficient to hold harmless an indemnified
party in respect of any losses, liabilities, claims, damages or expenses
referred to therein, then each indemnifying party shall contribute to the
aggregate amount of such losses, liabilities, claims, damages and expenses
incurred by such indemnified party, as incurred, in such proportion as is
appropriate to reflect the relative fault of the indemnifying party or parties
on the one hand and of the indemnified party on the other hand in connection
with the statements or omissions which resulted in such losses, liabilities,
claims, damages or expenses, as well as any other relevant equitable
considerations.

                  The relative fault of the Company on the one hand and the
holders of the Registrable Securities or the Initial Purchaser on the other hand
shall be determined by reference to, among other things, whether any such untrue
or alleged untrue statement of a material fact or omission or alleged omission
to state a material fact relates to information supplied by the Company or by
the Holder, including without limitation the Initial Purchaser's and the
parties' relative intent, knowledge, access to information and opportunity to
correct or prevent such statement or omission.

                  The parties hereto agree that it would not be just and
equitable if contribution pursuant to this Section 6(e) were determined by pro
rata allocation or by any other method of allocation which does not take account
of the equitable considerations referred to above in this Section 6(e). The
aggregate amount of losses, liabilities, claims, damages, and expenses incurred
by an indemnified party and referred to above in this Section 6(e) shall be
deemed to include any legal or other expenses reasonably incurred by such
indemnified party in investigating, preparing or defending against any
litigation, or any investigation or proceeding by any governmental agency or
body, commenced or threatened, or any claim whatsoever based upon any such
untrue or alleged untrue statement or omission or alleged omission.

                  Notwithstanding the provisions of this Section 6, neither the
Holders nor the Initial Purchaser, shall be required to indemnify or contribute
any amount in excess of the amount by which the total price at which the
Registrable Securities sold by such Holder or underwritten by the Initial
Purchaser, as the case may be, and distributed to the public were offered to the
public exceeds the amount of any damages that such Holder or the Initial


                                       15
<PAGE>

Purchaser has otherwise been required to pay by reason of such untrue or alleged
untrue statement or omission or alleged omission.

                  No person guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) shall be entitled to
contribution from any person who was not guilty of such fraudulent
misrepresentation.

                  For purposes of this Section 6(e), each person, if any, who
controls the Initial Purchaser or any Holder within the meaning of Section 15 of
the Securities Act or Section 20 of the Exchange Act shall have the same rights
to contribution as the Initial Purchaser or such holder, and each person, if
any, who controls the Company within the meaning of Section 15 of the Securities
Act or Section 20 of the Exchange Act shall have the same rights to contribution
as the Company.

                  Section 7. Information Requirements. The Company covenants
that, if at any time before the end of the Effectiveness Period the Company is
not subject to the reporting requirements of the Exchange Act, it will cooperate
with any Holder and take such further reasonable action as any Holder may
reasonably request in writing (including, without limitation, making such
reasonable representations as any such Holder may reasonably request), all to
the extent required from time to time to enable such Holder to sell Registrable
Securities without registration under the Securities Act within the limitation
of the exemptions provided by Rule 144 and Rule 144A under the Securities Act
and customarily taken in connection with sales pursuant to such exemptions. Upon
the written request of any Holder, the Company shall deliver to such Holder a
written statement as to whether it has complied with such filing requirements,
unless such a statement has been included in the Company's most recent report
required to be filed and filed pursuant to Section 13 or Section 15(d) of
Exchange Act.

                  Section 8. Miscellaneous.

                  (a) No Conflicting Agreements. The Company is not, as of the
date hereof, a party to, nor shall it, on or after the date of this Agreement,
enter into, any agreement with respect to its securities that conflicts with the
rights granted to the Holders of Registrable Securities in this Agreement. The
Company represents and warrants that the rights granted to the Holders of
Registrable Securities hereunder do not in any way conflict with the rights
granted to the holders of the Company's securities under any other agreements.

                  (b) Amendments and Waivers. The provisions of this Agreement,
including the provisions of this sentence, may not be amended, modified or
supplemented, and waivers or consents to departures from the provisions hereof
may not be given, unless the Company has obtained the written consent of Holders
of a majority of the then outstanding Underlying Common Stock constituting
Registrable Securities (with Holders of Securities deemed to be the Holders, for
purposes of this Section, of the number of outstanding shares of Underlying
Common Stock into which such Securities are or would be convertible or
exchangeable as of the date on which such consent is requested). Notwithstanding
the foregoing, a waiver or consent to depart from the provisions hereof with
respect to a matter that relates exclusively to the rights of Holders of
Registrable


                                       16
<PAGE>

Securities whose securities are being sold pursuant to a Registration Statement
and that does not directly or indirectly affect the rights of other Holders of
Registrable Securities may be given by Holders of at least a majority of the
Registrable Securities being sold by such Holders pursuant to such Registration
Statement; provided, that the provisions of this sentence may not be amended,
modified, or supplemented except in accordance with the provisions of the
immediately preceding sentence. Each Holder shall be bound by any such
amendment, modification, supplement, waiver or consent effected pursuant to this
Section 8(b), whether or not any notice, writing or marking indicating such
amendment, modification, supplement, waiver or consent appears on the
Registrable Securities or is delivered to such Holder.

                  (c) Notices. All notices and other communications provided for
or permitted hereunder shall be made in writing by hand delivery, by telecopier,
by courier guaranteeing overnight delivery or by first-class mail, return
receipt requested, and shall be deemed given (i) when made, if made by hand
delivery, (ii) upon confirmation, if made by telecopier, (iii) one (1) Business
Day after being deposited with such courier, if made by overnight courier or
(iv) on the date indicated on the notice of receipt, if made by first-class
mail, to the parties as follows:

                  (w) if to a Holder, at the most current address given by such
        Holder to the Company in a Notice and Questionnaire or any amendment
        thereto;

                  (x)         if to the Company, to:

                              Sierra Pacific Resources
                              6100 Neil Road
                              Reno, Nevada  89520-0400
                              Attention:  Richard Atkinson,
                              Chief Financial Officer
                              Telecopy No.: (775) 834-4011

                              with a copy to:

                              Choate, Hall & Stewart
                              53 State Street
                              Boston, MA 02109
                              Attention:  James A. McDaniel, Esq.
                              Telecopy No.: (617) 248-4000

                              and

                  (y)         if to the Initial Purchaser, to:

                              Merrill Lynch & Co., Merrill Lynch, Pierce,
                              Fenner & Smith Incorporated
                              4 World Financial Center
                              New York, New York 10080
                              Attention:  Syndicate Department
                              Telecopy No.:  (212) 738-1069


                                       17
<PAGE>

or to such other address as such person may have furnished to the other persons
identified in this Section 8(c) in writing in accordance herewith.

                  (d) Approval of Holders. Whenever the consent or approval of
Holders of a specified percentage of Registrable Securities is required
hereunder, the Registrable Securities held by the Company or its Affiliates
(other than the Initial Purchaser or subsequent Holders of Registrable
Securities if such subsequent Holders are deemed to be such affiliates solely by
reason of their holdings of such Registrable Securities) shall not be counted in
determining whether such consent or approval was given by the Holders of such
required percentage.

                  (e) Successors and Assigns. Any person who purchases any
Registrable Securities from the Initial Purchaser shall be deemed, for purposes
of this Agreement, to be an assignee of the Initial Purchaser. This Agreement
shall inure to the benefit of and be binding upon the successors and assigns of
each of the parties and shall inure to the benefit of and be binding upon each
Holder.

                  (f) Counterparts. This Agreement may be executed in any number
of counterparts and by the parties hereto in separate counterparts, each of
which when so executed shall be deemed to be original and all of which taken
together shall constitute one and the same agreement.

                  (g) Headings. The headings in this Agreement are for
convenience of reference only and shall not limit or otherwise affect the
meaning hereof.

                  (h) Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY AND
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK.

                  (i) Severability. If any term, provision, covenant or
restriction of this Agreement is held to be invalid, illegal, void or
unenforceable, the remainder of the terms, provisions, covenants and
restrictions set forth herein shall remain in full force and effect and shall in
no way be affected, impaired or invalidated thereby, and the parties hereto
shall use their best efforts to find and employ an alternative means to achieve
the same or substantially the same result as that contemplated by such term,
provision, covenant or restriction, it being intended that all of the rights and
privileges of the parties shall be enforceable to the fullest extent permitted
by law.

                  (j) Entire Agreement. This Agreement is intended by the
parties as a final expression of their agreement and is intended to be a
complete and exclusive statement of the agreement and understanding of the
parties hereto in respect of the subject matter contained herein and the
registration rights granted by the Company with respect to the Registrable
Securities. Except as provided in the Purchase Agreement, there are no
restrictions, promises, warranties or undertakings, other than those set forth
or referred to herein, with respect to the registration rights granted by the
Company with respect to the Registrable Securities. This Agreement supersedes
all prior agreements and undertakings among the parties with respect to such
registration rights.


                                       18
<PAGE>

                  (k) Termination. This Agreement and the obligations of the
parties hereunder shall terminate upon the expiration of the Effectiveness
Period, except for any liabilities or obligations under Sections 4, 5 or 6
hereof and the obligations to make payments of and provide for liquidated
damages under Section 2(e) hereof to the extent such damages have accrued prior
to the end of the Effectiveness Period, each of which shall remain in effect in
accordance with its terms.

                                 * * * * * * * *


                                       19
<PAGE>

                  IN WITNESS WHEREOF, the parties have executed this
Registration Rights Agreement as of the date first written above.

                                           SIERRA PACIFIC RESOURCES



                                           By:
                                              ----------------------------------
                                              Name:
                                              Title:


Confirmed and accepted as of the date
first above written:

MERRILL LYNCH & CO.,
MERRILL LYNCH, PIERCE, FENNER & SMITH
                        INCORPORATED

By:
   -----------------------------------
   Name:
   Title:


                                       20