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                                                                   Exhibit 10(b)

1800 M Street, N.W.                                               [MORGAN, LEWIS
Washington, D.C. 20036-5869                                  & BOCKIUS LLP LOGO]
202-467-7000                                                   COUNSELORS AT LAW
Fax: 202-467-7176




April 21, 2000




Mr. David P. Boergers
Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, D.C. 20426

Re:      Amended Filing in Docket No. ER00-1857-000
         ------------------------------------------

Dear Mr. Boergers:

Enclosed  for  filing are six copies of the  response  of Split Rock  Energy LLC
("Split Rock") and Minnesota Power, Inc. ("MP"), to the deficiency letter issued
on April 10, 2000, in regards to the above-referenced  docket. Split Rock and MP
respectfully request that the Commission shorten the time for responding to this
filing, in an effort to permit Split Rock to become  operational by May 1, 2000,
the beginning of the Mid-Continent Area Power Pool ("MAPP") summer season. There
have been no interventions to date in this proceeding.

I.       BACKGROUND

On  March  10,  2000,  Split  Rock  submitted  for  filing  an  Application  for
Market-Based  Rate  Authority   ("Market  Rate   Application"),   along  with  a
Market-Based Wholesale Power Sales Tariff ("Market Rate Tariff").  Split Rock is
a limited  liability  company formed pursuant to the laws of Minnesota by MP and
Great  River  Energy  ("GRE"),   a  generation  and   transmission   cooperative
(collectively Split Rock's "Members"). The Members formed Split Rock to schedule
and dispatch their combined generation  resources to optimally meet their native
load needs and obligations  under power sales contracts with third parties,  and
to market their excess generation resources.

In its Market Rate Application,  Split Rock requested authorization to engage in
wholesale   bulk  power  sales  at   market-determined   prices  and  to  resell
transmission  services.  Split  Rock  indicated  that it will sell  power to its
Members and will buy the excess power of its Members




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                                                                  [MORGAN, LEWIS
Mr. David P. Boergers                                        & BOCKIUS LLP LOGO]
April 21, 2000
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for resale,  at negotiated  rates under the proposed  Market Rate Tariff.  Split
Rock will also purchase power from third parties as necessary to optimally serve
the Members' native load needs and obligations under power sales contracts.

Split  Rock  explained  that  it  will  function  in  much  the  same  way  as a
cooperative,  in that  it  will  not  retain  net  revenues,  but  instead  will
periodically  disburse  any profits to the  Members.  Split  Rock's  Market Rate
Application  indicated that MP committed to treating  revenues  flowing  through
Split Rock,  the same as if the revenues were obtained  directly by MP. In other
words,  like a  cooperative,  Split  Rock is owned by  those  who use its  joint
dispatch and marketing  services - MP and GRE - and any profits flow back to its
owners, MP and GRE. Again, MP has committed to treating revenues from Split Rock
as if  they  were  earned  within  the  utility.  Due to the  "cooperative-like"
structure of Split Rock  vis-a-vis its Members,  there is no need for Split Rock
to commit not to transact  with its  affiliates  MP and GRE, nor is there a need
for a code of conduct to govern the interactions or relationships  between Split
Rock and its Members.

On April 10, 2000, Mr. Michael C.  McLaughlin,  Director,  Division of Corporate
Applications,  issued a deficiency  letter  regarding  Split Rock's  Market Rate
Application. The letter requested that Split Rock provide additional information
about  the  affiliate  relationships  noted  above.  Specifically,   the  letter
requested  that Split Rock explain why MP is a  cooperative,  and requested that
Split Rock respond to two scenarios specified in the letter.

II.      SPLIT ROCK'S AMENDED FILING

Split Rock and its  Members  have spent  considerable  time and effort to ensure
that captive customers will not be adversely affected by affiliate transactions.
As  explained  in further  detail  below,  Split Rock  retains no profits at its
level, but rather  regularly  distributes any profits to its Members MP and GRE.
MP has  expressly  committed to treat  revenues  from Split Rock as if they were
earned within MP, and as such,  there is no opportunity  for such revenues to be
diverted to MP's shareholders.  Ratepayers will benefit from the revenues in the
same manner as if such revenues were obtained directly by MP.

         A.       Transactions Between MP and Split Rock Will Not Adversely
                  ---------------------------------------------------------
                  Affect MP's Ratepayers
                  ----------------------

The  deficiency  letter first asks for a detailed  explanation as to why MP is a
cooperative  and how its customers  are the  cooperative's  owners,  and are not
captive  ratepayers.  MP is a traditional  investor-owned  utility,  and neither
Split Rock nor MP contends  that MP is a  cooperative.  Split Rock does  contend
that Split Rock itself, although not a cooperative, is


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                                                                  [MORGAN, LEWIS
Mr. David P. Boergers                                        & BOCKIUS LLP LOGO]
April 21, 2000
Page 3

structured like a cooperative,  and that this structure  eliminates any concerns
about affiliate abuse.

In the  traditional  case where a power marketer is seeking to transact with its
affiliated  public utility,  the Commission is concerned that the power marketer
and the  affiliated  utility  may  transact in ways that result in a transfer of
benefits from the  affiliated  utility (and its  ratepayers),  to the affiliated
power marketer (and its shareholders).  See, e.g., GS Electric Generating Corp.,
Inc., 81 FERC Paragraph 61,042 (1997). For example, the utility may purchase
power from its  affiliated  marketer  at  higher-than-market  rates,  or sell
power to its affiliated  power  marketer at  lower-than-market  rates - at the
expense of the utility's ratepayers - in exchange for other benefits which are
not passed on to the utility's  ratepayers. See, e.g., Hinson Power Co., 72 FERC
Paragraph 61,190,  at 61,911 (1995). In the case of cooperatives, however, this
concern is not present because the cooperative's owners are also its ratepayers;
thus, any profits or benefits  inuring to the  cooperative  are passed through
automatically  to the ratepayer/owners. See, e.g., Hinson, 72 FERC Paragraph
61,190, at 61,911.

Here,  Split Rock is  wholly-owned  by its sole Members MP and GRE, who are also
the  recipients  of Split Rock's joint  dispatch and power  marketing  services.
Split Rock is essentially a service entity for its Members.  Split Rock does not
have any "shareholders" separate and apart from these Members.

Although Split Rock will sell power to its Members, all sales by Split Rock to a
Member will be priced based on Split  Rock's cost,  and Split Rock will not earn
any  margins on power  sales to  Members.  Because  Split Rock will not earn any
margin  on sales of power to MP, no  revenues  of MP will be  diverted  to Split
Rock.  MP's ratepayers will thus be indifferent as to whether MP purchases power
from Split Rock, or directly from an unaffiliated third party.

Likewise,  although Split Rock will also purchase power from its Members, all of
Split  Rock's  purchases  from MP and GRE will be  priced  based  on a  transfer
pricing methodology agreed to and developed by the Members, which is intended to
track  market  prices.  Split Rock may sell power  purchased  from MP or GRE, to
third parties at a price that differs slightly from the price paid by Split Rock
to MP or GRE.  However,  Split Rock will not retain any profits earned from such
transactions.  Rather,  all  profits  obtained  by Split Rock will be  regularly
distributed to its Members, MP and GRE.

Accordingly,   Split  Rock  is  structured  like  a  cooperative,  in  that  its
Member-owners are also its customers,  and any profits earned by Split Rock will
be  regularly  disbursed  to its  Member-owners,  MP and GRE.  As noted,  MP has
expressly  committed  to treat  such  revenues  from  Split Rock as if they were
revenues earned by MP. MP's ratepayers will not be adversely


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                                                                  [MORGAN, LEWIS
Mr. David P. Boergers                                        & BOCKIUS LLP LOGO]
April 21, 2000
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affected by Split Rock's  involvement in  transactions  with its Members.  Split
Rock is simply a joint  dispatch and power  marketing  organization,  created to
provide its  Members  with the  economic  benefits  of jointly  dispatching  and
marketing their combined resources.

         B.       Examples of Transactions
                  ------------------------

The letter  also  requests  that Split Rock  address  two  specific  examples of
transactions  and revenue flows.  Split Rock will address each of these examples
in turn.

         (1) Purchases by MP: "If MP purchases power at market-based  rates from
         Split Rock at a price that is above the prevailing market,  explain why
         this transaction will not adversely affect MP's captive ratepayers.  In
         your example,  trace the stream of revenues from MP to Split Rock, back
         to MP and its captive ratepayers."

The short answer is that MP's ratepayers and  shareholders  will be in precisely
the same  position  as if MP made the  purchase  from the market.  Split  Rock's
involvement in a purchase  transaction for one of its Members is similar to that
of a broker. Split Rock purchases power and resells it to the Member at the same
price paid by Split  Rock.  There is no mark-up  for such  purchases,  and Split
Rock's administrative and other non-power costs of the transaction are recovered
separately through its dispatch agreements with its Members. To the extent Split
Rock buys power at a price higher than a perceived  market price,  the result is
the same as if MP had made  such a  purchase  itself.  This  should  not  occur,
however,  as under the  pricing  methodology  established  by the  Members,  the
Members have the right to the lowest-cost energy purchased by Split Rock.

Accordingly,  Split Rock will not earn any margins from sales to MP. The results
will be the same as if MP had entered into a  transaction  directly with a third
party, leaving MP's ratepayers indifferent as to whether MP purchases power from
Split Rock, or directly from unaffiliated third parties.

         (2)  Purchases  by  Split  Rock:  "If  Split  Rock  purchases  power at
         market-based  rates  from MP at a price  that is below  the  prevailing
         market,  explain why this  transaction  will not adversely  affect MP's
         captive ratepayers.  In your example,  trace the stream of revenues and
         describe  the  impact  this  transaction  will  have  on  MP's  captive
         ratepayers."

The pricing  methodology  developed  by the Members for  purchases by Split Rock
from MP or GRE,  combines a regional  day-ahead  market  index with Split Rock's
actual market experience.


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                                                                  [MORGAN, LEWIS
Mr. David P. Boergers                                        & BOCKIUS LLP LOGO]
April 21, 2000
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Accordingly,  the price paid by Split  Rock to MP for power may differ  from the
price  obtained by Split Rock upon  resale,  because  the market  price will not
reflect the market index factor upon which the price paid by Split Rock to MP is
based.

In the  event  that the  price  paid by Split  Rock to MP for power is below the
prevailing market price subsequently obtained by Split Rock, however, Split Rock
does not retain the difference.  Rather, as discussed above in Section II.A, any
Split Rock profit  will be  disbursed  to the  Members,  MP and GRE.  Although a
portion of Split Rock profits from sales of power  originally  purchased from MP
may go to GRE,  the sharing of profits will also work to MP's  benefit:  MP will
receive a similar  share of any Split Rock profits  obtained from sales of power
which Split Rock  originally  purchased  from GRE. As noted,  MP will treat such
disbursements  from Split Rock as if they were obtained  directly  through MP as
utility revenues.

         C.       Overall Benefits of Split Rock
                  ------------------------------

Although  the April 10, 2000  letter did not ask that MP or Split Rock  describe
the anticipated  benefits of Split Rock, Split Rock's activities are expected to
result in significant  savings to MP's ratepayers.  The economic dispatch of the
Members'  combined  generation  resources  will result in increased  operational
efficiencies.  Further,  Split Rock will  engage in  marketing  on behalf of its
Members,  with the goal of optimizing the value of their  resources.  Split Rock
will also engage in power trading  transactions with third parties,  and MP will
receive its  proportionate  share of Split Rock's profits from its power trading
activities. As noted, MP has committed to treat all revenues obtained from Split
Rock as utility  revenues.  Overall,  the Members  anticipate  that Split Rock's
economic  dispatch,  marketing,  and power  trading  activities  will  result in
significant cost savings and economic benefits to MP, and to MP's ratepayers.

III.     REQUEST FOR EXPEDITED NOTICE AND COMMENT PERIOD

As noted in the Market Rate Application, Split Rock and its Members desire Split
Rock to commence commercial operations on May 1, 2000, the beginning of the MAPP
summer season.  Accordingly,  Split Rock requested waiver of the standard 60-day
notice  requirement  to permit its Market Rate Tariff to become  effective  as a
rate schedule as of May 1, 2000. Such an effective date will allow Split Rock to
engage  in  transactions  under  the  Market  Rate  Tariff  as soon as it begins
operations, and to begin its joint dispatch and marketing functions on behalf of
the Members for the full upcoming MAPP summer season.

Split Rock  respectfully  requests that the Commission issue the attached notice
of amendment no later than April 24, 2000, and that the Commission  provide that
comments must be received


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                                                                  [MORGAN, LEWIS
Mr. David P. Boergers                                        & BOCKIUS LLP LOGO]
April 21, 2000
Page 6

no later than April 28, 2000.  This will allow the Commission to issue its order
as soon as possible.

A notice of filing of amendment suitable for publication in the Federal Register
and a copy of the notice on diskette are also included.

In the event  additional  information  is needed,  please  contact either of the
undersigned.

Sincerely,


/s/ Kristina E. Beard

John D. McGrane
Kristina E. Beard

Attorneys for Minnesota Power, Inc., on behalf of Split Rock Energy LLC,
and Minnesota Power, Inc.


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                            UNITED STATES OF AMERICA
                                   BEFORE THE
                      FEDERAL ENERGY REGULATORY COMMISSION

SPLIT ROCK ENERGY LLC                       )           DOCKET NO. ER00-1857-000
MINNESOTA POWER, INC.                       )

                                NOTICE OF FILING
                                (April   , 2000)
                                       --
Take notice that on April 21, 2000,  Split Rock Energy LLC, and Minnesota Power,
Inc.,  submitted an amendment to the  Application  of Split Rock Energy LLC, for
Market-Based  Rate Authority,  and Proposed  Revisions to Minnesota Power,  Inc.
Wholesale Coordination Service Tariff No. 2.

Any person  desiring to be heard or to protest such filing  should file a motion
to intervene or protest with the Federal Energy Regulatory Commission, 888 First
Street,  N.E.,  Washington,  D.C. 20426, in accordance with Rules 211 and 214 of
the Commission's  regulations (18 C.F.R. Sections 385.211 and 385.214). All such
motions or protests should be filed on or before       , 2000. Protests will
be considered by the  Commission in  determining  the  appropriate  action to be
taken,  but will not serve to make  protestants  parties to the proceeding.  Any
person  wishing to become a party must file a petition to  intervene.  Copies of
this  filing  are on file  with the  Commission  and are  available  for  public
inspection.   This   filing   may   also   be   viewed   on  the   Internet   at
http://www.ferc.fed.us/online/rims.htm (call 202-208-2222 for assistance).

                                                     David P. Boergers
                                                     Secretary


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                             CERTIFICATE OF SERVICE

         I hereby certify that I have this day caused to be served the foregoing

document upon each person  designated  on the official  service list compiled by

the Secretary in these proceedings.

         Dated at Washington, D.C. this 21st day of April, 2000.



                                                     /s/ Kristina E. Beard
                                                     ---------------------------

                                                     Kristina E. Beard
                                                     Morgan, Lewis & Bockius LLP
                                                     1800 M Street, N.W.
                                                     Washington, D.C. 20036