KEYSPAN CORPORATION
                              One MetroTech Center
                          Brooklyn, New York 11201-3850
                                 (718) 403-1000
                           --------------------------


May 10, 2007

VIA EDGAR TRANSMISSION
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Securities and Exchange Commission
Division of Corporation Finance
100 F Street, N.E.
Washington, D.C. 20549

Attn:  Michael Moran, Branch Chief

         Re:      KeySpan Corporation
                  Form 10-K for Fiscal Year Ended December 31, 2006
                  Filed February 22, 2007
                  File No. 1-14161

Dear Mr. Moran:

     KeySpan  Corporation  (the  "Company") sets forth below its response to the
comments of the staff of the Division of  Corporation  Finance (the  "Staff") of
the  Securities  and Exchange  Commission  (the  "Commission")  contained in the
letter  received  by  telecopy  dated  March 30,  2007 (the  "Comment  Letter"),
concerning  the KeySpan  Form 10-K for the fiscal year ended  December 31, 2006.
For your  convenience,  we have set  forth  the  text of the  comments  from the
Comment Letter, followed in each case by the response.

     We are  enclosing  five copies of this  response  letter.  Page  references
included  in  responses  to the Staff's  comments  are to pages set forth in the
edgarized version of the Form 10-K.

Note 2.  Business Segments, page 125
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     1.   Please  tell us in more detail how you  determined  that you have only
          one reportable gas and one electric services segments. We note that on
          page  105 you  disclose  that  only  four of your  six  regulated  gas
          utilities (KEDNY,  KEDLI,  Boston Gas Company and EnergyNorth  Natural
          Gas, Inc.) and your Long Island based electric generation subsidiaries
          are subject to the provisions of SFAS no. 71. Please  supplement  your
          response by providing  us with  examples of current  internal  reports




          that  management  uses to assess the performance of your business such
          as internal financial statements. In this regard, please explain to us
          in detail  your  operating  segments  and provide to us three years of
          revenue  information for each operating  segment you have  identified.
          Also,  provide  three years of profit (loss) and margin  history,  and
          asset information for each operating segment  identified.  We may have
          further comment.

     KeySpan applies the provisions of SFAS 131 in determining the components of
each of its four  operating  segments.  SFAS 131 requires the financial  results
reported for each segment to be based upon what is used by the "chief  operating
decision maker" (the "CODM") in formulating a determination  as to how to assign
resources  to a segment and how to appraise  the  performance  of that  segment.
KeySpan's segments are based upon a management approach,  which is indicative of
its organizational structure,  revenue sources and nature of activities,  and is
also consistent with information presented to the Board of Directors.

     With regard to the Gas Distribution segment, KeySpan records results of its
operations  for four of its regulated  gas utilities  under SFAS 71. In 1999 and
1998,  respectively,  base rates charged by two gas utility companies  (Colonial
Gas Company and Essex Gas Company) were frozen at their  current  levels for ten
year periods ending 2009 and 2008, respectively. Due to the length of these base
rate  freezes,  the  Colonial  Gas and  Essex  Gas  companies  discontinued  the
application  of SFAS 71. We do not believe this factor alone would require these
companies to be considered a separate operating segment.

     The  operations of all of our six gas  utilities  are centrally  managed by
Nickolas  Stavropoulos,  President,  KeySpan Energy Delivery.  Mr.  Stavropoulos
serves as the CODM for the  consolidated  gas utility  group.  Mr.  Stavropoulos
considers the revenues,  expenses,  cash flows and asset  allocation for the gas
utility  companies for purposes of  allocating  resources to each of the six gas
utilities  and  assesses  their  performance  as part  of the  Gas  Distribution
segment. More importantly, three operations officers who have responsibility for
gas  construction,   service  and  maintenance  operations  across  all  service
territories   report   directly  to  the  CODM  and  the  chief   engineer   has
responsibility  to the CODM for asset management and resource  management across
all regions.

     KeySpan's  Gas  Distribution  segment  utilizes a  disciplined  approach to
enterprise-wide  asset  management and resource  planning.  The segment  manages
field operations as one enterprise across all regions.  In addition,  a Resource
Management  group is responsible  to the CODM and acts as the primary  interface
between asset and field operations. The chief responsibility of this group is to
optimize  capital   utilization  by  deploying  resources  across  all  regions.
Directors and managers in the Gas  Distribution  segment are aligned in the same
manner as the operations officers, all of whom ultimately report up to the CODM.
Moreover,  the management  and operation of the gas supply  function for each of
the six utilities is centralized within one organization, which employs a system
wide  strategy  related  to the  gas  supply  portfolio  of all  six  utilities.


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Furthermore,   the  operating  results  of  the  Gas  Distribution  segment  are
considered in the aggregate for purposes of  determining  performance  under the
Company's incentive compensation plan applicable to employees in this segment.

     The CODM  also  holds  monthly  operating  meetings  in which  results  are
analyzed,  issues  discussed,  and tactics  developed  to ensure  financial  and
operating  goals  are met for the  consolidated  gas  business  unit.  Officers,
directors,  and  managers  attend  these  meetings,  which are held in revolving
service  territories.  The  CODM is also  responsible  for a  reporting  package
referred to as the  Quarterly  Strategic  Review,  which  outlines the financial
performance  of the entire gas business as one operating  segment.  The internal
financial goals of the Gas  Distribution  segment are reviewed by the CODM on an
enterprise-wide  basis,  incorporating  all  six  gas  utilities  together  on a
consolidated basis.

     In addition  to being  centrally  managed by the CODM,  each of the six gas
utilities  generate revenues and incur expenses while providing gas distribution
services  to  customers  in  a  franchised  distribution  area  granted  by  the
respective  state in which it operates.  Notwithstanding  the fact that Colonial
Gas Company and Essex Gas Company are under  10-year rate  freezes,  each of the
gas utilities is subject to rate regulation by its respective  state  regulatory
authority, which includes recovery of all gas procurement costs. As a result, we
view all six gas utilities as a single operating segment.

     The Electric Services segment,  comprised of generation as well as services
providing for management of the electric  transmission and  distribution  assets
owned by the Long Island Power  Authority  ("LIPA"),  is managed as one business
unit  under  the  direction  of Steven  Zelkowitz,  the  President  of the Asset
Optimization Group. Mr. Zelkowitz is the CODM for the Electric Services segment,
and is  responsible  for  the  operating  results  of  this  segment  as well as
allocating  resources among its components.  Mr. Zelkowitz  evaluates  operating
results,   growth   prospects,   earning  potential  and  areas  of  risk  while
facilitating  the  appraisal  of  historical  performance  and  expected  future
performance.

     The Electric  Services  segment  generates  revenues  and incurs  expenses,
forecasts  and tracks its revenues,  expenses and  operating  income as a single
business unit.  This segment owns,  leases and operates the electric  generating
plants on Long Island and in New York City ("Generation").  The sale of electric
energy and  capacity at  wholesale  rates by this  segment is  regulated  by the
Federal Energy Regulatory Commission ("FERC") pursuant to the Federal Power Act.
Such wholesale sales are made pursuant to tariffs approved by and filed at FERC.
All of our Long Island and New York City generation units are bid daily into the
New York electric  energy market  operated by the NYISO.  NYISO  dispatches  the
units based on  economics  to meet the needs of the New York State  Transmission
Operators.  Maintenance  and  testing of units and the  products  the units sell
(capacity,  energy and  ancillary  services) are all done in  coordination  with
NYISO as required by NYISO tariffs and procedures. As discussed in detail in our
Form 10-K, this segment provides capacity, energy and ancillary services to LIPA
from our Long Island generation facilities, as well as the day-to-day operation,
maintenance and capital  improvement  services for the Long Island  transmission


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and  distribution  ("T&D")  system (which is owned by LIPA)  pursuant to several
complex and interrelated  agreements  entered into in 1998. KeySpan does not own
any T&D assets but simply provides  operation and  maintenance  services to LIPA
pursuant to these unique agreements.

     All of the generation  facilities use the same fuels,  burning natural gas,
residual  oil or oil  distillate.  The  management  and  operation  of the  fuel
procurement function for all our generating facilities is centralized within one
organization,  which  employs  a  system  wide  strategy  related  to  the  fuel
procurement portfolio.

     The larger  generating  units are  generally  operated by dedicated  onsite
staff. Smaller units are operated remotely from a central location.  Maintenance
of the units is  generally  performed  by a central  maintenance  department  or
outside contractors depending on the nature and timing of the work.  Engineering
and  environmental  support are also provided by a central group that travels as
necessary throughout the Long Island and New York City service territory.  Shops
and  equipment  repair  support  for all of the units are  provided at a central
location.  Personnel are rotated among the  generating  units and central groups
according to business needs.

     Operations  planning,   maintenance  planning  and  scheduling,   staffing,
budgets,  human  resources,  finance and all of the other myriad  management and
support  functions  for all of our  generating  facilities  are  also  centrally
located. This arrangement has proved to be the most flexible and efficient,  and
is consistent with the manner in which we operate the Electric Services segment.
A recent  review by the NYS PSC  confirmed  the  efficacy  of this  organization
structure.  In addition,  management  is  periodically  rotated to the different
generating  facility sites between Long Island and New York City.  This leads to
increased productivity and reliability, uniformity of procedures, and sharing of
best practices  among the entire fleet of generating  units,  utilizing a common
criterion  based on a cohesive  approach for the required  preventive and demand
maintenance,   local  electric  system   reliability,   and  anticipated  future
operations.  Furthermore, the operating results of the Electric Services segment
are  considered in the aggregate for purposes of determining  performance  under
the  Company's  incentive  compensation  plan  applicable  to  employees in this
segment.

     The Electric  Services  segment conducts monthly meetings where results are
analyzed and resources  are  allocated.  The CODM holds staff  meetings with his
officer team for Generation  and T&D services to review  operating and financial
performance as well as regulatory issues on an  enterprise-wide  basis. Based on
the foregoing, we view our Generation and T&D management service operations as a
single operating segment.

     Attached to this  response are current  examples of select  financial  data
contained in internal  reports that management uses to assess the performance of
our  gas  and  electric  business,   appended  hereto  as  Exhibit  A.[1]  Also,
incorporated by reference are three years of revenue information, profit (loss),

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(1)  It should be noted that values  reported in such  internal  reports may not
     match corresponding values in the associated Forms 10-K and 10-Q due to the
     fact that these reports are generated prior to finalization of calculations
     and  reporting.  Further,  certain  intercompany  eliminating  entries were
     recorded for financial  reporting  purposes that were not made for internal
     reporting.

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and asset information presented in Footnote 2 to the Company's Form 10-K for the
year ended  December 31, 2006,  as well as the margin  history  presented in the
Management Discussion and Analysis of the Company's Form 10-K for the year ended
December 31, 2006, for each operating segment.



Note 8.  Hedging, Derivative Financial Instruments and Fair Values, page 156
- ----------------------------------------------------------------------------

     2.   Please  describe  for us and  enhance  future  disclosure  to  clearly
          articulate  the  nature and  purpose  of the fixed for float  unforced
          capacity  financial swap with Morgan Stanley Capital Group Inc. Please
          be detailed in your response. Furthermore, it is unclear to us why you
          disclose in Note 8 that the recognized fair value associated with this
          instrument is immaterial to the consolidated  financial  statements at
          December 31, 2006.  In this regard you disclose on page 58 the results
          of your Electric Services  Segment.  Based on the table you present it
          appears that the fixed for floating swap impacted  operating income by
          approximately  16% for the year ended December 31, 2006. See paragraph
          44 of SFAS no. 133. Also, please enhance future Item 7A disclosures to
          provide  a  sensitivity  analysis  with  respect  to  this  derivative
          instrument. See Item 305 of Regulation S-K.

     In  response  to Staff's  comment  regarding  the fixed for float  unforced
capacity  financial  swap (the "Swap  Agreement"),  as  disclosed  in Note 8, we
entered into a three year  financial swap with a third party related to New York
City electric capacity. This contract is not intended to be an economic hedge of
physical assets.

     The Company undertakes to modify future disclosure to include the following
additional text:

          Based  upon the  Company's  experience  in the New York City  electric
     capacity  market and our assessment  that a financial  opportunity  existed
     related to this market,  the Company entered into the Swap  Agreement.  The
     Swap Agreement  involves a financial  transaction and is not intended to be
     an economic hedge of our physical  generation  assets or a contract for the
     physical delivery of capacity or energy.  However, the same market dynamics
     that are expected to enhance our physical  generation business are expected
     to enhance the value of the financial Swap Agreement as well.


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     In  addition,  we also  advise the Staff that at  contract  inception,  the
initial fair value of the Swap Agreement was fully deferred under the provisions
of Emerging Issues Task Force Abstract 02-3 ("EITF 02-3"),  due to the Company's
belief  that  market  prices  for the  underlying  capacity  were  unobservable.
Accordingly, no fair value was recorded on the balance sheet at inception of the
contract.  Our  disclosure  in Note 8 was  referring  to  changes  in fair value
subsequent to contract inception,  which were minimal during 2006,  resulting in
the recognition of $0.3 million derivative asset relating to the unrealized fair
value at December 31, 2006. We believe this amount is immaterial  for disclosure
purposes.  Our MD&A  disclosure  was  referring  to  monthly  cash  settlements,
resulting in realized  annual gains during 2006 of $46.5  million,  disclosed as
Derivative  Financial  Instrument income for the Electric  Services segment.  At
December 31, 2006,  a derivative  asset of $0.3 million was recorded  related to
the swap,  while the  remainder of the fair value  associated  with the contract
remained deferred under the EITF 02-3 guidance.

     As  requested,  we undertake to enhance our Item 7A  disclosures  in future
reports  to  provide  an  adequate  sensitivity  analysis  with  respect to this
derivative  instrument,  and propose  the  following  disclosure  in such future
reports:

          The  main  driver  of the  Swap  Agreement  is the  clearing  price of
     capacity  in the  NYISO  administered  Spot  auction.  If the Spot  auction
     clearing  prices were to clear at $7.32,  which is $0.25 per kW-Month below
     the fixed price of $7.57 per  kW-Month in the Swap  Agreement,  assuming no
     other capacity market  changes,  KeySpan would incur a loss of $450,000 per
     month. If the Spot auction clearing prices were to clear at $7.82, which is
     $0.25 per kW-Month  above the fixed price of $7.57 per kW-Month in the Swap
     Agreement, assuming no other capacity market changes, KeySpan would realize
     a gain of $450,000 per month.

     The undersigned hereby acknowledges that (i) the Company is responsible for
the adequacy and accuracy of the  disclosure in the filing;  (ii) Staff comments
or changes to  disclosure  in response to Staff  comments do not  foreclose  the
Commission  from  taking any action with  respect to the  filing;  and (iii) the
Company may not assert Staff comments as a defense in any  proceeding  initiated
by the Commission or any person under the federal  securities laws of the United
States.

     Please direct any questions  concerning  this letter to the  undersigned at
(718)  403-6904 or to Alfred C. Bereche,  Associate  General  Counsel,  at (516)
545-5028.

                                                    Very truly yours,
                                                    /s/ Theresa A. Balog
                                                    --------------------
                                                    Theresa A. Balog
                                                    Vice President and
                                                    Chief Accounting Officer


cc:   Robert Babula
       Alfred C. Bereche




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                                    EXHIBIT A


Note 2.  Business Segments
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Gas Distribution Segment Sample Internal Report:
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         Gas Business Unit Quarterly Strategic Review - February 13, 2007

Electric Services Segment Sample Internal Report:
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         Electric Business Unit Quarterly Strategic Review - February 13, 2007






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