UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 --------------


                                    Form 11-K

                      FOR ANNUAL REPORTS OF EMPLOYEE STOCK
                      REPURCHASE SAVINGS AND SIMILAR PLANS
                        PERSUANT TO SECTION 15(d) OF THE
                         SECURITIES EXCHANGE ACT OF 1934

(Mark One)

[X]
                 ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE
                SECURITIES EXCHANGE ACT OF 1934 (NO FEE REQUIRED)

                   For the fiscal year ended December 31, 2006

                                       OR

[ ]
               TRANSITION REPORT PURSUANT TO SECTION 15 (d) OF THE
                SECURITIES EXCHANGE ACT OF 1934 (NO FEE REQUIRED)

             For the transition period from ___________ to _________

                                  ------------


                           Commission file no. 1-14161

                                  ------------


                                 KeySpan Energy
                         401(k) Plan for Union Employees
                            (Full title of the Plan)

                               KeySpan Corporation
          (Name of issuer of the securities held pursuant to the Plan)

                              One MetroTech Center

                             Brooklyn, NY 11201-3385

                     (Address of principal executive office)










KEYSPAN ENERGY 401(k) PLAN FOR UNION EMPLOYEES



TABLE OF CONTENTS
- ------------------------------------------------------------------------------------------------------------------------------

                                                                                                                          Page
                                                                                                                      
REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM                                                                    1

FINANCIAL STATEMENTS:

   Statements of Assets Available for Benefits as of December 31, 2006 and 2005                                            2

   Statement of Changes in Assets Available for Benefits for the Year Ended December 31, 2006                              3

   Notes to Financial Statements as of December 31, 2006 and 2005 and for the Year Ended December 31, 2006                4-13

SUPPLEMENTAL SCHEDULES:

   Form 5500, Schedule H, Part IV, Line 4i - Schedule of Assets (Held at End of Year)
      as of December 31, 2006                                                                                             14

   Form 5500, Schedule H, Part IV, Line 4a - Delinquent Participant Contributions for the Year                            15
      Ended December 31, 2006

SIGNATURES                                                                                                                16

EXHIBIT INDEX:

   Consent of Independent Registered Public Accounting Firm                                                               17



All other schedules required by Section 2520.103-10 of the Department of Labor's
Rules and Regulations for Reporting and Disclosure under the Employee Retirement
Income  Security Act of 1974  ("ERISA"),  have been omitted because they are not
applicable




REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Investment  Review  Committee and  Participants  of KeySpan Energy 401(k)
Plan for Union Employees:

We have audited the accompanying  statements of assets available for benefits of
KeySpan  Energy 401(k) Plan for Union  Employees (the "Plan") as of December 31,
2006 and 2005,  and the related  statement  of changes in assets  available  for
benefits for the year ended December 31, 2006.  These  financial  statements are
the responsibility of the Plan's management. Our responsibility is to express an
opinion on these  financial  statements  based on our audits.

We conducted  our audits in  accordance  with  standards  of the Public  Company
Accounting Oversight Board (United States). Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements are free of material misstatement.  The Plan is not required to have,
nor were we engaged to perform,  an audit of its internal control over financial
reporting as a basis for designing audit  procedures that are appropriate in the
circumstances,  but  not  for  the  purpose  of  expressing  an  opinion  on the
effectiveness  of  the  Plan's  internal   control  over  financial   reporting.
Accordingly we express no such opinion. An audit also includes  examining,  on a
test basis,  evidence  supporting  the amounts and  disclosures in the financial
statements,  assessing the accounting  principles used and significant estimates
made by  management,  as well as  evaluating  the  overall  financial  statement
presentation.  We believe  that our audits  provide a  reasonable  basis for our
opinion.

In our  opinion,  such  financial  statements  present  fairly,  in all material
respects,  the assets available for benefits of the Plan as of December 31, 2006
and 2005,  and the changes in assets  available  for benefits for the year ended
December 31, 2006 in conformity with accounting principles generally accepted in
the United States of America.

Our audits  were  conducted  for the  purpose of forming an opinion on the basic
financial  statements taken as a whole. The supplemental  schedule of (1) assets
(held at end of year) as of December 31, 2006 and (2) the schedule of delinquent
participant  contributions are presented for the purpose of additional  analysis
and  are  not a  required  part  of the  basic  financial  statements,  but  are
supplementary  information  required  by the  Department  of  Labor's  Rules and
Regulations for Reporting and Disclosure  under the Employee  Retirement  Income
Security Act of 1974. These supplemental schedules are the responsibility of the
Plan's  management.  The  supplemental  schedules  have  been  subjected  to the
auditing procedures applied in our audit of the basic 2006 financial  statements
and, in our opinion,  are fairly stated in all material respects when considered
in relation to the basic financial statements taken as a whole.

/s/Deloitte & Touche LLP
New York, New York
June 27, 2007







KEYSPAN ENERGY 401(K) PLAN FOR UNION EMPLOYEES

STATEMENTS OF ASSETS AVAILABLE FOR BENEFITS
DECEMBER 31, 2006 AND 2005
- ---------------------------------------------------------------------------------------------------------------------------


                                                                              2006                               2005
                                                                                                        
ASSETS:
 Participant-directed investments
  Investments-at fair value                                                $ 585,652,281                     $ 390,476,043
  Investment in Master Trust-at fair value                                   145,770,975                       136,824,078
Nonparticipant-directed investments                                                    -                       106,977,442
                                                                -------------------------       ---------------------------
                   Total investments                                         731,423,256                       634,277,563

RECEIVABLES:
 Participant contributions                                                 $     579,607                     $     561,778
 Employer contributions                                                           49,458                            51,583
                                                                -------------------------       ---------------------------
                   Total receivables                                             629,065                           613,361

ASSETS AVAILABLE FOR BENEFITS AT FAIR VALUE                                  732,052,321                       634,890,924

 Adjustments from fair value to contract value for fully
 benefit-responsive investments contracts                                      1,175,572                         1,804,385

                                                                -------------------------       ---------------------------
ASSETS AVAILABLE FOR BENEFITS                                              $ 733,227,893                     $ 636,695,309
                                                                =========================       ===========================




See notes to financial statements.



                                       2




KEYSPAN ENERGY 401(K) PLAN FOR UNION EMPLOYEES

STATEMENT OF CHANGES IN ASSETS AVAILABLE FOR BENEFITS
YEAR ENDED DECEMBER 31, 2006
- ------------------------------------------------------------------------------

ADDITIONS:
Investment income:
 Net appreciation in fair value of investments                   $  44,820,822
 Interest                                                            7,400,693
 Plan interest in Master Trust                                         851,808
 Dividends                                                          29,934,476
                                                        ----------------------
  Net investment income                                             83,007,799
                                                        ----------------------

Contributions:
 Participants                                                       38,249,026
 Employer                                                            3,334,388
 Rollovers                                                             625,130
                                                        ----------------------
  Total contributions                                               42,208,544
                                                        ----------------------

  Total additions                                                  125,216,343

DEDUCTIONS:
 Benefits paid to participants                                     (26,673,559)
 Plan administration fees                                              (17,166)
                                                        ----------------------

  Total deductions                                                 (26,690,725)
                                                        ----------------------

INCREASE IN ASSETS                                                  98,525,618

 Net assets transferred out to the Management Plan                  (1,993,034)

ASSETS AVAILABLE FOR BENEFITS:
Beginning of year                                                  636,695,309
                                                        ----------------------


End of year                                                      $ 733,227,893
                                                        ======================



See notes to financial statements


                                       3





KEYSPAN ENERGY 401(k) PLAN FOR UNION EMPLOYEES

NOTES TO FINANCIAL STATEMENTS
AS OF DECEMBER 31, 2006 AND 2005 AND FOR THE YEAR ENDED DECEMBER 31, 2006
- --------------------------------------------------------------------------


1.   DESCRIPTION OF THE PLAN

     The  following  description  of the  KeySpan  Energy  401(k) Plan for Union
     Employees  (the  "Plan")   available  to  eligible   employees  of  KeySpan
     Corporation   (the   "Company"  or   "KeySpan"),   provides   only  general
     information.  Participants  should  refer to the Plan  document  for a more
     complete description of the Plan's provisions.

     General - The Plan was approved by the  shareholders  of the Company at the
     annual meeting of  shareholders  on February 3, 1983. The Plan provides for
     eligible  employees of the Company and its selected  subsidiaries to become
     participants of the Plan. In general, all union employees as defined in the
     Plan  document are eligible to  participate  in the Plan  immediately  upon
     hire.  The  Plan is a  defined  contribution  plan  and is  subject  to the
     provisions  of  the  Employee   Retirement  Income  Security  Act  of  1974
     ("ERISA").  Effective January 1, 2002, the Plan was amended and restated to
     incorporate   the   provisions  of  a  stock  bonus  plan  that  meets  the
     requirements of an Employee Stock Ownership Plan ("ESOP"),  pursuant to the
     requirements of Section 4975 of the Internal Revenue Code ("IRC").

     The Plan consists of two distinct  components.  The first  component is the
     profit sharing portion,  including a cash or deferred arrangement ("CODA"),
     intended to be qualified  under Section  401(k) of the IRC, and consists of
     all Plan assets and funds, except for Plan assets and funds invested in the
     KeySpan  Common Stock Fund.  The second  component of the Plan is the ESOP,
     which  consists  solely of Plan  assets and funds  invested  in the KeySpan
     Common Stock Fund.

     The Plan  Administrator  is the KeySpan  Investment  Review  Committee (the
     "Committee").  The Committee was appointed by KeySpan's  Board of Directors
     to act as the Plan's named fiduciary  (within the meaning of ERISA) and has
     the power and duty to control and manage the operation  and  administration
     of the Plan.  The Committee  appointed The Vanguard Group  ("Vanguard")  as
     Plan recordkeeper and custodian.  In addition,  the Committee appointed The
     Vanguard  Fiduciary  Trust Company as the trustee under the Plan to receive
     and hold Company  Common Stock and the investment of  contributions  in the
     other funds as  described  herein and in the Plan  document.  Pursuant to a
     trust  document  executed by The  Vanguard  Fiduciary  Trust  Company,  the
     trustee  is  subject  to the same  fiduciary  responsibility  to the Plan's
     participants as an independent trustee.

     On November 21,  2006,  the KeySpan  Energy  401(k) Plans Stable Value Fund
     Master Trust ("Master Trust") was established. The Master Trust was created
     for the sole  purpose of holding the JPMorgan  Stable  Value Fund  ("Stable
     Value  Fund")  assets of the Plan and the Stable  Value Fund  assets of the
     KeySpan Energy 401(k) Plan for Management Employees.  The Stable Value Fund
     through the Master Trust is participant-directed (see Note 5).

     Plan  Amendments  -  Effective  March 1,  2005,  the  involuntary  cash-out
     threshold was reduced from $5,000 to $1,000.


                                       4




     Effective  May  1,  2005,  11  Algonquin  LNG,  Inc.  management  employees
     unionized  under Local 251  Teamsters.  The new union  members were given a
     match prospectively of $0.25 of each $1.00 that participants  contribute to
     the Plan, up to a maximum of 6% of the employee's compensation.

     On February 16, 2005, the Committee  approved the adoption of ERISA section
     404(c) for the mutual  funds in the Plan.  Section  404(c) of ERISA  states
     that if a plan sponsor,  such as KeySpan,  gives participants a broad range
     of investment  options from which to choose,  the  opportunity  to exercise
     control  over their  accounts,  and  enough  information  to make  informed
     investment  decisions,  then each participant  becomes  responsible for the
     success or failure of his or her own investment program.

     On September 22, 2005, the KeySpan Board of Directors approved an amendment
     to the Plan,  effective  January 1, 2006,  allowing  participants to invest
     Company  match into any of the funds  available in the Plan.  Prior to this
     amendment, Company match was initially invested in the KeySpan Common Stock
     Fund.  As of December  31,  2005,  the KeySpan  Common  Stock Fund,  with a
     balance of  $106,977,442,  was  represented as a  non-participant  directed
     investment on the Statement of Assets  Available for Benefits.  As a result
     of this amendment, all assets, including the KeySpan Common Stock Fund, are
     now fully participant directed.

     Effective January 1, 2006, the Plan adopted all relevant  provisions of the
     Internal  Revenue Service ("IRS")  regulations  applicable for 401(k) plans
     that  were  amended  and  restated   effective   December  29,  2004.  This
     restatement generally applies for the Plan year commencing January 1, 2006.

     Contributions  - All  participants  of the  Plan may  elect  to have  their
     compensation  reduced by no less than 1% and no more than 50% (in multiples
     of 1%) and  contributed  to the  Plan on the  participants'  behalf  by the
     Company.  Compensation  during  each year may not be  reduced  by an amount
     greater  than the  limitation  imposed by Section  402(g) of the IRC.  Such
     contributions  reduce the amount of participants' salary subject to current
     federal income tax and,  subject to applicable laws, state and local income
     taxes. Such contributions are subject to Social Security taxes.

     All  employees  who are eligible  pursuant to their  collective  bargaining
     agreement  and  contributing  to  the  Plan  will  receive  employer  match
     contributions and a 10% discount on the purchase of Company Common Stock on
     the first of the month  following  completion  of twelve months of service.
     Prior  to  January  1,  2006,  all  eligible  employees  received  matching
     contributions  in Company  Common Stock and a 10% discount on Company Stock
     for such  matching  contributions  regardless of where  employees  chose to
     invest their  contributions.  Effective  January 1, 2006,  participants are
     permitted  to  invest  Company  match  into any of the  investment  options
     available in the Plan.

     Any  contributions  invested in Company  Common Stock may be transferred to
     another  investment  option  immediately.  There are no holding  periods or
     restrictions with respect to Company Common Stock.

     Rollover   Contributions  -  If  a  participant  of  the  Plan  receives  a
     distribution  from a qualified savings or profit sharing plan of a previous
     employer, a "rollover" contribution by the participant in the amount of the
     distribution may be made to the Plan.

     Participant   Accounts  -  Individual  accounts  are  maintained  for  each
     participant.  Each participant's account is credited with the participant's
     contribution,  the Company's matching  contribution and discount on Company
     Common Stock, if applicable,  and allocations of (1) Company  discretionary
     contributions,  if  applicable,  and (2) Plan  earnings,  and charged  with
     withdrawals  and an  allocation  of Plan losses.  Allocations  are based on
     participant  earnings  or account  balances,  as defined.  A  participant's
     benefit is distributed from the participant's vested account as provided in
     the Plan document.


                                       5




     Vesting  and  Forfeitures  -  Participants  will be 100% vested in employer
     match, discount, and employer non-elective  contributions on the earlier to
     occur of: (i) the  participant's  completion  of three (3) years of service
     with the Company; (ii) the participant's retirement from the Company at age
     fifty-five  or  older;  (iii)  the  death  of  the  participant;  (iv)  the
     disability of the  participant if the  participant is receiving  disability
     benefits under Title II of the Social  Security Act; or (v) the termination
     or partial  termination  of the Plan.  A  participant  will be 100%  vested
     immediately  in his or her deferred cash  contributions,  rollover/transfer
     contributions,  and earnings  thereon,  if any. If a  participant  does not
     vest,  such  participant  will forfeit the  employer  match  discount,  and
     employer  non-elective  contributions  including  earnings  thereon  into a
     forfeiture account, which is maintained by Vanguard.

     As of December 31, 2006 and 2005,  forfeited  non-vested  accounts  totaled
     $4,538  and  $6,467,  respectively.  These  accounts  may be used to reduce
     future employer contributions and pay Plan administration expenses.  During
     the year ended December 31, 2006,  forfeited  non-vested  accounts were not
     utilized to reduce employer contributions.

     Investments - The Plan makes available the funds in which  participants may
     invest. Such investment options may be changed from time to time.

     All  employees  who are eligible  pursuant to their  collective  bargaining
     agreement  have an  opportunity  to acquire  shares of Company Common Stock
     ($.01 par value) at a 10%  discount.  In addition to Company  Common Stock,
     participants  may invest in other  investment  options  (collectively,  the
     "Funds").

     At the  direction  of the  participants,  Plan  assets are  invested in the
     KeySpan  Common  Stock  Fund,  and/or one or more of the  following  funds,
     namely:  Vanguard  Windsor Fund,  Vanguard 500 Index Fund,  JPMorgan Stable
     Value Fund,  Vanguard  Explorer Fund,  Vanguard  LifeStrategy  Conservative
     Growth  Fund,   Vanguard   LifeStrategy   Moderate  Growth  Fund,  Vanguard
     LifeStrategy Growth Fund, Vanguard Windsor II Fund, Vanguard PRIMECAP Fund,
     Vanguard  International Growth Fund, Vanguard Total Bond Market Index Fund,
     Vanguard  Mid-Cap  Index Fund,  and American  Funds Growth Fund of America,
     Class R-5.  Participants  should refer to the applicable  fund's prospectus
     for a complete description of each fund.

     On January 20, 2005, all  participant  balances in the Vanguard  Retirement
     Savings Trust,  with an expense ratio of 0.30%,  were moved to the Vanguard
     Retirement Savings Trust V, which offers an expense ratio of 0.25%.

     On June 13, 2006,  the Committee  approved the  replacement of the Vanguard
     Retirement Savings Trust V with the JPMorgan Stable Value Fund. On November
     20, 2006,  participant  balances in the Vanguard Retirement Savings Trust V
     totaling  $147,105,599  were transferred to the JPMorgan Stable Value Fund.
     The JPMorgan  Stable Value Fund is a separate  account  managed by JPMorgan
     Investment  Management  Inc.  for the Plan.  The  master  trustee  for this
     separate account is The Vanguard  Fiduciary Trust Company and the custodian
     is JP Morgan  Chase Bank,  N.A. The total fee for this fund is 0.225% which
     includes investment management and administrative fees.

     Participant  Loans -  Participants  may  borrow a minimum  of $1,000  and a
     maximum  amount  not  to  exceed  the  lesser  of  $50,000  or  50%  of the
     participant's  account  balance from the Plan (only employee  deferred cash
     contributions,  rollover/transfer  contributions  and earnings  thereon are


                                       6



     used to determine the maximum loan amount that can be taken). Currently, no
     more than two loans per  participant  are allowed  outstanding  at the same
     time.  General  purpose  loans are payable over a period not to exceed five
     years,  and bear  interest at the prime rate plus 1% (the prime rate at the
     time the loan is requested) as described in the Plan  document.  Currently,
     participants  may also  amortize a loan for the  purchase of their  primary
     residence  over a  fifteen-year  period,  which bears interest at the prime
     rate plus 1%. The loans are  secured by the  participant's  interest in the
     Plan.

     Payment  of  Benefits - Upon  termination  of  service,  a  participant  or
     eligible  beneficiary  whose  account  balance is greater than $1,000,  may
     elect to leave their balance in the Plan,  receive a lump-sum  amount equal
     to  the  value  of  the  participant's   vested  account,   receive  annual
     installments  or a partial  distribution,  or roll over their balance to an
     Individual Retirement Account or another qualified plan.

2.   SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

     Basis of  Accounting  - The  accompanying  financial  statements  have been
     prepared in accordance with accounting principles generally accepted in the
     United States of America.

     Use of Estimates - The  preparation  of financial  statements in conformity
     with  accounting  principles  generally  accepted  in the United  States of
     America  requires  management to make estimates and assumptions that affect
     the  reported  amounts of assets,  liabilities,  and  changes  therein  and
     disclosure  of  contingent  assets and  liabilities.  Actual  results could
     differ from those estimates.

     Risks and Uncertainties - The Plan provides for various investment options.
     The  Plan's  mutual  funds  invest in  various  securities  including  U.S.
     Government  securities,  corporate debt  instruments and corporate  stocks.
     Investment  securities,  in general,  are exposed to various  risks such as
     interest rate,  credit and overall market  volatility.  Due to the level of
     risk  associated  with  certain  investment  securities,  it is  reasonably
     possible that changes in the values of investment  securities will occur in
     the near term and that such changes could materially  affect  participants'
     account balances and the amount reported in the financial statements.

     Adoption of New Accounting Guidance - The financial  statements reflect the
     retroactive   adoption  of  Financial   Accounting  Standards  Board  Staff
     Position,   FSP   AAG   INV-1   and  SOP   94-4-1,   Reporting   of   Fully
     Benefit-Responsive  Contracts Held by Certain Investment  Companies Subject
     to the AICPA Investment Company Guide and  Defined-Contribution  Health and
     Welfare  and  Pension  Plans  (the  "FSP").  As  required  by the FSP,  the
     statements of assets available for benefits presents  investment  contracts
     at fair value as well as an  additional  line item showing an adjustment of
     fully benefit contracts from fair value to contract value. The statement of
     changes in assets  available for benefits is presented on a contract  value
     basis and was not  affected by the adoption of the FSP. The adoption of the
     FSP did not impact the reported amount of assets  available for benefits at
     December 31, 2006 and 2005.

     Investment  Valuation and Income  Recognition - The Plan's  investments are
     stated at fair value.  Shares of mutual funds are valued at quoted  closing
     market  prices,  which  represent the net asset value of shares held by the
     Plan on the last business day of the year.

     The Master Trust is  comprised  of the Stable  Value Fund which  includes a
     synthetic guaranteed investment contract ("Synthetic GIC") whose underlying
     investments  are  stated  at  fair  value.  Fair  value  of the  underlying
     investments is determined  taking into account values supplied by reputable
     pricing  or  quotation  service  or  quotations  furnished  by one or  more
     reputable  sources,  such as  securities  brokers,  dealers  or  investment
     bankers,  mutual fund  administrators or other relevant  information.  Fair
     value of the insurance contracts,  known as wrapper contracts,  is based on
     quoted  market  prices at the time of valuation  versus  actual cost of the
     contracts. The fair value of wrapper contracts for the Stable Value Fund as
     of December 31, 2006 was zero (see Note 4).


                                       7




     Fair value of the common  collective  trust has been estimated based on the
     underlying assets of the portfolio. The fair value of wrapper contracts the
     Vanguard Retirement Savings Trust V as of December 31, 2005 was zero.

     Amounts for securities that have no quoted market price represent estimated
     fair  value.  The fair value of the KeySpan  Common  Stock Fund is based on
     quoted market  prices and cash  balances.  The estimated  fair value of the
     KeySpan  Common  Stock Fund may differ from the quoted  market price of the
     Company's  Common  Stock  because the KeySpan  Common Stock Fund is divided
     into fund units.  Each unit  represents  a portion of ownership in the fund
     and consists  primarily of shares of Company  Common Stock and a small cash
     balance so that transactions can be processed daily.

     Participant   loans  are  valued  at  outstanding   loan  balances,   which
     approximate fair value.

     Purchases  and sales of  securities  are  recorded on a  trade-date  basis.
     Dividend  income is recorded on the  ex-dividend  date.  Interest income is
     recorded on an accrual basis.

     Management fees and operating expenses are charged to Plan participants and
     are reflected as a reduction of investment return in the mutual funds. Such
     management fees and operating expenses are deducted from income earned on a
     daily basis.

     Administrative  Expenses - Expenses for the  administration of the Plan are
     paid  for  either  by the Plan  Sponsor,  the  Plan as  stated  in the Plan
     document,  or  participants  as  described  above in the  section  entitled
     Investment Valuation and Income Recognition.

     Transfers - Along with the Plan,  the Company  also  sponsors a 401(k) Plan
     for Management  Employees.  If employees  change their status from union to
     management  or  from  management  to  union,  their  account  balances  are
     transferred  into the  corresponding  Plan. For the year ended December 31,
     2006, net transfers to the Plan totaled ($1,993,034).

     Payment of  Benefits - Benefits to  participants  are  recorded  when paid.
     There have been no amounts accrued but not yet paid as of December 31, 2006
     and 2005.

3.   INVESTMENTS

     The following  investments at fair value represent 5% or more of the Plan's
     assets available as of December 31, 2006 and 2005:



                                                                                   2006                                 2005
                                                                                                              
     KeySpan Common Stock Fund -
        KeySpan Common Stock Fund, 3,060,082 and
        3,009,211 and units, respectively**                                    $125,432,777                         $106,977,442

     Master Trust Investment -
        JP Morgan Stable Value Fund, 145,770,975 and
        0 shares, respectively**(1)                                             145,770,975                              __

     Common and Collective Trust -
        Vanguard Retirement Savings Trust V, 0 and
        136,824,078 shares, respectively**(2)                                       __                               136,824,078


                                       8




     Mutual Funds:
        Vanguard PRIMECAP Fund, 1,562,230 and
        1,503,779 shares, respectively**                                        107,715,772                           98,211,792

        Vanguard 500 Index Fund, 407,509 and
        390,236 shares, respectively**                                           53,216,577                           44,845,936

        Vanguard Windsor Fund, 2,617,740 and
        2,401,624 shares, respectively**                                         48,794,676                           41,187,859

        Vanguard Windsor Fund II, 1,706,961 and
        1,560,720 shares, respectively**                                         59,316,895                           48,897,367

        Vanguard Explorer Fund, 507,598 and
        451,534 shares, respectively**                                           37,922,645                           33,914,727


        ** Permitted party-in-interest

     (1)  The contract  value was  $146,946,457  and $0 at 12/31/06 and 12/31/05
          respectively.

     (2)  The contract  value was $0 and  $138,628,463  at 12/31/06 and 12/31/05
          respectively.

     During  2006,  the  Plan's  investments  (including  gains  and  losses  on
     investments  bought and sold, as well as held during the year)  appreciated
     (depreciated) in value by $44,820,822 as follows:




                                                                             
KeySpan Common Stock Fund                                                       $16,571,580
American Funds Growth Fund of America                                               720,547
Vanguard PRIMECAP Fund                                                            5,349,382
Vanguard 500 Index Fund                                                           6,210,161
Vanguard Windsor Fund                                                             3,560,411
Vanguard Windsor II Fund                                                          5,368,371
Vanguard Total Bond Market Index Fund                                              (156,673)
Vanguard LifeStrategy Moderate Growth Fund                                        2,542,420
Vanguard Explorer Fund                                                             (260,583)
Vanguard International Growth Fund                                                2,079,628
Vanguard LifeStrategy Growth Fund                                                 1,451,473
Vanguard LifeStrategy Conservative Growth Fund                                      440,564
Vanguard Mid-Cap Index Fund                                                         943,541
                                                                           ------------------

Net appreciation in fair value of investments                                   $44,820,822
                                                                           ==================


4.   SYNTHETIC GUARANTEED INVESTMENT CONTRACT

     The Plan provides a stable value  investment  option to  participants  that
     includes  a  Synthetic  GIC  which  is made up of  wrapper  contracts  that
     guarantee  principal and accumulated  interest and a portfolio of financial
     instruments that are owned by the Plan. The Synthetic GIC contract includes
     underlying  assets which are held in the Master Trust owned by the Plan and
     utilizes  benefit-responsive  wrapper  contracts  issued  by AIG  Financial
     Products Corp., Royal Bank of Canada,  State Street Bank and Trust Company,
     and  UBS AG,  proportionately.  The  contracts  provide  that  participants
     execute plan  transactions  at contract  value.  Contract value  represents
     contributions   made  to  the  fund,   plus  earnings,   less   participant
     withdrawals.  The interest rates are reset  quarterly  based on the current
     yield of the underlying investments and the spread between the market value
     and contract  value,  but the rate cannot be less than 0%.  Certain  events
     such as a plan  termination or a plan merger  initiated by the Plan Sponsor
     which result in a material and adverse effect on the wrapper  contracts may
     limit the ability of the Plan to  transact  at contract  value or may allow
     for the  termination of the wrapper  contracts at less than contract value.
     At this time, the Plan Sponsor  believes that any events that may limit the
     ability of the Plan to transact at contract value are remote.


                                       9




        Average yields:
          Based on annualized earnings (1)                                 0.14%
          Based on interest rate credited to participants (2)              5.31%

     (1)  Computed by dividing the  annualized  one-day  actual  earnings of the
          investments  on the last day of the plan year by the fair value of the
          investments on the same date.

     (2)  Computed by  dividing  the  annualized  one-day  earnings  credited to
          participants on the last day of the plan year by the fair value of the
          investments on the same date.

5.   INVESTMENTS IN MASTER TRUST

     The Master  Trust was  created  for the sole  purpose of holding the Stable
     Value  Fund  assets of the Plan and the  Stable  Value  Fund  assets of the
     KeySpan Energy 401(k) Plan for Management Employees. The Vanguard Fiduciary
     Trust Company is the master trustee and holds the investment  assets of the
     Master Trust as a commingled  fund in which each separate plan is deemed to
     have a  proportionate  undivided  interest in the investments in which they
     participate. At December 31, 2006, the Plan's interest in the net assets of
     the Master Trust was approximately 55%.

     The  following  table  summarizes  the net assets of the Master Trust as of
     December 31, 2006:




                                                                                                 
INVESTMENTS
JPMorgan Stable Value Fund at fair value                                                            $263,550,190

Adjustment from fair value to contract value for fully benefit-responsive
investment contracts                                                                                  $2,125,404

NET ASSETS OF THE MASTER TRUST AT CONTRACT VALUE                                                    $265,675,594

Plan's investment in Master Trust at fair value                                                     $145,770,975

Plan's percentage interest in Master Trust net assets                                                     55.31%

The KeySpan Energy 401(k) Plan for Management Employees investment
 in Master Trust at fair value                                                                      $117,779,215

The KeySpan Energy 401(k) Plan for Management Employees percentage
 interest in Master Trust net assets                                                                      44.69%


     The following  table  summarizes the investment  income of the Master Trust
     for the period beginning November 20, 2006 through December 31, 2006:




                                                                                                   
INVESTMENT INCOME
 Interest income                                                                                      $1,538,086

NET INVESTMENT INCOME                                                                                 $1,538,086

NET INVESTMENT INCOME FROM MASTER TRUST - BY PLAN
The KeySpan Energy 401(k) Plan for Union Employees                                                      $851,808
The KeySpan Energy 401(k) Plan for Management Employees                                                 $686,278



                                       10





6.   FEDERAL INCOME TAX STATUS

     The IRS has  determined  and  informed the Plan  administrator  by a letter
     dated January 15, 2003 that the Plan is qualified and the Trust established
     under the Plan is tax-exempt,  under the  appropriate  sections of the IRC.
     The  Plan  has been  amended  since  receiving  the  determination  letter;
     however,  the Company and the Plan  administrator  believe that the Plan is
     currently  designed and being  operated in compliance  with the  applicable
     requirements of the IRC. Therefore,  no provision for income taxes has been
     included in the Plan's financial statements.

7.   EXEMPT PARTY-IN-INTEREST TRANSACTIONS

     Certain Plan investments are shares of mutual funds and a common collective
     trust managed by the asset custodian and recordkeeper,  Vanguard,  with The
     Vanguard  Fiduciary  Trust  Company  as  Trustee,  as  defined  by the Plan
     document,    and   therefore   these   transactions   qualify   as   exempt
     party-in-interest  transactions. In addition, the Stable Value Fund managed
     by JP Morgan Investment  Management Inc., with The Vanguard Fiduciary Trust
     Company as trustee, Vanguard as recordkeeper, and JP Morgan Chase Bank N.A.
     as  asset   custodian   also   qualifies  as  an   exempt-party-in-interest
     transaction.  Fees paid for investment  management  services are charged to
     Plan  participants  and are included as a reduction of the return earned on
     each fund. The Plan's transactions  involving Company Common Stock are also
     party-in-interest  transactions.  Certain  employees  and  officers  of the
     Company,  who may also be participants in the Plan, perform  administrative
     services  to the  Plan  at no  cost to the  Plan.  These  party-in-interest
     transactions  are  not  deemed  prohibited  because  they  are  covered  by
     statutory  and  administrative  exemptions  from the IRC and the  rules and
     prohibited transactions of ERISA.

     At December 31, 2006 and 2005, the Plan held 3,060,082 and 3,009,211 units,
     respectively,  of the  KeySpan  Common  Stock  Fund,  with a cost  basis of
     $100,975,418 and $96,314,388,  respectively. During the year ended December
     31, 2006,  the Plan recorded  dividend  income for the KeySpan Common Stock
     Fund of $5,631,082.

8.   NON-EXEMPT PARTY-IN-INTEREST TRANSACTIONS

     In November 2006, the Department of Labor ("DOL") completed a review of the
     Plan and  identified  certain  transactions  in which the DOL believed that
     employee  contributions from some subsidiary  payrolls were deposited later
     than required under DOL regulation 2510.3-102. The contributions identified
     in these transactions totaled $1,247,506.  The DOL calculated lost earnings
     attributable to these  transactions to be eight hundred  fifty-nine dollars
     ($859).  In  light of this  deminimus  amount  and to  avoid  the cost of a
     protracted administrative proceeding, the Company has deposited this amount
     into  the  Plan  as a  discretionary  employer  contribution  to  pay  Plan
     expenses.

9.   PLAN TERMINATION

     Although  the  Company  has  not  expressed  any  intent  to do so,  it may
     terminate  the Plan at any  time.  In the  event of Plan  termination,  the
     accounts  of all  participants  affected  shall  become  fully  vested  and
     non-forfeitable.  Assets remaining in the trust fund will be distributed to
     the  participants  and  beneficiaries  in  proportion  to their  respective
     account balances.


                                       11




10.  PLAN SPONSOR MERGER

     On February 25, 2006,  KeySpan entered into an Agreement and Plan of Merger
     (the "Merger Agreement"),  with National Grid plc, a public limited company
     incorporated  under the laws of England and Wales  ("Parent")  and National
     Grid US8, Inc., a New York  Corporation  ("Merger Sub"),  pursuant to which
     Merger Sub will merge with and into  KeySpan (the  "Merger"),  with KeySpan
     continuing  as the  surviving  company  and  thereby  becoming  an indirect
     wholly-owned subsidiary of the Parent. Pursuant to the Merger Agreement, at
     the effective time of the Merger,  each outstanding share of KeySpan Common
     Stock,  par value  $0.01 per share of KeySpan  (the  "Shares"),  other than
     treasury shares and shares held by the Parent and its  subsidiaries,  shall
     be  canceled  and shall be  converted  into the right to receive  $42.00 in
     cash, without interest.

     Consummation  of the  Merger is  subject  to  various  closing  conditions,
     including but not limited to the receipt of requisite  regulatory approvals
     from certain United States federal and state public utility,  antitrust and
     other  regulatory  authorities,  many of which have been filed or obtained.
     KeySpan  and  National  Grid plc  will  continue  to  pursue  all  required
     approvals.  We are,  however,  unable  to  predict  the  outcome  of  these
     regulatory  proceedings  and no assurance can be given that the Merger will
     occur or the timing of its completion.  For more  information on the Merger
     see KeySpan's  reports filed with the  Securities  and Exchange  Commission
     during 2007.

     Upon completion of the Merger participants in the Plan who own units of the
     KeySpan  Common  Stock  Fund  will  receive  cash in  their  Plan  accounts
     representing  the number of units held  multiplied by the unitized value of
     the fund on the Merger date. The unitized value of the fund may differ from
     the transaction  price of $42.00 per share.  See the section above entitled
     Investment  Valuation and Income  Recognition for a further  description of
     the unitized pricing in the KeySpan Common Stock Fund.


11.  SUBSEQUENT EVENTS

     Effective  March 31, 2007, in accordance  with the Pension  Protection Act,
     all  restrictions  with respect to transfers  into the KeySpan Common Stock
     Fund were eliminated.  Participant  transfers  resulting in the purchase of
     Company  Common Stock in the KeySpan  Common Stock Fund are not eligible to
     receive a 10% discount.

12.  RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500

     The following is a reconciliation  of assets available for benefits and the
     statement of changes in assets  available  for  benefits per the  financial
     statements  to Form 5500 as of December  31, 2006 and 2005 and for the year
     ended December 31, 2006:



Statements of assets available for benefits:
                                                                                                             
  Assets available for benefits per the
    financial statements                                                         $ 733,227,893                    $ 636,695,309
  Less: Loans to participants deemed distributed for tax purposes                     (167,988)                          -
  Less: Adjustment from contract value to fair value for
    fully benefit-responsive investment contracts                                   (1,175,572)                      (1,804,385)
                                                                                 --------------                   --------------

  Net assets available for benefits per the Form 5500, at fair value             $ 731,884,333                    $ 634,890,924
                                                                                 ==============                   ==============


                                       12




Statement of changes in assets available for benefits:
  Increase in assets per the financial statements                                 $ 98,525,618
 Less: Deemed loan defaults included on Form 5500, Schedule H, Line 2g                (167,988)
 Less: Adjustment from contract value to fair value for
     fully benefit-responsive wrap contracts                                        (1,175,572)
                                                                                  -------------

  Net income per Form 5500                                                        $ 97,182,058
                                                                                  =============


     The line  item for the value of  interest  in  common/collective  trusts as
     presented on the asset and  liability  statement as of December 31, 2005 on
     Schedule  H,  Form  5500  differs  from  the  investment  line  item on the
     financial  statements by $1,804,385.  This amount represents the difference
     between  investments  at fair  value per the  financial  statements  versus
     contract value as presented on Form 5500.


                                     *******


                                       13






KEYSPAN ENERGY 401(k) PLAN FOR UNION EMPLOYEES

FORM 5500, SCHEDULE H, PART IV, LINE 4i--
SCHEDULE OF ASSETS (HELD AT END OF YEAR)
DECEMBER 31, 2006
- -----------------------------------------------------------------------------------------------------------------------------------
                                                     (c) Description of Investment,
                                                         Including Maturity Date,
           (b) Identity of Issue, Borrower,              Rate of Interest, Collateral,
(a)            Lessor or Similar Party                   Par or Maturity Value                (d) Cost    Shares   (e) Current Value

                                                                                                       
*   KeySpan Common Stock Fund                         Common Stock                              **      3,060,082    $ 125,432,777
    American Funds Growth Fund of America             Mutual Fund                               **        412,556       13,556,580

    Vanguard Funds:
*   Vanguard PRIMECAP Fund                            Mutual Fund                               **      1,562,230      107,715,772
*   Vanguard 500 Index Fund                           Mutual Fund                               **        407,509       53,216,577
*   Vanguard Windsor Fund                             Mutual Fund                               **      2,617,740       48,794,676
*   Vanguard Windsor II Fund                          Mutual Fund                               **      1,706,961       59,316,895
*   Vanguard Total Bond Market Index Fund             Mutual Fund                               **      2,631,440       26,288,083
*   Vanguard LifeStrategy Moderate Growth Fund        Mutual Fund                               **      1,402,142       28,547,606
*   Vanguard Explorer Fund                            Mutual Fund                               **        507,598       37,922,645
*   Vanguard International Growth Fund                Mutual Fund                               **      1,009,952       24,097,455
*   Vanguard LifeStrategy Growth Fund                 Mutual Fund                               **        567,604       13,548,715
*   Vanguard LifeStrategy Conservative Growth Fund    Mutual Fund                               **        459,868        7,629,207
*   Vanguard Mid-Cap Index Fund                       Mutual Fund                               **        492,026        9,732,275
                                                                                                                   ----------------
                                                                                                                       555,799,263

*   Participant loans receivable                      Participant loans (maturing 2007 to 2021 at                       29,853,018
                                                      interest rates ranging from 5.0% to 10.5%)                   ----------------

    Total                                                                                                            $ 585,652,281
                                                                                                                   ================

*    Permitted party-in-interest.

**   Cost information is not required for participant-directed  investments and,
     therefore, is not included.



                                       14






                 KEYSPAN ENERGY 401(k) PLAN FOR UNION EMPLOYEES

FORM 5500 SCHEDULE H, PART IV, LINE 4a -
DELINQUENT PARTICIPANT CONTRIBUTIONS
YEAR ENDED DECEMBER 31, 2006
- -----------------------------------------------------------------------------------------------------------------------------------
                                                                                                           
                   Relationship to                                                                                   Participant
Identity of        Plan, Employer,                                                                                  Contributions
Party Involved     or Other Party-in-                                                                                Transferred
                   Interest               Description of Transactions                                              Late to the Plan

KeySpan            Employer/              In  November  2006,  the  Department  of Labor  ("DOL")  completed a        $1,247,506
Corporation        Plan Sponsor           review of the Plan and identified certain  transactions in which the
                                          DOL  believed  that  employee  contributions  from  some  subsidiary
                                          payrolls were  deposited  later than required  under DOL  regulation
                                          2510.3-102.  The  contributions  identified  in  these  transactions
                                          totaled  $1,247,506.  The DOL calculated lost earnings  attributable
                                          to  these  transactions  to  be  eight  hundred  fifty-nine  dollars
                                          ($859).  In light of this deminimus  amount and to avoid the cost of
                                          a protracted  administrative  proceeding,  the Company has deposited
                                          this amount into the Plan as a discretionary  employer  contribution
                                          to pay Plan expenses.








                                       15






                                   SIGNATURES




The Plan.  Pursuant to the requirements of the Securities  Exchange Act of 1934,
the trustees (or other persons who  administer  the employee  benefit plan) have
duly  caused this  annual  report to be signed on its behalf by the  undersigned
hereunto duly authorized.



                                         KeySpan Energy 401(k) Plan for
                                         Union Employees





                                           BY:  /s/ Michael J. Taunton
                                           ---------------------------
                                           Michael J. Taunton
                                           Senior Vice President and Treasurer
                                           KeySpan Corporation





                                           Date:  June 27, 2007



                                       16