Exhibit 10.1

EXECUTION VERSION

IDR ENTITY ASSUMPTION AGREEMENT

THIS IDR ENTITY ASSUMPTION AGREEMENT (this “Agreement”) is entered into as of
September 28, 2009, by and among Magellan Midstream Partners, L.P., a Delaware
limited partnership (“Partners”), Magellan IDR LP, LLC, a Delaware limited
liability company (“IDR LLC”), and Magellan IDR, L.P., a Delaware limited
partnership (“IDR LP”). Each of the foregoing shall be referred to individually
as a “Party” and collectively as the “Parties.” Certain capitalized terms used
but not defined herein have the meanings assigned to them in the Simplification
Agreement (as defined below).

RECITALS

WHEREAS, Partners, Partners GP, Holdings and Holdings GP have entered into that
certain Agreement Relating to Simplification of Capital Structure dated as of
March 3, 2009 (the “Simplification Agreement”) pursuant to which, among other
items, (i) Partners will simplify its capital structure by an amendment of the
Partners Partnership Agreement which transforms (a) the Partners General Partner
Interest into Partners Common Units and a non-economic general partner interest
in Partners and (b) the IDRs held by IDR LP, representing 100% of the IDRs, into
Partners Common Units (together, the “Transformation”) and (ii) two days
thereafter, Holdings will dissolve and wind up its affairs, and the holders of
Holdings Common Units will receive a liquidating distribution of Partners Common
Units; and

WHEREAS, on the date of this Agreement and pursuant to the Simplification
Agreement and the Restated Partners Partnership Agreement: (i) the
Transformation was consummated, (ii) Partners GP will cause IDR LP to distribute
all of its Partners Common Units to Partners GP and IDR LLC, (iii) Partners GP
will cause IDR LLC to distribute all of its Partners Common Units to Partners
GP, (iv) Partners GP will distribute all of its Partners Common Units to
Holdings and (v) pursuant to the terms of this Agreement, Partners will assume
all liabilities of IDR LP and IDR LLC (collectively, the “Distributions”).

AGREEMENT

NOW, THEREFORE, in consideration of their mutual undertakings and agreements
hereunder, the Parties undertake and agree, effective immediately following the
Transformation, as follows:

ARTICLE I

ASSUMPTION

1.1 Assumption by Partners of Liabilities of IDR LP. In connection with the
Distributions contemplated by the Simplification Agreement, Partners hereby
assumes and agrees to duly and timely pay, perform and discharge any and all
liabilities of IDR LP, whether arising or accruing before or after the Effective
Time, whether known or unknown, accrued or contingent, and whether or not
reflected on the books and records of IDR LP (the “IDR LP Liabilities”), to the
full extent that IDR LP has been heretofore or would have been in the future

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

obligated to pay, perform and discharge such IDR LP Liabilities were it not for
the execution, delivery and performance of this Agreement and the Simplification
Agreement (the “IDR LP Assumption”); provided, however, that said IDR LP
Assumption shall not (i) increase the obligation of Partners with respect to IDR
LP Liabilities beyond that of IDR LP, (ii) waive any valid defense that was
available to IDR LP with respect to the IDR LP Liabilities or (iii) enlarge any
rights or remedies of any third party, if any, under any of the IDR LP
Liabilities.

1.2 Assumption by Partners of Liabilities of IDR LLC. In connection with the
Distributions contemplated by the Simplification Agreement, Partners hereby
assumes and agrees to duly and timely pay, perform and discharge any and all
liabilities of IDR LLC, whether arising or accruing before or after the
Effective Time, whether known or unknown, accrued or contingent, and whether or
not reflected on the books and records of IDR LLC (the “IDR LLC Liabilities”),
to the full extent that IDR LLC has been heretofore or would have been in the
future obligated to pay, perform and discharge such IDR LLC Liabilities were it
not for the execution, delivery and performance of this Agreement and the
Simplification Agreement (the “IDR LLC Assumption”); provided, however, that
said IDR LLC Assumption shall not (i) increase the obligation of Partners with
respect to the IDR LLC Liabilities beyond that of IDR LLC, (ii) waive any valid
defense that was available to IDR LLC with respect to the IDR LLC Liabilities or
(iii) enlarge any rights or remedies of any third party, if any, under any of
the IDR LLC Liabilities.

ARTICLE II

FURTHER ASSURANCES

2.1 Further Assurances. From time to time after the date of this Agreement, and
without any further consideration, the Parties agree to execute, acknowledge and
deliver all such additional deeds, assignments, bills of sale, conveyances,
instruments, notices, releases and other documents, and will do all such other
acts and things, all in accordance with applicable law, as may be necessary or
appropriate to carry out the purposes and intent of this Agreement.

ARTICLE III

MISCELLANEOUS

3.1 Successors and Assigns. This Agreement shall inure to the benefit of, and be
binding upon, the Parties and their respective successors and permitted assigns;
provided, however, that no Party shall assign or delegate any of the obligations
created under this Agreement without the prior written consent of the other
Parties.

3.2 Fees and Expenses. Except as otherwise expressly provided in the
Simplification Agreement, all legal, accounting and other fees, costs and
expenses of a Party hereto incurred in connection with this Agreement and the
matters contemplated hereby shall be paid by the Party incurring such fees,
costs or expenses.

 

2

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

3.3 Notices. All notices and other communications given or made pursuant hereto
shall be in writing and shall be deemed given if personally delivered,
telecopied (with confirmation) or mailed by registered or certified mail (return
receipt requested) to the Parties at the addresses set forth in the
Simplification Agreement or to such other Persons or at such other addresses as
shall be furnished by any Party by like notice to the others, and such notice or
communication shall be deemed to have been given or made as of the date so
delivered or mailed.

3.4 Entire Understanding; No Third Party Beneficiaries. This Agreement and the
Simplification Agreement represent the entire understanding of the Parties with
reference to the matters contemplated hereby and supersede any and all other
oral or written agreements heretofore made. Nothing in this Agreement, express
or implied, is intended to confer upon any Person, other than the Parties or
their respective successors, any rights, remedies, obligations or liabilities
under or by reason of this Agreement.

3.5 Amendment. This Agreement may be amended, modified or supplemented only by a
written instrument executed by all Parties hereto.

3.6 Severability. Any provision of this Agreement that is invalid, illegal or
unenforceable in any jurisdiction shall, as to that jurisdiction, be ineffective
to the extent of such invalidity, illegality or unenforceability, without
affecting in any way the remaining provisions hereof in such jurisdiction or
rendering that or any other provision of this Agreement invalid, illegal or
unenforceable in any other jurisdiction.

3.7 Titles and Headings. The Article and Section headings contained in this
Agreement are solely for convenience of reference and shall not affect the
meaning or interpretation of this Agreement or of any term or provision hereof.

3.8 Signatures and Counterparts. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall be considered one and the same agreement.

3.9 Enforcement of Agreement; Damages. The Parties hereto agree that irreparable
damage would occur if any of the provisions of this Agreement were not performed
in accordance with their specific terms or were otherwise breached. It is
accordingly agreed that the Parties shall, to the fullest extent permitted by
law, be entitled to an injunction or injunctions to prevent breaches of this
Agreement and to enforce specifically the terms and provisions hereto, this
being in addition to any other remedy to which they are entitled at law or in
equity.

3.10 Governing Law; Jurisdiction. This Agreement shall be governed by, and
interpreted in accordance with, the laws of the State of Delaware, without
regard to the conflict of law principles thereof that would call for the
application of the laws of any other jurisdiction (except to the extent that
mandatory provisions of federal or Delaware law govern). Each of the Parties
hereto irrevocably and unconditionally confirms and agrees that it is and shall
continue to be (i) subject to the jurisdiction of the courts of the State of
Delaware and of the federal courts sitting in the State of Delaware, and
(ii) subject to service of process in the State of Delaware.

 

3

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

The Parties agree that any suit, action or proceeding seeking to enforce any
provision of, or based on any matter arising out of or in connection with, this
Agreement or the matters contemplated hereby shall be brought in any federal or
state court located in the State of Delaware, and each of the Parties hereby
irrevocably consents to the exclusive jurisdiction of such courts (and of the
appropriate appellate courts therefrom) in any such suit, action or proceeding
and irrevocably waives, to the fullest extent permitted by law, any objection
that it may now or hereafter have to the laying of the venue of any such suit,
action or proceeding in any such court or that any such suit, action or
proceeding brought in any such court has been brought in an inconvenient forum.
Process in any such suit, action or proceeding may be served on any Party
anywhere in the world, whether within or without the jurisdiction of any such
court. Without limiting the foregoing, each Party agrees that, to the fullest
extent permitted by law, service of process on such Party as provided in
Section 3.3 shall be deemed effective service of process on such Party.

Remainder of Page Intentionally Left Blank

 

4

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

IN WITNESS WHEREOF, this Agreement has been duly executed by the Parties as of
the date first written above.

 

MAGELLAN MIDSTREAM PARTNERS, L.P. By:   MAGELLAN GP, LLC, its general partner
By:   /s/ Don R. Wellendorf   Name: Don R. Wellendorf   Title: President and
Chief Executive Officer MAGELLAN IDR LP, LLC By:   MAGELLAN GP, LLC, its sole
member By:   /s/ Don R. Wellendorf   Name: Don R. Wellendorf   Title: President
and Chief Executive Officer MAGELLAN IDR, L.P. By:   MAGELLAN GP, LLC, its
general partner By:   /s/ Don R. Wellendorf   Name: Don R. Wellendorf   Title:
President and Chief Executive Officer

Signature Page to IDR Entity Assumption Agreement

 

5