Exhibit
31.1




CERTIFICATION


PURSUANT
TO AND IN CONNECTION WITH THE REPORTS


TO
BE FILED UNDER SECTION 13 AND 15(d) OF THE


SECURITIES
EXCHANGE ACT OF 1934, AS AMENDED




I, Kevin
L. Foxx, certify that:




1. I have
reviewed this quarterly report on Form 10-Q of SemGroup Energy Partners,
L.P.;




2. Based
on my knowledge, this report does not contain any untrue statement of a material
fact or omit to state a material fact necessary to make the statements made, in
light of the circumstances under which such statements were made, not misleading
with respect to the period covered by this report;




3. Based
on my knowledge, the financial statements, and other financial information
included in this report, fairly present in all material respects the financial
condition, results of operations and cash flows of the registrant as of, and
for, the periods presented in this report;




4. The
registrant’s other certifying officer(s) and I are responsible for establishing
and maintaining disclosure controls and procedures (as defined in Exchange Act
Rules 13a-15(e) and 15d-15(e)) for the registrant and have:




a.
Designed such disclosure controls and procedures, or caused such disclosure
controls and procedures to be designed under our supervision, to ensure that
material information relating to the registrant, including its consolidated
subsidiaries, is made known to us by others within those entities, particularly
during the period in which this report is being prepared;




b.
[Intentionally omitted pursuant to SEC Release No. 34-47986];




c.
Evaluated the effectiveness of the registrant’s disclosure controls and
procedures and presented in this report our conclusions about the effectiveness
of the disclosure controls and procedures, as of the end of the period covered
by this report based on such evaluation; and




d.
Disclosed in this report any change in the registrant’s internal control over
financial reporting that occurred during the registrant’s most recent fiscal
quarter (the registrant’s fourth fiscal quarter in the case of an annual report)
that has materially affected, or is reasonably likely to materially affect, the
registrant’s internal control over financial reporting; and




5. The
registrant’s other certifying officer(s) and I have disclosed, based on our most
recent evaluation of internal control over financial reporting, to the
registrant’s auditors and the audit committee of the registrant’s board of
directors (or persons performing the equivalent functions):




a. All
significant deficiencies and material weaknesses in the design or operation of
internal control over financial reporting which are reasonably likely to
adversely affect the registrant’s ability to record, process, summarize and
report financial information; and




b. Any
fraud, whether or not material, that involves management or other employees who
have a significant role in the registrant’s internal control over financial
reporting.




Date: March23,
2009




/s/
      Kevin L. FoxxKevin
      L. FoxxPresident
      and Chief Executive Officer of
                SemGroup
      Energy Partners G.P., L.L.C.,
                general partner of SemGroup Energy Partners, L.P.