UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-Q/A

Amendment No. 1

[X]

QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarter ended June 30, 2010

[  ]

TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from ___ to ___

QUESTAR CORPORATION

(Exact name of registrant as specified in its charter)

STATE OF UTAH	001-08796	87-0407509
(State or other jurisdiction of incorporation or organization)	Commission File No.	(I.R.S. Employer Identification No.)

180 East 100 South Street, P.O. Box 45433 Salt Lake City, Utah 84145-0433

(Address of principal executive offices)

Registrant's telephone number, including area code (801) 324-5699

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes [X]   No [   ]

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (Section 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

Yes [X]   No [   ]

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See definitions of "large accelerated filer," "accelerated filer" and "smaller reporting company" in Rule 12b-2 of the Exchange Act.  (Check one):

Large accelerated filer [X]	Accelerated filer [   ]
Non-accelerated filer [   ]   (Do not check if a smaller reporting company)	Smaller reporting company [   ]

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

Yes [   ]   No [X]

At July 31, 2010, there were 175,558,963 shares of the registrant's common stock, without par value, outstanding.

EXPLANATORY NOTE

Amendment No. 1 to the Questar Corporation (the Company) Quarterly Report on Form 10-Q for the period ended June 30, 2010, is filed solely to provide Exhibit 101 in accordance with Rule 405(a)(2) of Regulation S-T. Exhibit 101 includes information about the Company in Extensible Business Reporting Language (XBRL). The Securities and Exchange Commission (SEC) allowed 30 days beyond the filing date of the second quarter 2010 Form 10-Q for the initial submission of Exhibit 101 containing detailed note tagging. No other changes have been made to the Company’s Form 10-Q, which was filed with the SEC on August 5, 2010 (Original Filing). Amendment No. 1 does not amend any other information set forth in the Original Filing and the Company has not updated disclosures included therein to reflect any events that occurred subsequent to August 5, 2010.

Users of this data are advised that pursuant to Rule 406T of Regulation S-T, these interactive data files are deemed not filed or part of a registration statement or prospectus for purposes of sections 11 or 12 of the Securities Act of 1933, and are deemed not filed for purposes of section 18 of the Securities and Exchange Act of 1934, and otherwise are not subject to liability

ITEM 6.  EXHIBITS.

The following exhibits are being filed as part of this report:

Exhibit No.

Exhibits

12.*

Ratio of earnings to fixed charges.

31.1.*

Certification signed by Ronald W. Jibson, President and Chief Executive Officer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

31.2.*

Certification signed by Martin H. Craven, Vice President, Chief Financial Officer and Treasurer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

32.*

Certification signed by Ronald W. Jibson, President and Chief Executive Officer, and Martin H. Craven, Vice President, Chief Financial Officer and Treasurer, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS**

XBRL Instance.

101.SCH**

XBRL Taxonomy.

101.LAB**

XBRL Labels.

101.PRE**

XBRL Presentation.

101.CAL**

XBRL Calculations.

101.DEF**

XBRL Definitions.

  *Previously filed on August 5, 2010.

**Furnished herewith.

Questar 2010 Form 10-Q/A

2

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

QUESTAR CORPORATION

(Registrant)

August 19, 2010

/s/ Ronald W. Jibson

Ronald W. Jibson,

President and Chief Executive Officer

August 19, 2010

/s/ Martin H. Craven

Martin H. Craven,

Vice President, Chief Financial Officer

and Treasurer

Exhibits List

Exhibits

12.*

Ratio of earnings to fixed charges.  

31.1.*

Certification signed by Ronald W. Jibson, President and Chief Executive Officer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

31.2.*

Certification signed by Martin H. Craven, Vice President, Chief Financial Officer and Treasurer, pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

32.*

Certification signed by Ronald W. Jibson, President and Chief Executive Officer, and Martin H. Craven, Vice President, Chief Financial Officer and Treasurer, pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.

101.INS**

XBRL Instance.

101.SCH**

XBRL Taxonomy.

101.LAB**

XBRL Labels.

101.PRE**

XBRL Presentation.

101.CAL**

XBRL Calculations.

101.DEF**

XBRL Definitions.

  *Previously filed on August 5, 2010.

**Furnished herewith.

Questar 2010 Form 10-Q/A

3