FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * CASH R D   2. Issuer Name and Ticker or Trading Symbol QUESTAR CORP [STR] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 180 E 100 S 3. Date of Earliest Transaction (Month/Day/Year) 05/03/2006 (Street) SALT LAKE CITY, UT 84111 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock and attached Common Stock Purchase Rights               316,621 (1) D   Common Stock and attached Common Stock Purchase Rights               49,043 I Private Foundation

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Phantom Stock Units

$ 80.05

05/03/2006

D

15,730.4632

05/01/2004

05/01/2006

Phantom Stock Units

15,730.4632

$ 80.05

0 (2)

D

Phantom Stock Units

$ 0

05/01/2004

05/01/2006

Phantom Stock Units

5,757.5697

5,757.5698 (3)

D

Stock Option

$ 15

08/08/2000

02/08/2010

Common Stock and attached Common Stock Purchase Rights

198,440

198,440

D

Stock Option

$ 28.01

08/13/2001

02/13/2011

Common Stock and attached Common Stock Purchase Rights

180,000

180,000

D

Stock Option

$ 22.95

08/11/2002

02/11/2012

Common Stock and attached Common Stock Purchase Rights

19,912

19,912

D

Stock Option

$ 27.11

08/11/2003

02/11/2013

Common Stock and attached Common Stock Purchase Rights

7,000

7,000

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
CASH R D 180 E 100 S SALT LAKE CITY, UT 84111	X

Signatures

Abigail L. Jones Attorney in Fact for R. D. Cash		05/03/2006
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	This total does not include 7,534 shares held indirectly through family trusts for which I have voting and investment control.
(2)	This total reflects payment made on 5/3/2006 for 15,730.4632 phantom stock units that was paid in cash and calculated using 4/28/2006's closing price of $80.05 a share. This total includes 12,647.5865 phantom stock units held in an excess benefits plan. I began receiving cash payments for the value of phantom stock units (exclusive of deferral director's fees) effective May 1, 2003 this is the fourth of four such cash payments.
(3)	I have account balances in several deferred compensation plans for directors. Such account balances are credited with dividends. I began receiving annual cash payments for the value of my phantom stock units attributable to deferred director's fees effective June 1, 2004.

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