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

OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

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) 3205 61ST STREET 3. Date of Earliest Transaction (Month/Day/Year) 08/31/2005 (Street) LUBBOCK, TX 79413 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 08/31/2005   M   20,316 A $ 22.95 333,360 D   Common Stock and attached Common Stock Purchase Rights 08/31/2005   F   12,136 D $ 78.02 321,224 (1) D   Common Stock and attached Common Stock Purchase Rights               44,043 I Private Foundation

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.		SEC 1474 (9-02)

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

Common Stock and attached Common Stock Purchase Rights

$ 22.95

08/31/2005

M

20,316

08/11/2002

04/30/2009

Common Stock and attached Common Stock Purchase Rights

20,316

$ 22.95

448,127

D

Phantom Stock Units

$ 0

(2)

(2)

Phantom Stock Units

0

5,713.9934 (3)

D

Phantom Stock Units

$ 0

(2)

(2)

Phantom Stock Units

0

15,591.1521 (4)

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
CASH R D 3205 61ST STREET LUBBOCK, TX 79413	X

Signatures

Abigail L. Jones Attorney in Fact for R.D. Cash		09/01/2005
**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)	May 1, 2004-2006.
(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.
(4)	This total includes 12,535.5778 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.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.