SEC Form 3 
FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940 	  
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1. Name and Address of Reporting Person*
Plains All American GP LLC	

(Last)	(First)	(Middle)	
333 CLAY STREET, SUITE 1600	

(Street) 
HOUSTON	TX	77002	

(City)	(State)	(Zip)	
	2. Date of Event Requiring Statement (Month/Day/Year)
04/29/2010 	3. Issuer Name and Ticker or Trading Symbol 
PAA NATURAL GAS STORAGE LP [ PNG ] 		
		4. Relationship of Reporting Person(s) to Issuer 
(Check all applicable) 
	Director	X	10% Owner	
	Officer (give title below)		Other (specify below)	
	
	5. If Amendment, Date of Original Filed (Month/Day/Year)				
			6. Individual or Joint/Group Filing (Check Applicable Line) 
	Form filed by One Reporting Person	
X	Form filed by More than One Reporting Person	
	
Table I - Non-Derivative Securities Beneficially Owned	
1. Title of Security (Instr. 4) 	2. Amount of Securities Beneficially Owned (Instr. 4) 	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 	4. Nature of Indirect Beneficial Ownership (Instr. 5) 	
Common Units	0(1)(2)(3) 	I	See Note(1) 	
Table II - Derivative Securities Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities) 	
1. Title of Derivative Security (Instr. 4) 	2. Date Exercisable and Expiration Date (Month/Day/Year)	3. Title and Amount of Securities Underlying Derivative Security (Instr. 4) 	4. Conversion or Exercise Price of Derivative Security 	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 	6. Nature of Indirect Beneficial Ownership (Instr. 5) 	
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares				
Series A Subordinated Units	(4) 	(4) 	Common Units	0(1)(2)(3) 	0(4) 	I	See Note(1) 	
Series B Subordinated Units	(4) 	(4) 	Common Units	0(1)(2)(3) 	0(4) 	I	See Note(1) 	
1. Name and Address of Reporting Person*
Plains All American GP LLC	

(Last)	(First)	(Middle)	
333 CLAY STREET, SUITE 1600	

(Street) 
HOUSTON	TX	77002	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
Plains AAP, L.P.	

(Last)	(First)	(Middle)	
333 CLAY STREET, SUITE 1600	

(Street) 
HOUSTON	TX	77002	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
PAA GP LLC	

(Last)	(First)	(Middle)	
333 CLAY STREET, SUITE 1600	

(Street) 
HOUSTON	TX	77002	

(City)	(State)	(Zip)	
	
1. Name and Address of Reporting Person*
PLAINS ALL AMERICAN PIPELINE LP	

(Last)	(First)	(Middle)	
333 CLAY STREET, SUITE 1600	

(Street) 
HOUSTON	TX	77002	

(City)	(State)	(Zip)	
	
Explanation of Responses:	
1. As of April 29, 2010, (i) Plains All American Pipeline, L.P. ("PAA") owns a 98% limited partner interest in the Issuer, (ii) PAA GP LLC is the general partner of PAA, (iii) Plains AAP, L.P. owns all of the membership interests in PAA GP LLC, and (iv) Plains All American GP LLC is the general partner of Plains AAP, L.P. Accordingly, PAA GP LLC, Plains AAP, L.P. and Plains All American GP LLC may be deemed to be indirect beneficial owners of any securities held by PAA.	
2. Immediately following the closing of the initial public offering of the Issuer's Common Units (the "Offering") and in exchange for the contribution of certain assets to the Issuer by PAA and certain of its affiliates, PAA will own 20,084,529 Common Units, 13,934,351 Series A Subordinated Units and 11,500,000 Series B Subordinated Units, representing an 80.8% limited partner interest.	
3. In connection with the Offering, the Issuer will grant to the underwriters a 30-day option to purchase up to an additional 1,500,000 Common Units ("Over-Allotment Units"), which will be issued to such underwriters upon an exercise of such option, if any. If the underwriters do not exercise their option, all of the Over-Allotment Units will be issued to PAA. If the underwriters exercise their option for less than all of the Over-Allotment Units, the remaining Over-Allotment Units not purchased by the underwriters will be issued to PAA.	
4. The Series A Subordinated Units will convert into Common Units on a one-for one basis at the end of the subordination period described in the Issuer's Registration Statement on Form S-1 (333-164492). The Series B Subordinated Units will convert into Series A Subordinated Units on a one-for-one basis upon satisfaction of certain operational and financial conditions described in the Issuer's Registration Statement (or directly into Common Units on a one-for-one basis if the subordination period has already ended at the time such operational and financial conditions are satisfied). The Series A Subordinated Units have no expiration date. The Series B Subordinated Units that remain outstanding as of December 31, 2018 will automatically be cancelled.	
Remarks:	
	
	/s/ Tim Moore, Vice President	04/29/2010	
	** Signature of Reporting Person	Date	
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.	
* If the form is filed by more than one reporting person, see Instruction 5 (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).	
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