EXHIBIT 99.1a.

EXHIBIT A

AGREEMENT REGARDING THE JOINT FILING OF SCHEDULE 13D

The undersigned hereby agree as follows:

(i) Each of them is individually eligible to use the Schedule 13D to which this Exhibit is attached, and such Schedule 13D is filed on behalf of each of them; and

(ii) Each of them is responsible for the timely filing of such Schedule 13D and any amendments thereto, and for the completeness and accuracy of the information concerning such person contained therein; but None. of them is responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate.

Date: June 26, 2003

[Signature Pages Follow]

	WEG ACQUISITIONS, L.P.
	By:	WEG Acquisition Management, LLC
		Its: General Partner
		By:	/s/ John D. Chandler
			Name: John D. Chandler
			Title: Chief Financial Officer, Vice President and Treasurer
	WEG ACQUISITION MANAGEMENT, LLC
		By:	/s/ John D. Chandler
			Name: John D. Chandler
			Title: Chief Financial Officer, Vice President and Treasurer

2

	CARLYLE/RIVERSTONE MLP HOLDINGS, L.P.
	By:	Carlyle/Riverstone Energy Partners II, L.P.
		Its: General Partner
		By:	C/R Energy GP II, LLC
			Its: General Partner
		By:	/s/ Pierre F. Lapeyre, Jr.
			Name: Pierre F. Lapeyre, Jr.
			Title:  Managing Director
	CARLYLE/RIVERSTONE ENERGY PARTNERS II, L.P.
	By:	C/R Energy GP II, LLC
		Its: General Partner
		By:	/s/ Pierre F. Lapeyre, Jr.
			Name: Pierre F. Lapeyre, Jr.
			Title:  Managing Director
	C/R ENERGY GP II, LLC
		By:	/s/ Pierre F. Lapeyre, Jr.
			Name: Pierre F. Lapeyre, Jr.
			Title:  Managing Director
	RIVERSTONE HOLDINGS, LLC
		By:	/s/ Pierre F. Lapeyre, Jr.
			Name: Pierre F. Lapeyre, Jr.
			Title:  Managing Director

3

	CARLYLE INVESTMENT MANAGEMENT, L.L.C.
	By:	TC Group, L.L.C.
		Its: Managing Member
		By:	TCG Holdings, L.L.C.
			Its: Managing Member
		By:	/s/ Daniel A. D’Aniello
			Name:  Daniel A. D’Aniello
			Title:  Managing Director

4

	TCG HOLDINGS, L.L.C.
		By:	/s/ Daniel A. D’Aniello
			Name:  Daniel A. D’Aniello
			Title:  Managing Director
	TC GROUP, L.L.C.
	By:	TCG Holdings, L.L.C.
		Its: Managing Member
		By:	/s/ Daniel A. D’Aniello
			Name:  Daniel A. D’Aniello
			Title:  Managing Director

5

	MADISON DEARBORN CAPITAL PARTNERS IV, L.P.
	By:	Madison Dearborn Partners IV, L.P.
		Its:  General Partner
		By:	Madison Dearborn Partners, L.L.C.
			Its:     General Partner
		By:	/s/ Justin S. Huscher
			Name: Justin S. Huscher
			Title:  Managing Director
	MADISON DEARBORN PARTNERS IV, L.P.
	By:	Madison Dearborn Partners IV, L.P.
		Its:     General Partner
		By:	/s/ Justin S. Huscher
			Name: Justin S. Huscher
			Title:  Managing Director
	MADISON DEARBORN PARTNERS, L.L.C.
		By:	/s/ Justin S. Huscher
			Name: Justin S. Huscher
			Title:  Managing Director

6