Exhibit 99.1

JOINT FILING AGREEMENT

          In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, the persons named below agree to the joint filing on behalf of each of them a statement on Schedule 13D (including amendments thereto) with respect to the common stock of HALLADOR PETROLEUM COMPANY and further agree that this Joint Filing Agreement be included as an Exhibit to such joint filings. In evidence thereof each of the undersigned, being duly authorized, hereby execute this Agreement on the date set forth below.

Date: August 26, 2008

YORKTOWN ENERGY PARTNERS VII, L.P.
By:	Yorktown VII Company LP,
	Its General Partner
By:	Yorktown VII Associates LLC,
	Its General Partner
By:	/s/ Bryan H. Lawrence
	Name:	Bryan H. Lawrence
	Title:	Member
YORKTOWN VII COMPANY LP
By:	Yorktown VII Associates LLC,
	Its General Partner
By:	/s/ Bryan H. Lawrence
	Name:	Bryan H. Lawrence
	Title:	Member
YORKTOWN VII ASSOCIATES LLC
By:	/s/ Bryan H. Lawrence
	Name:	Bryan H. Lawrence
	Title:	Member