Williams Partners L.P. (NYSE: WPZ) announced today that it is initiating an open season from July 24 to August 23, 2012, for an expansion of its Transco interstate pipeline to provide firm natural gas transportation capacity to markets in the southeastern United States by the fall of 2014. Williams (NYSE:WMB) owns approximately 68 percent of Williams Partners, including the general-partner interest. The Mobile Bay South III Expansion Project is being designed to provide up to 325,000 dekatherms per day of firm transportation service on the Transco Mobile Bay Lateral from the Station 85 4A Pooling Point in Choctaw County, Ala., to points along the lateral as far south as the interconnection with Bay Gas Storage in Mobile County, Ala. “Mobile Bay South III is an extremely efficient way to move additional supply from Station 85 and a number of regional storage facilities to growing southeastern markets,” said Randy Barnard, president of Williams’ natural gas pipeline business. The final capacity, scope and cost of the project will be determined by the results of the open season. The proposed project will be subject to approval by the Federal Energy Regulatory Commission and other agencies. For customer inquiries, contact Toi Anderson at (713) 215-4540. About Williams Partners L.P. (NYSE: WPZ) Williams Partners L.P. is a leading diversified master limited partnership focused on natural gas transportation; gathering, treating, and processing; storage; natural gas liquid (NGL) fractionation; and oil transportation. The partnership owns interests in three major interstate natural gas pipelines that, combined, deliver 14 percent of the natural gas consumed in the United States. The partnership’s gathering and processing assets include large-scale operations in the U.S. Rocky Mountains and both onshore and offshore along the Gulf of Mexico. Williams (NYSE: WMB) owns approximately 68 percent of Williams Partners, including the general-partner interest. More information is available at www.williamslp.com. Portions of this document may constitute “forward-looking statements” as defined by federal law. Although the partnership believes any such statements are based on reasonable assumptions, there is no assurance that actual outcomes will not be materially different. Any such statements are made in reliance on the “safe harbor” protections provided under the Private Securities Reform Act of 1995. Additional information about issues that could lead to material changes in performance is contained in the partnership’s annual reports filed with the Securities and Exchange Commission.