Exhibit 99.1

Williams Partners Reaffirms Distribution-Growth Guidance Despite Lower Commodity Margins and Earnings Guidance

TULSA, Okla. – Williams Partners (NYSE: WPZ) today reaffirmed its previously published outlook through 2014 for strong growth in the cash distributions it pays to unitholders, despite lowering its earnings outlook for the same period to reflect less-favorable commodity prices.

The partnership continues to expect to pay unitholders a full-year 2012 distribution of $3.14 per unit, an 8 percent increase over 2011. As well, the partnership confirmed it expects the midpoint of guidance for the full-year distribution it pays unitholders in each 2013 and 2014 to increase by 9 percent – to $3.43 and $3.75, respectively.

Williams Partners expects its second-quarter distributable cash flow will be significantly lower than the first-quarter’s results primarily because of an unexpectedly sharp decline in natural-gas-liquids margins in May and June. Additional factors in the change include normal seasonal increases in maintenance capital expenditures; higher expenses at Midstream because of maintenance accelerated during a third-party fractionator outage; somewhat lower-than-expected volumes because of construction timing; costs associated with recent acquisitions; and normal seasonal demand changes and maintenance at Gas Pipeline. Higher fee-based revenues partially offset these factors.

The partnership estimates its second-quarter distributable cash flow will be approximately $289 million, down from $475 million in the first quarter this year. The partnership’s estimates of its second-quarter results are preliminary and subject to change based on completion of its normal quarter-end review process. As previously announced, the partnership plans to report its finalized second-quarter financial results on Aug. 1.

Williams Partners’ revised guidance midpoints for full-year distributable cash flow are $1.6 billion for 2012; $1.9 billion for 2013; and $2.3 billion for 2014. The partnership’s 2012 DCF guidance reflects the effect of significantly lower than expected NGL prices and higher than normal maintenance capital expenditures. The partnership’s projected 2014 distributable cash flow is 37 percent higher than its 2011 DCF of $1.7 billion.

Regarding commodity prices, the partnership referenced an NGL-to-crude-oil price ratio that is approximately 40 percent below the 10-year average. Key factors in that weakness are high propane inventories caused by the extremely warm winter and the effect of the propane oversupply on ethane inventories and pricing.

The partnership continues to expect the influence of NGL prices on its performance to diminish over the next few years as it transitions to a business mix that is largely fee-based. The partnership’s revised 2013 and 2014 performance expectations reflect that shift to greater fee-based business; the benefit of projects coming into service; and some improvement from current depressed NGL market prices as excess inventories are brought into balance as a result of additions to North American capacity for steam-cracking, propane dehydrogenation (PDH) and exports, as well as more normal weather.

Williams Partners’ assumptions for certain energy commodity prices for 2012 through 2014 and the corresponding guidance for the partnership’s earnings and capital expenditures are displayed in the following table:

The increases Williams Partners expects to make in its cash distributions are subject to quarterly approval by the board of directors of the partnership’s general partner.

In other news today, Williams Partners and Williams issued a news release announcing they are pursuing an agreement for the partnership to acquire Williams’ 83.3 percent interest and operatorship of the olefins-production facility in Geismar, La.

The partnership expects that the addition of olefins production to its business via this acquisition would create significant additional income, reduce the partnership’s exposure to ethane margins and be accretive to distributable cash flow, on a per-unit basis for the partnership’s unitholders.

As contemplated, Williams Partners would fund the transaction largely with the issuance of limited-partner units to Williams.

The transaction is subject to execution of an agreement between the two parties, review and recommendation by the conflicts committee of the general partner of Williams Partners, and approval of the two parties’ boards of directors. As a result, the benefits of this planned transaction are not included in current guidance.

Non-GAAP Measures

This press release includes certain financial measures – Distributable Cash Flow, Cash Distribution Coverage Ratio, and Adjusted Segment Profit – that are non-GAAP financial measures as defined under the rules of the SEC.

For Williams Partners L.P., Adjusted Segment Profit excludes items of income or loss that we characterize as unrepresentative of our ongoing operations. Management believes Adjusted Segment Profit provides investors meaningful insight into Williams Partners L.P.’s results from ongoing operations.

For Williams Partners L.P. we define Distributable Cash Flow as net income plus depreciation and amortization and cash distributions from our equity investments less our earnings from our equity investments, distributions to noncontrolling interests and maintenance capital expenditures. We also adjust for payments and/or reimbursements under omnibus agreements with Williams and certain other items.

For Williams Partners L.P. we also calculate the ratio of Distributable Cash Flow to the total cash distributed (Cash Distribution Coverage Ratio). This measure reflects the amount of Distributable Cash Flow relative to our cash distribution. We have also provided this ratio calculated using the most directly comparable GAAP measure, net income.

This press release is accompanied by a reconciliation of these non-GAAP financial measures to their nearest GAAP financial measures. Management uses these financial measures because they are accepted financial indicators used by investors to compare company performance. In addition, management believes that these measures provide investors an enhanced perspective of the operating performance of the Partnership’s assets and the cash that the business is generating. Neither Adjusted Segment Profit nor Distributable Cash Flow are intended to represent cash flows for the period, nor are they presented as an alternative to net income or cash flow from operations. They should not be considered in isolation or as substitutes for a measure of performance prepared in accordance with United States generally accepted accounting principles.

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.

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Williams Partners L.P. is a limited partnership formed by The Williams Companies, Inc. (Williams). Our reports, filings, and other public announcements may contain or incorporate by reference statements that do not directly or exclusively relate to historical facts. Such statements are “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. You typically can identify forward-looking statements by various forms of words such as “anticipates,” “believes,” “seeks,” “could,” “may,” “should,” “continues,” “estimates,” “expects,” “forecasts,” “intends,” “might,” “goals,” “objectives,” “targets,” “planned,” “potential,” “projects,” “scheduled,” “will,” or other similar expressions. These forward-looking statements are based on management’s beliefs and assumptions and on information currently available to management and include, among others, statements regarding:

Forward-looking statements are based on numerous assumptions, uncertainties and risks that could cause future events or results to be materially different from those stated or implied in this announcement. Many of the factors that will determine these results are beyond our ability to control or predict. Specific factors that could cause actual results to differ from results contemplated by the forward-looking statements include, among others, the following:

Given the uncertainties and risk factors that could cause our actual results to differ materially from those contained in any forward-looking statement, we caution investors not to unduly rely on our forward-looking statements. We disclaim any obligations to and do not intend to update the above list or to announce publicly the result of any revisions to any of the forward-looking statements to reflect future events or developments.

In addition to causing our actual results to differ, the factors listed above may cause our intentions to change from those statements of intention set forth in this announcement. Such changes in our intentions may also cause our results to differ. We may change our intentions, at any time and without notice, based upon changes in such factors, our assumptions, or otherwise.

Limited partner interests are inherently different from the capital stock of a corporation, although many of the business risks to which we are subject are similar to those that would be faced by a corporation engaged in a similar business. Investors are urged to closely consider the disclosures and risk factors in our annual report on Form 10-K filed with the SEC on February 28, 2012, and our quarterly reports on Form 10-Q available from our offices or from our website

Reconciliation of Non-GAAP “Distributable Cash Flow” to GAAP “Net income”

* The estimates of second quarter results are preliminary and subject to change based on completion of the company’s normal quarter-end review process. As previously announced, the company plans to report its final second-quarter financial results on August 1, 2012.

Segment profit guidance – reported to adjusted

Net income & distributable cash flow