Exhibit 99.1

WGL Holdings, Inc. Reports Second Quarter Fiscal Year 2012 Financial Results;

Updates Fiscal Year 2012 Non-GAAP Guidance

Consolidated Results

WGL Holdings, Inc. (NYSE: WGL), the parent company of Washington Gas Light Company (Washington Gas) and other energy-related subsidiaries, today reported net income determined in accordance with generally accepted accounting principles in the United States of America (GAAP) for the quarter ended March 31, 2012 of $74.2 million, or $1.44 per share, compared to net income of $79.4 million, or $1.55 per share, reported for the quarter ended March 31, 2011.

For the first six months of fiscal year 2012, we reported net income determined in accordance with GAAP of $124.6 million, or $2.42 per share, compared to net income of $144.7 million, or $2.83 per share, reported for the comparative period of fiscal year 2011. Our operations are seasonal and, accordingly, our operating results for the three and six months ended March 31, 2012, are not indicative of the results expected for the 12 months ending September 30, 2012.

Financial performance is also evaluated based on non-GAAP operating earnings (loss). Non-GAAP operating earnings (loss) excludes the effects of: (i) unrealized mark-to-market gains (losses) on energy-related derivatives for our regulated utility and retail energy marketing segments; (ii) certain gains and losses associated with optimizing the utility segment’s system capacity assets; (iii) changes in the measured value of our inventory for our wholesale energy solutions segment; (iv) the financial effects of warm or cold weather that exceeds weather protection for our regulated utility segment and (v) certain unusual transactions. Refer to “Use of Non-GAAP Operating Earnings (Loss)” and supporting reconciliations attached to this news release for a detailed discussion of management’s use of this non-GAAP financial measure, as well as reconciliations of net income determined in accordance with GAAP to non-GAAP operating earnings (loss) for both our consolidated and segment results.

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For the quarter ended March 31, 2012, non-GAAP operating earnings were $81.3 million, or $1.58 per share, an increase of $3.7 million or $0.07 per share, over non-GAAP operating earnings of $77.6 million, or $1.51 per share, for the same quarter of the prior fiscal year. For the six months ended March 31, 2012, non-GAAP operating earnings were $139.4 million, or $2.70 per share, an increase of $9.2 million, or $0.16 per share, over non-GAAP operating earnings of $130.2 million, or $2.54 per share, for the same period of the prior fiscal year.

“In the second quarter we continued to see improvements in our non-GAAP earnings compared to prior year levels, driven primarily by recent rate cases in Virginia and Maryland,” said Terry McCallister, Chairman and Chief Executive Officer of WGL Holdings. “On a year to date basis, we are pleased with the balance of earnings growth from both our utility and non-utility segments, particularly in the face of the warmest winter in our service area’s recorded history. While we are generally on track for our 2012 non-GAAP guidance we provided last quarter, we have lowered our guidance by $0.03 to reflect our share of this year’s expected expenses of the Commonwealth Pipeline project.”

Second Quarter Results by Business Segment

Regulated Utility Segment

For the quarter ended March 31, 2012, the regulated utility segment reported net income of $72.4 million, or $1.40 per share, an increase of $1.6 million, or $0.02 per share, over net income of $70.8 million, or $1.38 per share, reported for the same quarter of the prior fiscal year. After adjustments, non-GAAP operating income for the regulated utility segment was $77.0 million, or $1.49 per share, for the quarter ended March 31, 2012, an increase of $4.5 million, or $0.08 per share, over non-GAAP operating earnings of $72.5 million, or $1.41 per share, for the same quarter of the prior fiscal year.

For the six months ended March 31, 2012, our regulated utility segment reported net income of $116.8 million, or $2.27 per share, an increase of $5.3 million, or $0.09 per share, over net income $111.5 million, or $2.18 per share, reported for the six months ended March 31, 2011. After adjustments, non-GAAP operating earnings for the regulated utility segment were $121.1 million, or $2.35 per share, for the six months ended March 31, 2012, an increase of $4.3 million, or $0.07 per share, compared to non-GAAP operating earnings of $116.8 million, or $2.28 per share, for the same period of the prior fiscal year.

For both the three and six months ended March 31, 2012, higher non-GAAP operating earnings reflect higher revenues from the implementation of new rates in Virginia and Maryland and an increase in average active customer meters, partially offset by: (i) lower margins associated with our asset optimization program; (ii) higher operation and maintenance expenses; (iii) higher depreciation expense due to the growth in, and changes in the asset mix of, our investment in utility and (iv) higher income tax expense due to an increase in the effective tax rate.

Retail Energy-Marketing Segment

For the quarter ended March 31, 2012, the retail energy-marketing segment reported net income of $4.5 million, or $0.09 per share, compared to net income of $9.7 million, or $0.19 per share, reported for the same quarter of the prior fiscal year. Non-GAAP operating earnings for the retail energy-marketing segment were $5.3 million, or $0.10 per share, for the quarter ended March 31, 2012, compared to non-GAAP operating earnings of $8.0 million, or $0.16 per share, for the same quarter of the prior fiscal year.

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For the six months ended March 31, 2012, the retail energy-marketing segment reported net income of $5.3 million, or $0.10 per share, compared to net income of $34.6 million, or $0.68 per share, reported for the same period of the prior fiscal year. Non-GAAP operating earnings for the retail energy-marketing segment were $18.4 million, or $0.36 per share, for the six months ended March 31, 2012, an increase of $3.6 million, or $0.07 per share, over non-GAAP operating earnings of $14.8 million, or $0.29 per share, for the same period of the prior fiscal year.

The differences between GAAP net income and non-GAAP operating earnings are due to adjustments to eliminate unrealized mark-to-market gains and losses attributable to certain wholesale energy supply and retail sales contracts.

For the quarter ended March 31, 2012, non-GAAP operating earnings reflect lower realized natural gas margins primarily attributed to lower margins on portfolio optimization activities, lower retail sales volumes resulting from warm weather, and a less favorable pattern of margin recognition in the current quarter versus the same quarter of the prior year. Realized electric margins were higher due to favorable price conditions, higher sales volumes due to customer growth, and a more favorable pattern of margin recognition in the current period versus the same quarter of the prior year. The pattern of margin recognition that the retail energy-marketing segment realizes in a given quarter varies from year to year. Operating expenses in the current quarter increased primarily due to higher customer acquisition and customer service costs.

For the six months ended March 31, 2012, non-GAAP operating earnings reflect higher realized electric margins that are attributable to favorable price conditions, higher sales volumes due to customer growth and a more favorable pattern of margin recognition in the current period versus the same period of the prior year. Realized natural gas margins are lower primarily due to lower margins on portfolio optimization activities and lower retail sales volumes resulting from warm weather. As noted above, the pattern of margin recognition varies from year to year. Operating expenses in the current period increased primarily due to higher customer service costs and other expenses.

Commercial Energy Systems

For the quarter ended March 31, 2012, the commercial energy systems segment reported net income of $0.5 million compared to a net loss of $(18,000) for the same quarter last year. For the six months ended March 31, 2012, the commercial energy systems segment reported net income of $0.8 million compared to a net loss of $(20,000) for the same period last year. The increase in earnings is primarily due to higher revenue from commercial solar projects in the current period and the commencement of project work for government agency customers that was delayed in the prior year. There were no non-GAAP adjustments for this segment for any of the periods presented.

Wholesale Energy Solutions

For the quarter ended March 31, 2012, the wholesale energy solutions segment reported a net loss of $(2.7) million, or $(0.05) per share, compared to net income of $0.1 million for the same period of the prior fiscal year. Non-GAAP operating losses for the wholesale energy solutions segment were $(1.1) million, or $(0.02) per share, compared to a loss of $(1.7) million, or $(0.03) per share, for the same period of the prior fiscal year.

For the six months ended March 31, 2012, the wholesale energy solutions segment reported net income of $2.5 million, or $0.05 per share, compared to net income of $0.2 million for the same period of the prior fiscal year. Wholesale energy solutions had a non-GAAP operating loss of $(0.1) million, compared to net income of $0.3 million, or $0.01 per share, for the same period of the prior fiscal year.

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For both the quarter and year to date periods, non-GAAP operating losses reflect low storage and transportation spreads due to one of the warmest winters on record across the country, which affected optimization opportunities as well as higher operation and maintenance expense as a result of new storage and optimization arrangements.

Earnings Outlook

We are lowering our GAAP earnings estimate for the fiscal year 2012 to a range of $2.40 per share to $2.52 per share. This estimate includes projected fiscal year 2012 earnings from our regulated utility segment in a range of $1.76 per share to $1.82 per share and projected fiscal year 2012 earnings from our unregulated business segments in a range of $0.64 per share to $0.70 per share.

We are also lowering our consolidated earnings estimate for fiscal year 2012 based on non-GAAP operating earnings to a range of $2.43 per share to $2.55 per share to reflect our share of this year’s expected expenses of the Commonwealth Pipeline. This estimate includes projected fiscal year 2012 non-GAAP operating earnings from our regulated utility segment in a range of $1.82 per share to $1.88 per share, and projected fiscal year 2012 non-GAAP operating earnings from our unregulated business segments in a range of $0.61 per share to $0.67 per share. Refer to the “Reconciliation of GAAP Earnings Guidance to Non-GAAP Earnings Guidance” attached to this press release for a reconciliation of our GAAP earnings per share estimate to our estimate based on non-GAAP operating earnings per share.

We assume no obligation to update this guidance. The absence of any statement by us in the future should not be presumed to represent an affirmation of this earnings guidance. For the assumptions underlying this guidance, please refer to the slides accompanying our webcast that will be posted to the WGL Holdings website, www.wglholdings.com.

Other Information

We will hold a conference call at 10:30 a.m. Eastern Time on May 3, 2012, to discuss our second quarter fiscal year 2012 financial results. The live conference call will be available to the public via a link located on the WGL Holdings website, www.wglholdings.com. To hear the live webcast, click on the “Webcast” link located on the home page of the referenced site. The webcast and related slides will be archived on the WGL Holdings website through June 3, 2012.

Headquartered in Washington, D.C., WGL Holdings, Inc. has four operating segments: (i) the regulated utility segment which primarily consists of Washington Gas, a natural gas utility that serves over one million customers throughout metropolitan Washington, D.C., and the surrounding region; (ii) the retail-energy marketing segment which consists of Washington Gas Energy Services, Inc., a third-party marketer that competitively sells natural gas and electricity; (iii) the commercial energy systems segment which consists of Washington Gas Energy Systems, Inc., a provider of design-build energy efficiency solutions to government and commercial clients and commercial solar projects and (iv) the wholesale energy solutions segment which consists of Capitol Energy Ventures Corp., an asset optimization business that acquires, manages and optimizes natural gas storage and transportation assets. Additional information about WGL Holdings, Inc. is available on our website, www.wglholdings.com.

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Unless otherwise noted, earnings per share amounts are presented on a diluted basis, and are based on weighted average common and common equivalent shares outstanding.

Please see the attached comparative statements for additional information on our operating results. Also attached to this news release are reconciliations of net income determined in accordance with GAAP to non-GAAP operating earnings (loss) for both our consolidated and segment results as well as reconciliations of our GAAP earnings guidance to our non-GAAP earnings guidance.

Forward-Looking Statements

This news release and other statements by us include forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 with respect to the outlook for earnings, revenues and other future financial business performance or strategies and expectations. Forward-looking statements are typically identified by words such as, but not limited to, “estimates,” “expects,” “anticipates,” “intends,” “believes,” “plans,” and similar expressions, or future or conditional verbs such as “will,” “should,” “would,” and “could.” Although we believe such forward-looking statements are based on reasonable assumptions, we cannot give assurance that every objective will be achieved. Forward-looking statements speak only as of today, and we assume no duty to update them. Factors that could cause actual results to differ materially from those expressed or implied include, but are not limited to, general economic conditions and the factors discussed under the “Risk Factors” heading in our most recent annual report on Form 10-K and other documents we have filed with, or furnished to, the U.S. Securities and Exchange Commission.

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WGL Holdings, Inc.

Consolidated Balance Sheets

(Unaudited)

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WGL Holdings, Inc.

Consolidated Statements of Income

(Unaudited)

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WGL Holdings, Inc.

Consolidated Financial and Operating Statistics

(Unaudited)

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WGL HOLDINGS, INC.

USE OF NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)

The attached reconciliations are provided to clearly identify adjustments made to net income calculated in accordance with GAAP to derive non-GAAP operating earnings (loss). Management believes non-GAAP operating earnings (loss) provides a more meaningful representation of our earnings from ongoing operations by adjusting for the effects of: (i) unrealized mark-to-market gains and losses from energy-related derivatives for our regulated utility and retail marketing operations; (ii) certain gains and losses associated with optimizing the utility segment’s capacity assets; (iii) changes in the measured value of our inventory for our wholesale energy solutions segment; (iv) the financial effects of warmer-than-normal/colder-than-normal weather that exceeds weather protection for our regulated utility segment and (v) certain unusual transactions. This presentation facilitates analysis by providing a consistent and comparable measure to help management, investors and analysts better understand and evaluate our operating results and performance trends, and assist in analyzing period-to-period comparisons. Additionally, we use this non-GAAP measure to report to the board of directors and to evaluate management’s performance. The economic substance underlying our adjustments to calculate non-GAAP operating earnings (loss) is as follows:

We also exclude valuation adjustments to the carrying value of non-system natural gas storage inventory in our regulated utility segment. This inventory is held solely to support asset optimization transactions. Valuation adjustments to reflect lower-of-cost or market under current accounting standards may not be representative of the margins that will be realized and shared with our utility ratepayers. Non-GAAP earnings reflect actual margins realized based on the unadjusted historical cost in storage when inventory is withdrawn and sold.

There are limits in using non-GAAP operating earnings (loss) to analyze our results, as they are not prepared in accordance with GAAP and may be different from non-GAAP financial measures used by other companies. In addition, using non-GAAP operating earnings (loss) per share to analyze our earnings may have limited value as it excludes certain items that may have a material impact on our reported financial results. We compensate for these limitations by providing investors with the attached reconciliations to net income, the most directly comparable GAAP financial measure.

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WGL HOLDINGS, INC. (Consolidating by Segment)

RECONCILIATION OF GAAP NET INCOME (LOSS) TO

NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)