Exhibit 99.1

WGL Holdings, Inc. Reports Third Quarter Fiscal Year 2014 Financial Results;

Raises Fiscal Year 2014 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 a net loss determined in accordance with generally accepted accounting principles in the United States of America (GAAP) for the quarter ended June 30, 2014, of $(11.9) million, or $(0.23) per share, compared to a net loss of $(10.0) million, or $(0.19) per share, reported for the quarter ended June 30, 2013.

For the first nine months of fiscal year 2014, we reported net income determined in accordance with GAAP of $67.9 million, or $1.31 per share, compared to net income of $131.9 million, or $2.55 per share, reported for the comparative period of fiscal year 2013. Our operations are seasonal and, accordingly, our operating results for the three and nine months ended June 30, 2014, are not indicative of the results expected for the 12 months ending September 30, 2014.

Financial performance is also evaluated based on non-GAAP operating earnings (loss). Non-GAAP operating earnings (loss) adjusts for the effects of applying GAAP to certain transactions or classes of transactions that are not representative of the ongoing operating earnings of the company. 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 non-GAAP operating earnings, 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.

For the quarter ended June 30, 2014, non-GAAP operating earnings were $0.8 million, or $0.02 per share, an increase of $2.4 million, or $0.05 per share, over non-GAAP operating losses of $(1.6) million, or $(0.03) per share, for the same quarter of the prior fiscal

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year. For the nine months ended June 30, 2014, non-GAAP operating earnings were $147.8 million, or $2.85 per share, compared to non-GAAP operating earnings of $148.0 million, or $2.86 per share, for the same period of the prior fiscal year.

“I am happy to announce strong third quarter results driven by our Regulated Utility and Commercial Energy Systems segments,” said Terry McCallister, Chairman and Chief Executive Officer. “Both businesses showed earnings improvements in the third quarter compared to the prior year. Our Regulated Utility segment is performing extremely well and is benefiting from robust customer growth, the implementation of accelerated pipeline replacement programs and the impact from recent rate cases. The Commercial Energy Systems segment is experiencing earnings growth in both distributed generation and in partnerships such as American Solar Direct, reflecting our continued investments in clean energy assets. We are well positioned to exceed our original performance targets for the year.”

“Based on our year-to-date performance and expectations for the fourth quarter, we are raising our non-GAAP earnings per share guidance by $0.15.”

Third Quarter Results by Business Segment

Regulated Utility Segment

For the quarter ended June 30, 2014, our regulated utility segment reported a net loss of $(0.3) million, or $(0.01) per share, an increase of $4.0 million, or $0.07 per share, over a net loss of $(4.3) million, or $(0.08) per share, reported for the same quarter of the prior fiscal year. After adjustments, non-GAAP operating earnings for the regulated utility segment were $0.7 million, or $0.01 per share, for the quarter ended June 30, 2014, an increase of $3.8 million, or $0.07 per share, over non-GAAP operating losses of $(3.1) million, or $(0.06) per share, for the same quarter of the prior fiscal year.

For the nine months ended June 30, 2014, our regulated utility segment reported net income of $87.9 million, or $1.69 per share, compared to net income of $111.5 million, or $2.15 per share, reported for the nine months ended June 30, 2013. After adjustments, non-GAAP operating earnings for the regulated utility segment were $144.1 million, or $2.78 per share, for the nine months ended June 30, 2014, an increase of $22.1 million, or $0.42 per share, over non-GAAP operating earnings of $122.0 million, or $2.36 per share, for the same period of the prior fiscal year.

For both the three and nine months ended June 30, 2014, higher non-GAAP operating earnings reflect: higher revenues from customer growth; new base rates in the District of Columbia and Maryland; an increase in realized margins associated with our asset optimization program; rate recovery related to accelerated pipeline replacement programs and a decrease in the effective tax rate. Partially offsetting these favorable variances were higher depreciation expenses due to the growth in our investment in utility plant and operating expenses for the year-to-date only.

Retail Energy-Marketing Segment

For the quarter ended June 30, 2014, the retail energy-marketing segment reported $25,000 in net income compared to a net loss of $(4.2) million, or $(0.08) per share, reported for the same quarter of the prior fiscal year. Non-GAAP operating earnings for the retail energy-marketing segment were $2.0 million, or $0.04 per share, for the quarter ended June 30, 2014, compared to non-GAAP operating earnings of $6.2 million, or $0.12 per share, for the same quarter of the prior fiscal year.

For the nine months ended June 30, 2014, the retail energy-marketing segment reported net income of $3.4 million, or $0.07 per share, compared to net income of $30.5 million, or $0.59 per share, reported for the same period of the prior fiscal year. Non-GAAP operating losses for the retail energy-marketing segment were $(0.8) million, or $(0.02) per share, for the nine months ended June 30, 2014, compared to non-GAAP operating earnings of $29.9 million, or $0.58 per share, for the same period of the prior fiscal year.

For both the three and nine months ended June 30, 2014, non-GAAP operating earnings reflect lower realized electric margins due to fluctuations in commodity prices and higher capacity and ancillary charges from the regional power grid operator (PJM). The price

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movements were primarily the result of colder than normal weather that occurred throughout January 2014. Partially offsetting the electric margins were higher natural gas margins. Realized natural gas margins increased due to higher margins on portfolio optimization activity and higher sales volumes related to spot sales to interruptible customers. The quarterly pattern of margin recognition that the retail energy-marketing segment realizes varies from year to year.

Commercial Energy Systems Segment

For the quarter ended June 30, 2014, the commercial energy systems segment reported net income of $3.7 million, or $0.07 per share, an increase of $3.4 million, or $0.07 per share, over net income of $0.3 million for the same quarter of the prior fiscal year. For the nine months ended June 30, 2014, the commercial energy systems segment reported net income of $5.2 million, or $0.10 per share, an increase of $3.3 million, or $0.06 per share, over net income of $1.9 million, or $0.04 per share, for the same period of the prior fiscal year. Net income for both the three and nine months ended June 30, 2014, increased due to higher solar renewable credits (SRECs) and solar generation revenue from commercial solar assets, as well earnings growth in the American Solar Direct venture. There were no non-GAAP adjustments for this segment for any of the periods presented.

WGL also reported that it has been cooperating in an investigation by the U.S. Department of Justice into certain American Recovery and Reinvestment Act projects in which its non-utility subsidiary, Washington Gas Energy Systems, Inc., participated as subcontractor to a prime contractor under the Small Business Administration’s 8(a) Business Development Program. WGL believes that it is probable it will ultimately incur a loss in connection with this matter, but it cannot estimate either the timing or amount of loss. We do not expect that the resolution of this matter will have a material adverse effect on WGL’s business, financial condition or cash flow, although the resolution of the matter in any particular period could have a material adverse effect on our results of operations for that particular period. For more information on this matter, please refer to Part II, Item 1, Legal Proceedings, of our Quarterly Report on Form 10-Q.

Midstream Energy Services Segment

For the quarter ended June 30, 2014, the midstream energy services segment reported a net loss of $(10.5) million, or $(0.20) per share, compared to net income of $1.1 million, or $0.02 per share, for the same quarter of the prior fiscal year. Non-GAAP operating losses for the midstream energy services segment were $(2.4) million, or $(0.05) per share, compared to non-GAAP operating losses of $(2.9) million, or $(0.06) per share, for the same period of the prior fiscal year.

For the nine months ended June 30, 2014, the midstream energy services segment reported a net loss of $(18.5) million, or $(0.36) per share, compared to a net loss of $(7.0) million, or $(0.14) per share, for the same period of the prior fiscal year. Midstream energy services reported non-GAAP operating earnings of $5.8 million, or $0.11 per share, an increase of $7.3 million, or $0.14 per share, over non-GAAP operating losses of $(1.5) million, or $(0.03) per share, for the same period of the prior fiscal year. The non-GAAP comparisons for both the quarter and year-to-date reflect favorable transportation spreads primarily as a result of colder weather.

Other Activities

For the quarter ended June 30, 2014, other activities reported a net loss of $(4.7) million, or $(0.09) per share, compared to a net loss of $(2.8) million, or $(0.05) per share, for the same quarter of the prior fiscal year. Non-GAAP operating losses for other activities were $(2.9) million, or $(0.05) per share, compared to non-GAAP operating losses of $(2.2) million, or $(0.03) per share, for the same period of the prior fiscal year.

For the nine months ended June 30, 2014, other activities reported a net loss of $(10.4) million, or $(0.20) per share, compared to a net loss of $(5.0) million, or $(0.09) per share, for the same period of the prior fiscal year. Other activities reported non-GAAP operating losses of $(6.9) million, or $(0.13) per share, compared to a non-GAAP operating loss of $(4.4) million, or $(0.09) per share, for the same period of the prior fiscal year. The non-GAAP comparisons for both the quarter and year-to-date reflect our corporate branding initiative costs and an increase in our ongoing business development activities.

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Earnings Outlook

We are raising our non-GAAP consolidated earnings estimate for fiscal year 2014 to a range of $2.55 per share to $2.75 per share. In providing fiscal year 2014 earnings guidance, management is aware that there could be differences between what is reported earnings and estimated earnings for matters such as, but not limited to, unrealized mark-to-market positions for our energy-related derivatives. At this time, WGL management is not able to reasonably estimate the aggregate impact of these items on reported earnings and therefore is not able to provide a corresponding GAAP equivalent for its operating earnings guidance.

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 WGL’s website, www.wglholdings.com.

Other Information

We will hold a conference call at 10:30 a.m., Eastern Time on August 7, 2014, to discuss our third quarter fiscal year 2014 financial results. The live conference call will be available to the public via a link located on WGL’s 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 WGL’s website through September 6, 2014.

Headquartered in Washington, D.C., WGL is a leading source for clean and efficient energy solutions. Through our affiliates and strategic relationships, WGL offers a diverse set of energy sources including natural gas, wind and solar as well as a range of energy solutions – generation, storage, transportation, distribution, supply and efficiency – which serve customers in more than 25 states. WGL’s regulated utility and non-utility subsidiaries include the following: Washington Gas Light Company, a regulated natural gas utility serving approximately 1.1 million customers in the metropolitan Washington, D.C., area; Washington Gas Energy Services, Inc., one of the largest natural gas, electricity and green energy suppliers in the Mid-Atlantic; Washington Gas Energy Systems, Inc., a distributed generation and energy efficiency business, offering solar, fuel cell, combined heat and power, and other technologies across the United States; WGL Midstream, Inc., a midstream energy services business, investing in and optimizing natural gas pipelines and storage facilities in the Midwest and Eastern United States; and Hampshire Gas, a natural gas storage business which owns and operates facilities in and around Hampshire County, West Virginia. As product and service innovation are critical for value creation and sustaining growth, we are continuously increasing our assets and investments in targeted clean energy sectors. This strategy supports WGL’s core business, as well as provides opportunity for growth through partnerships and investments. WGL’s diversity is its strength. We are dedicated to the sustainability of our business, the customers and communities we serve, and the environment. To learn more, visit www.wglholdings.com.

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.

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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)

FINANCIAL STATISTICS

UTILITY GAS STATISTICS

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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 segments; (ii) unrealized gains (losses) on certain derivatives for the long-term purchase of natural gas for the midstream energy services segment; (iii) certain gains and losses associated with optimizing the utility segment’s capacity assets; (iv) changes in the measured value of our inventory for our midstream energy services segment; (v) for our regulated utility segment, the estimated financial effects of warmer-than-normal/colder-than-normal weather as measured consistent with our jurisdictional tariffs, to the extent the effects are not offset by weather protection mechanisms; (vi) incremental legal and consulting costs associated with business development activities; and (vii) 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, to forecast future results 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:

With the exception of certain transactions related to the optimization of system capacity assets as discussed below, when these derivatives settle, the realized economic impact is reflected in our non-GAAP operating results, as we are only removing interim unrealized mark-to-market amounts.

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.

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WGL HOLDINGS, INC.

USE OF NON-GAAP OPERATING EARNINGS (LOSS)

(Unaudited)

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)