Exhibit 99.1

NW Natural Reports Results for the

Three & Six Months Ended June 30, 2012

PORTLAND, ORE.—Northwest Natural Gas Company, dba NW Natural (NYSE: NWN), reported earnings of 5 cents per share on net income of $1.4 million for the second quarter of 2012, compared to earnings of 8 cents per share on net income of $2.2 million for the same period of 2011. The company typically reports lower earnings during the second and third quarters due to lower volumes used in spring and summer months. Earnings per share for the first six months of 2012 were $1.56 on net income of $42.0 million, compared to $1.61 per share on net income of $43.0 million for the first six months of 2011.

“We continued to take advantage of the current low gas price environment for our customers,” said Gregg Kantor, President and CEO of NW Natural. “The benefit of these low prices resulted in an early refund to our Oregon and Washington utility customers of $39 million, which was applied to customers’ bills beginning in June. It was gratifying to be able to pass those savings along to customers early.”

Second quarter 2012 financial and operating results

Consolidated operations produced second quarter net income of $1.4 million (5 cents per share), compared to $2.2 million (8 cents per share) for the same period of the prior year. The company’s utility operations earned $0.3 million (1 cent per share), compared to $1.1 million (4 cents per share) for the same quarter of the prior year. Gas storage contributed net income of $1.1 million (4 cents per share), compared to $1.3 million (5 cents per share) for the second quarter of 2011. Utility results for the second quarter primarily reflected higher operating costs and the effects of warmer weather on margin revenues in 2012 compared to the prior year, which was significantly colder than average. Gas storage results were lower due to higher interest expense from Gill Ranch’s $40 million of long-term debt and lower storage prices, partially offset by higher contracted capacity at Gill Ranch.

Utility customer growth rate remains around 1 percent

NW Natural’s customer growth rate for the trailing 12-month period ending June 30, 2012 was 0.9 percent, with the company adding approximately 5,900 new customers during the period. This compared to an annual growth rate of 0.8 percent a year ago.

Early gas cost credits to customers

The company received approval from the Public Utility Commission of Oregon (OPUC) and the Washington Utilities and Transportation Commission (WUTC) to refund $35 million to its Oregon customers and $4 million to its Washington customers as a result of lower wholesale natural gas prices. These refunds were credited to customers’ bills beginning in June 2012 rather than in November when purchased gas adjustments would typically be filed for the next heating season.

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NW Natural also received approval from the OPUC to provide its Oregon customers with another $9 million credit, also beginning in June, related to revenues from gas storage and asset management services that are part of a separate regulatory mechanism.

Gas reserves investment update

The company remains on track to invest approximately $45-$55 million a year over a five-year period that began in 2011, to acquire long-term gas reserves on behalf of its utility customers. At the end of the five-year period, the company expects to have invested a total of $250 million. This investment with Encana Oil & Gas (USA) began in May 2011 and covers a portion of the expected drilling costs in exchange for working interests in multiple sections of the Jonah Field in Wyoming. The drilling area includes both future and currently producing wells. NW Natural’s total net investment to date was $76.0 million through June 30, 2012.

Results of utility operations

NW Natural’s total gas sales and transportation deliveries for the second quarter of 2012, excluding deliveries of gas stored for others, were 219 million therms, down 10 percent from 243 million therms for 2011’s second quarter. The decrease in usage was mainly due to weather, which was 25 percent warmer compared to the prior year and 3 percent colder than average. Margin revenues from utility operations for the second quarter of 2012 increased 2 percent to $61.4 million, compared to $60.0 million for 2011. The 2012 net margin increase over last year was largely due to a one-time, pre-tax $7.4 million charge taken in the second quarter of 2011 for the repeal of an Oregon utility tax law, which negatively impacted last year’s second quarter and six month results. Excluding the utility tax charge, margin for the second quarter of 2012 decreased by $6.1 million, primarily due to the earnings impact of colder weather in the second quarter of 2011.

Volumes sold to residential and commercial customers for the second quarter of 2012 were 108 million therms, down 17 percent from 130 million therms for the second quarter of 2011, mainly due to warmer weather compared to last year. Utility margins from residential and commercial customers for the quarter totaled $52.7 million, a decrease of 10 percent over the second-quarter of 2011’s margin of $58.4 million. These amounts included our weather normalization and decoupling adjustments, which adjusted margin down by $0.2 million for 2012, compared to a margin decrease of $2.6 million for the second quarter of 2011. The decrease in margin largely reflects the warmer weather in 2012 compared to last year’s colder second quarter as the company’s weather normalization mechanism phases out in May.

Gas deliveries to industrial customers for the second quarter of 2012 were 111 million therms for the second quarter of 2012, compared to 113 million therms for the second quarter of 2011. Margin from industrial customers was unchanged at $6.8 million for the second quarters of 2012 and 2011.

General rate case

As previously reported, NW Natural filed a general rate case in Oregon in December 2011, the first such case filed by the company since 2002. In early July, the company, the Public Utility Commission of Oregon (OPUC) staff, and other parties filed a partial settlement in the rate case. While the partial settlement resolves several issues in the case, resolution was not reached on terms of other issues, including capital structure and rates of return. As a result of the partial settlement, NW Natural has revised its application to request a $35.9 million (5.1 percent) rate increase reflecting an overall rate of return on average rate base of 8.14 percent based upon a 10.2 percent return on equity. The overall request addresses higher utility costs associated with maintaining service to customers and safe and reliable pipeline system operations. Hearings are scheduled in late August and results of this rate case are expected in late October, with rates effective Nov. 1, 2012.

Results of gas storage operations

The company’s gas storage segment consists of non-utility operations at the company’s Mist underground storage facility in Oregon and at the Gill Ranch Storage (GRS) underground facility in California. In addition, the company uses asset management services for available utility and non-utility storage and pipeline transportation capacity.

NW Natural’s gas storage segment reported net income of $1.1 million on net operating revenues of $8.0 million for the second quarter of 2012, compared to $1.3 million and $7.2 million, respectively, for the second quarter of 2011. These results primarily reflect higher interest expense from Gill Ranch’s $40 million of long-term debt and lower market prices for storage. This was partially offset by a slight improvement in operating income from GRS, which was primarily due to higher revenues from an increase in contracted capacity and lower-than-expected power costs.

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Consolidated operations and maintenance expenses

Operations and maintenance expenses were $1.8 million higher for the second quarter of 2012 compared to 2011. This increase was primarily due to higher payroll costs at the utility related to the hiring of field employees for pipeline safety and customer service work, as well as higher employee benefit costs and rate case expenses. Partially offsetting these cost increases was a decrease in utility bad debt expense.

Year-to-Date (Six Month) Financial and Operating Highlights

Consolidated earnings per share for the first six months of 2012 were $1.56 on net income of $42.0 million, compared to $1.61 per share on net income of $43.0 million for the first six months of 2011. The company’s utility operations contributed net income of $40.1 million ($1.49 per share), compared to $41.2 million ($1.54 per share), for the first six months of 2011. Gas storage contributed $1.9 million (7 cents per share), compared to $2.0 million (8 cents per share) for the same period of 2011.

Results of utility operations

NW Natural’s total gas sales and transportation deliveries for the first six months of 2012, excluding deliveries of gas stored for others, were 627 million therms, down 3 percent from 644 million therms for 2011. The decrease in usage was mainly due to weather that was 9 percent warmer than a year ago and 4 percent colder than the average. Margin from utility operations in 2012 increased 3 percent to $194.6 million, compared to $189.2 million for 2011. As noted for second quarter results, the increase in utility margin was largely due to the one-time, pre-tax $7.4 million charge related to the repeal of utility tax legislation in 2011. Excluding this charge, utility margin was down $1.8 million over last year, primarily due to warmer weather in 2012, which was partially offset by a $2.0 million increase in gains from lower gas costs realized under the company’s regulatory incentive sharing mechanism and a 0.9 percent increase in customer growth.

Volumes sold to residential and commercial customers for the first six months of 2012 were 384 million therms, down 5 percent from 403 million therms for the first six months of 2011 primarily due to 9 percent warmer weather than last year. Utility margin from residential and commercial customers for the first six months totaled $174 million, including weather normalization and decoupling adjustments, down 2 percent over margin for the first six months of 2011 of $178 million. NW Natural’s weather and decoupling mechanisms adjusted margin up by $2.6 million for the first six months of 2012, compared to a margin adjustment increase of $0.3 million for the first six months of 2011. As noted above, the variance in the weather mechanism was primarily due to the mechanism phasing out in May.

Gas deliveries to industrial customers for the first six months of 2012 were 243 million therms, or 1 percent higher than 241 million therms for the same period last year. Margin from industrial customers remained steady at $14.4 million for the first six months of 2012, compared to $14.5 million for the prior year.

The company’s gas cost incentive sharing mechanism in Oregon provided a margin contribution of $3.1 million for the first six months of 2012, compared to a contribution of $1.1 million for the first six months of 2011.

Results of gas storage operations

NW Natural’s gas storage segment reported net operating revenues of $14.7 million for the first six months of 2012, compared to $12.5 million for the first six months of 2011. These results primarily reflect higher revenues from an increase in contracted capacity at GRS and lower-than-expected power costs, partially offset by lower operating income from the Mist facility, which was due to lower market prices for storage. In addition, we had lower revenues from third-party asset management services.

Consolidated operations and maintenance costs

Operations and maintenance expenses were $5.0 million higher for the first six months of 2012, compared to the same period for 2011. The increase in O&M was primarily due to higher utility payroll costs related to an increase in field service employees, higher utility costs for new employee training, the Oregon general rate case, technology system maintenance and other customer service costs, and higher utility employee benefit costs. Partially offsetting these increases was a reduction in gas storage operating expenses and a decrease in utility bad debt expense. Utility bad debt expense as a percent of revenues remained well below 1 percent at 0.22 percent for the 12 months ended June 30, 2012.

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Cash flows and capital structure

Cash provided by operations for the first six months of 2012 was $175 million, compared to $169 million for the same period for 2011. The increase was primarily due to reductions in the utility’s receivable balances reflecting utility customer refunds in June 2012 and higher balances from colder weather at the end of 2011, which were collected early in 2012. This increase was partially offset by decreases in other working capital items, including regulatory, taxes, and accounts payable balances.

NW Natural’s capitalization at June 30, 2012 reflected 49.4 percent common equity, 43.0 percent long-term debt, and 7.6 percent short-term debt. This compared to 47.9 percent common equity, 37.0 percent long-term debt, and 15.1 percent of short-term debt and current maturities of long-term debt at June 30, 2011.

Earnings guidance reaffirmed for 2012

The company’s earnings guidance remains in the range of $2.35 to $2.55 per share. The company’s 2012 earnings guidance assumes a continued weak economic recovery and slow customer growth, normal weather conditions, and no significant changes in prevailing legislative and regulatory policies or outcomes.

Dividend declaration

The board of directors of NW Natural declared a quarterly dividend of 44.5 cents a share on the company’s common stock on July 5, 2012. The dividends will be payable on Aug. 15, 2012 to shareholders of record on July 31, 2012. The company’s indicated annual dividend rate is $1.78 per share.

Presentation of results

In addition to presenting results of operations and earnings amounts in total, NW Natural has expressed certain measures in this press release on an equivalent cents per share basis. These amounts reflect factors that directly impact the company’s earnings. In calculating these financial measures, we allocate income tax expense based on the effective tax rate. NW Natural believes this per share information is useful because it enables readers to better understand the impact of these factors on its earnings.

Conference call arrangements

As previously reported, NW Natural will conduct a conference call and webcast starting at 8 a.m. Pacific Time (11 a.m. Eastern Time) on August 3rd, to review the company’s 2012 second quarter and year-to-date financial and operating results. To hear the conference call live, please dial 1-877-317-6789 within the United States and 1-866-605-3852 from Canada. International callers can dial 1-412-317-6789. To access the conference replay, please call 1-877-344-7529 and enter the conference identification pass code (10015637). To hear the replay from international locations, please dial 1-412-317-0088.

To hear the conference by webcast, log on to NW Natural’s corporate website at www.nwnatural.com.

Forward-Looking Statements

This report, and other presentations made by NW Natural from time to time, may contain forward-looking statements within the meaning of the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements can be identified by words such as “anticipates,” “intends,” “plans,” “seeks,” “believes,” “estimates,” “expects” and similar references to future periods. Examples of forward-looking statements include, but are not limited to, statements regarding the following: plans, objectives, goals, strategies, future events, investments, estimated gas reserves and their financial value and benefit, customer growth, weather, commodity costs, customer rates, effects of financial derivatives, financial positions, revenues and earnings, dividends, performance, legislative actions and impact, rate case outcomes, regulatory actions or approvals, and other statements that are other than statements of historical facts.

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Forward-looking statements are based on our current expectations and assumptions regarding our business, the economy and other future conditions. Because forward-looking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict. Our actual results may differ materially from those contemplated by the forward-looking statements. We caution you therefore against relying on any of these forward-looking statements. They are neither statements of historical fact nor guarantees or assurances of future performance. Important factors that could cause actual results to differ materially from those in the forward-looking statements are discussed by reference to the factors described in Part I, Item 1A “Risk Factors”, and Part II, Item 7 and Item 7A “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Quantitative and Qualitative Disclosure about Market Risk” in the company’s most recent Annual Report on Form 10-K and in Part I, Items 2 and 3 “Management’s Discussion and Analysis of Financial Condition and Results of Operations” and “Quantitative and Qualitative Disclosures About Market Risk”, and Part II, Item 1A, “Risk Factors”, in the company’s quarterly reports filed thereafter.

All forward-looking statements made in this report and all subsequent forward-looking statements, whether written or oral and whether made by or on behalf of the company, are expressly qualified by these cautionary statements. Any forward-looking statement speaks only as of the date on which such statement is made, and we undertake no obligation to publicly update any forward-looking statement, whether as a result of new information, future developments or otherwise, except as may be required by law. New factors emerge from time to time and it is not possible for the company to predict all such factors, nor can it assess the impact of each such factor or the extent to which any factor, or combination of factors, may cause results to differ materially from those contained in any forward-looking statements.

About NW Natural

NW Natural (NYSE:NWN) is headquartered in Portland, Ore., and provides safe, reliable, cost-effective natural gas service to about 681,000 residential, commercial, and industrial customers through 14,000 miles of mains and service lines in western Oregon and southwestern Washington. It is the largest independent natural gas utility in the Pacific Northwest. The company has $2.6 billion in total assets. The company operates and owns 16 Bcf of underground storage capacity in Mist, Ore., and also operates the 20 Bcf Gill Ranch underground storage facility in California, in which it owns a 75 percent undivided interest. Together, NW Natural and its subsidiaries currently own and operate underground gas storage facilities with storage capacity of approximately 31 Bcf in Oregon and California. Additional information is available at www.nwnatural.com.

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Investor Contact:

Bob Hess

Phone: 503-220-2388

Email: bob.hess@nwnatural.com

or

Media Contact:

Kim Heiting

Phone: 503-220-2366

Email: kah@nwnatural.com

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NORTHWEST NATURAL GAS COMPANY

Comparative Income Statement

(Consolidated - Unaudited)

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NORTHWEST NATURAL GAS COMPANY

Consolidated Balance Sheets (unaudited)

Thousands

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NORTHWEST NATURAL GAS COMPANY

Consolidated Statements of Cash Flows (unaudited)

Thousands (three months ended June 30)

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NORTHWEST NATURAL GAS COMPANY

Financial Highlights

(Unaudited)

Second Quarter - 2012

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