Exhibit 99.1

Willbros Reports Fourth Quarter and Full Year 2016 Results

HOUSTON, TX, MARCH 7, 2017 — Willbros Group, Inc. (NYSE: WG) today reported fourth quarter and full year 2016 financial results. The company reported a net loss in the fourth quarter of 2016 of $14.2 million, or $(0.23) per diluted share, on revenue of $164.4 million, compared to net income of $77.4 million, or $1.26 per diluted share, on revenue of $217.7 million in the fourth quarter of 2015. For the full year 2016, the company reported a net loss of $47.8 million, or $(0.77) per diluted share, on revenue of $731.7 million, compared to net income of $31.5 million, or $0.54 per diluted share, on revenue of $909.0 million for the full year of 2015. The company’s fourth quarter of 2015 and full year 2015 results include gains on sales of subsidiaries of $109.3 million and $165.0 million, respectively, in relation to the 2015 sale of the company’s Professional Services segment and other subsidiaries.

Michael J. Fournier, President and CEO, commented, “We are beginning to see results in building backlog as both twelve-month and total backlog increased during the fourth quarter and we recently announced $151 million of significant awards so far in 2017. However, our fourth quarter 2016 results which included an additional loss on a Canadian pipeline project, coupled with our outlook for the first quarter of 2017, have required us to obtain an additional amendment to our term loan agreement.”

Continuing Operations

Included in this press release are certain non-GAAP financial measures that exclude special items that we believe affect the comparability of results between periods. These special items include losses associated with businesses and services we have exited as well as other items such as facility and equipment lease abandonment charges and gains or losses on sales of subsidiaries. A detailed listing of these special items and a related reconciliation of each of these special items is included in the accompanying supplemental schedules.

The company reported a loss from continuing operations in the fourth quarter of 2016 of $14.1 million, or $(0.23) per diluted share, on revenue of $164.4 million, compared to income from continuing operations of $19.2 million, or $0.31 per diluted share, on revenue of $217.7 million in the fourth quarter of 2015. The fourth quarter of 2015 income from continuing operations of $19.2 million consists of a $13.7 million loss from continuing operations before income taxes plus an income tax benefit of $32.9 million.

For the full year 2016, the company reported a loss from continuing operations of $43.8 million, or $(0.71) per diluted share, on revenue of $731.7 million, compared to a loss from continuing operations of $64.5 million, or $(1.12) per diluted share, for the full year 2015.

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Operating loss for the fourth quarter of 2016 was $12.1 million, compared to an operating loss of $6.3 million in the third quarter of 2016 and $5.4 million in the fourth quarter of 2015. The increase in the operating loss of $5.8 million compared to the third quarter of 2016 was primarily driven by a weather-impacted pipeline job in Canada. For the full year 2016, the company reported an operating loss of $30.7 million compared to a full year 2015 operating loss of $52.1 million.

Operating loss before special items was $9.5 million for the fourth quarter of 2016 compared to a $4.9 million operating loss before special items in the third quarter of 2016. For the full year 2016, the company reported an operating loss before special items of $18.5 million compared to a full year 2015 operating loss before special items of $31.6 million.

Segment Operating Results

The company has three reportable segments: Utility T&D, Oil and Gas, and Canada. During the fourth quarter of 2016, the company implemented a change to its organizational structure such that corporate overhead costs are no longer allocated to each segment. Corporate costs are now identified separately in the attached schedules and previously reported segment information has been revised to conform to this new presentation.

Utility T&D

For the fourth quarter of 2016, the Utility T&D segment reported operating income of $2.1 million on revenue of $105.3 million compared to operating income of $4.3 million on revenue of $106.4 million in the third quarter of 2016. The fourth quarter 2016 operating results were impacted by margin slippage on certain distribution jobs and under-utilization of equipment in the transmission business. For the full year 2016, the segment reported operating income of $15.6 million on revenue of $418.4 million. For the full year 2015, the segment reported operating income of $4.0 million on revenue of $379.6 million.

Oil & Gas

The Oil & Gas segment entered the fourth quarter of 2016 with minimal backlog but was active in addressing bid opportunities. The segment reported an operating loss during the fourth quarter of 2016 of $5.8 million on revenue of $23.3 million, a $1.4 million increase in operating loss from the third quarter of 2016 when the segment generated $33.1 million in revenue. For the full year 2016, the segment reported an operating loss of $16.8 million on revenue of $170.4 million. For the full year 2015, the segment reported an operating loss of $38.0 million on revenue of $297.1 million.

The segment reported an operating loss before special items in the fourth quarter of 2016 of $4.0 million,

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a $0.7 million increase in operating loss before special items from the third quarter of 2016. For the full year 2016, the segment reported an operating loss before special items of $9.6 million, compared to a full year 2015 operating loss before special items of $12.3 million.

Canada

For the fourth quarter of 2016, the Canada segment generated an operating loss of $1.8 million on revenue of $35.8 million, compared to an operating loss of $0.3 million on revenue of $35.4 million in the third quarter of 2016. The fourth quarter of 2016 operating loss included a $5.7 million loss on a pipeline project that was adversely impacted by weather conditions. For the full year 2016, the segment reported an operating loss of $0.7 million on revenue of $143.1 million. For the full year 2015, the segment reported operating income of $10.2 million on revenue of $232.5 million.

Corporate

The company continually assesses its cost structure and has taken action in recent years to reduce corporate overhead costs to better align with its lower revenue. For the full year 2016, the company recorded $28.8 million of corporate overhead costs compared to $41.1 million of corporate overhead costs for the full year 2015.

For the full year 2016, the Company recorded $25.2 million of corporate overhead costs before special items compared to $35.1 million of corporate overhead before special items for the full year 2015.

Backlog

At December 31, 2016, the company reported total backlog of $792.5 million compared to $646.6 million at September 30, 2016. Twelve-month backlog of $419.9 million at December 31, 2016 increased $44.1 million from September 30, 2016. All of the increase in twelve-month backlog is attributable to additions in the Utility T&D segment.

During the first quarter of 2017 we have received significant awards across all three segments, totaling $151 million.

Liquidity

On March 3, 2017, the company amended its Term Loan to extend its covenant holiday through June 30, 2017 and put in place less stringent financial covenants for the remainder of 2017.

Total liquidity (defined as cash and cash equivalents plus revolver availability) was $66.7 million at December 31, 2016, a decrease of $4.5 million from the end of the third quarter of 2016. Cash and cash equivalents totaled $41.4 million at December 31, 2016 and there were no revolver borrowings at December 31, 2016.

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At December 31, 2016, the principal amount due on the Term Loan remained unchanged from the prior quarter at $92.2 million.

Conference Call

In conjunction with this release, Willbros has scheduled a conference call, which will be broadcast live over the Internet, on Wednesday, March 08, 2017 at 10:00 a.m. Eastern Time (9:00 a.m. Central Time).

For those who cannot listen to the live call, a replay will be available through March 15, 2017 and may be accessed by calling 1-877-344-7529 (U.S. Toll Free), 1-855-669-9658 (Canada Toll Free) or 1-412-317-0088 (International) using Replay Access Code 10102327. Also, an archive of the webcast will be available shortly after the call on www.willbros.com.

Willbros is a specialty energy infrastructure contractor serving the oil and gas and power industries with offerings that primarily include construction, maintenance and facilities development services. For more information on Willbros, please visit our web site at www.willbros.com.

This announcement contains forward-looking statements. All statements, other than statements of historical facts, which address activities, events or developments the Company expects or anticipates will or may occur in the future, are forward-looking statements. A number of risks and uncertainties could cause actual results to differ materially from these statements, including unanticipated accounting or other issues regarding any material weaknesses in internal control over financial reporting; inability of the Company or its independent auditor to confirm relevant information or data; unanticipated issues that prevent or delay the Company’s independent auditor from completing its review of financial statements or that require additional efforts, procedures or review; the untimely filing of financial statements; pending and potential investigations and lawsuits; the identification of one or more issues that require restatement

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of one or more other prior period financial statements; ability to remain in compliance with, or obtain additional waivers or amendments under, the Company’s existing loan agreements; the existence of other material weaknesses in internal control over financial reporting; contract and billing disputes; availability of quality management; availability and terms of capital; changes in, or the failure to comply with, government regulations; the promulgation, application, and interpretation of environmental laws and regulations; future E&P capital expenditures; oil, gas, gas liquids, and power prices and demand; the amount and location of planned pipelines; development trends of the oil, gas, and power industries; as well as other risk factors described from time to time in the Company’s documents and reports filed with the SEC. The Company assumes no obligation to update publicly such forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required by law.

SCHEDULES TO FOLLOW

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WILLBROS GROUP, INC.

(In thousands, except per share amounts)

Adjusted EBITDA from continuing operations is not a financial measurement recognized under U.S. generally accepted accounting principles, or U.S. GAAP. When analyzing our operating performance, investors should use Adjusted EBITDA from continuing operations in addition to, and not as an alternative for, net income, operating income, or any other performance measure derived in accordance with U.S. GAAP, or as an alternative to cash flow from operating activities as a measure of our liquidity. Because all companies do not use identical calculations, our presentation of Adjusted EBITDA from continuing operations may be different from similarly titled measures of other companies.

Supplemental Schedule of Special Items

Supplemental Schedule of Special Items