Editor’s note: This story has been corrected to state the Amazon Wind Farm is in Pasquotank County. We regret the error.

A new study from the U.S. Navy says expanding the Amazon Wind Farm site near Elizabeth City, as the operator planned to do, may cause interference with the Navy’s radar-tracking facility in southern Virginia.

The Navy released the executive summary of its study July 9. It concluded the interference produced by the existing 104 Amazon Wind Farm turbines is allowable based on a 2014 agreement between the Navy and the wind farm operator Avangrid Renewables. But Avangrid’s to plan to add another 46 turbines could cause problems with the Relocatable Over-the-Horizon Radar.

The ROTHR receiver plays a key role in the military’s tracking of aircraft and ships suspected of transporting illegal drugs and other banned substances to the United States.

Senate Majority Leader Harry Brown, R-Onslow, told Carolina Journal the executive summary confirmed what he had been told privately by military officials.

“The report says no expansion of the wind turbines at this site,” he said. In addition to the radar interference issue, Brown said he is concerned about compatibility with military training flights in eastern North Carolina. “[Active] military guys are reluctant to speak up. If you talk to retired military, these things [500-foot turbines] are concerns. We need to be cautious about permitting these,” he said.

The Amazon Wind Farm is North Carolina’s only large-scale wind energy project.

In January 2017, just before it went into full operation, North Carolina legislative leaders asked the Trump administration to consider shutting down the $400-million, 208-megawatt, 104-turbine project. State lawmakers said the massive turbines in Pasquotank County would interfere with ROTHR.

Massachusetts Institute of Technology Lincoln Laboratory was the lead independent radar specialist organization for the study. The executive summary was four pages, but the Navy would not release the full report. “At this time, there is no releasable technical report to provide and the results were briefed to the Navy-led Mitigation Response Team with technical peer review provided by the ROTHR Program Office,” Navy spokeswoman Katisha Draughn-Fraguada told CJ.

Last year, the General Assembly instituted an 18-month moratorium on new North Carolina wind farms. The purpose of the moratorium was to allow the General Assembly time to study how wind projects and other development may pose a threat to military operations. The moratorium expires in December.

This CJ illustration shows how the footprint of the Amazon Wind Farm could interfere with the ROTHR surveillance project.

In June 2012, the government’s ROTHR Program Office released a study concluding that, to prevent interference with radar operation, a large-scale wind farm should be no closer than 28 miles from a ROTHR facility. The Navy released a map showing the “interference awareness area” relating to the ROTHR receiving facility in Virginia. The Amazon Wind Farm covers about 20,000 acres. It begins about 14 miles from the ROTHR facility stretching to a point about 22 miles away. It is entirely within the 28-mile interference awareness area described in the 2012 study.

The Obama administration’s Department of Defense reversed position in October 2014 and entered an agreement citing a goal “to ensure that the robust development of renewable energy sources.”

Under the agreement, the Navy would “discuss strategies” with Iberdrola Renewables [Avangrid] if the installation adversely affected radar operations. But under the agreement, if the turbines compromised the radar facility’s effectiveness, the Navy had no option to terminate the project or force Avangrid to reduce the wind farm’s operations.

If the Navy detects an adverse impact from the turbines, the parties will “confer with the assistance of a mutually acceptable technical expert” and discuss strategies likely to prevent problems.

The agreement also called for post-construction interference measurements, which formed the basis for the recent study.