A judge has suspended the captain of the Portland Spirit for running into other boats during a huge traffic jam on the Willamette River that forced the shutdown of the Redbull Flugtag competition two years ago.

An administrative law judge for the U.S. Coast Guard ruled Lowell Gillespie Jr. violated a navigation rule by failing to take appropriate actions to avoid collisions during the wild event on Aug. 1, 2015.

Gillespie's merchant mariner credentials were suspended for a month and he will be on probation for a year after the suspension.

About 90,000 people gathered onshore and in the water that year for the Flugtag, a contest that had teams propel their home-made flying machines off a 28-foot platform above the Willamette to see how far they could go.

Officials estimate 500 boats clogged river traffic. Redbull, the event sponsor, had estimated 100 boats would be on the river.

Gillespie, a veteran ship's captain with more than 40 years of experience, thought the channel looked clear from his vantage point as he departed for the Spirit's lunch cruise.

But he couldn't see the extent of the congestion from his vantage point, Portland Spirit Cruises and Events President Dan Yates told The Oregonian/OregonLive at the time.

Once the Spirit hits the channel, it is forbidden by a permit with the Coast Guard to turn around, Yates said then.

About 3 p.m. that day, Portland Spirit notified the Coast Guard that it could not pass through the crowded waterway.

Videos showed the Portland Spirit colliding with other boats as Gillespie tried to navigate the river.

The Coast Guard shut down the Flugtag early, saying that sponsors were not adequately controlling the crowd.

In 2015, the Coast Guard issued a letter of warning to Gillespie for violating waterway rules and failing to avoid a collision. Gillespie declined the letter and the agency filed a complaint against his merchant mariner credential, Coast Guard officials said.

The agency also issued a warning to Red Bull for misrepresenting the scale of the event and failing to keep the waterways clear. Red Bull accepted the warning, Coast Guard officials said.

In his ruling Tuesday, Judge George Jordan said Gillespie "should have recognized the likelihood of a large number of vessels impeding his normal route."

Gillespie has 60 days to appeal the ruling.

The Portland Spirit could not be immediately reached for comment Wednesday afternoon.

— Samantha Matsumoto

503-294-4001; @SMatsumoto55