The Sheriff’s Office in Travis County received multiple calls of boats in distress starting at 12.15pm ,local time, spokesman for the event Kristen Dark said.
Ms Christa Stedman, a spokesman for Austin-Travis County Emergency Medical Services, said no injuries had been reported.
Firefighters pulled numerous people out of the water, said Mr Braden Frame, president of the Lake Travis Fire Fighters Association. It was not clear how many had needed rescuing, he said.
The number of boats participating in the gathering was not immediately clear. Ms Dark said there were “too many variables” to say for sure what exactly happened.
“We had an exceptional number of boats on the lake today,” she said. “When they all started moving at the same time, it generated significant waves.”
With winds around 10mph (16kmh), and gusting to as much as 15mph, the weather conditions in and around the lake most likely would not have caused the boats to sink, Mr Aaron Treadway, a meteorologist with the National Weather Service in the Austin/San Antonio office, said.
The firefighters association’s Mr Frame praised the work of emergency responders, noting that the rescuers had faced “significant challenges due to the amount of waves and chop on the water today”.
He said: “We train for water rescues regularly, but this is the first multi-vessel, multi-incident water rescue that we’ve responded to not precipitated by a collision.”
Mr Steve Salinas, 42, said the water had been choppy and the swells had been high when he went to launch his 22-foot boat, decorated with 8-foot-tall flagpoles.
Mr Salinas, who helped organise the event, which was called the Lake Travis Trump Boat Parade and was organised on Facebook, said the boat parade was “one way that Trump supporters can get out and express themselves without causing too much trouble or congestion in streets”.
Mr Salinas said he had seen vessels of all sizes on Saturday – from 60-foot yachts to 8-foot boats. Mixed with the number of boats headed in the same direction, their various sizes and the choppy water, accidents were bound to happen, he added.
“You can have really great water one second, and it could get some pretty heavy swells in a matter of minutes,” he said. “Once boats get on a lake, Mother Nature has its own plans.”
Boats partially submerged from the large wakes of a flotilla of supporters of US President Donald Trump on Lake Travis near Lakeway, Texas on Sept 5, 2020. PHOTO: REUTERS
Boaters were set to travel around the lake, which is about 15 miles (24km) northwest of Austin, at 10mph, according to the event’s page.
Other boat parades to display support for President Donald Trump have taken place this summer.
In Oregon, a boat sank after it was swamped by waves from a passing boat parade, The Oregonian reported. The people on the boat, which was not involved in the parade, were not injured.
Another parade, the Nation’s Capital Trumptilla Boat Parade and Rally, is planned for Sunday on the Potomac River.