SAN DIEGO (Border Report) — As the first big storm of the season passes through the San Diego-Tijuana region this week, a recently-installed trash-collecting boom is about to get its first major test.

The boom, measuring about 1,000 feet in length, has been laid out across the Tijuana River channel just inside U.S. territory.

As the water rises, it’s designed to remain on the surface, keeping trash from getting through.

“The boom prevents the flow of floating trash,” said Oscar Romo, executive director of Alter Terra, an environmental conservation agency. “It’s already working.”

Alter Terra helped design, build and install the boom, which was finished late last year.

In recent weeks, with light rain falling in the area, the amount of water in the river has gone up, and so has the trash.

The boom has managed to stop about 5 tons of materials so far that would have found their way into the Tijuana River Valley and the Pacific Ocean, Romo said.

Crews have been busy picking up the trash while they can.

With more intense rain forecast for through Friday, the rising water levels will prevent workers from removing the debris.

“This is a pilot project, all the things we will learn from this will be used to plan a permanent structure, which we will come up with in a few years,” he said. “But this is helping us understand how the trash flows in this area, we may need to make some adjustments, but I’m excited and happy.”

The boom cost almost $5 million.

Romo is confident it will more than pay for itself by preventing a lot of trash, plastics and other debris from winding up along the Tijuana River Valley further damaging the ecosystem.

“All this trash comes from Tijuana, it gets trapped in the Valley sometimes for probably 40 years, this is an attempt to stop the flow of trash and start cleaning up the entire valley.”