PHILADELPHIA (CBS) — Rowers from all over the country will converge on the Schuylkill River this weekend for the prestigious Dad Vail regatta, but underneath their boats a growing problem threatens the future of the activity.

The river, from boathouse row to the twin bridges in East Falls, is so clogged with sediment that boats soon may not be able to safely row.

“There’s becoming-more-acute safety issues with regards to access,” says Paul Laskow, chair of the River Restoration Committee of the Schuylkill Navy, the boat club association.

“You see the coaches walking out onto the bow of the boat,trying to lift the engine out of the water,’cause the engines in the mud,” Laskow told Eyewitness News.

Laskow says sediment build-up is a natural outcome of damming the river, which created boathouse row and the race course, and it means regular dredging is necessary.

But the River hasn’t been dredged since 2000.

Dredging costs $3 million and the only practical way to get it done is through the Army Corps of Engineers. The Corps authorized dredging years ago for that part of the Schuylkill but hasn’t had the funding to actually do it.

“The priority, in the years when we can get funding for the Schuylkill at all, it’s only toward the lower part of the Schuylkill, down near the refinery and where it joins the Delaware,” says Corps spokesman Ed Voigt.

For an idea of how bad conditions could get, the picture above shows what happened in 1934 when the city stopped dredging during the Depression because of lack of funds.

“Vesper Boat Club became a bicycle club,” says Laskow.

Laskow is meeting with Corps officials on Wednesday in hopes of getting the project funded in fiscal year 2017.

If it doesn’t, he fears the city could lose not only an economic engine—he estimates rowing competitions bring in about $50 Million a year to the local economy—but a civic tradition and treasure.

“Boats will not be able to put in to the water and there’ll be no rowing from boathouse row,” he says. “The pretty lights might be on on the outside but there’ll be no lights on in the inside because there won’t be any rowing.

“It’s only a matter of time before there’s no Dad Vail or Stotesbury, if something isn’t done soon,” he said.

CBS 3’s Walt Hunter contributed to this report.