MANATEE -- Subpar federal investments into seaports could cripple the U.S. economy, threatening 1 million jobs during the next decade, a new study shows.

But Port Manatee remains ahead of the curve, with a $13 million project now underway aimed at attracting larger container ships in accordance with the 2015 expected completion of the Panama Canal expansion.

Aging infrastructure coupled with rising demand has left a $16 billion investment gap in the U.S. port system at a time when more domestic firms rely on global trade to keep pace.

That shortfall could create a drag on the U.S. economy to the tune of 1 million jobs and $700 billion worth of GDP by 2020, according to a report released Thursday by the American Society of Civil Engineers.

The group lobbied for the federal government to fortify maritime infrastructure, in lockstep with local progress, to remain competitive.

"This is a critical time for modernization," ASCE Andrew Herrmann said during a media conference call Thursday. "A big challenge for marine ports, especially on the East Coast, will become their ability to work with these new huge Panamax ships."

Between now and 2020, investment needs in the nation's marine ports and inland waterways total $30 billion, while planned expenditures are less than half that, leaving an investment gap of nearly $16 billion, according to the ASCE report.

The nation's 300 commercial ports, including 15 in Florida, carry 70 percent of U.S. imports by weight and just more than half based on value.

Unless the country takes steps to renew investment in the port system, the cost of goods will rise -- also deflating GDP, employment and personal income by $1 trillion, the report shows.

"The federal government has been slow to realize that their lack of investment in critical infrastructure needs will harm the

economy and eliminate jobs throughout the country," said Doug Wheeler, president of the Florida Ports Council.

State lawmakers are on notice.

During a visit to Port Manatee last month, Gov. Rick Scott told a crowd of business stakeholders and area policy makers his investment in ports will help drive Florida's recovery faster than other states.

Investment in expanding Florida's seaport system has ballooned by 278 percent in the past year to $562.7 million, while other states have tamed their spending, according to Scott's office.

One of the problems lies with the $7 billion Harbor Maintenance Trust Fund, established by the federal government in the late 1980s. The account is funded through user fees collected by the ports.

But the federal government has not utilized the earmark for maintenance, tying up money in the Army Corps budget that could instead be used for new infrastructure, said Steve Tyndal, senior director of trade and special projects for Port Manatee.

"It's frustrating for port managers all across the country because we know the money is there, but we can't access it," Tyndal said. "So far, there really hasn't been a satisfying answer."

When improvements are finished at the Panama Canal, a massive new cargo vessel that stretches upwards of 1,200 feet in length and dubbed the Post Panamax will become king.

As a result, the existing 965-foot Panamax, which is now the largest ship traveling through the canal, will become more of a staple than specialty.

Maritime experts, discussing the ASCE report Thursday, said ports along the Eastern Seaboard must prepare themselves for those larger loads. That's where many of the investment shortfalls now exist.

Because the Post Panamax ships require such a deep draft, the entire length of the Tampa Bay channel would need to be dredged another 50 feet to make room. Estimates for the dredging tally upwards of $2 billion.

"We don't see that as a reasonable scenario," Tyndal said.

Instead, area ports have put their focus on the existing Panamax vessels, which will still bring larger cargoes than what can now be accommodated.

Construction began in August on a new 10-acre container yard at Port Manatee that will eventually grow to 52 acres to store larger containers from Panamax ships.

The container yard is part of the extension of Berth 12 -- the focus of South Port, a $200 million, decade-long expansion at Port Manatee.

The new berth becomes the port's first dedicated container terminal, allowing the quasi-government agency to tap into a new source of revenue. About $9 million of the project was funded through federal transportation help.

The berth also will create 595 construction jobs and another 180 permanent jobs. Upon completion, Port Manatee will become Florida's closest deepwater port in proximity to the Panama Canal expansion.

"(The Panama Canal) is the starting line, not the finish line," Tyndal said. "What's at stake, as a nation, is exports will grow faster than imports, and if we don't move quickly, we'll be left behind."

Josh Salman, Herald business writer, can be reached at 941-745-7095. Follow him on Twitter @JoshSalman