For all the obsessive editorializing from the Seattle Times over the potential negative impact a new Sodo arena might have on the Port of Seattle, they've done little to explain what this impact might actually be. And for all the positive things I've written about the financial guarantees in Chris Hansen's arena proposal, I freely admit that the potentially negative impact on the port might be a deal-killer in itself. So for the sake of fostering an informed debate on this issue, I thought I'd take a moment to discuss what's at stake, and how it might be threatened.

According to a 2009 economic impact study, the marine cargo operations at the Port of Seattle produce 12,428 direct jobs, mostly good-paying union jobs. The study also finds the cargo operations generating an additional 16,639 "induced" jobs and 4,224 "indirect."

That's a lot of jobs.

It also represents a lot of revenue, over $3 billion annually, and over $254 million in state and local taxes. Just from the port's marine cargo operations alone.

And the port has ambitious plans to grow. According to its proposed Century Agenda, over the next 25 years the seaport plans to grow its annual containerized cargo from 2 million TEUs (one TEU represents the cargo capacity of a 20-foot intermodal container) to 3.5 million TEUs, while tripling the value of its outbound sea and air cargo to more than $50 billion a year.

Clearly, the marine cargo operations at Seattle's seaport directly represent a huge chunk of our local economy, but they're also absolutely critical to sustaining other industries throughout the region and the state. Closer to Asia and Alaska than any other major US port (our biggest trading partner is actually Alaska, with nearly all of southeast Alaska serviced from the Duwamish), Seattle's seaport is a destination for imports headed throughout the nation, earning it the nickname "The Port of Chicago." This in turn leaves a lot of otherwise empty container ships heading back out, which among other things we fill with agricultural products, providing relatively affordable export transport for farmers from Eastern Washington and beyond.

All those Washington apples would cost a helluva lot more to export if not for the imports flooding the Seattle seaport. That's the way this business works. And the same holds true for nearly every other product we export. Seattle, King County and Washington state as a whole are trade dependent economies—indeed, Washington is perhaps the most trade dependent state in the nation.

Obviously, we wouldn't want to do anything to harm such a vital economic resource.

So, is that what a new Sodo arena would do? Port commissioners and maritime union leaders seem to think so, and their arguments hinge on two major concerns: east/west freight mobility and changing land use patterns within the Sodo neighborhood.

I'm not sure what the editorialists are talking about when they fret about the additional traffic a Sodo arena might generate, but seaport stakeholders are mostly worried about east/west freight mobility between I-5/I-90 and the gates at Terminal 46 (and to a lesser extent, Terminal 30 just to the south).

You know those gigantic cranes you see towering over the waterfront just south of the downtown? That's Terminal 46, part of the heart of the seaport's cargo operations, featuring three natural deep-water berths, five container-handling cranes, an on-dock intermodal yard, and convenient access to both I-5 and I-90. And it's that latter feature that seaport stakeholders fear the new arena threatens.

It's not a new concern. Thanks to the tangle of railroad yards and freeways, east/west mobility has long been a problem through Sodo, a problem that has only been exacerbated as recent development has increased street traffic through the neighborhood. At the time Safeco Field was built, the port was promised new ramps and overpasses to ease truck access to I-90 at both Atlantic (Edgar Martinez Drive) and Royal Brougham, but only the former was built. And thanks to construction of the Silver Cloud Hotel and the new Viaduct tunnel, the Royal Brougham overpass is no longer even an option.

Seaport stakeholders have long fought for a promised Lander Street overpass (money that has since been diverted toward fixing Mercer), but even that would not fully address their concerns. There simply aren't a lot of options available for mitigating east/west traffic within the vicinity of Terminal 46, whose lease expires in 2014. "The mere perception by a terminal operator of the risk of continued disruption of freight movement is enough for reconsideration of their operations for that location," ILWU Local 19 president Cameron Williams recently wrote in a letter to the Seattle City Council. "We can build an arena anywhere," Williams continued, "but we can't build a world class deep water port terminal anywhere."

Hansen and his backers point out that the gates at Terminal 46 and Terminal 30 both close at 4:30 pm, while weekday sporting events almost always start at night, hours later. Furthermore, at little more than 18,000, the arena's maximum attendance would be smaller than the Mariners' average, and yet these terminals already manage to function during the long baseball season. Playoffs pose the possibility of NBA/NHL/MLB seasons overlapping, but even the combined attendance of the two facilities would be less than that of the Seahawks, who occasionally play on Monday nights. Other bookings could be scheduled so as not to overlap.

But even if all that were true, that still wouldn't alleviate the concerns of seaport stakeholders who cite changing land use patterns in the neighborhood as an existential threat to cargo operations as a whole. The Sodo arena Hansen is proposing is part of a larger complex that includes an "energetic mix of retail, dining, and entertainment establishments" north of the arena site and a pedestrian mall along Occidental between Atlantic and Massachusetts. This sort of development would almost surely generate upward pressure on surrounding land values, while serving as an engine of further "gentrification" in and of itself. As more light industrial property is converted to entertainment, retail, commercial, and even residential use, Sodo gentrification would expand, pricing even more port related businesses out of the neighborhood—businesses that are crucial to supporting freight operations.

This is a process that can already be seen up and down First Avenue, and one that a new arena will likely only accelerate. It is also a process that generates its own traffic independent of an arena, as Sodo transforms into a daytime and nighttime retail and entertainment destination. While NBA games may not start until hours after the terminals close their gates (I'll leave for others the debate over when pre-game traffic actually starts), the changing character of the neighborhood is gradually increasing traffic throughout the day, exacerbating existing freight mobility problems. Meanwhile the Viaduct tunnel is projected to dump thousands more cars onto crowded city streets, further slowing traffic through the area.

That, as I understand it, is the heart of the anti-arena argument from the people the arena would impact the most. So do I buy it? Yes and no.

I've no doubt that the seaport stakeholders I've talked to would prefer to see the arena proposal killed, but while they deny it, I can't help but wonder if they'd grudgingly drop their opposition in exchange for the Lander Street overpass and other mitigation. Meanwhile, city hall and SDOT officials uniformly acknowledge the existing need for the Lander Street overpass, but seem fearful of creating the optics in which the cost of construction is seen as a taxpayer subsidy of the arena project. Furthermore, if east/west freight mobility was really on the verge of choking cargo operations, I've got to wonder why the Port of Seattle—subsidized by a $73 million a year King countywide property tax levy, and with bonding capacity of its own—hasn't stepped up to fix the problem? The Port's Century Agenda looks to a substantial expansion of cargo operations over the next 25 years, but says nothing about addressing freight mobility issues it claims could cost it existing business. That just seems weird.

Finally, I'm not so sure that the Sodo gentrification that seaport stakeholders rightly fear, and the higher property values and increased traffic it would bring with it, wouldn't happen regardless of whether a new arena was built? It wouldn't happen as quickly as it would with a new sports/entertainment development driving the process, but thanks to low land values and proximity to the downtown, it is already happening nonetheless. So while I empathize with seaport stakeholders, their opposition doesn't strike me as a long term solution to the ongoing erosion of Sodo as an industrial district.

What I can say for sure after exploring these issues is that maintaining a competitive seaport is absolutely crucial to our economy, and in fact should take priority over other land uses in the Sodo neighborhood, regardless of how much we might want an NBA and/or NHL team. The question is whether these two goals are mutually exclusive, and that's a question that's not quite as easy to answer as both sides in this debate insist.