On my way to the Occupy the port action this morning, I stopped by Oscar Grant Plaza, the tiny patch of lawn in front of Oakland's city hall where – until the city evicted them for the second time on 14 November – Occupy Oakland's tents, kitchen, library, and meeting place had stood. Now it's little more than a muddy swamp. The city's sprinklers run overtime to keep the soil saturated with water, so that no more tents can be put up. It's cheaper than paying police to evict the occupiers. Easier just to leave the water on all night and turn the space into a mud pit.

Ever since Occupy Oakland was evicted, the movement has been stuck in the mud. Efforts to find a new site for the camp have been less than successful, while the general assemblies have been alternately racked by controversy and sparsely attended. Shutting down "Wall Street on the Waterfront", as they've called it, is an effort to get some of their momentum back. And so far, it looks promising: perhaps a thousand community members gathered in West Oakland at 5.30am yesterday morning, marched into the port of Oakland and prevented port workers and container trucks from entering. Busloads of riot police were on the scene, but there was no riot and they went home. By late morning the port of Oakland was officially shut down: port officials cited "health and safety risks" and sent workers home, leaving container ships loaded at the docks.

Officially, the longshoreman union is not sanctioning the blockade. But then, given how firmly its hands are tied by anti-union legislation, it would be shocking if it had. While longshoremen are under no obligation to cross a community picket line, they are forbidden by law from striking except during very specific circumstances (say, during contract negotiations). If the International Longshore and Warehouse Union (ILWU) had endorsed the blockade – even unofficially – union officials and stewards could face jail time. And so, ironically, while occupiers across the west coast are blockading ports in the name of labour – in particular Los Angeles truck drivers (non-unionised) who were fired for wearing union T-shirts and ILWU workers engaged in a labour dispute against EGT in Longview, Washington – labour has little power to speak in its own name here, except by refusing to cross a community picket line.

Another aspect to the blockade is the port's relationship with the city of Oakland. While Oakland's coffers are so perpetually empty that it recently voted to close five elementary schools – for annual savings of a mere $2m – the terms of the port's financialisation ensure that its operating revenues do little to plug the holes in Oakland's social services budget. It's the fifth largest port in the US, with operating revenues of over $27bn a year, and as Betty Olson-Jones, president of the Oakland Education Association, pointed out, a mere 1% tax on the ports operating revenue would be enough to plug almost every shortfall the city's education budget faces. But while the port operates (rent-free) on public land, all of its operating profits go to pay back the bonds that paid for its modernisation, or are reinvested in the port itself. Capital profits, as a growing number of Oakland residents are pointing out, while schools close and workers suffer.

Today, we'll have a better sense of how widespread the west coast port blockade truly was. Oakland was only one of dozens of occupations, and ports in Washington, Oregon, Vancouver and southern California, as well as in non-west coast cities such as New York and Houston, have seen significant mobilisations. But in Oakland, at least, shutting down the port seems to have given Occupy a significant shot in the arm.