Residents of San Francisco's newest neighborhood, in Mission Bay and around China Basin, say that building and sidewalk settlement has caused a lot of wonky walkways for years. But it may be getting worse at the clay underneath the area contracts due to the drought.

As you likely know, Mission Bay — with its big new residential, office, laboratory, and hospital complexes — is built on landfill. It was, once, more of a bay on the larger Bay, and later it was filled in with dirt and refuse and rubble from the 1906 earthquake and fire and turned into a rail yard. The built-up landscape we now know is only about a decade old, with some of the buildings having gone in a bit earlier. And for at least a decade, residents say, the sidewalks have been sinking, cracking, and generally going cattywonkus under everyone's feet.

"You are like 'Wow, these are really enormous cracks!'" says resident Jeannette Revel-Mauro, speaking to KPIX last week. "We have lost on the north side, I would say, probably anywhere between 3 and 4 inches."

As the area settles into the clay and mud below, the buildings themselves aren't necessarily settling so much, because they've been built on concrete piles. But, the streets and sidewalks aren't on those piles, so they continue to sink.

The city isn't taking responsibility for the situation because, as Rachel Gordon with the Department of Public Works tells the station, there's a difference between the sidewalks in this part of town and those, say, on Market Street, that are maintained by the city.

"We don't want to point the finger at anyone saying you know you should have known this, but that is the situation," Gordon says, "that the city is not going to be fixing sidewalks for private property."

The Examiner has some photos of the current state of the sidewalks, including those outside one residential building along Mission Bay Boulevard North where black-and-yellow caution tape has been installed along the edges of paving stones that sticking out and no longer level.

Geotechnical engineer Lawrence Karp explained in the KPIX piece that a loss of groundwater is likely to blame, with the area formerly being drainage for Twin Peaks. And the drought may be exacerbating the situation, though it's not all clear.

Millennium Tower, which sits almost two miles away but also on bay mud, has been the most notable example of a sinking building in San Francisco — a skyscraper that likely needed to have its piles drilled down to bedrock to support all of its weight. Over the years, the sidewalks around Millennium Tower have had to be re-poured several times, and the building is now undergoing a $100 million fix that involves shoring up the existing foundation with piles that go down to bedrock.

Whether or not climate change or the ongoing drought will continue to make Mission Bay's sidewalks more tough to navigate is not clear, or if a wet winter will stop the sinking for a bit. Some business owners have had to take matters into their own hands, like Cafe Reveille (610 Long Bridge Street), which has "watch your step" signage and ramps leading form the sunken sidewalk to their front entrance.

Resident Linda Hawkins tells KPIX that the city ought to at least be helping with the situation, out of safety concerns.

"To me there's some joint responsibility," Hawkins said. "Are we going to do this over and over and over, or are we going to try and find a longer term solution so that we don’t just, every ten years, have to redo all the sidewalks."

Gordon says that this isn't the only neighborhood that has troubled sidewalks, and the policy has always been that sidewalks are the responsibility of building owners.

"If we fix a sidewalk in Mission Bay, are we going to get asked to fix the sidewalk in the Mission and the Richmond district and North Beach?" Gordon says.

Photo: Alfred Twu