The Juneau Assembly will broach the discussion of adopting new hazard maps again next year after making little progress in 2022. City Manager Rorie Watt said there has been disagreement on one central topic.
“Fundamentally, the question is, how much do we know about risk,” he said.
“We started the hazard mapping update very innocently, right? We had old bad maps, we got a FEMA grant, let’s do new maps,” Watt said. “And then they came back with new mapping information that doesn’t square up with the common person’s assessment of risk.”
The new maps were developed to replace the city’s current maps, which were adopted in 1987. They place about half the buildings in downtown Juneau at a moderate-to-severe threat of damage or destruction from avalanches, landslides or both.
They also make a distinction between avalanche zones and landslide zones. The old maps combined the two, while the new maps introduce four categories for landslide hazard: low, moderate, high and severe.
The new maps are much more detailed — the study’s authors developed them using a combination of geologic mapping, analysis of historical events and fieldwork. For some neighborhoods, they outline landslide hazards for the first time.
In Starr Hill, for instance, some properties went from no slide hazard to severe slide hazard. Others were upgraded from moderate to severe. Those changes have been tough to understand for many downtown homeowners.
That’s partly because hazard mapping can’t tell people when landslides will happen. Instead, they describe factors that make a given area more prone to landslides — things like steepness, geology and historical activity. Those factors are hard for individuals to observe, and many exist far upslope rather than on or near an at-risk property.
The report’s authors also stress that human lifespans don’t line up with the timescales of avalanches and landslides. In moderate zones, for instance, landslides might happen every 10 to 100 years, which means someone could live in their home for decades without seeing one.
Watt says the lack of more specific information about the likelihood and consequences of landslides presents a particular challenge from a municipal policy perspective.
“What’s our rational basis as a municipal government to tell somebody, you’re, you know, high, medium, low, severe — but we can’t tell you about the probability of that,” Watt said. “We’re going to be fundamentally telling people, you know, you can or can’t develop, more and less, depending on these maps.”
Juneau’s land use code limits development in severe zones to single family homes, and property owners are not allowed to increase density. Watt says there’s also concern that updating the maps could have a negative impact on financing, property values and insurance.
“I don’t think it would result in the inability to get financing or insurance. But I think it could be harder,” Watt said.
Watt hopes that the city planning commission can draft new building codes over the next six to eight months, but he believes prioritizing public engagement in the coming months will be key.
“And hope that process results in something where most people say, okay, it’s an imperfect world, it’s complicated, but this seems like a reasonable way forward.”
In a memo to the Assembly last month, Watt recommended a full adoption of avalanche hazard zones and a partial adoption for landslides, by only restricting development in severe zones. He also hopes to open up avenues for residents to suggest changes to the maps.