Mudflow risk grows with valley population
TUCKER; The Tacoma News Tribune
Puyallup, WA - 6/19/04 - Puyallup Valley cities and Pierce County
continue to plan for a disastrous Mount Rainier mudflow, but relentless
population growth could hamper their response if they ever have to
put their plans into action.
The valley floor lies squarely in the historic pathway of lahars -
what one expert described as rapidly moving flows up to 30 feet high
and packing the destructive force of flowing concrete. Scientists
say another lahar, traveling 60 miles and growing larger as it gathers
debris, could strike tomorrow - or hundreds of years from now.
Whenever it happens, it will inundate a much more heavily populated
area than when the last lahar hit 500 years ago. More than 59,000
people live today on the valley floor in cities and unincorporated
areas, according to rough population estimates compiled by the Puget
Sound Regional Council. Since 2000, nearly 3,000 people have moved
And there's no end in sight. All four valley cities are planning to
take even more residents, guided by state growth management laws that
say cities, not rural areas, should absorb population increases.
Faced with these growth pressures, none of the main cities standing
in the way of a potential lahar - Orting, Sumner, Puyallup and Fife
- has restricted the density of single-family homes on the valley
floor. And only one of the four, Sumner, has capped the occupancy
size of large new buildings from which people would have to escape.
One of Orting's former mayors says the lack of building regulations
is evidence that the lahar threat isn't as bad as alarmists suggest.
"Why are we allowing people to build houses in the valley?"
said Wayne Harman, who led the city in the 1970s and 1980s. "Maybe
(governments) are not that concerned."
Pierce County does limit housing density and building occupancy in
its part of the lahar zone. But the County Council next month might
consider easing some of these restrictions, which would allow the
fast-growing Orting School District and other agencies more latitude
on where to build.
Local governments are uneven in their preparedness for lahars. But
they are still considered pioneers on the international stage, said
Kevin Scott, a scientist with the U.S. Geological Survey.
Scott, who works at the Cascades Volcano Observatory in Vancouver,
Wash., said Pierce County governments took preventive measures far
ahead of other places located near active volcanos.
"We use them as the poster child worldwide," Scott said.
But he allows for the possibility that local officials aren't doing
exactly the right kind of lahar planning. In an article he wrote for
a conference in January, he suggested forming a national advisory
panel to assess Mount Rainier lahar risks. The experts' panel could
justify local preparations or recommend that some be discontinued
because of cost or ineffectiveness.
Here's a look at what local governments are doing:
This Puyallup Valley city is most at risk because it is entirely contained
inside the lahar pathway and would be the first city hit by a mudflow
from the glaciers on the west side of Mount Rainier.
Orting has doubled its population since 1990, with another 1,183 home
lots proposed or approved for construction. It has no lahar-related
The city distributes lahar evacuation and related information to new
residents. It is developing a pre-disaster mitigation plan, just as
Pierce County and other cities are, said City Administrator Mark Bethune.
Orting officials are identifying, analyzing for risk and ranking the
probability of different types of disasters. Then the city will determine
how to help people in each scenario. State and federal authorities
will review and coordinate.
"We're all trying to get on the same page," Bethune said.
"And we're getting there. There aren't many places that are really
safe. Seattle's on a big (earthquake) fault."
Sumner is the only one of the threatened cities that restricts building
in the lahar area, which includes the entire city. No new building
that holds 5,000 or more people can be built, said senior planner
Sumner is also one of the slower-growing places in East Pierce County
right now. Fewer than 300 proposed home lots and apartment units are
proposed in the city, Windish said.
Puyallup has no restrictions on building in the lahar pathway, but
planners will discuss limits on building occupancy and land use later
this summer, said Steve Pilcher, Puyallup city planning manager.
To avoid being arbitrary, they also want to factor in the proximity
of large buildings to high ground. For instance, the Puyallup Fair
handles tens of thousands of people each day during its 17-day run,
but the grounds are at the base of South Hill where large crowds presumably
could evacuate quickly and safely.
About 1,730 housing units are proposed for construction on the valley
floor in Puyallup. Pilcher said proposals include an 80-home housing
development and a 450-unit apartment complex, both on East Main Avenue,
and a 1,200-unit senior housing project along West Stewart
People continue moving into the four cities
in the Puyallup Valley that stand in the way of a lahar, a potential
volcanic mudflow. Fife, Orting and Sumner are entirely contained
inside the lahar zone, but much of Puyallup's growth is happening
on South Hill, out of harm's way. Puyallup has no breakdown
on population growth on the valley floor versus growth on South
City 1990 pop. 2000 pop. 2003 pop.*
Puyallup 23,875 33,011 35,490
Sumner 6,281 8,504 8,780
Fife 3,864 4,784 4,905
Orting 2,106 3,760 4,295
Note: Comparative population numbers for unincorporated
areas on the valley floor aren't available.)
SOURCES: U.S. Census Bureau, State of Washington
Fife also has no restrictions on building in the lahar area, which
encompasses the entire city. Fife officials ensure that all proposed
subdivisions have streets built in a pattern that allows orderly evacuation,
said Steve Worthington, community development director.
The industrial city behind the Port of Tacoma has increased its population
169 percent since 1980. As more farmland is plowed under and sewer
service expands, the number of residents will only snowball. The city
has 2,100 new home lots or housing units proposed for construction.
And full-time residents are only part of the equation.
"We have 15,000 employees in Fife during the working day,"
The Tacoma Tideflats part of the city resides inside the lahar pathway.
It's a heavy industrial area that also encompasses the Port of Tacoma,
one of the largest ports in the United States.
Thousands of people work on the Tideflats during the day. The Tacoma
Fire Department has established a way to notify businesses with an
automatic telephone dialing system and recorded messages.
Meanwhile, the Fire Department is talking to the port about designating
Tideflats evacuation routes because the port changes street patterns
occasionally to install or modify large container facilities, said
assistant chief Jeff Jensen.
County officials approved building restrictions in ancient lahar inundation
areas 13 years ago. The rules apply to unincorporated parts of the
Puyallup, Carbon, White and Nisqually river valleys.
When the county adopted its new comprehensive land-use plan in the
mid-1990s, officials zoned much of the valley floor to allow only
one home per 5 acres in mudflow areas, said county planner Katherine
The county also capped the occupancy of bigger buildings in these
areas. But now the County Council might modify those restrictions.
Currently, a school with a capacity of more than 250 people can't
be built in a lahar area. Nor can any jail, medical facility with
50 or more incapacitated residents or any structure holding more than
5,000 people, according to the 1991 county ordinance on volcanic hazard
But the county planning commission has proposed allowing larger buildings
and covered assembly areas, as long as it's demonstrated that occupants
have time to walk to safety before the projected arrival of a lahar.
Large developments close to Mount Rainier would face more restrictions
than they do now: A building that's within 30 minutes of a lahar's
point of origin could house only up to 100 people.
But developers of big buildings farther from the mountain would have
more leeway: an allowed capacity of 500 to 5,000 people, depending
on their distance from the lahar source.
The Orting School District illustrates the argument for this increased
flexibility. It wanted to build a middle school in the unincorporated
area south of the city but was blocked by the county's rules.
A school there would lie in the lahar zone and thus automatically
violate county regulations, despite being next to a hill with a road
that students could use to escape.
The district also explored buying land on high ground in the unincorporated
area but couldn't find anything suitable for a school, said Superintendent
So instead it bought 100 acres inside Orting - even though it lies
directly in the path of a lahar - because the city allows unfettered
school construction. The land will stay vacant for now because of
last month's school bond failure.
Until the rules change, Orting school officials have little choice
but to make imperfect decisions about school locations.
"We have to react to growth," Davis said.
(Editor's Note: This is the second of two parts. Go to Part One.)
Staff writer Eijiro Kawada contributed to this report.
Rob Tucker: 253-597-8374
Part 2. Go to Part 1.