Before their consignment store closed last summer because of declining business, Roy and Kelly Richards would look out their window on Carnation's main street and see the blur of traffic outside. It was a rare moment when someone would pause to explore what the 90-year-old town had to offer.

"Nobody's stopping," Kelly Richards said. "Nobody's stopping for anything."

These days, Kelly works at Target in Redmond and Roy is on disability.

Change is also coming to the couple's sleepy town.

After years of debate, a sewer system will soon replace the city's aging septic tanks and allow extensive building for the first time in 20 years, potentially saving local businesses and even the town itself.

The Richardses have mixed feelings about what lies ahead, feelings shared by residents throughout the Snoqualmie Valley facing similar upheaval.

"I'm torn ... because I've lived here so long," Roy Richards said. "I'd hate to see the place grow so much, but then again, I know it's going to happen."

Carnation is one of four Snoqualmie Valley cities struggling to maintain its rural, small-town character as it plans for unprecedented growth. State growth-management laws require cities to absorb their share of new residents, but Snoqualmie, North Bend, Duvall and Carnation are taking in even more people to stay vital as old industries such as dairy and timber disappear.

• Snoqualmie's population tripled, from 1,500 to 4,500, since city leaders approved the Snoqualmie Ridge urban village in the mid-1990s. Between 1997 and 2003, the city's budget quadrupled to $20 million, and its assessed property value jumped from $123 million to a projected $667 million.

• After freezing building permits five years ago, Duvall is grappling with how to handle a new wave of growth expected once an expanded sewer plant is completed this year.

• North Bend expects to lift its five-year building moratorium now that questions over water rights apparently have been resolved — a change that could triple its population over the next 20 years.

But change does not come easily in towns surrounded by greenscape and filled with people who know each other's names.

"There's definitely a sentiment that they want to be a little more deliberate about their destiny," said Larry Stockton, North Bend's planning director.

Pricing people out?

In Carnation — the smallest and most untouched city in the valley — the battle is just beginning. Construction is scheduled to start next year on the $10.6 million sewage plant and finish in 2007.

The city is treating the project as a referendum on its future: How many people and businesses to let in? Where to put them? What kind of city to be?

The city can't spread far: Its 1,900 people are wedged onto 1 square mile between the Tolt River to the south and east, the Snoqualmie River to the west and wetlands to the north. Still, a sewer system will double the population over the next two decades, officials say.

"The ideal is to be like Mayberry, but that's an ideal," said Mayor Yvonne Funderburg.

Funderburg is one of the leading supporters of the sewer system and takes comments from polarized residents about the project at City Council meetings twice a month. King County is building the treatment plant, but the city must eventually pay the money back. Carnation will also pitch in $11.4 million to build the pipes.

JOHN LOK / THE SEATTLE TIMES Carnation has 1,900 residents and no traffic lights. A sewer system is expected to bring a population influx, but some fear the town risks losing its small-town qualities.

Last year the city laid off three people, bringing the dwindling staff to seven, and its budget was just $5.6 million.

Duvall and Snoqualmie built their sewers using lucrative federal grants in the 1970s and 1980s, but now such money isn't available to Carnation.

The largest cost estimates to residents — $150 a month per household — could push many lower-income residents out of town, city officials said.

Soaring populations

The three other Snoqualmie Valley cities are going through similar growing pains. Duvall, one of the fastest-growing cities in the state, jumped from 729 people in 1980 to 2,700 in 1990, and now, 5,500.

With a new influx of people expected once its expanded sewer system is completed next year, city officials are finishing "visioning" plans for the future. Developers will have to build parks along with their subdivisions. Main Street will have wide sidewalks and on-street parking. Apartments will be allowed above stores. "We're going to have that livability that everyone wanted," Mayor Becky Nixon said.

But large portions of the city are unrecognizable from their appearance 20 years ago. Two large strip malls greet drivers at the city's southern entrance. Developments full of large homes stretch for miles in the hills rising east of downtown.

As part of the Growth Management Act, the county proposes adding as many as 2,000 people to Duvall in the next two decades, but the city is planning for 4,500.

The county's growth estimate isn't practical, said city planning director Doreen Booth. The demand for new housing is high, and the city is surrounded by large patches of undeveloped land identified as official growth areas.

"We're trying to be a little more realistic," Booth said.

In Snoqualmie, the second phase of Snoqualmie Ridge was approved by the City Council last spring and will bring 2,150 more homes. Over the next decade, the city's population is expected to triple again to 15,000.

In North Bend, off Interstate 90, the population nearly doubled from 1990 to 2000, and is now hovering around 4,700 people.

City officials expect to get water rights this year that will allow building permits for the first time in five years, but they are proceeding carefully. The county wants to add as many as 11,000 people over the next 20 years; the City Council is considering a range between 6,000 and 15,000.

"The city's vision is one of a rural and livable community," said North Bend Mayor Ken Hearing. "The size isn't important if it looks and feels small."

Ashley Bach: 206-464-2567 or abach@seattletimes.com